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812 User Manual

1. Q 162 167 Q NI18 23 RESERVED PARAMETER 18 23 Q 168 Q RTEXCD REAL TIME EXCD REPORT x Q 169 Q RTINTV REAL TIME INTV REPORT x Q 170 Q RTHIST REAL TIME HIST REPORT x Q171 Q RTLOG REAL TIME RUN LOG RPT x Q172 Q RTDAY REAL TIME DAILY REPORT x 173 Q RTCAL REAL TIME CAL REPORT x Q 174 Q RTFRMT UNFORMATTED REPORTS x Q 175 Q RPTBEG Begin Printing x Q 176 Q PTYPE PRINTER TYPE x Q177 Q RPT DATA REPORT x Q 178 Q RPT R S AND CAL LOG x Q 179 Q RPT SETUP REPORT x Q 180 Q RPT RMS HISTOGRAM TABLE x Q 181 Q RMSLO RMS HISTOGRAM TABLE LOW VALUE n Q 182 Q RMSHI RMS HISTOGRAM TABLE HI VALUE n 5 27 05 Model 812 User Manual B 21 Q183 Q RMSRS RMS HISTOGRAM TABLE RESOLUTION x Q184 Q RPT PEAK HISTOGRAM TABLE x Q 185 Q RPT PEAK HISTOGRAM TABLE LOW VALUE n Q 186 Q RPT PEAK HISTOGRAM TABLE HI VALUE n Q 187 Q RPT PEAK HISTOGRAM TABLE RESOL x Q 188 Q RPT UWPK HISTOGRAM TABLE x Q 189 Q RPT UWPK HISTOGRAM TABLE LOW VALUE n Q 190 Q RPT UWPK HISTOGRAM TABLE HI VALUE n Q 191 Q RPT UWPK HISTOGRAM TABLE RESOL x Q 192 Q RPT EXCD REPORT x Q 193 Q RPT EXCD REPORT LOW RECORD n Q 194 Q RPT EXCD REPORT HIGH RECORD n Q 195 Q RPT NTV REPORT x Q 196 Q RPT NTV REPORT LOW RECORD n Q 197 Q RPT NTV REPORT HIGH RECORD n Q 198 Q RPT
2. Example P1 cr If Example P9cr 1 sets all report enables in setup to No S177 ler 2 sets the Data report Run log and EXCD report enables short to S178 ler Yes and 192 ler 3 begins printing to the computer P100cr Syntax Description PO Standard Report Formatted from normal setup parameters PI Data Report P2 Data amp Histograms P3 Short Full Report Histories with SHORT option B 30 Model 812 User Manual 5 27 05 P4 Long Full Report Histories with LONG option P9 All Report Enables Turned OFF P 100 Begin Printing a Report P 101 Begin Printing using RXD as Hardware Handshake flow control P 999 Abort Printing X 100 XMODEM Begin Printing same as P100 except through the XMODEM communication protocol X X CANcel transfer mode 2 in a row ASCII CAN or CHR 24 Error Messages and Warnings The code listed is the number provided by R98 All error messages begin with CHR 7 ERROR Error Code Message 1 COUNT OVERFLOW 2 EXPONENTIAL OVERFLOW 3 RTX TASK SELECT 4 ILLEGAL EXCHANGE RATE 5 UNKNOWN INTERRUPT 6 WATCHDOG RESET 7 OPCODE ERROR All warning messages begin with CHR 7 WARN ING Add 128 to these numbers to get the actual warning number Warning Code Message 128 Out of Memory 12
3. B 20 History commands B 5 tus 25 Hysteresis 8 14 I O Error Checking B 23 B 13 Indexed Parameters B 13 ATLL LACE n sce neta den Ed 8 7 International Electrotechnical Commission BEC dd 1 5 Interval History 8 14 Interval Variables B 26 Intrusion alarm B 17 K Key Lmin Lmax 8 14 key Shift s iia decide eels 2 9 keys functions of 2 3 L Leq glossary C 5 AA Rue titt tette C 9 Dept of Defense C 5 LN Ln Statistical Levels 8 13 LN Statistical Levels 8 13 DOCK c ette do 8 11 M Messages Index 2 error messages and warnings B 31 Microphone guidelines C 9 what it measures C 10 microphone reference number 1 13 Microphone Extension Cables specifications A 8 Microphones capacitor C 9 C 9 USOS e eer
4. Max Level for A Weight C Weight SS Overload Pulses of Microphone Noise Floor Noise Floor E Level oabi Crest Factor dBSPL dBSPL dBSPL 10 dBSPL 2541 17 5 16 5 23 5 130 0 133 0 112 0 2559 29 0 28 0 35 0 141 5 144 5 123 5 5 27 05 Model 812 User Manual A 3 The data in the above table was obtained by electrically testing a number of instruments For all electrical tests the microphone was replaced with an equivalent electri cal impedance Larson Davis ADP005 microphone adapter Other Detectors Weighted Peak Detector 85 0 dB Unweighted Peak Detector 38 0 dB AC Output 88 0 dB DCOutput 105 0 dB Reference Level The reference level is 114 0 dB SPL Frequency Weightings The available frequency weightings for the Models 812 820 are described in the table below Detector A Weight C Weight Flat n RMS y N Weighted Peak y y Unweighted Peak y NI AC Output y y y DC Output y 4 NOTES 1 The RMS frequency weighting is selected via parame ter 40 Frequency Weighting The Weighted Peak Detector and DC Output frequency weighting always A 4 Model 812 User Manual 5 27 05 matches the RMS Detector frequency weighting 2 The Unweighted Peak Detector frequency weighting is selected via parameter 42 UWPK Weighting there fore it can be set independent of the RMS Detector fre quency weighting The Unweighted Peak Detector s typical FLAT f
5. eese eene 1 20 Preparing to Use the Model 812 Connecting the Mic Preamp 1 20 Overview to Model 812 2 1 Understanding the Model 812 2 2 Turning On the Model 812 sss eee nnne 2 10 Turning Off the Model 812 osoei onia eene 2 12 Calibration 3 1 Calibrating the Model 812 sse eene enne 3 1 Quick Start 4 1 Setting Parameters Using Function Keys sss 4 1 Setting Parameters Using Numbers and Other Characters 4 3 Setting Time Date and Day parameters 4 6 Performing a Measurement Reading the Data 5 1 Takinga sis ee Dee pedea epit ride era dee 5 1 SJ ERR 5 1 se tee e eese eee A oe ee retenu 5 6 PEAK U WMPK 5 neben catt et 5 7 5 8 Iq ccc in etti tore ruga t e 5 9 DOS ir eatin 5 9 1 Chapter 6 Chapter 7 Chapter 8 Chapter 9 BATTERY soie A e estt tiet t eaa ita 5 13 E 5 14 Stopping the Measurement eee n nnne 5 14 Timed Measurement 6 1 Using the Timer for Unattended Readings sss 6 1 History Functions 7 1 Setting and Viewing Advanced Functions 7 1
6. GAM ee Need eet etae edes History Data Variables Interval History Run Log Calibration History Time History Histogram Table Variables Print Commands essere Error Messages and Warnings Glossary Warranty Customer Satisfaction Model 812 User Manual 5 27 05 Introduction Welcome to the Larson Davis Model 812 Your new hand held Model 812 from Larson Davis is a combina tion Type 1 precision integrating sound level meter and a statistical data logger that exceeds all worldwide accu racy requirements for the measurement of noise The Model 812 measures sound with the ease of opera tion of a point and shoot sound level meter The latest advances in surface mount technology air condenser microphones and internal firmware have been com bined in a rugged lightweight yet extremely versatile unit Many sound level meters in the market can create signif icant measurement errors because of their limited dynamic range pulse range and crest factor The Model 812 does not have these limitations Furthermore i
7. 82 Hist Save Peak No Peak UWPk Lmax This option allows saving the history period s highest weighted Peak unweighted Peak UWPk or rms level Lmax with each RMS history sample 83 Hist Period 1 255 units Multiplier of units of time in parame ter 84 sets rate at which history sam ples are stored Ex 1 x 60 0s for minute by minute history 16 x 1 32s for 0 5 second history 85 Hist Base 0 255 dB This is for editing purposes only All history is stored regardless of this base level However only noise data above the base level are displayed on the screen 5 27 05 Model 812 User Manual 8 15 86 Hist Base Mode Off RMS Peak Type of noise data used by the base mode 87 Hist Resolution 1 8 1 2 1 0 2 0 5 0 Selects the interval in dB of the over 10 all time level amplitude distribution Print Options 89 112 s These parameters allow for tailored reports of the Model 812 data during or after the measurement They can be accessed from outside the SETUP by pressing s then 7 for printer type and options Refer to section on print outs for samples of information found on each printout No Prompt Entry Comment 89 Prn Data Report No Yes Prints quick data report 90 R S and Cal Log No Yes Prints Run Stop and calibration log report 91 Setup Report No Yes Prints list of current se
8. I9 5 current record is 17 RMS Exceedance count in record 22 1 Date and Time of Occurrence ddmmmyy hh mm ss 2 Duration hh mm ss mm ss ss 3 Lint nnn n dB 4 SEL nnn n dB 3 Lmin nnn n dB 16 Lmax nnn n dB 7 Lpeak nnn n dB 8 UnWeighted Peak nnn n dB 9 RMS Exceedance Count nnn 110 Peak Exceedance Count nnn 11 UnWeighted Peak Excd Count nnn 12 Overload Counts nnn 13 nn 1 Lnn 14 En 1 nnn n dB 15 nn2 Lnn 16 Ln2 nnn n dB 17 nn3 Lnn 18 Ln3 nnn n dB 19 nn4 Lnn 20 Ln4 nnn n dB 21 nn 5 Lnn 22 Ln 5 nnn n dB 5 27 05 Model 812 User Manual B 27 123 nn6 Lnn I24 Ln6 nnn n dB I101 Intv Variables 1 24 Macro Run Log Variables Brackets in the syntax indicate optional characters and operands Syntax Response L og var nolog var Example L1 Run Stop number L1 Run Stop Number nnnnn L2 Run Stop Type RUN STOP CONT PAUSE MARK L3 Cause TIMER KEY A D n HALT INTV BATT L4 Day Date and Time ddd ddmmmyyyy hh mm ss L101 Run Log Variables L1 L4 all variable values Calibration History Variables Brackets in the syntax indicate optional characters Syntax Response C alibration var_no cal_var Example Cl checked level CI Checked Level nnn n EZ Day Date and Time ddd ddmmmyy
9. 812 64k byte Memory Typically 3 month memory retention with fresh battery Memory protected during battery change 2 minutes minimum Data Communications Serial interface for computer printer and modem communications Data Rate 19 200 bits per second Digital Display 2line 32 digit 7 segment LCD Full ASCII character set Fully annotated date displays parameter with units A 10 Model 812 User Manual 5 27 05 Digital Display Resolution dBlevels 0 1 dB Dose 0 01 Elapsed Time 0 1 second Display Bargraph e 120 dB range 1 dB resolution for SPL Real time Clock Calendar e 24 hour clock hh mm ss e 1 second resolution 100 year calendar 01JAN1999 Automatic run stop timer with two alarms and four alarm times Run time Clock e 0 1 second resolution e Format hhhhh mm ss s Maximum gt 4 years Standards Met ANSI 51 4 1983 Type 1 e ANSI 1 25 1991 Type 1 IEC 651 Type 1 5 27 05 Model 812 User Manual A 11 IEC 804 Type 1 Directive 86 188 EEC Directive IEC TC 29 Power Supply Internal 9 V battery typically 20 hour operation actual run times vary depending on operating con ditions External 7 to 16 VDC 30 mA current drain Battery life indication selected from keyboard or computer program Dimensions Weight with Microphone Preamplifier and Battery Width 3in 7 6 cm Length 13 in 33 cm Depth 1 0 in 2 5 cm
10. B 16 Setting B 13 template nete iet B 13 Time History Data 7 3 Peak eet e aerei 8 16 Pii nre Tr RTT TR B 3 Pin configurations B 3 polatizati n ione ese 3 1 Power external esee 1 18 specifications A 12 Powet Saye acuden ipee 8 10 Preamplifier 13 PE s etre 8 17 10 1 30 parameters 10 1 10 3 R RAM registers senperan 8 6 Reference Direction specifications A 2 Reference Level 8 12 specifications A 4 Register RAM Sev Meneses 8 5 Register EEPROM 8 5 eee etel tilo 3 4 RESEEI ALL uAii isani 8 1 RS 232 6 unsere atento ie 1 6 data communications A 10 RS 232 Address 8 8 RS 232 interface B 1 Run Log Variables B 28 R tvmode i eee eee eren 2 8 S serial number 1 13 Setup parameters 8 7 setup Dt ae EAS 10 3 Setup Memory
11. Syntax Response G0 or 03 cr values of variables separated by commas In order to define the variables read by group read com mands use the following command for each desired read variable Syntax Response G roup n var cr If Where n is from 1 to 8 indicating the group list index and var no is the number of the variable associated with the index Use var no of 0 to define the last group list index when n lt 8 Example Gl 4cr assigns the current SPL to the first group index G2 15 cr assigns Lmin to the second index G3 19 cr assigns Lmax to the third index G4 0 cr terminates group command programming B 12 Model 812 User Manual 5 27 05 After programming this group read list the response to GO is 59 5 38 6 102 2 the SPL Lyin and Lmax Setting Parameters All commands begin with S See Chapter 8 for a list of all the parameters and their settings Note that the parame ter numbers are for both Set 5 and Query Q com mands There are four types of parameters Numeric ndexed Character strings Template Brackets indicate optional characters and operands cr carriage return lf line feed _ space Numeric Parameters Syntax Response S et item number parameter valuecr If Example S62 120 sets RMS Excd Level 2 to 120 Indexed Parameters Indexed parameters can
12. R 116 131 _unused unused variable R 137 _ALMTIM Next Alarm Time hh mm R 138 _IVTIME Interval Date and Time of Occurrence ddmmmyy hh mm ss R 139 _IVDUR Interval Duration hh mm ss mm ss ss R 140 _IVLINT Interval Lint nnn n dB R 141 _IVSEL Interval SEL nnn n dB R 142 _IVMAX Interval Lmin nnn n dB R 143 _IVMIN Interval Lmax nnn n dB R 144 _IVPEAK Interval Lpeak nnn n dB R 145 _IVUWPK Interval UnWeighted Peak nnn n dB R 146 _HISTLEQ AUTO SEND HISTORY LEQ nnn n dB R 147 149 _ unused unused variable R 150 RUNCNT Number of RUNS amp CONTINUES nnnnn R 151 POFAULT Power On Fault Cause Character c D Data Checksum Corrupt E EEPROM Checksum Corrupt Key Reset 4 RESET 1 On P Parameter Checksum Corrupt O Opcode Error R RAM Setup Register Corrupt T Test Memory Corrupt W Watchdog Reset An indicator has been added to the ON display on the top line of the 812 s display to show faults that were detected by the power on test procedure The R151 command will display the fault character to a computer The indicators are R 152 _INRMS Internal RMS detector level nnn nn dB R 153 _INPEAK Internal PEAK detector level nnn nn dB B 10 Model 812 User Manual 5 27 05 R 154 _INUWPK Internal UwPk detector level nnn nn dB R155 _KEYCNT Free Bytes in Keyboard Stack nnn R 156 _BGTIM Background Leq Time hhhhh mm ss ss R157 _CALSTAT Calibration Status lt lt UnStable gt gt R158 _MEMSIZ Total numbe
13. After taking a reading you may wish to examine the Max Passby event You may also look at this while the instru ment is running To do this follow this step Step 1 Press to view Passby Step 2 Usingthe M or 1 keys scroll through the Four screens are available here by information available in Passby using the key giving time and date of the occurrence duration and Leg a PSBY a Time and date b PSBY b Duration of PassBy event c PSBY c SEL and Leq of PassBy event d PSBY d Max RMS level andL of PassBy record 7 8 Model 812 User Manual 5 27 05 Overload It should be noted that during any measurement an OVERLOAD may occur Such an occurrence happens when input exceeds all reasonable parameters set by the Model 812 such as dropping or jarring the instrument Should an OVERLOAD occur during a measurement the data accumulated during the occurrence will not be accurate The Model 812 registers an OVERLOAD in the upper right corner of the display where the running figure appears The figure takes one step each second At inter vals 8 seconds apart the letters O V L D will appear in succession The measurement should be retaken The Interval Report on the printout will indicate which inter val had the OVERLOAD 5 27 05 Model 812 User Manual 7 9 7 10 Model 812 User Manual 5 27 05 CHAPTER Parameters As we have seen in previous chapters the Model 812 owes its versatili
14. Alkaline battery 9 volts IEC GLR61 or NEDA ANSI 1604A User manual e Soft carrying case belt pouch Larson Davis part CCS009 e WS001 a3 1 2 inch windscreen e SWW SLM software 5 27 05 Model 812 User Manual A good quality alkaline cell should provide more than 16 hours of Model 812 operation Since most rechargeable cells have less capacity expect shorter use Wind noise can adversely affect measurements Using the windscreen on the microphone reduces wind noise and protects the element from dust and bumps Utility software package allowing data retrieval and translation of 1 13 Model 812 User Manual binary files generated by the Model 812 to ASCII File Format via RS 232 connection and is capable of editing and storing instrument setup parameter to the PC or loaded directly to sound level meter 5 27 05 Optional Equipment The following optional equipment is also available CBLO033 Printer cable for direct printout to serial printer 6 feet CBL034 Connects Model 812 to bare ended cable end 4 conductor shielded CBL035 Connects Model 812 and customer supplied external battery CBL042 AC DC output of the Model 812 to RCA BNC connectors CBL116 Connects Model 820 to to a PC or a modem Provides connection for external power adaptor such as 017 or similar INTO002 RS 232 cable level converter for data transfer to PC Requires 9 V battery or external AC powe
15. HIST REPORT x Q 199 Q RPT HIST REPORT LOW RECORD n Q 200 Q RPT HIST REPORT HIGH RECORD n Q201 Q RPTEND DAILY NOISE REPORT x Q202 Q CALMODE CALIBRATION MODE Q 203 Q ULCOMB UNLOCK Q 204 Q IONAME FILENAME cccececc Q 205 Q ERCHK ENABLE ERROR CHECKING I O B 22 Model 812 User Manual 5 27 05 Error Checking I O The error checking I O protocol verifies that commands and data are transferred without errors To enable error checking the command or 5205 1 command is used To disable error checking two CR characters in a row may be sent if not in the Modem Mode or the S205 OF command is sent The F is the check character for the 205 0 command A detailed description of the protocol is available from Larson Davis and the latest revisions of software utilize the protocol Q 206 Q TBLMODE Ln table mode Q 207 Q NFLVL NOISE FLOOR LEVEL Overall Daily This parameter is set to the noise floor of the instrument so that it can properly indicate Near Noise Floor mes sages when within 10dB of the noise floor It is also used with NF Compensate Q208 which will place the Model 812 in an extended Linearity Range Mode The true noise floor of the entire system must be measured and entered in Q207 This will vary with the selected input weighting or microphone sensitivity An equivalent microphone capacitance can be used after calibration
16. The TAKT is the final function we will consider in this area This function gives Takt 3 and Takt 5 levels which are an integration of the largest level in a 3 second and a 5 second period respectively Step 2 Access by pressing and 5 12 Model 812 User Manual The measurement ran for 6 hours 14 minutes and the dose was 0 08 The Projected Dose extrapolates the eight hour dose from dose A which is the current measured dose Notice in this reading the Pa2H value is given along with the mea surement time The measurement is C weighted and the values as indicated 5 27 05 BATTERY In Chapter 2 we accessed the Battery information to check the amount or voltage remaining in our battery This function has additional screens available The first two indicate the amount of voltage remaining and the second shows the information related to the last revi sion Step 1 Access the Battery display by pressing SHIFT and 1 Press the 0 key to access the second screen Step 2 Press the v key and a screen similar to the fol lowing will appear 5 27 05 Model 812 User Manua The Revision date is shown Eight additional screens are available from this function Warning or Error messages encountered during normal operation will be displayed here in the order they happen They are accessed by either the and 0 keys or the a and 3 keys which will scroll only the warning
17. The continuous equivalent sound level See definition is generally calculated on an hourly basis and is shown in the equation as L The values for the hourly periods from mid night to 7 a m have 10 added to them to represent less toler ance for noise during sleeping hours The same occurs from 10 p m to midnight They are energy summed and con verted to an average noise exposure rating A logarithmic form of any measured physical quantity typi cally used in sound and vibration measurements Whenever Model 812 User Manual C 3 C4 the word level is used it implies this logarithmic form The relationship is relatively simple but the mathematics can become complex It is widely used and was developed so that the very wide range of any quantity could be repre sented more simply It is not possible to directly add or sub tract physical quantities when expressed in decibel form The word level is always attached to a physical quantity when it is expressed in decibels for example L represents the sound pressure level The table below shows the actual value of a specific item such as sound pressure for which the level is to be determined First the value is put into expo nential form in powers of ten the exponent is the Bel The exponent is then multiplied by ten to yield the decibel This procedure converts multiplication into addition every time 10 is added to the level the value is multiplied by 10 When the value is not a eve
18. later OFF ON Turns on the Model 812 ON CANCEL When the Model 812 is on this button serves to return to a previous menu or Cancel the present function OFF SHIFT OFF turns off the Model 812 after it has been stopped ance PRINT Access to a list of reports scrolled PRINT through the display a key name is indi cated for each one If there is a fol lowing the key name then the options function will be invoked after selecting that key otherwise the particular report will be printed immediately STR A permanent storage register for parameters and calibration data in EEPROM type memory that is not lost when all power is lost There are 10 RAM registers to store data SETUP Enables the setting of desired SETUP parameters each accessed by using the up and down arrow keys RCL The EEPROM register and the RAM register may be recalled by pressing the RCL key scrolling to the desired register and pressing ENTER 3 5 27 05 Model 812 User Manua 2 3 Functions R S This key starts and stops measure ment RESET Restarts a measurement by eras ing the values just measured This func tion can be used whether a measurement is in the run or stop mode Enter used to enter new parameters selected by the user SHIFT Allows access to the Orange letter functions on the keypad PASSBY The PassBy function is a special event detector which measures the Lmax Leq and
19. will appear There are several options here which include HPJet HPLzr ASCII Epson IBM You can change the printer selection by press ing the key and then 0 to the printer you will use and press Enter Press the key to the next display item 89 duplicated here as item 177 the beginning of the parameters that manage printouts Scroll through these parameters with the v key and make your selections Press to access the appropriate choice and press Enter Model 812 User Manual Items 89 112 allow you to select the reports which are to be printed and how the output data are to be configured Items 89 112 are copied sequen tially into items 177 200 for print ing tailored reports and may be edited directly for one printing and then they will revert to set tings of parameters 89 112 For a complete list of Print Options see Chapter 8 5 27 05 Printing Reports Printing reports is easy as connecting your Model 812 to a printer and pressing a key Using the CBL033 serial printer cable connect your serial printer to the Model 812 at its bottom port Let s look at the print options again Step 1 Turn the Model 812 on and press The display will begin to scroll through the various print options available Here are some of the screens 5 27 05 Model 812 User Manual You will notice that the scroll is quite rapid To slow it down so you can stud
20. May 27 2005 812 Manual D 1 E NO SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES LD S SOLE OBLIGATIONS UNDER THIS LIMITED WARRANTY ARE SET FORTH ABOVE IN PARAGRAPHS A B C AND D IN NO EVENT SHALL LD ITS CONTRACTORS OR SUPPLIERS BE LIABLE TO THE BUYER FOR ANY LOST PROFITS DIRECT INDIRECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES WHETHER BASED ON CONTRACT IN TORT OR ANY OTHER LEGAL THEORY SUCH DAMAGES FOR WHICH LD SHALL NOT BE RESPONSIBLE INCLUDE BUT ARE NOT LIMITED TO LOST TIME AND CONVENIENCE LOSS OF USE OF THE PRODUCT THE COST OF A PRODUCT RENTAL COSTS OF GASOLINE TELEPHONE TRAVEL OR LODGING THE LOSS OF PERSONAL OR COMMERCIAL PROPERTY AND THE LOSS OF REVENUE Some states do not permit the limitation or disclaimer of incidental or consequential damages Therefore the above disclaimer of incidental or consequential damages may not apply to certain purchasers F NO LIABILITY IN EXCESS OF PURCHASE PRICE IN NO EVENT SHALL LD S OBLIGATIONS UNDER THIS LIMITED WARRANTY EXCEED THE PURCHASE PRICE OF THE PRODUCT PLUS ANY SHIPPING CHARGES THAT LD MAY BE OBLIGATED TO PAY PURSUANT TO PARAGRAPH C ABOVE G NO EXTENSION OF STATUTE OF LIMITATIONS ANY REPAIRS PERFORMED UNDER THIS LIMITED WARRANTY SHALL NOT IN ANY WAY EXTEND THE STATUTES OF LIMITATIONS FOR CLAIMS UNDER THIS LIMITED WARRANTY H WAIVER OF OTHER WARRANTIES THE EXPRESS WARRANTIES SET FORTH IN THIS LIMITED WARRANTY ARE IN LIEU OF AND EXCLUDE ANY AND ALL OTHER WARRANT
21. 61 65 V These parameters define noise threshold levels to be used when counting the number of exceedances during a measurement viewed in MAX b and c displays for rms PEAK b and UWPK b for peak exceedance No Prompt Entry Comment 61 RMS Excd Lvl 1 0 255 dB First rms detector exceedance level 62 RMS Excd Lvl 2 0 255 dB Set above Level 1 63 Peak Excd Level 0 255 dB Weighted peak exceedance level 64 Uwpk Excd Level 0 255 dB Unweighted peak exceedance level 5 27 05 Model 812 User Manual 8 13 65 Excd Hysteresis 0 9 This sets the amount once an exceed ance occurs that the level must drop below the exceedance level before the Exceedance event ends and a new exceedance can occur Normally set this level to 2 or 3 dB This prevents multiple exceedances for a single event if the level flickers around the threshold Interval History 72 79 M 72 No Prompt Intv Enable Entry No Yes Comment Interval report will be stored in mem ory if Yes is entered 73 Intv Exchange 3dB 4dB 5dB 6dB Used to calculate interval integrated level Normally this is set to 3 dB Leq 4 dB gives L_ DOD 5 dB LOSHA 6 dB L Avg 74 75 Intv Threshold Intv Period 0 to 255 dB hh mm Levels above threshold are integrated during each interval normally 0 dB for Leq For noise hygiene interval TWA set to do
22. ICA Eo aieo eei 7 1 Time History Data seit ease ete Den tee erri Pri iere 7 3 Log and Data esis ii 7 4 Interval History ae rc n de e d tees 7 5 petting PassBy Funct Ons oe dei rea d horti etat 7 7 Parameters 8 1 Parameter Key Access Revie We 8 1 Entering and Exiting the Setup 8 1 Locating Parameters 8 2 Changing Parameters Enter Modify sse 8 3 Error Messages cala ai pedi dnt dens 8 4 Learning to Store and Retrieve Setup Memory 8 4 otorga SUP 8 5 Recalling a Setup iere rte eee deed ete 8 6 Model 812 Setup Parameters eee nnne 8 7 System 1 20 ie GHIFT 8 7 Timer 21 27 GME sal iih ettet s 8 10 Lock 29 SHET a 8 11 Calibration 35 36 GHIFT 8 8 11 Sound Level Meter 39 50 8 11 o 8 13 LN Statistical Levels 55 58 881 sse 8 13 Exceedance Level Count 61 65 8 14 Interval History 72 79 M Time History 80 87 escisiones H8 14 Print Options 89 112 8 17 Memory Usage 9 1 Determine Storable 9 1 Estimating Memory Usage sss eene eene 9 3 Model 812 Use
23. R 86 _BATT Battery Level nnn R87 _BATTSRC Battery Source INT EXT cec R88 TEMP Temperature nnn n R89 _SERNUM Serial Number R90 _REVNUM Software Rev 8 Rev Date n nnn ddmmmyyyy R9I _FREEMEM Free Memory nnnnnnn R92 RECLOG Number of RUN STOP Records nnnnn R94 RECINTV Number of INTV Records nnnnn R95 _RECHIST Number of HIST Records nnnnn R97 _RECCAL Number of Daily Records nnnnn R98 n _ERRMSG Error Message List is the error list number 1 8 1 being latest error or nnn nnn nnn if n 0 or omitted then the 8 error codes are output as number R99 _LOGIC1 Logic Output 1 State On Off unused R 100 LOGIC2 Logic Output 2 State On Off unused R 101 REPORT Report Number nnnnn R 102 _PAGE Page Number nnnnn R 103 _PRNLINE Printer Line Number nnn R 104 _CALTIME Calibration Date Time ddmmmyy hh mm ss R 105 _CHKTIME Cal Check Date Time ddmmmyy hh mm ss R 106 OFFSET Cal Offset nnn n R 107 _CHKLVL Cal check Level nnn n OFFSET R 108 _RMSEX RMS Exceedance Flag 1 5 27 05 Model 812 User Manual B 9 R 109 RMSEX2 RMS Exceedance Flag 2 R 110 _PKEX PEAK Exceedance Flag R111 _UWPKEX UWPK Exceedance Flag R 112 _OVLD System Overload Flag R 113 _EXXR Excd Exchange Rate Text R114 _IVXR Intv Exchange Rate Text R 115 _AUTOADV Auto Advance History Ind
24. Serial handshaking protocol Model shaking Register Both 812 SW1 uses None Note To con serve power the Model 812 turns off the serial port after 255 sec of non use To keep unit on and connected an external power supply must be used 14 Output 1 Logic Off True takes it to 5 volts RMS R When set to Off DTR is DTR PEAK P R P Indication that Interval started and INTV D will stay on time set in parameter 15 R I R P I Logic control including A are not A D applicable to the Model 812 R A P A R P A R I A P I A Run Stop R P I A R S Model 812 User Manual 5 27 05 15 Output 1 Timer enter time There are 2 modes to the Logic Out put Time now If the time is set to 5 sec or less it is assumed to be a mini mum time and the output will be asserted for a minimum of the time selected If the time is programmed to be greater than 5 sec then the time is considered to be the maximum dura tion that the pulse should last and the output will be asserted for a minimum of 5 sec and a maximum of the time programmed 20 Power Save Auto Off Manual Off Audio Off Auto Off If in the Stop mode and 1f no keys are pressed or commands given for 12 min the Model 812 will turn off automatically Manual Off The Model 812 will not turn off until the OFF key is pressed a computer OFF command is given or the batteries become low Audio Off Not
25. and q is the Exchange Rate Factor Only sound lev els above the Threshold Level are included in the integral Standard ANSI 12 19 Calibration Adjustment of a sound or vibration measurement system so that it agrees with a reference sound or vibration source It should be done before each set of measurements Community Noise Equivalent Level CNEL L4en A rating of community noise exposure to all sources of sound that differentiates between daytime evening and nighttime noise exposure The equation for it is 0700 1900 2200 2400 Li 10 10 L 10 L 5 10 Li 10 10 Lien 101080 10 10 10 10 0000 0700 1900 2200 The continuous equivalent sound level is generally calcu lated on an hourly basis and is shown in the equation as L The levels for the hourly periods from midnight to 7 a m have 10 added to them to represent less tolerance for noise during sleeping hours The same occurs from 10 p m to mid night The levels for the hourly periods between 7 p m and 10 p m have 5 added to them to represent a lessened toler ance for noise during evening activities They are energy summed and converted to an average noise exposure rating Criterion Duration Itis the time required for a constant sound level equal to the Criterion Level to produce a Noise Dose of 100 Criterion Duration is typically 8 hours Example If the Criterion Level 90 dB and the Criterion Duration is 8 hours then a sound level of 90 dB for 8
26. detector and through the selected A or C weighting fil ter to the root mean square rms and weighted peak detectors Analog to digital conversion is performed maintaining a full 110 dB range for the RMS signal The numeric data is then analyzed by the Model 812 s dedi cated digital processor 1 10 Model 812 User Manual 5 27 05 812 Block Diagram RMS 9 Slow Fast Impl Bias Supply Indicates parameter number Figure 1 3 812 Block Diagram 5 27 05 Model 812 User Manual 1 11 With system programming residing in Flash ROM reprogrammable read only memory upgrades or future changes in regulations can easily be accommo dated Measurement modes are selected and shown in informative screens on the 32 character liquid crystal display LCD The custom keypad provides direct access to the needed data or setup item An accurate built in Quartz clock calendar and timer are ideal for unattended measurements and time stamping of events The 64 KB memory can be used to store time exceedance or interval data as selected by the user All can be printed or transferred to an external computer via the serial port even during data gathering Larson Davis PC compatible software employs a binary data dump method for even faster data transfer External battery or DC power may be supplied through the same five pin connector Getting Started This section outlines the steps you need to follow when you first receive and unpack the
27. range history number acknowledge F ind record number history number acknowledge P rint report number acknowledge Mode Commands Format for the Mode Commands is Command Description MI Power On clear error message list and reset display functions to windows M2 Power Off M3 Run M4 Stop MS View M6 Mark M7 Reset Current Data use S1 1 for Reset All 5 27 05 Model 812 User Manual B 5 M8 Reset Histories Only M9 High Resolution Levels to I O channel only Increased resolution I O is possible by using the M9 1 command All sound levels are then sent with an additional fractional character nnn nn giving 1 100th dB resolution The Model 812 acquires noise data with 1 32 dB resolution Greater resolution is achieved through averaging HOWEVER THIS DOES NOT IMPROVE ACCURACY Refer to the specifications or device specific perfor mance results for the accuracy of the system M 10 Lock 812 leave 812 s power on 11 Lock 812 and Power Off To unlock the unit and send the lock combination to the unlock parameter with the 5230 command where is the correct combination entered before locking M 1000 Non destructive memory test walking bit M 1001 Destructive memory test pattern test Read Variables Syntax Variable Description Response RI DEVTYPE Device manf and model String R2 _DT
28. template eee been Template Parameters Threshold eee Time allowed Exposure time Ti weighting mnis Time History data TWA time weighted average sound level TWA LTWA TC Type specifications Type 1 Variables calibration history exceedance history histogram rerom histogram table interval interval history r b log time history Index 4 A 7 B 15 B 15 8 12 1 18 8 14 7 3 18 Vabtration idad C 18 W Warnings error messages B 31 Warranty nasa lala bis D 1 warranty AAA 1 7 Wavelength l PlOSSALY AAA C 18 Wavenumber glossary A cues eed C 19 Weighted 8 hour time weighted average sound level 5 Weighting ecce er ee tee 8 12 frequency A ny C 7 18 Weightings Aand tested 5 4
29. 20 Model 812 User Manual 5 27 05 the mating connector 5 27 05 Model 812 User Manual 1 21 1 22 Model 812 User Manual 5 27 05 Overview to Model 812 Once your Model 812 is unpacked and connected to a battery or external power supply you can turn it on and take simple measurements In this chapter we dis cuss the following Understanding the Model 812 Keypad Understanding the Model 812 Screen Getting to Know Screen Symbols Turning on the Model 812 Checking the Battery Voltage Turning off the Model 812 5 27 05 Model 812 User Manua 2 1 Understanding the Model 812 Keypad The keypad for the Model 812 has 20 keys as seen in the following figure Figure 2 1 LARSON DAVIS 012 SLM Modify gt 7 8 9 TIME TIMER Lon LDL Leo SEL T A DOSE 4 5 6 CAL Lmin BATT SLM Lmax Ln 1 2 3 Lock MEM LOG SHIFT exco HIST Cancel Enter 0 STR RCL RESET 0 PRINT SETUP R S TYPE 1 INTEGRATING SOUND LEVEL METER Figure 2 1 Model 812 Keypad 2 2 Model 812 User Manual 5 27 05 These keys perform the following functions This infor mation is covered in more detail in chapter 4 of this manual Keys Functions White White functions are accessed by pushing buttons directly Orange Orange functions are accessed by first pressing the U Key The smaller letters numbers above the keys are accessed by the adjoining key at the appropriate time to be explained
30. 8 4 SLM Sound Level Meter 8 11 Sound average level lavg C 1 day night average level C 3 energy average Leq C 16 C 14 exposure level C 14 fixed average C 15 GIOSSALY A binis C 13 eee C 16 instantaneous C 16 intensity l C 17 moving average C 15 pressure C 14 sound pressure level SPL Lp C 15 unweighted peak C 16 weighted peak C 17 yearly average level YDNL Lydn C 19 Sound Level threshold Lt C 17 Sound Level Meter SEMI e itus cedet teres oe ets 8 11 Sound Power C 17 level PWL LW C 17 Index 3 Sound Pressure Level see Sound Sound Speed eei Specifications frequency weightings microphone extension cables reference direction reference level temperature nd Spectrum frequency Standards ANS uenis Status command T Temperature specifications
31. History Run Log and Calibration Check records that will be per formed in a day Based on the options chosen calculate the number of bytes required for each record type Multiply by the number of records expected per day Sum these values and this is the number of bytes required per day Divide this value into the amount of available mem ory in the Model 812 see U M and this is the number of days the Model 812 can gather data As an example Interval Memory Estimation Bytes needed Basic Interval Record 34 Intv Save L s Yes Prm 77 Intv Save L Table 384 TOTAL Bytes Intv sum lines 6 8 Anticipated Intv Day Enter Number TOTAL Bytes Day Multiply lines 9 amp 10 Line Time History Memory Calculation Bytes Bytes Hist Resolution Hist Save Peak 16 1 0dB No 1 5 27 05 Model 812 User Manual 9 3 Time History Memory Calculation Bytes 0 1dB No 1 0d B Peak UwPk Max Wind 0 1dB Peak UwPk Max Wind TOTAL bytes Hist Record Select the appropriate of bytes from lines 16 19 Hist Records Day 24 hours divided by Hist Period in hours Enter Number Calculate i e 24 60 sec 3600 sec per hour 1440 TOTAL Hist Bytes Day Memory Use per Day Calculation Multiply lines 20 and 21 copy to 26 Bytes Interval History bytes day from line 11 Time History bytes day
32. Model 812 The follow ing topics are covered e Unpacking and Inspection e Accessories and Optional Equipment Connecting Internal or External Power Environmental Considerations Preparing to use the Model 812 Connecting the Amp Preamp You will then be ready to use the Model 812 for actual measurements as described later in Chapter 4 of this manual Unpacking and Inspection 1 12 Model 812 User Manual 5 27 05 Your Model 812 has been shipped in protective packag ing Please verify the package contents with the follow ing list Accessories and Optional Equipment and retain the shipping containers for safe shipment at a future date Report any damage or shortage immediately to Larson Davis Inc at 801 375 0177 If you have not already done so please record at the beginning of this manual see the copyright page your instrument s serial number located on the label on the back of the Model 812 the microphone serial number located inside the micro phone the preamp serial number and the purchase date You will be asked to give this information in any future communi cations you may have with Larson Davis Inc Accessories The Model 812 is delivered with the following standard accessories The standard Model 812 Precision Sound Level Meter including one of the 1 2 inch precision air condenser microphones in Table 1 1 Microphones for use with 812 on page 1 8 and Model 828 preamplifier
33. PEAK HISTOGRAM TABLE x Q97 Q PRN PEAK HISTOGRAM TABLE LOW VALUE n Q 98 Q PRN PEAK HISTOGRAM TABLE HI VALUE n Q 99 Q PRN PEAK HISTOGRAM TABLE RESOL x Q 100 Q PRN UWPK HISTOGRAM TABLE x Q 101 Q PRN UWPK HISTOGRAM TABLE LOW VALUE n Q 102 Q PRN UWPK HISTOGRAM TABLE HI VALUE n Q 103 Q PRN UWPK HISTOGRAM TABLE RESOL x Tailored Report Q 104 Q PRN EXCD REPORT x Q 105 Q PRN EXCD REPORT LOW RECORD n Q 106 Q PRN EXCD REPORT HIGH RECORD n Q 107 Q PRN NTV REPORT x Q 108 Q PRN INTV REPORT LOW RECORD n Q 109 Q PRN NTV REPORT HIGH RECORD n Q 110 Q PRN HIST REPORT x Q111 Q PRN HIST REPORT LOW RECORD n Q112 Q PRN HIST REPORT HIGH RECORD n Q 113 Q PRN DAILY NOISE REPORT x Q 114 120 RESERVED PARAMETER 18 24 respectively B 20 Model 812 User Manual 5 27 05 Q 121 150 Reserved Miscellaneous Q 151 Q AUTOLEQ AUTO SEND HISTORY LEQ TO PRN unused Q152 Q EAON ELECTROSTATIC ACTUATOR OFF ON Q 153 Q HEATER HEATER LINE OFF ON unused Q 154 Q MDMMD MODEM MODE x Q 155 Q DIAL MODEM DIAL OUT MODE x Q 156 Q PHONE MODEM PHONE NUMBER 30 char Q 157 Q MONNUM Monitor Number nnn Q 158 Q MDMI MODEM INIT STRING 30 char Q 159 Q PWRMD POWER MODE Normal Ext CO Q 160 Q PWRCO EXTERNAL POWER CUT OFF VOLTAGE Q 161 Q TMEXPR TIMED EXCD PERIOD Special Functions Advanced use only Remaining commands are not available on SETUP menu
34. SHIFT 58 SHIFT key Step 2 Press and enter your personal combina If you choose to use this feature tion of numbers or letters from 1 8 characters enter something you won t forget i e a name or birth year and press Enter Step 3 To turn on the Lock press the x and M keys When Yes appears press Enter Step 4 If you should wish to unlock the system for fur Notice that as you enter your code ther input or readings press and 5 only appear to protect then Modity your password Again make the password easy to remember should you wish to use this function Enter your password code and press The Model 812 is now unlocked and accessible for additional entries 6 6 Model 812 User Manual 5 27 05 History Functions The process of measuring and recording units of sound and retrieving the data for study and understanding is enhanced by additional functional capabilities of the Model 812 Sound Level Meter This chapter will cover Setting and Viewing Advanced Functions Time History and Data Log and Data Interval History Interval History Data PassBy functions Dealing with OVERLOAD Setting and Viewing Advanced Functions The Model 812 has a variety of advanced functions that allow for gathering and storing great amounts of data with any given measurement In this section you will learn how to access the parameters choose the prope
35. Step 3 5 4 To access these parameters turn the Model 812 on by pressing Next press 3 9 Or press amp 5 and the following screen will appear The Detector prompt has three possibilities indicated above Press Modity amp to access desired setting and To set the Frequency Weighting press to item 40 There are several possibilities here A A16 C C16 Flt Model 812 User Manual The Model 812 has been pro grammed to save power whenever it can Each time input is made the internal timer will start at 100 and count downward If not pro grammed to do otherwise the Model 812 will turn itself off when this screen reaches 0 just over two minutes Slow exponential avg 1 second constant Fast exponential avg 1 8 second constant Impl impulse response For OSHA measurements this is normally set to Slow For environ mental measurements Fast or Slow may be used Within a given period of time the Fast detector will take more measurements than the Slow Therefore the Fast detec tor is likely to measure more higher and lower levels than the Slow detector The A and C weightings simulate human hearing response and meet Type 1 precision standards for accuracy Flat no weighting allows the signal to pass through unfiltered A16 C16 and Flat do not apply to the Model 812 5 27 05 Step 4 Step 5 Step 6 Step 7 5 27 05 The Model 812 has been preset at A
36. TM Current Date and Time ddd ddmmmyyyy hh mm ss R3 STAT Status RUN PAUSE STOP RESET C RESET O LOCKED A short form of the status command is R3 1 which has a 5 character response The first is an s when stabilizing or a space when stable The second is the current mode S for Stopped R for Running P for Paused C for Calibrating V for View mode O for stopped with overall data reset and C for stopped with Current data set reset The third character is the Lock Status and is either an or a U The fourth character is the Halt Line Status and is a 1 if high and a 0 if low The fifth or last character will be an a if an Alarm has been detected R4 _C SPL Current SPL nnn nn dB R5 _O RTIME OverAll Runtime hhhhh mm ss s R6 _O STIME OverAll Start Date and Time ddmmmyy hh mm ss B 6 Model 812 User Manual 5 27 05 R7 C RTIME Current Runtime hhhhh mm ss s R8 _C STIME Current Start Date and Time ddmmmyy hh mm ss R9 _O TWA Overall TWA Time Wght Avg nnn n dB R10 _O XR Overall Exchange Rate Text Rll _C TWA Current TWA Time Wght Avg nnn n dB R12 _C XR Current Exchange Rate Text R13 _O SEL Overall SEL nnn n dB R14 _C SEL Current SEL nnn n dB R15 _O LMIN OverAll Minimum Level nnn n dB R16 _O TMIN OverAl
37. U C No Prompt Entry Comment 35 CAL Level 114 00 Enter the sound pressure level of your 0 255 dB calibrator 36 Calibrator S N to 8 char Calibrator serial no will be printed Sound Level Meter 39 50 C These parameters define the sound level meter charac teristics Most changes will require a US if memory holds previous data No Prompt Entry Comment 39 Detector Slow Fast Impl Slow exponential avg 1 second con stant Fast exponential avg 1 8 second con stant Impl impulse response 40 Frequency Weighting A A16 C C16 A and C weightings meet Type 1 spec ifications Note A16 and C16 not applicable to the Model 812 41 AC Out Weighting Flat Wght F 20 F 20 Flat Level with 20 dB gain W 20 W 20 Weighted with 20 dB gain 42 Unweighted Peak Flat C 43 Mic Polarization 0 28 200 This selects the polarization voltage Voltage for the microphone Chose 28 or 200 V for condenser type microphones and 0 V for pre polarized microphones electret 44 Reference Level 0 to 255 dB measured level reference level rel ative level used in some functions 45 Currant Exchange 3dB 4dB 5dB 6dB Exchange rate for currant TWA or Rate 1 Dose readings For OSHA use 5dB 5 27 05 Model 812 User Manual 8 11 46 Current 0 to 255 dB Levels above threshold are integrated Threshold 1 into currant TWA or Dose re
38. available on the Model 812 Timer 21 27 UT These parameters are used when Start and Stop of measurements are to be controlled by the clock No Prompt Entry Comment 21 Timer Mode Off Block 1 day 2 Block Run Time 1 on Run Date to day Stop Time 1 on Stop Date 1 day Run Time to Stop Time 1 each day from Run Date to Stop Date 2 day Run Time 1 to Stop Time 1 and Run Time 2 to Stop Time 2 each day from Run date to Stop Date 22 Timer Run Date dd mm yy See Timer Mode comment 5 27 05 Model 812 User Manual 8 9 23 Timer Stop Date dd mm yy See Timer Mode comment 24 Timer Run Time 1 hh mm ss See Timer Mode comment 25 Timer Stop Time 1 hh mm ss See Timer Mode comment 26 Timer Run Time 2 hh mm ss See Timer Mode comment 27 Timer Stop Time 2 hh mm ss See Timer Mode comment Lock 28 29 UP These parameters limit access of certain functions to those with the correct password Step 1 After setting password and lock options exit For complete instruction on set the setup and press U P to lock ting the Lock parameters see chap ter 6 Step 2 To unlock press UP then m and enter the pass word No Prompt Entry Comment 28 Lock Password 8 characters Enter your password 29 Lock R S Key No Yes Lock mode change Model 812 User Manual 5 27 05 Calibration 35 36
39. basic functions Chapter 9 Memory Usage Sizing parameter needs to insure adequate memory for any given measurement Chapter 10 Printing a Report Turning gathered data into a printed report Appendix A Specifications A listing of acoustic elec tronic environmental and physical characteristics of the Model 812 1 2 Model 812 User Manual 5 27 05 e Appendix B Model 812 Serial Port Interface Remote Con trol Setting interface commands with their syntax e Appendix C Glossary Standard definitions of key terms and concepts used in the sound industry e Appendix D Index Alphabetical listing of all major components of this manual About This Chapter Specifically this introductory chapter covers the follow ing topics e Formatting Conventions Explanation of the fonts and other formatting conventions used in this manual e Model 812 Features A listing of the featured character istic and capabilities of the Model 812 Model 812 Components Description and diagrams of the Model 812 external parts Getting Started Instructions for unpacking a listing of accessories and optional equipment and initial setup Formatting Conventions This manual uses the following formatting conventions Functions accessed by pressing a key on the Model 812 keypad are shown with an icon for example Press and then press Cancel In step by step directions the process what you do is shown in the lef
40. be set in two ways a index number and b actual indexed parameter value a Index Number Syntax Response S et item numberindex number cr If 5 27 05 Model 812 User Manual B 13 Example S9 3 sets parameter 9 Baud Rate to third possible value of 2400 S66 1 sets Excd History Enable to Yes S84 0 sets Hist Period Units to 1 32s S84 1 sets Hist Period Units to _1 0s b Index Parameter Text Indexed parameter texts must be preceded by a semico lon and enclosed by brackets Indexed parameter texts must include the maximum number of characters including spaces which are indicated below with This command may be used with flag 2 of the query command which automatically encloses the parameter and required spaces in brackets Syntax Response S et item number indexed parameter text cr If Examples S9 2400 sets Baud Rate to 2400 S66 Yes sets Excd History Enable to Yes S84 1 325 sets Hist Period Units to 1 32s S84 1 05 sets Hist Period Units to 1 0s Character String Parameters To include leading spaces in a character string parame ter precede the character string with a leading sin gle quote or grave accent ASCII 9610 or 6016 Syntax Response S et item number character string cr B 14 Model 812 User Manual 5 27 05 Example S2
41. instru ments with 2 100 kQ input impedance when making AC or DC output readings AC Output Output Impedance 600 Q Gain 0 dB or 20 dB User Selectable Measurement Range 88 0 dB A 8 Model 812 User Manual 5 27 05 DC Output Output Impedance 600 Scale 20 mV dB Measurement Range 105 0 dB Voltage Range 0 to3 volts e Temperature Coefficient 936 C Reference Frequency The reference frequency is 1000 Hz Stabilization Time The model 812 will not proceed to a running condition until it is allowed to stabilize At power on with the polarization voltage set to 200V or 28V the stabilization time is approximately 45 seconds With the polarization voltage set to OV the stabilization time is approximately 10 seconds A shorter stabilization time is also invoked when certain settings Weighting Detector etc are changed Microphone Electrical Impedance The Larson Davis ADP005 should be substituted for the 1 2 microphone when performing electrical tests on the Model 812 The Larson Davis ADP002 is used in place of 1 4 microphone and the Larson Davis ADPO006 is used in place of the 1 microphones 5 27 05 Model 812 User Manual A 9 Functions Measured Ley Lmax Lmin TWA SEL Dose Projected Dose Ln 1 99 Sound Exposure in pascal squared hours SE in Pa H Time History Histograms Measurement Time Date Duration Taktmaximal 3 and 5 Data Storage
42. messages 5 13 MEMORY Memory will be addressed in Chapter 9 but it would be well to examine the key functions here Standard memory size is 64 KBytes Three screens are available from this function Press GHIFT and 9 A screen similar to the following will appear Step 1 Step 2 Press the 0 key to access the next screen N Step 3 The third screen gives additional information Press the gt i key to examine this screen Stopping the Measurement Press to stop the measurement The stick figure will resume the resting position To view any of the previous measurement data simply press the appropriate key and the information will appear 5 14 Model 812 User Manual This screen shows the percentage of memory left of the total avail able 55099 divided by 55197 99 82 Total Exceedances were 37 total Intervals were 4 and 1 Daily His tories This display indicates there are 18 Histories in memory 8 Logs and 0 Calibrations Hs is the number of time history samples Lg is the number of RUN STOPs made and CL is the number of calibra tion check records 5 27 05 Timed Measurement The ability to take a measurement at a specific time and date is one of the unique qualities of the Model 812 This feature allows you to take unattended measurements Accessed through the TIMER key this flexible system has modes to permit one or two measurements a day between two dat
43. more detail This definition is often used in conjunction with reverberant field The rate at which an oscillating signal completes a complete cycle by returning to the original value It can be expressed in cycles per second and the value has the unit symbol Hz Model 812 User Manual 5 27 05 Frequency Filter Band Pass Hertz added and the letter f is used for a universal descrip tor It can also be expressed in radians per second which has no symbol and the greek letter is used for a universal descriptor The two expressions are related through the expression 0 2 The part of certain sound level meters that divides the fre quency spectrum on the sound or vibration into a part that is unchanged and a part that is filtered out It can be composed of one or more of the following types Low Pass A frequency filter that permits signals to pass through that have frequencies below a certain fixed fre quency called a cutoff frequency It is used to discriminate against higher frequencies High Pass A frequency filter that permits signals to pass through that have frequencies above a certain fixed fre quency called a cutoff frequency It is used to discriminate against lower frequencies Bandpass A frequency filter that permits signals to pass through that have frequencies above a certain fixed fre quency called a lower cutoff frequency and below a certain fixed frequency called an upper cutoff frequency The diffe
44. of these are active in the Model 870 the Model 812 s big brother System 1 20 RUS The following parameters define measurement names set clock and determine interface parameters for dBuV ROM registers A B and do not affect calibration data No Prompt Entry 1 Reset ALL Data No Yes Comment This parameter allows a GHIFT without leaving SETUP Note If this parameter is set to Yes a RESET will occur and the parameter will automatically revert to No 2 4 Name up to 30 characters Place any message you desire in these 3 lines The 3 lines of name are sav able only in EEPROM Title up to 30 characters Used to describe a measurement or setup Current Time hh mm ss also accessed Ut 5 27 05 Model 812 User Manual 8 7 7 Current Date mm dd yy The 812 is year 2000 compliant Leap years are considered For years less than the year manufactured the 21st century 1s assumed 2000 2092 oth erwise the 20th century is used 1993 1999 8 Day of Week Sun Sat 9 Baud Rate 300 19200 Baud rate of the serial interface Serial printer or computer rate should be the same 10 RS 232 Address 0 127 Enables addressed communication mode for a network of Larson Davis SLMs Each must have a unique address Normally only one Model 812 is used thus the address should be set to 0 to disable 12 COM Ports Hand None Hdwr XOFF
45. the measurement Step 2 Press the 0 key and examine the second screen available in this series Step 3 5 6 Model 812 User Manual The highest RMS level occurred at 11 25 hrs and was 91 6 dBA on the given date Additional screens are available here recording the number of times the current read ing has reached predetermined lev els selected in parameters 61 62 In this example parameter 61 was set to 55 dB and C weighted parameter 40 In this measure ment the RMS has topped this level 13 times The display shows that parameter 62 was set to 65 dB and is C weighted This measurement topped this level 9 times 5 27 05 The same key Gis finds the Lmin values in conjunction with the GHIFT key Step 1 Examine these values press and The current measurement Lmin the following display will appear occurred on November 1 1996 at 11 22 hrs Remember the Model 812 used military time to desig nate between A M and P M That Lmin value was 49 6 dB There are no other screens avail able from this display PEAK UWPK The Model 812 also has a peak level detector Its values during the measurement or when stopped are found by pressing the key Step 1 Access Peak values Press PEAK is a weighted value and rep resents a true Peak SPL from the on board Peak Detector In this example the PEAK is 111 2 dB and occurred at the time and date shown on the s
46. to Stop 1 and Run Time 2 to Stop Time 2 each day from Run Date to Stop Date If the date is incorrect simply press m and enter the correct data then press e 5 27 05 Step 6 access Timer Stop press the v A Previ ously entered date will appear Step7 change the date press and enter the b day ending date i e first of October i e 01 10 96 and the following display will appear The five day block is now set Next we will set the time periods each day within the block Step 8 Pressthe 3 to Run Time 1 and press Modify Our start up time is 8 30 A M so press 08 30 and Enter and the display should look like this Step 9 Press the to Stop Time 1 Press m to enter the numbers 12 00 and then press Enter Step 10 Press thed to Run Time 2 Press to enter 13 Notice that military time is used 00 our afternoon start time Press Enter 0 01 24 00 to avoid confusion A M to P M 5 27 05 Model 812 User Manual 6 3 Step 11 Press the v to Stop Time 2 Press to enter 1630and Enter Step 12 To check your Timer setup press This will return you to the main screen Press SHIFT and the following screen should appear Step 13 If you press the M key it will give you the morning time run If you press the M again it will give you the afternoon time run settings The Model 812 can now be turned off by pressing UO and plac
47. to determine the noise floor It may also be possible to remove the microphone bias to obtain this value When properly set up the linearity range can be increased by 10dB NOTE The mode is always turned off with a CAL Change Q 208 Q NFMODE NOISE FLOOR COMP MODE Q 209 Q 875MD 875 RTA MODE None Excd Intv Dual unused Q 210 Q CNTLREG AUX CONTROL REG Q211 Q EXREC EXCD RECORD NUMBER Q212 Q IVREC INTV RECORD NUMBER Q213 Q HSTREC HIST RECORD NUMBER Q214 Q LOGREC RUN LOG RECORD NUMBER 5 27 05 Model 812 User Manual B 23 Q215 Q DYREC DAILY RECORD NUMBER Q 216 Q CALREC CALIBRATION RECORD NUMBER Q 217 Q TBLLVL LOCATE HISTOGRAM TABLE LEVEL Q 218 225 Q NI42 Q N149 RESERVED PARAMETER 42 49 respectively Q 226 Q OVLDLVL OVERLOAD LEVEL Q 227 Q RMSOS RMS CALIBRATION OFFSET Q 228 Q PKOS PEAK TO RMS CAL OFFSET Q 229 Q UWPKOS UwPk TO RMS CAL OFFSET Q 230 231 Q NI51 Q N152 RESERVED PARAMETER 51 52 Q 232 Q TEMP ENTER CURRENT TEMPERATURE Q 233 Q SERNUM ENTER SERIAL NUMBER B 24 Model 812 User Manual 5 27 05 History Records The various histories of the Model 812 are accessed in a similar fashion After using a direct index to the correct record one can advance or back up a certain number of records to the new value to be read Brackets in the syntax indicate optional characters and operands cr carriage return lf line feed Types of History Denot
48. to vibra tion particularly in direction at right angles to the plane of the diaphragm 4 Keep microphones away from strong electrical fields A microphone measures forces not pressures We would like the microphone to measure sound pressure force per unit area instead of sound force If the pressure is applied uniformly over the microphone diaphragm a simple constant the dia phragm area relates the two but if the pressure varies across the diaphragm the relationship is more complex For example if a negative pressure is applied on one half the diaphragm and an equal positive pressure is applied to the other half the net force is zero and essentially no motion of the diaphragm occurs This occurs at high frequencies and for specific orientations of the microphone Rules 1 Do not use a microphone at frequencies higher than speci fied by the manufacturer to increase the frequency response choose smaller microphones 2 Choose a microphone for free field or random incidence to minimize the influence of orientation A microphone influences the sound being measured The micro phone measures very small forces low level sound can run about one billionth of a PSI Every measurement instrument changes the thing being measured and for very small forces that effect can be significant When sound impinges directly on a microphone the incident wave must be reflected since it cannot pass through the microphone This results in the Mode
49. top or bottom of the parameters list Step Press SHIFT to move to the bottom of the parameter list Step 4 Press the 5 key Step 5 Press the keys and then 6 1 Press Enter 2 Model 812 User Manual All items in the list of parame ters can be accessed by using the and The Model 812 moves you to the RMS detector parameters You are now at the beginning of the Exceedance parameters item 61 5 27 05 NOTE Numbers are entered at the current cursor position Enter leading zeros if necessary Changing Parameters Enter Modify Parameters may consist of numerical values character This one has rounded brackets that fields or selected choices Numerical or character fields mean this is an entry parameter are shown between parentheses Type the number or character desired see Chapter 4 If there is an angle bracket gt then the entry field is too big to fit the screen and will scroll with the key Another parameter type is the template entry parameter These prompt for specific data entry For example For both types follow these simple steps Step 1 Press Step 2 Enter a value from the numerical keypad Use For complete coverage of numeri the SHIFT key for alphabetical input cal and alpha entry see chapter 4 5 27 05 Model 812 User Manual 8 3 Step 3 Confirm any change with Enter Step4 Cancelany change by pressing before Enter Parameters
50. 2 at setup parameter 43 To do this turn on the Model 812 press Eg Modify 4 3 and Enter The following display will appear Should the brackets contain a value other than 200 e g 28 or 0 press ther until the value 200 appears and then press Enter If you are using a pre polarized microphone this parameter should be set to 0 Press Cancel to return to the main screen To begin the calibration process check or insert the new calibration level given in parameter 35 To do this press 8 Modify 3 and 5 then Enter The following screen will appear Model 812 User Manual The flashing f the Keyboard Sta tus Indicator displays which key functions are active This indicates that the function keys are used for different purpose in current func tion In this screen the value 200 is selected from three options 200 28 0 The Larson Davis Model CA200 calibrator outputs 114 dB re20 uPa Note that the Model 812 automatically uses the C weight ing while calibrating This ensures a correct reading at typical calibra tion frequencies of 250 Hz to 1 kHz 5 27 05 Step 5 Step 6 Step 7 Step 8 Step 9 5 27 05 Press then enter the SPL value of your calibrator if other than 114 0 including any corrections for pressure etc The next setup item allows entry of the calibra tor serial number for record keeping p
51. 3 ABC Acoustics sets Name to ABC Acoustics Template Parameters Date The month day and year are entered in that order and are separated by The display shows day month abbreviated and year in that order Syntax Response S et item number mm dd yy cr If Example S22 05 23 89 sets Timer Run Date to 23May1989 Time The hour minutes and seconds are entered in that order and are separated by Military 24 hour clock time is used i e add 12 to afternoon hours Syntax Response S et item number hh mm ss cr If Example S24 14 25 33 sets Timer Run Time 1 to 14 25 33 5 27 05 Model 812 User Manual B 15 Query Parameters All these commands begin with Q Brackets indicate optional characters and operands See Chapter on SETUP for a list of all the parameters and their settings cr carriage return lf line feed _ space Syntax Response Q uery item_number flag Depends on flag Option flags elicit the following responses Flag Response none Current parameter 1 Parameter name and current setting 2 Current parameter setting including spaces in brackets or parentheses 3 Parameter name and current setting including spaces in brackets or parentheses 32 Index number for indexed parameter Flag values may be added together for desired combina tions Example R
52. 8 Model 812 User Manual 5 27 05 L The average RMS level the L 15 eq is displayed by pressing Dose DOSE the noise exposure may be calculated with two different sets of parameters e Current e Overall Parameters 45 51 are used with the calculation to arrive at the current dose from the current data and sets the exchange rate threshold level and criteria level for the current measurement These can be set differently from the overall in order to give different dose readings To protect the measurement the OVERALL Dose set tings parameters 48 50 may not be modified once the measurement has started without a reset However OVERALL CRITERION may be changed at any time 5 27 05 Model 812 User Manua The average RMS level in this reading is 82 2 dB slow average for the 8 minute and 14 5 second measurement period Parameter 51 Full Dose Period or Criterion Time applies to Current Overall 5 9 A new measurement may be started at any time without effecting the Overall Dose using the Current Dose set tings by modifying the CURRENT exchange rate and threshold settings An automatic reset occurs when CURRENT settings are modified creating a new CUR RENT dose measurement based on data collected from that time on Before we continue with our present measurement take a minute to examine the parameter values available all of which will effect the measurement The Current Ex
53. 812 5 DTR Data Terminal Ready 1 Ground Figure 1 2 External 5 pin Cable Connector Pinout 5 27 05 Model 812 User Manual 1 9 Block Diagram All the standard functions of a precision sound level meter are provided instantaneous level Leg SEL Lmax Lmin Dose projected dose etc In addition many valu able parameters can be stored time history interval data such as Ls and Leg etc Level calibration is performed in a few key strokes and every change or check is entered in a calibration log The Model 812 s large data memory relieves the user from the worry of data loss caused by memory limita tions Furthermore measurements can be printed or transmitted at up to 19 2 K baud via RS 232 for further manipulation or archiving Despite its numerous functions the Model 812 is still extremely easy to use Annotated displays indicate units and measurement mode The single setup menu lets the user scroll through and program parameters or use an index key to modify specific information Multiple measurement setups can be stored in memory for later recall And of course com plete setups can also be transferred from a computer The block diagram below shows how the Model 812 sound level meter merges state of the art analog cir cuitry a powerful microcomputer controller and a large amount of usable data memory The signal from the precision air condenser micro phone preamplifier is input directly to the linear peak
54. 9 Battery Low 130 POWER FAILURE 131 DIVISION BY ZERO 5 27 05 Model 812 User Manual B 31 32 Operand 1 Range 33 Operand 2 Range 34 DPC Format 35 Key Has No Effect 36 Stop Required 37 Key Has No Effect In VIEW 38 Parameter Entered Wrong 39 RESET ALL Required 40 Use ARROWS ON to Exit 41 Use NEXT PREV or ENTER 42 Invalid Numeric Entry 43 OPEN 44 Already Open 45 No History Yet 46 At End of History 47 At Start of History 48 History Format Error 49 Unknown I O Command 50 Operand Invalid 51 Unable to Calibrate 52 EEPROM Write Error 53 Memory was Lost Data Reset 54 RECALL Not Found 55 Function Not Implemented 56 System Locked 57 A D Stack Full 58 A D Over Run 59 Serial Port Framing 60 Serial Port Line Noisy 61 Serial Port Over Run 62 Wait for Stabilization B 32 Model 812 User Manual 5 27 05 163 Power Turned Off 164 Time Date Not Set 165 Printer Already BUSY 166 Lithium Battery Low 167 Timer ON Pending 5 27 05 Model 812 User Manual B 33 B 34 Model 812 User Manual 5 27 05 APPENDIX Glossary This appendix contains technic
55. EMI and RFI protection Environmental enclosures available for system secu rity and inclement weather conditions Durable membrane keypad Two year warranty see warranty statement on the copyright page at the front of this manual Model 812 Components A layout of the Model 812 is shown below 1 6 Model 812 User Manual 5 27 05 Microphone Microphone Preamplifier LCD Display Keypad Connector AC DC Out Connector k A Cal Heater Port Optional Connector Serial Battery Port Compartment Figure 1 1 Model 812 The Model 812 is a convenient hand held sound level meter with a simple user interface 5 27 05 Model 812 User Manual As can be seen the standard Model 812 includes the fol lowing e Model PRM828 is a 5 1 2 inch precision preamplifier using a standard 5 pin microphone SwitchCraft connector and may be extended up to 20 feet with EXCXXX microphone cable The preamplifier is removed by depressing the small black latch button with a fingertip while gently pulling it away from the mating connector Atwo line 32 character high contrast LCD display One of the 12 inch precision air condenser micro phones in Table 1 8 Microphones for use with 812 The microphones are rugged and reliable but should be kept in their protective case when not in use Avoid unnecessary shock Although a Larson Davis microphone can survive being dropped it is a deli cate preci
56. ER 8 5 Step2 The z 3 keys will scroll through the two RAM registers 0 9 For example press v twice The RAM register 1 is empty Step 3 To store the current setup to the displayed RAM register press Enter Recalling a Setup Memory must be reset before a recall of setup parame ters can be accomplished Step 1 Inthe stop mode press SHIFT Enter to reset memory Then press SHIFT Step 2 The EEPROM is again the default Use r and d to scroll through the two RAM registers or the programmed ROM setups 6 Model 812 User Manual RAM registers 0 to 9 and EEPROM register will recall pre viously stored calibration data STORE saves the CAL data so that the calibration for several dif ferent microphones may be stored and recalled as desired For exam ple Register 1 could store the cali bration for a Model 2560 microphone 2 for a Model 2540 3 5 27 05 Model 812 Setup Parameters Setup parameters of the Model 812 are listed below Modifying some setup parameters such as going from a FAST to a SLOW meter response may not be allowed unless the data is reset This prevents corruption of the overall noise data Parameters are listed below in logical groups with their number and direct index key if available Valid entry formats are listed 0 for numerical 0 for selection Some reserved parameters or selections are not avail able Many
57. IES EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE Some states do not permit the disclaimer of implied warranties Therefore the above disclaimer of implied warranties may not apply to certain purchasers I Procedure for Warranty Performance If the product fails to perform to LD s specifications the Buyer must provide LD with the applicable model and serial numbers the date of purchase and the nature of the problem J ADDITIONAL EXCLUSIONS FROM THIS LIMITED WARRANTY NOTWITHSTANDING ANYTHING TO THE CONTRARY CONTAINED IN THIS LIMITED WARRANTY THIS LIMITED WARRANTY DOES NOT COVER ANY OF THE FOLLOWING 1 EQUIPMENT THAT HAS BEEN ABUSED DAMAGED USED BEYOND RATED CAPACITY OR REPAIRED BY PERSONS OTHER THAN AUTHORIZED SERVICE PERSONNEL D 2 812 Manual May 27 2005 2 DAMAGE CAUSED BY ACTS OF GOD THAT INCLUDE BUT ARE NOT LIMITED TO HAILSTORMS WINDSTORMS HURRICANES TORNADOES SANDSTORMS LIGHTNING FLOODS AND EARTHQUAKES 3 DAMAGE UNDER CONDITIONS CAUSED BY FIRE OR ACCIDENT BY ABUSE OR BY NEGLIGENCE OF THE USER OR ANY OTHER PERSON OTHER THAN LD BY IMPROPER INSTALLATION BY MISUSE BY INCORRECT OPERATION BY NORMAL WEAR AND TEAR BY IMPROPER ADJUSTMENT OR ALTERATION BY ALTERATIONS NOT COMPLETED BY AUTHORIZED SERVICE PERSONNEL OR BY FAILURE OF PRODUCTS PARTS FROM SUCH ALTERATIONS 4 COSTS OF REPAIRING DAMAGE CAUSED BY POOR OR IMPROPER MA
58. INTENANCE OR UNAUTHORIZED REPAIR S COSTS OF MODIFYING THE PRODUCT IN ANY WAY ONCE DELIVERED TO THE BUYER EVEN IF SUCH MODIFICATIONS WERE ADDED AS A PRODUCTION CHANGE ON OTHER PRODUCTS MADE AFTER THE BUYER S PRODUCT WAS BUILT Authority to Alter This Limited Warranty No agent representative distributor or authorized dealer of LD has any authority to alter the terms of this Limited Warranty in any way This Limited Warranty may be altered only in a writing signed by an authorized officer of LD May 27 2005 812 Manual D 3 D 4 812 Manual May 27 2005 Index A AC output specifications A 9 American National Standards Institute ANSI 1 5 ANSI standards met A 11 B Battery internal life of 1 18 Battery Voltage directions for checking 2 11 ANA 8 8 C Calendar real time A 11 Calibration 1 6 Ba 8 11 C 1 B O xen 2 calibration 3 2 Character Parameters B 14 Clock real time 11 run time cocccccncnoonnnnonnnnonnnnnncnnonancnnnonnne A 11 Clorinda 8 7 Commands Status NN B 6 Criterion noia das 8 12 C 2 sound level C 3 D Daily Histor
59. Model 812 Reference Manual Larson Davis Inc 1681 West 820 North Provo UT 84601 1341 Phone 801 375 0177 FAX 801 375 0182 www larsondavis com 1812 01 Rev C Copyright Copyright 2003 by Larson Davis Incorporated This manual is copyrighted with all rights reserved The manual may not be copied in whole or in part for any use without prior written consent of Larson Davis Inc Disclaimer The following paragraph does not apply in any state or country where such statements are not agreeable with local law Even though Larson Davis Inc has reviewed its documentation Larson Davis Incorporated makes no warranty or representation either expressed or implied with respect to this software and documentation its quality performance merchantability or fitness for a particular purpose This documentation is subject to change without notice and should not be construed as a commitment or representation by Larson Davis Inc This publication may contain inaccuracies or typographical errors Larson Davis Inc will periodically update the material for inclusion in new editions Changes and improvements to the information described in this manual may be made at any time Equal Opportunity Employer Larson Davis is an equal opportunity employer and does not discriminate on the basis of race color religion gender national origin disability or veteran status Please examine your instrument and record the following in
60. SEL of the highest SPL event making a 10dB or greater SPL excursion Three additional fields show Duration Exchange rates SEL and Lmax LOCK The lock functions protect instru ment data and configuration The level of security is configured in Setup MEM INTV The Interval History provides a INTV history of a number of statistical values for a moderate size time interval 1 minute to larger than 99 hours in one minute or greater steps It is pro grammed by parameters 72 79 MEM Memory use in percent bytes free and total byte available are provided as well as a count of all of the History Records stored in memory HIST The Time History function is a HIST record of short interval reading and optionally a Peak UWPK or Lmax read ing The interval can vary from 1 second to 255 sec History period is set by parameters 83 84 LOG The Run Stop Log is a time record of all the actions which start or stop the data taking process of the Model 812 2 4 Model 812 User Manual 5 27 05 Keys Functions CAL SLM CAL Calibration information and con trol Initially in the CAL a display the current calibration offset is displayed with a flashing prompt to press either the UP arrow key to check the calibration or press the d key to change the calibration SLM The Sound Level Meter function displays the current Sound Pressure Level SPL while the instrument is in the Run Mode or the SPL at the instant it w
61. T ENABLE Q 70 Q EXPER EXCD TIME HIST PERIOD Q71 Q EXADEN EXCD SAVE A D ENABLE unused Q72 Q IVENB ENABLE INTV HISTORY Q73 Q IVXRT INTV EXCHANGE RATE Q74 Q IVTHOLD INTV THRESHOLD 075 Q IVPER INTV PERIOD Q 76 Q IVSYNC INTV TIME SYNC Q77 Q IVLN INTV SAVE Ln S Q 78 Q IVADEN INTV SAVE A D unused Q 79 Q IVSTOP INTV AUTO STOP Q80 Q HSTENB ENABLE TIME HIST 081 HIST RESOLUTION Q 82 Q HSTPK HIST SAVE PEAK Q 83 Q HSTPER HIST PERIOD Q84 Q HSTUNIT HIST PERIOD UNITS Q 85 Q HSTBASE HIST BASE Q 86 Q HSTMODE HIST BASE MODE Q87 Q HGRES HISTOGRAM TABLE RESOLUTION Q 88 Q DYENB ENABLE DAILY LDN HISTORY Q 89 Q PRNRPT DATA REPORT x Q 90 Q PRNLOG R S AND CAL LOG x Q91 Q PRN SETUP REPORT x 5 27 05 Model 812 User Manual B 19 Histogram Reports The RMS Peak and UWPk histogram reports have been implemented with this revision The unformatted reports have also been developed and the format is the level of the first bin followed by the number of samples in each bin in hex 0 9 amp a There are 1024 RMS bins and 128 Peak and UWPk bins this corresponds to 1 8th dB resolution for RMS and 1dB resolution for the peak tables Q92 Q PRN RMS HISTOGRAM TABLE x Q 93 Q PRN RMS HISTOGRAM TABLE LOW VALUE n Q94 Q PRN RMS HISTOGRAM TABLE HI VALUE n Q 95 Q PRN RMS HISTOGRAM TABLE RESOLUTION x Q 96 Q PRN
62. To change the setting press 0 to the pre ferred setting and Enter Find item 41 by pressing AC Out Weighting which has the values listed here Choose one by pressing Flat Whgt F 20 W 20 Item 42 UwPk Weighting press the v key again Chose from the values listed with gt Flat C Item 43 Mic Polarization was touched upon earlier Model 812 User Manua F 20 means Flat plus 20 dB of level added W 20 means Weighted with 20 dB of level added Flat record all sound and C weighting simulates the human hearing at higher sound levels This selects the polarization volt age for the microphone Choose 28 or 200 V typically 200 V is cho sen for condenser type micro phones and 0 V for pre polarized microphones electret 5 5 Step 8 Item 44 the Reference Level All measurements are offset by this dB reference level normally set at 114 0 dB or 94 0 dB Step9 Press to exit setup mode Emax Lmin We have already looked at the Lmax and Lmin in a previ ous screen These values are also available directly from display keys They can be accessed while the unit is tak ing a measurement or in the stop mode Only when the unit is running is the data recorded These measure ments are usually read after they have been taken and the measurement is stopped Here we will examine them while a measurement is being taken Step 1 Press to display the greatest RMS SPL value since the beginning of
63. Usage Each of the Model 812 s History Functions use space out of a common memory The amount each record takes is based on the options selected In this chapter we will provide information that will assist you to Determine the amount of storable data considering the given options Estimate memory usage by giving an example of a test reading and an associated chart to determine the memory needed to complete the reading Determine Storable Data The following tables indicate the amount of memory used for each type of record Interval Records Intv History Enable Yes Prm 72 Options add bytes shown if enabled Bytes Basic Interval Record 34 Intv Save L s Yes Prm 77 18 Time History Records Time History Enable Yes Prm 80 Options Options Hist Resolution Prm 81 Hist Save Peak Prm 82 Bytes 5 27 05 Model 812 User Manual 9 1 1 0dB No 1 0 14 2 1 04 Peak UwPk Max Wind 2 0 1dB Peak UwPk Max Wind 4 Other Histories and Memory Usage Run Log History 20 bytes per record Calibration Log History 17 bytes per record Ram Setup Register 506 bytes per register REgisters 0 9 Bytes used per register stored 9 2 Model 812 User Manual 5 27 05 Estimating Memory Usage The easiest way to estimate the memory usage is to work on a time basis such as one day Consider the following Calculate the number of Interval Time
64. Weight 13 oz 370 gm Weight w o preamp amp microphone 11 oz 310 gm Shipping weight 3 lbs 1 4 kg A 12 Model 812 User Manual 5 27 05 APPENDIX Serial Port Interface Remote Control The Model 812 is fully controllable remotely via Serial Port interface Setup items and operational mode can be altered Data can also be dumped to or queried by the controlling computer The Model 812 may be connected to the computer directly or through a modem A network of many instru ments can be formed all controlled by one computer by using the address ability mode This chapter will describe the Serial Port interfacing of the Model 812 and the various interface commands with their syntax Modem control is also covered These com mands are a subset of the Larson Davis Model 870 com mands In this chapter we will cover the following items e Model INT002 Interface 2 e Daisy Chain 3 e Commands be e RE ed EHE 3 Group Read 11 Setting Parameters 12 e Query 15 History Records iii ede ee 23 e History Data 5 25 Print Commands nuit editor
65. Weightings The available RMS detector time weightings are FAST SLOW and IMPULSE There are also two available PEAK detectors Weighted Peak Unweighted Peak Weighted Peak Detector Rise Time 60 us Unweighted Peak Detector Rise Time 30 us Effects of Temperature The SPL level varies 6 0 5 dB when the complete instru ment is tested over the 10 C to 50 C temperature range The reference reading for this test is taken at 20 C and 36 relative humidity RH the input signal is at 1000 Hz Effects of Humidly The SPL level varies 6 0 5 dB when the complete instru ment is tested over the 30 to 90 RH range This test is performed at 40 C with an input signal of 1000 Hz Limits of Temperature and Humidity Permanent damage can occur when stored or operated above 60 C or below 20 C Condensation of moisture will make readings inaccurate but will be correct when moisture has dissipated 5 27 05 Model 812 User Manual A 7 Microphone Extension Cables When measuring signals below 20 kHz up to a 12 foot microphone extension cable may be used with the model 812 Optimal Positioning of Instrument and Observer Measurements can be made with the model 812 held in one hand with the arm extended away from the body however better measurements can be made with the Model 812 placed on a tripod AC and DC Outputs The output impedance is 600 for both the AC and DC outputs of the Model 812 For minimal error use
66. adings For OSHA use 80 dB 47 Currant 0 to 255 dB 100 dose if this level is maintained Criterion 1 for full dose period For OSHA use 90 dB 48 Overall 3dB 4dB 5dB 6dB Exchange rate for overall TWA or Exchange Rate 2 Dose readings 49 Overall 0 to 255 dB Levels above threshold are integrated Threshold 2 into overall TWA or Dose readings 50 Overall 0 to 255 dB 100 dose if this level is maintained Criterion 2 for full dose period Dose 51 o The noise exposure Dose may be calculated with three different set of parameters CURRENT OVERALL and LDL See section on occupational noise for additional information The dose displayed with the o key is Dose 2 No Prompt Entry 51 Full Dose Hours 0 99 Comment This is normally set to 8 for an 8 hour workday It is used with the criterion level to determine a 10096 projected dose 12 Model 812 User Manual 5 27 05 Ly Statistical Levels 55 58 B Lnn is the rms noise level which was exceeded nn of the time The Ln s are computed from the overall level distribution histogram or each interval s level histogram see item 77 The measured and displayed Lnn may be changed during the measurement The six nn are auto matically listed in increasing order No Prompt Entry Comment 55 Lnn 1 Percent 0 to 99 56 Lnn 2 Percent 0 to 99 57 Lnn 3 Percent 0 to 99 58 Lnn 4 Percent 0 to 99 Exceedance Level Count
67. ain The i 8 Gi keys are in the 2 field Press SHIFT twice to access the 2 field To Clear the field press SHIFT twice to access the 2 chart and press the Clear key To replace a character with a Space press SHIFT twice to access the 2 field and press the Space key When the first line is completed press the v to go to the next field the second line Press and select the appropriate chart by pressing SHIFT and the desired character key When the second line is complete press the v to go to the next field the third line and repeat the process The fourth line is for the Measurement Title Press the 3 key To exit the setup mode press Enter the A key Enter the GN keys consecutively or one at a time Complete the rest of the entries in the same fashion Three lines are available for entry i e company address telephone The first and fourth lines will appear on screen when the Model 812 is turned on Setting Time Date and Day parameters Once you have set the parameters you can now enter the correct time and date The Model 812 has a 24 hour military time clock where afternoon hours are denoted by adding 12 hours e g 3 45 pm 15 45 hrs Modify this parameter as follows Step 1 4 6 With the Model 812 on press SHIFT 1949 Model 812 User Manual The current time is displayed If it is incorrect enter the correct time 5 27 05 Step 2 Press the m
68. al definitions of key acoustical and vibration terms commonly used with Larson Davis instruments The reader is referred to American National Standards Institute document S1 1 1994 for additional definitions Specific use of the terms defined are in the main body of the text Allowed Exposure Time Tj It is the allowed time of exposure to sound of a constant A weighted sound level given a chosen Criterion Level Crite rion Duration and Exchange Rate The equation for it is T T T 2 P OUO a 7 where L is the Criterion Level is the Criterion Duration Q is the Exchange Rate K is the Exchange Rate Factor and Lavg is the Average Sound Level Example If L 90 T 8 Q and L 95 then 8 8 E T 1965 3916 365 995 5 656 5 hours and 39 minutes This means that if a person is in this area for 5 hours and 39 minutes he will have accumulated a Noise Dose of 100 Standard ANSI 12 19 Average Sound Level Layg Itis the logarithmic average of the sound during a Measure ment Duration specific time period using the chosen Exchange Rate Factor Exposure to this sound level over the period would result in the same noise dose and the actual 5 27 05 Model 812 User Manual C 1 unsteady sound levels If the Measurement Duration is the same as the Criterion Duration then Layg LTwA LC 1 Log m qLogio 7 10 GOV where the Measurement Duration specified time period is T T T
69. an average since the refer ence time is not the same as the integration time The physical characteristic of sound that can be detected by microphones Not all pressure signals detected by a micro Model 812 User Manual 5 27 05 5 27 05 phone are sound e g wind noise It is the amplitude of the oscillating sound pressure and is measured in Pascals Pa Newtons per square meter which is a metric equivalent of pounds per square inch To measure sound the oscillating pressure must be separated from the steady barometric pressure with a detector The detector takes out the steady pressure so only the oscillating pressure remains It then squares the pressure takes the time average and then takes the square root this is called rms for root mean square There are several ways this can be done Moving Average The averaging process is continually accept ing new data so it is similar to an exponential moving aver age The equation for it is t If 2 t T Prms 7 Se 45 t 5 The sound pressure is squared and multiplied by exponen tial decay factor so that when the time of integration is near the current time t it is essentially undiminished For times older less than the current time the value is diminished and so becomes less important The rate at which older data are made less influential is expressed by the constant T The larger is it the slower the decay factor reduces and the slower the resp
70. and are accessed in the same way Step 5 access items 48 50 Overall Exchange Rate Overall Threshold Overall Criterion press the v key Full Dose Hours item 51 has a range of 0 to 99 hours but is normally set to an 8 hour workday Step 6 access Full Dose Hours press the v key Step 7 To look at DOSE press dose Step 8 To look at Projected Dose press bi to the PROJ b screen Step 9 To look at Sound Exposure 5 press SHIFT and 5 27 05 Model 812 User Manua Damage to hearing normally occurs with lengthy exposure to sound at 90 dB and above For this reason the Criterion is generally set at 90 dB Changes can be made in any dis play by pressing Modify entering desired values and pressing Enter The overall criterion level set in item 50 and the dose hours set in item 51 determine what is 100 dose This step will not work while in the SETUP mode This step will not work while in the SETUP mode either 5 11 Dose readings are usually read and have more meaning after the measurement is completed Returning to our recent measurement let s examine the key and look at the values recorded there Step 1 Press the key where two screens are available Press the 0 key to access the sec ond screen The Exposure reading is displayed on the next screen We will visit this screen using the following steps Step 1 Pressthe SHIFT and keys
71. arameter 43 Microphone Polar ization and found it preset to 200 4 1 Step 2 To access parameters using numeric values Step 3 Step 4 4 2 press To access the Current Time press 0 then 6 The number 6 is assigned to the Cur rent Time parameter and press Press to prepare the screen for changes in the Current Time Notice the flashing f changes to n Model 812 User Manual Notice that the flashing f has been replaced by a flashing n indicating the numeric key access The flashing parenthesis indicate this field is ready to receive numeric input Entering 0 before the new number will remove any prior parameter settings The third way to access Current Time parameter press SHIFT 175 Remember press m to change or correct the field and press Enter 5 27 05 Step 5 Using numeric keys make changes and press Enter or if the time is correct just press Enter Step 6 exit the setup mode press Cancel Setting Parameters Using Numbers and Other Characters The Model 812 has the ability to show 3 lines for your Company Name and one line for the Measurement Title which is used on the reports These parameters are entered from the keyboard Through the keyboard you can enter all of the capital letters from A to Z the digits 0 to 9 and some punctua tion characters There are three levels of func tions when in the Alpha Parameter Mod
72. as last stopped LMAX Lyin The maximum SPL or Lmax is the largest sampled SPL for the overall mea surement period displayed with the date and time of its occurrence Two addi tional screens accessed by pressing the left or right arrows show the number of times the SPL exceeded two fixed levels Lmax The minimum SPL or Lmin is the lowest sampled SPL for the overall mea surement UWPK PEAK PEAK The highest weighted Peak Detec tor output level Lok Date and time of the occurrence of the Lpy is shown The num ber of times the weighted peak level exceeds a programmed threshold is also counted and displayed b window UWPK The highest UnWeighted Peak Detector output level Lywpx The date and time of the occurrence of the Luwpk is also shown The number of times the weighted peak level exceeds a pro grammed threshold is also counted and displayed b window 5 27 05 Model 812 User Manua 2 5 Keys Functions BATT LN Ly The L values represent the SPL exceeded n of the run time All values from 1 to 99 are available two of the four are displayed at a time and can be changed even while running BATT This key gives the percentage of power remaining in the 9 V battery or external supply BATT b Gives Model 812 revision num ber and date TIME Leo Leg The Equivalent Level or Leq is a Time Weighted Average based on an exchange rate of 3dB true energy mea sure with n
73. change Rate parameter item 45 is accessed by the following steps Press and 5 then choices here are listed below Step 1 Enter The 3dB 4dB 5dB 6dB The Current Threshold item 46 has a range from 0 to 255 dB Step 2 Pressthe v key and choose the desired dB level for the Current Threshold Larson Davis has preset this parameter to 80 dB 5 10 Model 812 User Manual The appropriate value for this parameter is established by enforcement authorities in various countries In the USA OSHA mandates a 5 dB exchange rate 3 dB is common in most other coun tries Note that these can be changed without a reset all The normal Dose setting for threshold is 80 dB which allows the instrument to virtually ignore sound below that level as it does not contribute significantly to the weight of the measurement data sought and saves memory as well 5 27 05 Step3 If you wish to change this level press enter the desired dB numerically and press Enter The Current Criterion is the next parameter item 47 and has been preset to 90 dB in a range of 0 to 255 dB Step 4 Pressthe v key item 47 Press if you wish to keep the 90 dB level or press enter the desired dB numerically and press Enter The Current Dose is often used as a second Dose mea surement The collected data is available on the printout The Overall Dose parameters have the same available set tings as the current settings
74. creen Parameter 63 sets the level above which the read ings must go to be recorded by the Model 812 Step 2 The second display available from this function Parameter 63 controls the setting is accessed by pressing the M key for this measurement Here the set ting is 74 dB C weighted and in this measurement was equal to or exceeded 156 times Unweighted Peak UWPK has two screens available as The unweighted Peak value is the well and are accessed with the SHIFT and keys unfiltered no A or C weighting signal from the Peak Detector 5 27 05 Model 812 User Manua 5 7 Step 1 Press SHIFT and and examine these val ues for the current reading Step 2 For the second screen press the M key The value for the UWPK is set in parameter 64 and is 85 dB This value was reached 161 times Ln Ln values are determined by parameters 55 60 and should be examined next in our current measurement Step 1 Access L by pressing the key and a screen Parameters 55 56 in this example similar to the following will appear were set to 5 and 10 respectively This screen shows their values in this measurement These indicate the sound pressure levels that were exceeded 5 and 10 of the mea surement duration Step 2 Pressthe M key to access the second screen Parameters 57 58 were set at the given values shown in the screen ij FEES and their readings are apparent 5
75. ct Extended Labor Warranty In furtherance of LD s commitment to Total Customer Satisfaction LD offers an extended labor warranty of one 1 year on all products calibrated or certified by a factory technician at any time or from time to time during the first seven years of the product life from date of manufacture The customer s sole remedy pursuant to this extended warranty is to receive free labor for any repairs required during the period in which the extended warranty is effective This extended labor warranty is subject to the limitations as outlined in Paragraph J Service amp Repair Limited Warranty In addition to the limited warranties set forth above LD offers a 90 day parts and labor limited warranty for all repair work performed at the factory This warranty is limited to parts repaired or replaced at the factory by LD This warranty 1s also subject to the limitations as outlined in Paragraph J C Shipping Charges The buyer will return the product freight prepaid by the Buyer to an authorized service center The product will be returned to the buyer freight prepaid by LD D Products Manufactured by Others This Limited Warranty does not cover any products manufactured by others Such products are subject to the warranty if any of their respective manufacturers and to be repaired only by a respective authorized service person for such products LD shall have no obligation to undertake repairs of products manufactured by others
76. e 28 e Error Messages and 29 5 27 05 Model 812 User Manual B 1 Model INT002 Interface Cable The Serial Port communication is made through the 5 pin connector at the base of the Model 812 Interface interface signals usually need to be converted for proper communication with desktop computers The Model INT002 Cable level converter is required for this pur pose Its electronic circuits provide the correct signal lev els and polarities When used with the AC DC adapter the INT002 also powers the units externally minimizing battery depletion which can be substantial during Serial Port transfers Step 1 With the instrument turned off insert the cable connector in the 5 pin port Step 2 Connect the cable to the of the computer using Baud rate Serial Port address and the supplied 9 25 pin adapter if necessary handshaking protocol are selected using parameters 9 10 and 12 Unless using addressing set the address to 0 B 2 Model 812 User Manual 5 27 05 Signal 5 Pin configurations for the INT002 follow 812 5 pin Connector End Computer DB 9 Connector End Pin1 Shield Pin5 Shield Pin 2 Red Pin 3 Red Pin3 Yellow Pin 2 Yellow Pin4 Blue Pin 5 White Pin 4 Blue Pin 6 White Pin 8 White Daisy Chain Addressing A network of instruments may be interconnected to one computer using the appropriate cabling such as the 040 and each may be controlled
77. e ie Me C 9 Mode commands 5 Model 812 2 o a 3 1 Block Diagram 1 10 Components 1 7 Peat t s e rete etat 1 5 Keypad 2 2 optional equipment 1 15 n tS 2 10 System Diagram 1 10 Model 820 Glossary App C 1 Specifications App A A 1 N Near Field ACOUSTIC iii i i C 11 geometric C 11 gl ssaty s adeste d C 11 Noise C 12 Background C 12 compensate B 23 daily personal exposure C 3 13 HOOK eee eee ems B 23 gl ssaty ssh ei ied C 2 C 12 projected noise dose C 13 single event exposure level SENEL Lax C 13 HUME uas siat ce e ea 2 9 Numeric Parameters B 13 Off directions for turning off 2 12 OSHA level tonem C 13 Overa dirias 2 8 P Parameter eee agis B 13 B 15 Character caeci trol os B 14 character strings B 13 Exceedance 8 14 indexed 13 NMEN e nese Teide B 13 QUICK See
78. ecommended For most commu nity noise purposes set this parameter to 0 or slightly above the noise floor This sets the period for the interval history A 1 second Interval may be selected by entering 00 00 The Model 812 allows synchroniz ing the interval report with the Daily History Report If Yes is entered the Interval Report will be started or restarted if already run 7 5 Step 6 Step 7 Step 8 Step 9 7 6 Press the v to item 77 Intv Save L s The Choices are Yes No Press the 3 to item 79 Intv Auto Stop The choices are Yes No To view Interval Histories after a measurement has been taken press 8 A screen similar to the one below will appear Examine the data available in each INTV Press gt and scroll to each The 4 will also work and the scroll is a loop Model 812 User Manual ning at the start of each hour For this to work properly the Interval Time should be one hour or some multiples of hours The benefit of synchronizing the hourly levels and the interval reports is that all the statistics Lmax Ly etc are available for the hourly noise levels that make up the daily report Yes This option allows the four L s for the interval report to be stored Yes This option will cause the Model 812 to automatically stop at the end of each interval allowing the precise timing of a series of manual measurements To start a new measurement t
79. ed in syntax by history_no 1 Exceedance E 2 Interval I 3 Daily D 4 Run Log L 5 Calibration C 6 Time H 7 Histogram Table T Advance Advance a number of records from present record num ber If no num_record number of records is provided 1 is assumed Syntax Response A dvance num_record history_no cr If Example A9 5 current record is 17 calibration history s record 26 17 9 is located 5 27 05 Model 812 User Manual B 25 Backup Backup a number of records from present record num ber Syntax Response Backup num record history no cr If If no num_record number of records is provided 1 is assumed Example B9 5 current record is 17 locates calibration history record 8 17 9 Find Find record number directly Syntax Response F ind rec history_no cr If Example F9 5 locates calibration history record 9 Generally one uses the Find command to get to the first record F1 2 and the Advance command A to move up through the records History Data Variables Interval History Variables Brackets in the syntax indicate optional characters and operands Syntax Response I nterval var_noIntv_var B 26 Model 812 User Manual 5 27 05 Example I9 5 current record is 17 RMS Exceedance count in record 12 Example
80. ed in the test area Make sure to check the battery Chapter 2 or connect to external power Also consider the safety of the instrument during the test period Finally verify that the cur rent time and date are set correctly in the internal clock of the 812 The following section covers setting the time and date The Model 812 will turn itself on and begin measurement at the appropriate time 6 4 Model 812 User Manual 5 27 05 Using the Time Key Functions In Chapter 5 we learned to take a measurement and examine some of the data gathered during that reading The TIME key functions as a record of when the last measurement started Two screens are available in this function Step 1 Press and to access this informa tion 5 27 05 Model 812 User Manual Current time day and day of week are controlled by parame ter 6 8 This screen displays the time and date the current or last measure ment began The second display shows the cur rent date day and time 6 5 Step Press to return to the main screen Setting the Password Lock to Secure Settings The Model 812 SLM can insure that your settings will not be disturbed by providing a Lock Password parame ter items 28 29 Step 1 From the previous field press v or from the Refer to Chapter 4 to review enter main screen press 5 Modify 2 8 Enter ing numbers or letters by using the You can also press 59
81. efinition of Wave length the distance will vary with frequency The most common example of a near field is driving an automobile with an open window As you move your ear to the plane of the window the sound pressure level builds up rapidly wind noise since most of the pressure changes are to move the air and very little of it compresses the air to create sound Persons not far way can hardly hear what you hear The acoustic near field is characterized by pressures that do not create sound that can be measured in the far field Therefore measurements made here are not useful in predicting the sound levels far way or the sound power of the source Geometric Near Field The distance from a source of sound is less than the largest dimension of the sound source In the near field effect of source geometry is significant Sound Model 812 User Manual C 11 Noise Noise Dose D Noise Exposure C 12 sources often have a variety of specific sources within them such as exhaust and intake noise When in the near field the sound of a weaker but close source can be louder than that of a more distant but stronger source Therefore measure ments made here can be used to separate the various sources of sound but are not useful in predicting the sound levels and sound spectrum far from the source Typically it is unwanted sound This word adds the response of humans to the physical phenomenon of sound The descriptor should be used
82. el 812 User Manual Q31 Q LKEN LOCK FUNCTION Q32 Q LKRES LOCK RESET Q33 Q LKPWR LOCK THE ON KEY Q34 Q LKIO LOCK I O Q35 Q CALLVL CAL LEVEL Q 36 Q CALSN CALIBRATOR S N Q37 Q AUTOCAL AUTO CALIBRATION MODE Q38 Q CALTIM AUTO CAL TIME Q39 Q DETC DETECTOR Q 40 Q WGHT FREQUENCY WEIGHTING Q41 Q HPASS HIGH PASS FILTER unused Q42 Q LPASS LOW PASS FILTER unused Q 43 Q MICV MIC POLARIZATION unused Q44 Q REFLVL RELATIVE LEVEL REFERANCE Q 45 Q CXRATE CURRENT EXCHANGE RATE Q 46 Q CTHOLD CURRENT THRESHOLD Q47 Q CCRIT CURRENT CRITERION Q 48 Q OXRATE OVERALL EXCHANGE RATE Q 49 Q OTHOLD OVERALL THRESHOLD Q 50 Q OCRIT OVERALL CRITERION Q51 Q DOSET DOSE PERIOD Q52 Q LDLXRATE LDL EXCHANGE RATE Q 53 Q LDLTHOLD LDL THRESHOLD Q54 Q LDLCRIT LDL CRITERION 055 Q LNNI Lnn 1 PERCENT Q 56 Q LNN2 Lnn 2 PERCENT Q57 Q LNN3 Lnn 3 PERCENT Q 58 Q LNN4 Lnn 4 PERCENT Q59 Q LNN5 Lnn 5 PERCENT Q 60 Q LNN6 Lnn 6 PERCENT Q61 Q RMSTHI RMS EXCD LEVEL 1 B 18 Model 812 User Manual 5 27 05 Q 62 Q RMSTH2 RMS EXCD LEVEL 2 Q 63 Q PKTH PEAK EXCD LEVEL Q 64 Q UWTH UWPK EXCD LEVEL Q 65 Q HYST EXCD HYSTERESIS Q 66 Q EXENB ENABLE EXCD HISTORY Q67 Q EXXRT EXCD EXCHANGE RATE Q 68 Q EXMIN EXCD MINIMUM DURATION Q 69 Q EXHENB EXCD TIME HIS
83. ent on Step 2 Press Modify Notice the parentheses begin to flash and the f changes to n and the L is underscored Larson Davis You may now enter the appropriate letters here by using the Alpha Character Keyboard Entry shown above Step Press three times The flashing n is replaced by S 2 and 3 respectively and will remain for five seconds At this time you may select any character from the S 2 or 3 tables press that key and it will replace the let ter at the cursor _ The cursor then moves to the next letter Example To enter the company name of Larson Davis in the first line follow these steps Step 1 To access the Name Display turn on the meter The display in Step 1 above will Press 02 Enter appear Step 2 Press to place the cursor at the beginning or use the 4 or 0 to position the cursor Step 3 clear the field if necessary press SHIFT If you change your mind about twice and 4 key clearing the field hit c to return to the original title Repeat a and b in Step 5 to return to this point Step 4 The letter L is on the S field Press SHIFT Enter the 2 key second from the lower left The cursor will automatically move to the next let ter 5 27 05 Model 812 User Manual 4 5 Step 5 Step 6 Step 7 Step 8 Step 9 Step 10 Step 11 Step 12 Step 13 The letter A is on the S field Press SHIFT ag
84. es or a single block measurement from a start date and time to a stop date and time In this chapter we will discuss Using the Timer for Unattended Readings Using the Time Key Functions Setting the Password Lock to Protect Settings Using the Timer for Unattended Readings Examine the timer capabilities by looking at the parame ter fields Step 1 Turn the Model 812 on press 9 followed by The Timer parameters 21 27 2 and 1 The following display will begin with this screen parameter appear 21 5 27 05 Model 812 User Manual 6 1 Step 2 Press to access the cursor in brackets With the brackets flashing use the to select one of four possibilities Off Block 1 Day or 2 Day Example Suppose we want to measure a given area near a large machine in a factory for 5 days 2 periods each day Step 3 do this choose 2 Day and press Enter Step 4 To continue press the v to access the next parameter screen item 22 To continue our example we want to start 26 September at 8 30 A M and end at 12 00 noon begin again at 1 00 P M and end at 4 30 P M each day for 5 days Step 5 Press to change the date and enter 09 26 96 Press Enter The new Timer Run Date is now 26 Sep 1996 6 2 Model 812 User Manual Block Run Time 1 on Run Date to Stop Time 1 on Stop Date 1 Day Run Time 1 to Stop Time 1 each day from Run Date to Stop Date 2 Day Run Time 1
85. esponse 1 Q66 No 2 Q66 1 Excd History Enable No 3 Q66 2 _No 4 Q66 32 0 5 Q66 3 Excd History Enable _No Responses are denoted by x if Yes No or n if numeri cal Ql Q RESALL RESET ALL Q2 Q HDG1 HEADING LINE 1 Q3 Q HDG2 HEADING LINE 2 B 16 Model 812 User Manual 5 27 05 Q4 Q HDG3 HEADING LINE 3 Q5 Q TITLE MEASUREMENT TITLE Q6 Q TIME CURRENT TIME Q7 Q DATE CURRENT DATE Q8 Q DAY DAY OF WEEK Q9 Q BAUD COMI BAUD RATE Q10 Q SADDR COMI ADDRESS Q NI RESERVED PARAMETER Q12 Q HS COM PORT HANDSHAKING REGISTER Q13 Q NI RESERVED PARAMETER Q14 Q LOGIC1 OUTPUT 1 LOGIC unused Q15 Q OUTITIM OUTPUT 1 HOLD TIME unused Q16 Q LOGIC2 OUTPUT 2 LOGIC Q17M Q OUT2TI OUTPUT 2 HOLD TIME unused Q 18 Q HALT HALT LINE MODE Halt Line Mode Q18 has a None state available This allows systems with intrusion alarm hardware to be disabled during servicing The choices are None Pause Toggle Level Alarm Q19 Q BEEP BEEP WHILE RUNNING unused Q20 Q PWRSV POWER SAVE OPTIONS Q21 Q TIMMD TIMER MODE Q 22 Q RUND TIMER RUN DATE Q23 Q STOPD TIMER STOP DATE Q 24 Q RUNTI TIMER RUN TIME 1 Q25 Q STOPTI TIMER STOP TIME 1 Q26 Q RUNT2 TIMER RUN TIME 2 Q27 Q STOPT2 TIMER STOP TIME 2 Q 28 Q LKCOMB LOCK COMBINATION Q29 Q LKRS LOCK R S KEY Q30 Q LKSU LOCK SETUP 5 27 05 Mod
86. etup Model 812 User Manua 2 7 Getting to Know Screen Symbols Symbols basic to the Model 820 are included below These are generally found to the right of the screen The Operating Mode Indicator upper right character indi cates whether data is being accumulated or not and has the modes indicated by the first four examples The Keyboard Status Indicator displays which key func tions are active The lower four modes are possible and appear in the lower right corner or the display Symbol Functionality S S S flashing upper case to lower case Model 812 is stabilizing upon warm up 10 45 sec or SETUP weighting 8s or bias voltage 30s change in stop mode Stop mode no data is being taken Run mode OV Overload These letters in succession occur alternately with the stick figure with 8 second intervals when an over LD load has occurred 2 8 Model 812 User Manual 5 27 05 Functionality flashing Indicates that the function keys Lmin Dose etc are used for differ ent purpose in the current function Indicates that numeric key input mode is active SHIFT key active secondary function in orange lettering If the Model 812 is still stablizing upon warmup and the R S Run button is pushed r will flash alternately with S 5 27 05 Model 812 User Manua 2 9 Understanding the Model 812 Screen The operating screen for the Mode
87. evels of sound This weighting is seldom used See table below C Weighting A filter that adjusts the levels of a frequency spectrum in the same way the human ear does when exposed to high levels of sound This weighting is most often used for evaluation of equipment sounds See table below Flat Weighting A filter that does not adjust the levels of a fre quency spectrum It is usually an alternative selection for the frequency weighting selection Center Frequencies Hz Weighting Network Frequency Response 1 3 Octave 1 Octave A B 20 504 24 2 6 2 25 44 7 20 4 4 4 31 5 31 5 39 4 17 1 3 0 40 34 6 14 2 2 0 50 30 2 11 6 13 63 63 26 2 9 3 0 8 80 22 5 7 4 0 5 10 19 1 5 6 0 3 125 125 16 1 4 2 0 2 16 13 4 3 0 0 1 20 10 9 2 0 25 250 8 6 AS 0 315 6 6 0 8 40 4 8 0 5 50 500 3 2 0 3 0 63 1 9 0 1 80 0 8 0 1000 1000 0 0 1250 0 6 0 1600 1 0 0 0 1 2000 2000 12 0 1 02 2500 13 0 2 0 3 3150 1 2 0 4 0 5 4000 4000 1 0 0 7 0 8 5000 0 5 152 1 3 6300 0 1 1 9 2 0 8000 8000 1 1 2 9 3 0 10000 25 43 4 4 12500 4 3 6 1 6 2 16000 16000 6 6 8 4 8 5 20000 93 11 1 11 2 Model 812 User Manual 5 27 05 eq Level dB Measurement Duration T Microphone Guidelines 5 27 05 See Energy Equivalent Sound Level Sound Level Energy Average a
88. evious section In this example we are viewing the Leg and Peak data that was gathered during the history period This display contains History information about the measure ment It was started by a key stroke 7 3 Step 2 Press the v key to see what could be the beginning of dozens of readings depending upon your measurement Log and Data The Log key function in SETUP is a Run Stop log It indicates how many times the measurement was started and stopped and at what time Once the measurement is in progress information can be examined as follows Press SHIFT and and access Log screens Step 1 Step 2 Pressthe 0 key for the next screen Step 3 Go back to LOG a by pressing the key Tog gle through the record logs by pressing 3 7 4 Model 812 User Manual Press the readings v key to view other This screen gives you information about the most current readings This measurement was started by a key stroke If it had been started by preset alarm Key would have been replaced with Alm The Log information indicates that the measurement was stopped by keystroke If a low battery had been the reason for the measurement stopping BATT would have appeared To retain data already gathered the Model 812 will ter minate the measurement when battery power becomes low 5 27 05 Step 4 The z and keys may be used to look at addit
89. f far fields the acoustic far field and the geometric far field Acoustic Far Field The distance from a source of sound is greater than an acoustic wavelength In the far field the effect of the type of sound source is negligible Since the wavelength varies with frequency See the definition of Wavelength the distance will vary with frequency To be in the far field for all frequencies measured the lowest fre quency should be chosen for determining the distance For example if the lowest frequency is 20 Hz the wavelength at normal temperatures is near 56 ft 17 m at 1000 Hz the wavelength is near 1 1 ft 1 3 m See the definition of Acoustic Near Field for the advantages of in the acoustic far field Geometric Far Field The distance from a source of sound is greater than the largest dimension of the sound source In the far field the effect of source geometry is negligible Sound sources often have a variety of specific sources within them such as exhaust and intake noise When in the far field the sources have all merged into one so that measurements made even further away will be no different See the defini tion of Geometric Near Field for the advantages of being in the geometric far field A sound field that is free of reflections This does not mean that the sound is all coming from one direction as is often assumed since the source of sound may be spatially exten sive See the definitions of near and far fields for
90. formation below You may be asked to give this information in any future communications you have with Larson Davis Inc Record of Serial Number and Purchase Date System 812 Serial PRM3828 Pre amp Serial Microphone Model Microphone Serial Purchase Date Recycling Larson Davis Inc is an environmentally friendly organization and encourages our custom ers to be environmentally conscious When this product reaches its end of life please recycle the product through a local recycling center or return the product to Larson Davis Inc Attn Recycling Coordinator 1681 West 820 North Provo Utah USA 84601 where it will be accepted for disposal Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 5 27 05 Table of Contents Introduction 1 1 About This Manual sees entrent rne 1 2 About This Chapter teen re rettet ere e ete sheet 1 3 Formatting Conventions sessin nnne epenn 1 3 D 1 5 Model 812 eginean 1 7 Block Diagrams nostant 1 10 Started xe Oe oet et ides 1 12 Unpacking and Inspection eese 1 12 IA CCOSSOFIOS i oe 1 13 Optional Equipment fete rere nene e era 1 15 Battery Installation nerodas 1 17 Memory Retention enne nennen 1 19 Environmental Considerations
91. from line 22 Run Log bytes day n number of Run Log records day 2 nx20 X 20 n x 20 bytes record Calibration Log bytes day 1 nx17 X 17 nx 17 bytes record Setup RAM Registers bytes used n number of registers stored day 0 nx506 n x 506 bytes record TOTAL bytes used day Sum lines 23 29 Model 812 s Memory Size 64000 See SYSTEM b TOTAL Run Time in days until out of memory Divide line 32 by 31 Model 812 User Manual 5 27 05 The Model 812 allows for tailored reports of data during and after measurements In this chapter we will access the printing option parameters for Normal Printouts and print a report Normal Printout Parameters Before proceeding with printing baud rate needs to be determined and entered Set parameter 9 to proper baud rate determined by type of printer used If after starting printing bad information is printed baud rate or printer type is probably set incorrectly To cancel printing hit and E Normal printouts can be accessed from outside the SETUP mode by following these steps Step 1 Turn the Model 812 on and press s The follow ing display will appear briefly and then scroll automatically through several options Step2 tailor your report and select the printer type and options press 7 and the following screen 5 27 05 Model 812 User Manual Printing a Report 10 1 Step 3 Step 4 Step 5
92. he data collected Taking an actual measurement with the Model 812 only requires pressing the or RUN STOP key In this chapter we will e Take a measurement Examine and briefly explain the function keys associ ated with the measurement i e 6 Gm WM BT and 8 Stopping the measurement Taking a Measurement Performing a Measurement Reading the Data This section will address measurements and the infor mation available during and after the measurement has been taken The most basic function of the Model 812 is to measure sound pressure Follow these steps to exam ine the SLM function key SLM Step 1 Turn the Model 812 on and wait for the unit to 5 27 05 Model 812 User Manua Step 2 Step 3 5 2 become stable Press E The stick figure in the upper right corner will appear to be run ning With the instrument in RUN mode press The current sound pressure level is displayed An additional six screens are available from this display Press the v key to access the first a Parameter 61 RMS Exceedance b Parameter 62 RMS Exceedance 2 c Parameter 63 Peak Exceedance d Parameter 64 UWPK Exceedance e Parameter 112 Overload current f Parameter 160 O OVLD overall overload Model 812 User Manual This instrument can store a great variety of measurements in mem ory depending on the current parameter setup Nevertheless current meas
93. he instrument is calibrating The Model 812 will wait until the reading is stable indicator is 555555 then adjust the offset for the proper reading CcCcCc An improper calibration offset for instance something greater than 39 0dB may indicate that the cali bration tone was shut off before calibration was completed or that polarization was not properly set You may repeat the previous steps or perform a Cal check The display will ask if you want to Reset ALL Data You do 5 27 05 Quick Start Before running a simple measurement it is important to set a few parameters to meet your needs and become familiar with related functions In this chapter we will discuss these items Setting parameters using Using numbers and other characters Setting Time Date and Day parameters Setting Parameters Using Function Keys The Parameter fields can be accessed in several ways Byentering numbers assigned to each parameter the numbers are located above the keys on the keypad and are discussed later in the chapter By scrolling up or down using the u or d keys Byusing any white or Orange function keys Follow these steps to access the parameters using numeric values Step 1 With the Model 812 on press and the fol lowing screen appears 5 27 05 Model 812 User Manual A complete list of parameters and their assigned numbers is found in chapter 8 You have already visited p
94. he key must be pushed No This mode must be off for all automated measurements It is rec ommended that Into Time Sync be set to No to get the full desired period Eight screens are available from the INTV mode The screen at the left gives the Time and Date of a given Interval Duration Leg Linin and Lingx Peak and UWPK and the level setting measurements INTV a gives time interval num ber and date INTV b gives duration and inter val number 5 27 05 Step 10 Press the keys to view the next or previous interval respectively Setting PassBy Functions The PassBy Function is a special event detector that mea sures the Lmax Leg and SEL of the highest single event to raise and lower 5 10 dB in SPL over the measurement period It captures events such as a vehicle or aircraft passby or other event noises such as blasts or gas get ting noise In addition to the levels measured the date and time of the Lmax and the duration of the event are recorded The maximum duration of passby event may be 1 or 2 minutes depending on the shape of the event t Occurrence Time D Duration Figure 7 1 Passby Diagram Start of Passby URP 5 27 05 Model 812 User Manual INTV c gives SEL and Leg INTV d gives min and max level and the number of times level went over RMS exceedance 1 INTV e gives and unweighted peak levels INTV f h gives statistical infor mation 7 7
95. he signal then averages it in accordance with the time weighting char acteristic and then takes the square root This results in an amplitude described as rms root mean square Eight Hour Time Weighted Average Sound Level rwA g It is the constant sound level that would expose a person to the same Noise Dose as the actual unsteady sound levels The equation for it is D Lrwa s L qLogw o7 NOTE This definition applies only for a Criterion Duration of 8 hours Standard ANSI 12 19 Energy Equivalent Sound Level Leq The level of a constant sound over a specific time period that has the same sound energy as the actual unsteady sound over the same period T2 frr t dt 2 L ge l0Logig Pot e where p is the sound pressure and the Measurement Dura tion specific time period T T gt T See Sound Exposure Level Exchange Rate Q Exchange Rate Factor q Exposure Factor k It is defined in ANSI 51 25 as the change in sound level corresponding to a dou bling or halving of the duration of a sound level while a con stant percentage of criterion exposure is maintained The 5 27 05 Model 812 User Manual C 5 Far Field Free Field Frequency Hz rad sec C 6 rate and the factors are given in the table below Standard ANSI 12 19 Exchange Rate Q Exchange Rate Exposure Factor k Factor q 3 01 10 1 4 13 333 75 5 16 667 60 6 02 20 50 There are two types o
96. hen the voltage falls below 5 7 volts Therefore you should verify that the remaining battery capacity is sufficient before you make an especially critical or lengthy mea surement Step 1 To manually check battery voltage simply press the GHIFT keys Information simi lar to the following will display 5 27 05 Model 812 User Manua When the system initiation is com plete a stick figure in the upper right corner of the display will appear seated indicating the Model 812 is in STOP mode WARNING Do not press the key during a measure ment since it will pause the measurement while pressed Remember pushing a button can produce small low level noises which can affect your readings In addition the Model 812 momen tarily pauses the current measure ment whenever a key is pressed in order to interpret the keyboard event Therefore where possible do not press the key during a valid event you wish to measure The first screen shows the percent age of power left in the battery the internal power source INT sec ond display indicates external power is being used EXTV Turning Off the Model 812 To turn off the Model 812 simply press the The instrument will not allow key itself to be turned off until in Stop mode This feature will insure that no important data is lost 2 12 Model 812 User Manual 5 27 05 Calibration Because of variation in microphone sensitivities a sound
97. hours C 2 Model 812 User Manual 5 27 05 will produce a 100 Noise Dose See Noise Dose Standard ANSI 12 19 Criterion Sound Exposure CSE The product of the Criterion Duration and the mean Criterion Sound Level L square sound pressure associated with the Criterion Sound Level when adjusted for the Exchange Rate It is expressed in Pascals squared seconds when the exchange rate is 3 dB where q is the Exchange Rate Factor See Exchange Rate L q CSE T 10 Standard ANSI 1 25 It is the sound level which if continually applied for the Cri terion Duration will produce a Noise Dose of 100 The cur rent OSHA Criterion Level is 90 dB Standard ANSI 512 19 Daily Personal Noise Exposure gp It is the level of a constant sound over the Criterion Duration that contains the same sound energy as the actual unsteady sound over a specific period The period is gener ally shorter so the sound energy is spread out over the Crite rion Duration period Example If the Criterion Duration 8 hours and the specific period is 4 hours and the average level during the 4 hours is 86 dB then the Lgp 4 83 dB Day Night Average Sound Level DNL Lan A rating of community noise exposure to all Decibel dB 5 27 05 sources of sound that differentiates between daytime and nighttime noise exposure The equation for it is 0700 2200 2400 L 10 10 L 10 L 10 10 Lj 1910810 10 10 10 0000 0700 2200
98. ify Mode The charts below Figures 4 1 to4 4 show the charac ters that are available They are listed according to the number of times you consecutively press the SHIFT key The shift indicator in the lower right corner of the instrument s display will show the number of times the SHIFT key has been pressed by showing the letter n and S then 2 and 3 respectively for 0 to 3 presses Figure 4 1 Standard Alpha Numeric Keyboard Layout 5 27 05 Model 812 User Manual This panel is available without pressing the shift key or the equiv alent of 0 presses 4 3 CANCEL CANCEL Ea Figure 4 4 3 Shift Level Alpha numeric Keyboard 4 4 Model 812 User Manual This panel is accessed by pressing the shift key one time The S will appear in the lower right corner of the display indicating this panel is accessed This panel is accessed by pressing the shift key two times The num ber 2 appears in the lower right corner of the display indicating this panel is accessed This final panel is accessed by pressing the shift key three times The number 3 appears in the lower right corner of the display indicating this panel is accessed 5 27 05 Step 1 Turn the Model 812 on and press these keys All but the last of these screens you Modify O 2 Enter have seen before This display is to set one of four custom instrument name screens which will appears each time you turn the instrum
99. individually Each is given a unique address parameter or item 10 The addresses are sent as a single byte ranging in value from 129 to 255 representing address 1 to 127 respectively address plus 128 Whenever an address byte is received only the corresponding instrument is enabled to receive commands 5 27 05 Model 812 User Manual The following instruments are compatible on a common network Models 712 720 812 820 870 and TAC100 Future instruments may also be compatible with this network B 3 A broadcast command can be sent By sending an address of zero CHR 128 all units on the chain will become addressed and accept the commands that fol low Only the device with an address of 1 will respond to the commands if data transfer is required This will allow all units to be started at the same moment or to have the same parameter sent to all devices with one command i e set all clocks to the same time These devices cannot be just paralleled together That would short outputs together and damage the instru ments Use the designated cables Commands The commands are a series of ASCII characters with an alpha command and one or two numeric operands fol lowed by a charge return ASCII 13 The commands may be spelled out though only the first character is sig nificant ie READ 123 may be abbreviated to R123 Every command has a response to acknowledge that it was received correctly and to provide data requested Fo
100. ional records Press the i to look at associated dates and times Interval History The Interval History Parameters allow you to select and define the interval size and determine what data are to be saved Each interval gives you Leq SEL Min Max Peak UWPK Exceedance count and if you turn this feature on L s Listed below is each parameter and a brief explanation of its function Step 1 To access the Interval History parameters press You may also use numeric val ues Modify 7 2 Enter The choices are Yes No Step 2 Press the to access the next parameter 73 Into Exchange Rate for these choices 3dB 4dB 5dB 6dB Step 3 Press the v to item 74 Intv Threshold You may find 80 dB preset but you may enter another value 0 255 Step 4 Press the to item 75 Into Period Press and the numeric values for the interval period desired and then press Enter hh mm 5 Pressthe to Intv Time Sync item 76 for these choices Yes No 5 27 05 Model 812 User Manual With this item set to Yes the Interval Time History ITH is enabled Note Be sure that total memory requirements do not exceed available memory This parameter is the exchange rate used for each interval Set this to 3 dB for community noise and 5 dB for OSHA studies This sets the TWA threshold for the interval time history For hear ing conservation purposes 80 dB is r
101. key and use the numeric keys to enter correct time and then press Enter Step3 The Current Date is the next field Press the v to the next display Step 4 The Day of the Week is in the next field Press v to access that field 5 27 05 Model 812 User Manual The current date will appear If it is incorrect press m to access the field enter the correct date using the corresponding number keys and press e If the day is incorrect press m and r or 1 to the correct day Press Enter To exit the setup mode press Cancel 4 7 AC DC Output AC and DC is accessed by the use of the optional CBL042 or by using a stereo miniphone plug as shown in figure 4 5 The DC output provides a voltage from the RMS detector that is proportional to the sound level The scale is 20 3 mV dB The output voltage is 0 3 volts with an output impedance of 600 The AC output gives an AC signal proportional to input signal and can be Flat or A and C weighted It is used to record input signal to the Model 812 see Appendix A for more details CBLO42 DC Output ring AC Output tip a i is Ground sleeve Figure 4 5 AC DC Output Connector 4 8 Model 812 User Manual AC Output black DC Output red 5 27 05 With the basic parameters set and the instrument cali brated as discussed in Chapters 3 and 4 you are ready to take a measurement and examine the readings from t
102. l 5 27 05 OSHA Level LosuA Preamplifier Projected Noise Dose 1007 Z L Q 0 The Average Sound Level calculated in accordance with the Occupational Safety and Health Administration Exchange Rate and Threshold Level A part of the sound level meter that matches a particular model of microphone to the meter It must be chosen in con junction with a microphone and a cable that connects them Itis the Noise Dose expected if the current rate of noise expo sure continues for the full Criterion Duration period Single Event Noise Exposure Level SENEL Lax The total sound energy over a specific Sound 5 27 05 period It is a special form of the Sound Exposure Level where the time period is defined as the start and end times of a noise event such as an aircraft or automobile passby The rapid oscillatory compressional changes in a medium solid liquid or gas that propagate to distant points It is characterized by changes in density pressure motion and temperature as well as other physical quantities Not all rapid changes in the medium are sound wind noise since they do not propagate The auditory sensation evoked by the oscillatory changes Difference between sound and noise Sound is the physical phe nomenon associated with acoustic small pressure waves Use of the word sound provides a neutral description of some acoustic event Generally noise is defined as unwanted sound It can a
103. l 812 User Manual 5 27 05 Near Field 5 27 05 extra force required to reflect the sound and a microphone output that is higher than would exist if the microphone were not there This is more important at high frequencies and when the microphone is facing the sound source Rules 1 Do not use a microphone at frequencies higher than speci fied by the manufacturer to increase the frequency response choose smaller microphones 2 Choose a microphone for free field or random incidence to minimize the influence of orientation A microphone measures what is there from any direction Most measurements are intended to measure the sound level of a specific source but most microphones are not directional so they measure whatever is there regardless of source Rules 1 When making hand held measurements keep your body at right angles to the direction of the sound you are inter ested in and hold the meter as far from your body as possi ble Use a tripod whenever possible 2 Measure the influence of other sources by measuring the background sound level without the source of interest You may have to correct for the background There are two types of near fields the acoustic near field and the geometric near field Acoustic Near Field The distance from a source of sound is less than an acoustic wavelength In the near field the effect of the type of sound source is significant Since the wave length varies with frequency See the d
104. l 820 has several fields which vary according to the keys pressed on the keypad The most pertinent information is generally at the top and center to left and instructions are generally on the bottom center to left Several characters are consistent in their appearance We will now turn the Model 820 on and examine a variety of possible screens Turning On the Model 812 Step 1 Press to power the Model 812 and initiate a self test Step2 The third screen automatically appears 2 10 Model 812 User Manual Three successive displays will appear while the meter stabilizes for 10 45 seconds The first display has copyright information and appears only 1 to 2 seconds The second display shows the pro duction date and the serial number uniquely assigned to your Model 812 This message appears for only 1 or 2 seconds This screen will remain until the user inputs other commands The flashing uppercase S indicates system initiation and will con tinue 10 45 seconds 5 27 05 The third screen appears almost immediately showing the title information for the current or last reading and is programmable by the operator At this point you can change the parameters and begin taking actual measurements Checking the Battery Voltage The Model 812 continuously monitors its battery voltage to ensure accurate measurements It has a battery life of about sixteen hours It will turn off automatically w
105. l Lmin Date and Time ddmmmyy hh mm ss R17 _C LMIN Current Minimum Level nnn n dB R18 _C TMIN Current Lmin Date and Time ddmmmyy hh mm ss R19 _O LMAX OverAll Maximum Level nnn n dB R20 _O TMAX OverAll Lmax Date and Time ddmmmyy hh mm ss R21 _C LMAX Current Maximum Level nnn n dB R22 _C TMAX Current Lmax Date and Time ddmmmyy hh mm ss R23 _O LPEAK OverAll Peak Level nnn n dB R24 _O TPEAK OverAll Lpeak Date and Time ddmmmyy hh mm ss R25 _C LPEAK Current Peak Level nnn n dB R26 _C TPEAK Current Lpeak Date and Time ddmmmyy hh mm ss R27 _O LUWPK OverAll UWPk Level nnn n dB R 28 _O TUWPK OverAll Luwpk Date and Time ddmmmyy hh mm ss R29 C LUWPK Current UWPk Level nnn n dB R30 _C TUWPK Current Luwpk Date and Time ddmmmyy hh mm ss R31 RMSCNT OverAll RMS Exceedances 1 nnnnn R32 RMSCNT2 OverAll RMS Exceedances 2 nnnnn R33 _PEAKCNT OverAll Peak Exceedances nnnnn R34 _UWPKCNT OverAll UWPk Exceedances nnnnn R35 _OVLDCNT Overloads nnnnn R36 _PSECNT Number of PAUSES nnnnn R37 _PTIME PAUSE Time OFF not inc hhhhh mm ss 5 27 05 Model 812 User Manual R38 En 1 nnn n dB R 39 _EN2 Ln 2 nnn n dB R40 _LN3 Ln3 nnn n dB R41 _LN4 Ln4 nnn n dB R42 _LNS Ln 5 nnn n dB R43 _LN6 Ln6 nnn n dB R44 _O DOSE Overall Dose nnnnn n R45 _C DOSE Current Dose nnnnn n R46 _O PROJ Overall Projected Dose nnnnn n R47 _C PROJ Current Projected Dose nn
106. level meter must be calibrated to a reference sound level for accurate measurements This is easily performed with the Model 812 You will need a calibrator with an appropriate adapter for the Model 812 microphone such as the Larson Davis CAL200 This Larson Davis calibra tor outputs 114 dB or 94 dB with respect to 20 and at a frequency of 1000 Hz At this frequency the relative response for A and C weightings is the same NOTE A precision calibrator is not necessary for this part of the tutorial but you should make it a regular practice to perform an instrument calibration before and after you take actual measurements in the field However you do not have to recalibrate the Model 812 when you change the settings Please note that if you use a calibrator which uses another frequency some corrections may be required depending on the weighting The output level and the frequency of your calibrator should be listed on its label Use this level with specific environmental and weight ing corrections to calibrate the Model 812 level In order to perform calibration the Microphone Polar ization Voltage needs to be properly set Calibrating the Model 812 Microphone Polarization Voltage is preset by Larson Davis at 200 volts Should this parameter be incorrect the Model 812 will not calibrate correctly Step 1 Check the microphone polarization by looking 5 27 05 Model 812 User Manual 3 1 Step 2 Step 3 Step 4 3
107. lso be defined as sound that causes adverse effects on people such as hearing loss or annoyance It can also be defined as the sound made by other people In every case noise involves the judgment of someone and puts noise in the realm of psychology not physics Rules 1 Use word sound to describe measurements to remove the emotional overtones associated with the word noise Some Model 812 User Manual C 13 Sound Exposure SE sound metrics use noise in their name and it is proper to use the name as it is It is the total sound energy of the actual sound during spe cific time period It is expressed in Pascals squared seconds T SE where pa is the sound pressure and T Ty is the Measure ment Duration specific time period When applied to hearing damage potential the equation is changed to SE ore T where k is the Exposure Factor See Exchange Rate Standard ANSI 1 25 Sound Exposure Level SEL Lgr The total sound energy in a specific time period The Sound Pressure C 14 equation for it is 12 Poa SEL 10Log Po The sound pressure is squared and integrated over a specific period of time T gt T this is called the sound exposure and has the units Pascal squared seconds or Pascal squared hours PO is the reference pressure of 20 and T is the ref erence time of 1 second It is then put into logarithmic form Itis important to note that it is not
108. mperature Press the v key and the fifth screen will appear 5 27 05 Model 812 User Manua The Peak and Unweighted Peak are displayed here Note that even in the stop mode the Model 812 continues to display the detected values on the upper right hand side of the screen The numbers on the left are the highest during the measurement and the values on the right are the current Peak and Unweighted Peak The values are shown here to be 74 9 dB C weighted the measure ment ran for 5 minutes 46 8 sec onds Should an Overload occur one of four letters OVLD would flash alternately with the stick fig ure in the upper right corner see Chapter 7 The SEL level using 3dB exchange rate is 100 3 dB and the duration of the measurement is given The Alarm can be set to begin a measurement at a designated time The here indicates the next measurement has not been chosen The current internal tem perature as measured by the Model 812 is shown in the lower portion of the screen 5 3 Step 8 Pressing the v The property controlling the final screen in this series is built into the Model 812 to conserve power Press the v key 07 key again will scroll loop you back to the SLM original screen Now that you are more familiar with the information available in the displays above lets take a closer look at the parameters that affect these readings Step 1 Step 2
109. n multiple of ten the exponent is more com plicated as shown in the table Every time the level increases by 3 dB the value is multiplied by 2 doubled These two rules are worth remembering Linear form Level form Exponential Form of 10 Exponent Ration of Value to Reference E Ratio 1 10 0 10 10 10 100 10 20 200 10 23 1000 10 30 10000 10 40 100000 10 50 1000000 10 60 The definition of decibel is intended for power like quanti ties W Sometimes power is represented by the square of a measured quantity and this results in a different form of the equation See Sound Pressure Level L 10L0gyo y W Wo 0 The value of the item in the table is not the value of the quan tity itself but the ratio of that quantity to a reference quan tity So for every level in decibels there must be a reference quantity When the quantity equals the reference quantity Model 812 User Manual 5 27 05 the level is zero To keep the values above zero the reference is generally set to be the lowest value of the quantity Department of Defense Level Lpop The Average Sound Level calculated in accordance with Department of Defense Exchange Rate and Threshold Level See Average Sound Level Dose See Noise Dose Detector The part of a sound level meter that converts the actual fluc tuating sound or vibration signal from the microphone to one that indicates its amplitude It first squares t
110. nd Time Weighted Average A descriptor of a measured physical quantity typically used in sound and vibration measurements It is attached to the name of the physical quantity to denote that it is a logarith mic measure of the quantity and not the quantity itself The word decibel is often added after the number to express the same thing When frequency weighting is used the annota tion is often expressed as dB A or dB B The time period of measurement It applies to hearing dam age risk and is generally expressed in hours Standard ANSI 12 19 Microphone Types A device for detecting the presence of sound Most often it converts the changing pressure associ ated with sound into an electrical voltage that duplicates the changes It can be composed of one of the following types Capacitor Condenser A microphone that uses the motion of a thin diaphragm caused by the sound to change the capaci tance of an electrical circuit and thereby to create a signal For high sensitivity this device has a voltage applied across the diaphragm from an internal source Electret A microphone that uses the motion of a thin dia phragm caused by the sound to change the capacitance of an electrical circuit and thereby to create a signal The voltage across the diaphragm is caused by the charge embedded in the electret material so no internal source is needed Microphone Uses The frequency response of microphones can be adjusted to be used in
111. ne Preamplifier and Battery Type The Larson Davis Model 812 with attached PRM 828 preamp and Model 2541 microphone is a combination Type 1 precision integrating sound level meter and sta tistical data logger The Model 812 can also be used with any Of the Larson Davis 1 2 condenser microphones They may also be used with any Larson Davis 1 4 or 1 microphones provided they are used with an ADP011 1 4 to 1 2 preamp adapter or an ADP008 1 to1 2 preamp adapter attached to the PRM 828 The Model 812 polarization voltage can be set to either 200V or 28V Reference Direction The reference direction is perpendicular to the plane of the microphone diaphragm when using a free field microphone e g Larson Davis 2540 or 2541 in a free field The microphone should be pointed directly at the source A 2 Model 812 User Manual 5 27 05 When using a random incident microphone in a free field the microphone should be pointed 80 degrees off axis of the source of the sound When in a random sound field a random incident microphone e g Larson Davis 2559 or 2560 may be pointed in any direction Measurement Ranges RMS Detector Dynamic Range gt 110 0 dB Primary Indicator Range gt 105 0 dB The instrument will have a different Noise Floor Lower Limit and Overload Level depending on the sensitivity of the microphone used Some typical values for 2 dif ferent Larson Davis microphones are listed in the table below
112. nnn n R48 _LDLDOSE LDL Dose nnnnn n R49 _LDLPROJ LDL Projected Dose nnnnn n R50 _LDLLINT LDL Lint nnn n dB R51 _LDLSEL LDL SEL nnn n dB R52 _LDLXR LDL Exchange Rate Text R53 _LDLVALID LDL Valid display see note below R54 RELLVL Last Level Relative to REFLVL nnn n R55 TABLE Display Histogram Selected ccc R56 COUNT Display Overall Count nnnnnk R57 _O LEQ Overall Leq nnn n dB R58 _D LEQ Daily Leq nnn n dB R59 _H LEQ Hourly Leq nnn n dB 60 h _HNL Hourly Leq 0 23 nnn n dB 618 HNLPART Hourly Leq partial indicator nnn n dB R62 _O LDN Overall LDN nnn n dB R 63 _D LDN Daily LDN nnn n dB R64 _H LDN Hourly LDN nnn n dB R65 _O CNEL Overall CNEL nnn n dB R66 _D CNEL Daily CNEL nnn n dB R67 _H CNEL Hourly CNEL nnn n dB Model 812 User Manual 5 27 05 NOTE An LDL Logged Data Logic recalculation can be started with a LDLVALID I O Read Command When the Model 812 is RUNNING the Valid condition will remain in effect for 1 second The LDLVALID Read Command provides three responses LDL Valid Calculating and LDL Invalid NOTE The exceedance Leq R68 and exceedance time R69 include data from qualified events that are stored in the EXCD History If an event is discarded because it was shorter than the minimum duration then it will not be included in these values R 70 BGLEQ Background Leq nnn n dB R 71 85 unused unused variable
113. o threshold TIME The date and time of last reset or measurement start are available from the Time a display The current date and time are shown with the Time b display C A SEL SEL The Single Event Level or Sound Exposure Level is an energy reading in decibels It is the TWA level plus 10 times the log of measurement time in seconds SEL b Gives exposure Pa H which is a linear representation of energy C A The C A function a hearing protec tor evaluation calculates a running C weighted Leq and a running A weighted Leq in a sequential manner and the differ ence between them is calculated and shown giving a C A value TAKT TWA TWA Time Weighted Average SPL This display shows the Overall TWA and Run Time TAKT The German Takt Maximal Lev els Takt 3 and Takt 5 are an integration of the largest level in a 3 second and 5 second period respectively 2 6 Model 812 User Manual 5 27 05 Functions DOSE The Dose and Projected Dose sound exposure percentages are dis played in these screens Parameters 48 51 control the Dose measurement E Sound Exposure is a linear energy reading used to assess potential for hear ing loss or annoyance 5 27 05 Arrows Up Down Left and Right arrows are used to change fields to modify information within a given field and can be used in conjunction with other keys to allow other functions Modify Prepares the field for changes while in s
114. odel 812 is ready for use Environmental Considerations The Model 812 sound level meter can be both used and stored in a wide range of temperatures free of moisture and non condensing humidity conditions Moisture will cause the breakdown of an air condenser microphone Some common sense precautions should be taken For example allow the Model 812 ample time to adjust to abrupt temperature changes Condensation may form inside a cold Model 812 if it is brought into a warm room or vehicle and may persist long after the outside case has adjusted to the ambient temperature Also temperatures inside closed vehicles can reach excessive levels Therefore do not leave the instrument in direct sunlight in a vehicle A simple safeguard is to keep the instrument inside a sealed foam insulated case or bag with desiccant silica gel available at photographic equipment stores or from Larson Davis Preparing to Use the Model 812 Connecting the Mic Preamp Before powering the SLM carefully thread the micro phone on the preamplifier The microphone bias voltage is not dangerous but installing or removing the micro phone with the instrument on may damage the electron ics Insert the 828 in the nose cone or extension cable by lining up the latch button with the channel in the mating connector The small black dot should click and pro trude at the base of the 828 after insertion It must be depressed completely to remove the preamplifier from 1
115. on This option allows saving the weighted peak Peak unweighted Peak UWPK or Max RMS level Lmax with each RMS history sample See the following step This is for editing purposes only All history is stored regardless of this base level However only data above the base level are displayed This parameter controls the stored data which the preceding base level operates For example if this was set to Peak and the base level set to 5 27 05 Step 11 To change the field press f and Enter Step 12 Press the v to item 87 Histogram Resolution for these options 1 8 1 2 1 0 2 0 5 0 10 Step 13 Select the value you want Press 0 to the proper setting and then press Enter Time History Data In Chapter 5 you learned how to take a measurement To examine the History of that measurement take the fol lowing steps Step 1 To access Time History press and a screen similar to the following will appear 5 27 05 Model 812 User Manual 100 dB only peaks 100 dB and above would be displayed The Model 812 provides an ampli tude distribution that can be read on the display If the resolution is not satisfactory a different one may be selected and the amplitude distribution re displayed printed This is possible because all data is stored to the nearest 1 8 dB The Time History is used to view the data that was acquired with the settings discussed in the pr
116. only when negative effects on people are known to occur Unfortunately this word is used also to describe sounds with no tonal content random Ambient The all encompassing sound at a given location caused by all sources of sound It is generally random but need not be Background The all encompassing sound at a given location caused by all sources of sound but excluding the source to be measured It is essentially the sound that interferes with a measurement Pink It is a random sound that maintains constant energy per octave Pink light is similar to pink noise in that it has a higher level at the lower frequencies red end of the spec trum White It is a random sound that contains equal energy at each frequency In this respect it is similar to white light It is the percentage of time a person is exposed to noise that is potentially damaging to hearing Zero represents no expo sure and 100 or more represents complete exposure It is cal culated by dividing the actual time of exposure by the allowed time of exposure The allowed time of exposure is determined by the Criterion Duration and by the sound level the higher the level the shorter the allowed time The sound levels must be measured with A frequency weighting and slow exponential time weighting See Projected Noise Dose where T is the Measurement Duration and T is the Allowed Exposure Time Standard ANSI 12 19 See Sound Exposure Model 812 User Manua
117. onse of the system to rapid changes These are stan dardized into three values called Time Weighting See the values below Fixed Average The averaging process is over a fixed time period The equation for it is The sound pressure is squared and averaged over a fixed time period Unlike the moving average the sound pres sures in all time intervals are equally weighted Model 812 User Manual C 15 Sound Pressure Level SPL 1 The logarithmic form of sound pressure It is also expressed by attachment of the word decibel to the number The loga rithm is taken of the ratio of the actual sound pressure to a reference sound pressure which is 20 MicroPascals 1 Pa There are various descriptors attached to this level depend ing on how the actual sound pressure is processed in the meter Instantaneous The time varying reading on a meter face on in a meter output due to changes in the sound pressure The reading will depend on the time weighting applied The fundamental relationship between the two is logarith mic Prms L 20log P L 20 where is the reference sound pressure of 20 The square of the sound pressure is a power like quantity that can be expressed in the original form of the level definition 2 rms 2 2 L 10 L 2 Prms 10 Sound Pressure Level can be converted to sound pressure as follows If the sound pressure is 1 Pascal then the sound pre
118. quation for it is fas 101081 y w Wo 0 The speed at which sound waves propagate It is measured in meters per second It should not be confused with sound or particle velocity which relates to the physical motion of the medium itself c 20 05 4degC 273 m sec 49 03 degF 460 ft sec Spectrum Frequency Spectrum The amplitude of sound or vibration at various frequen 5 27 05 cies It is given by a set of numbers that describe the ampli tude at each frequency or band of frequencies It is often prefixed with a descriptor that identifies it such as sound Model 812 User Manual C 17 Threshold Sound Level Lt pressure spectrum It is generally expressed as a spectrum level The A weighted sound level below which the sound pro duces little or no Noise Dose accumulation and may be dis regarded It is used for hearing damage risk assessment Standard ANSI 51 25 Time Weighted Average Sound Level TWA LrwA rc It is the level of a constant sound Time Weighting Vibration over the Criterion Duration that would expose a person to the same Noise Dose as the actual unsteady sound over the same period If the Exchange Rate is 3 dB then the TWA is equal to the Leg 1 2 1 Lrwatc Klogjo zl 10 Ti ECR y where T T5 T4 is the Exchange Rate Factor It is used for hearing damage risk assessment Standard ANSI 12 19 The response speed of the detector in a sound level meter There are
119. r ence between the two cutoff frequencies is called the band width It is used to discriminate against both lower and higher frequencies so it passes only a band of frequencies Octave band A bandpass frequency filter that permits signals to pass through that have a bandwidth based on octaves An octave is a doubling of frequency so the upper cutoff fre quency is twice the lower cutoff frequency This filter is often further subdivided in 1 3 and 1 12 octaves 8 and 12 bands per octave for finer frequency resolution Instruments with these filters have a sufficient number of them to cover the usual range of frequencies encountered in sound and vibra tion measurements The frequency chosen to describe the band is that of the center frequency Note table in Frequency Filter Frequency Weighting Frequency Filter Frequency Weighting A special frequency filter that adjusts the ampli 5 27 05 tude of all parts of the frequency spectrum of the sound or vibration unlike band pass filters It can be composed of one or more of the following types Model 812 User Manual C 7 C 8 A Weighting A filter that adjusts the levels of a frequency spectrum in the same way the human ear does when exposed to low levels of sound This weighting is most often used for evaluation of environmental sounds See table below B Weighting A filter that adjusts the levels of a frequency spectrum in the same way the human ear does when exposed to higher l
120. r settings and view some of the data collected Time History Time History records includes the RMS integrated level and if selected Peak Unweighted Peak or Lmax Param eters 80 87 allow you to select the period for the history and what data are to be saved 5 27 05 Model 812 User Manual 7 1 Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Step 9 Step 10 Press the 7 2 Turn the Model 812 on and access Time History parameters Press G amp S The following screen item 80 Time history Enable appears To enter Yes press Press the x to item 81 History Resolution 0 to Yes and 1 0 dB 0 1 dB To change this setting press Modify To access item 82 Hist Save Peak press v No Peak UWPK Lmax You may press and make your selection with and then press Enter Press the to item 83 Hist Period 0 255 units Press the x to item 85 Hist Base The setting range is 0 255 dB To enter a value press the value Enter Y to item 86 Hist Base Mode Off RMS Peak Model 812 User Manual Enter Yes With this item set to Yes the time history function is enabled Despite Model 812 s large memory ensure anticipated requirements do not exceed avail able memory Normally all data is taken with 0 1 dB resolution 2 bytes level To save memory this option allows storage of history in 1 0 dB resolu ti
121. r supply 001 included Note that external supply will also power the Model 812 EXCXXX Microphone extension cable length XXX feet PSA001 AC DC power adapter 115 Vac to 9 Vdc 50 60 Hz for use with INTO002 5002 Custom hard shell airtight watertight case 131 2X127 8X 6 in CBL040 Similar to INT002 but allows one to daisy chain an additional Model 812 PSA002 AC DC power adapter 220 Vac to 9Vdc 50 60 Hz for use with INT002 EPS012 CCS002 weatherproof fiberglass case with custom cut foam interior and desiccant Sealed signal cable feedthrough Features lock hasp and may be chained through handle for security EPS013 Same as 5012 but with 8 Ah 12 Volt 5 27 05 Model 812 User Manual rechargeable battery BAT004 Provides 1 week opera tion in normal conditions Includes CBL038 and bat tery charger Note Figure 1 4 or call Larson Davis for additional infor mation on these and other accessories 5 wso001 A E S 8 B B WS005 Windscreen with birdspikes NE cT LS EPS012 Environmental Case ADPO08 amp amp 8 E mm om om mm f N JADPo11 2106 7 8 Nua _____ 812 SYSTEM EPS013 Environmental Ca
122. r Manual 5 27 05 Chapter 10 Printing a Report 10 1 App A App B 5 27 05 Normal Printout Parameters ener eret nennt 10 1 Printing Reports etude cd a Lid dd 10 3 Specifications A 1 VDC caso MM A 2 Reference Direction uel eitis A 2 Measurement RangeS 3 RMIS Det ctOP acu Hide eter e c rec ee RR A 3 Other Detectors iini tisie eratac HR MEA A 4 R f rence Level x pete etie eina A 4 Frequency Weightings sse eene nnne nennen A 4 Detector Time Weightings sees eee eee nnn A 7 Effects f Temperature vete tie eb e Bre Pee rH e grep tende A 7 Effects of iioi ise e eia eeii ara n quiate A 7 Limits of Temperature and Humidity see A 7 Microphone Extension Cables sss A 8 Optimal Positioning of Instrument and Observer A 8 AG and DC Outputs reete edi sted cbs st idee iHe doter eek EE eats A 8 UE 8 DC OVUpULbs s oen eost ese t A 9 Reference Frequency sis tie tede tiet tien tice ee een A 9 Stabilization epe neca a A 9 Microphone Electrical Impedance sse eee A 9 Functions bodie A 10 Data Stordge under tene A 10 Data Communications 0 A 10 Digital Displa
123. r high reliability systems there is an error checking protocol that is added to ensure proper command data transferal See Error Checking Protocol on page 34 The following tables summarize all of the commands and are listed in this order mode control commands first parameter commands next data extraction com mand and report data download command last Square brackets indicate optional characters or operands Syntax Response R ead variable number 0 operand 2 variable value S et parameter number parameter value acknowledge S et parameter number fixed parameter index acknowledge S et parameter number fixed parameter prompt acknowledge i e Set 8 Thu will set day of week to Thursday Q uery parameter number 0 option flags parameter value B 4 Model 812 User Manual 5 27 05 Option flags may be added for combined effect 32 Index Number 8 Tab over response 2 print in braces 1 Print parameter name K ey key_simulation_string acknowledge M ode mode_number acknowledge History Oriented Commands I nterval variable_number relative_rec variable_value L og variable number relative_rec0 variable value C alibration variable number variable value H istory variable number relative_rec variable value T ables variable number table variable value A dvance range history number acknowledge B ackup
124. r of bytes for histories nnnnnnn R 159 _MEMUSE Memory Available in percent nnn nn R 160 O OVLD OVERALL OVERLOAD FLAG c R 161 unused unused variable R 162 _O SE Overall Sound Exposure nnnnn n a The number of keys in the keyboard stack is available with the R155 command This is used with keyboard simulation to prevent the loss of keys Other Read Commands Sound Exposure E is calculated and displayed in pascal squared hours as needed in some of the European Coun tries This value is read with the R162 command and is available in the top line of the DOSE a display The for mula used is E T 10 Leq 10 20pPa where E is the Exposure T is the elapsed time in hours and 20 is the reference sound pressure 20 micro pas cal squared R 163 _TAKT3 Takt Maximal 3 Second nnn n dB R 164 _TAKTS Takt Maximal 5 Second nnn n dB 5 27 05 Model 812 User Manual Group Read Programming Code Description Response OI Read SLM data nnn n nnn n nnn n nnn n lt CR gt lt LF gt R 4 SPL R 11 TWA R 17 Lmin R21 Lmax lt CR gt lt LF gt 02 unused unused variable 03 Read Group of R variables pro grammed by n r 04 Read 812 LCD Display each line sep arated by lt LF gt The group read command and the Olther 3 com mand return the values of a list of up to 8 read variables previously defined by the programmer
125. requency response is shown in the table below 3 The AC Output frequency weighting is selected via parameter 41 AC Out Weighting It can be set to Flat weighting or it can be set to match the RMS Detector fre quency weighting The AC output s FLAT frequency response is shown in the table below Unweighted Peak FLAT Frequency Response Unweighted Peak Unweighted Peak Unweighted Peak B piden Hz FLAT Weighting FLAT Weighting EROR A Hz FLAT Weighting 10 3 4 160 0 0 2500 0 0 12 5 2 5 200 0 0 3150 0 1 16 1 7 250 0 0 4000 0 2 20 1 2 315 0 0 5000 0 2 25 0 8 400 0 0 6300 0 3 31 5 0 5 500 0 0 8000 0 4 40 0 3 630 0 0 10000 0 5 50 0 2 800 0 0 12500 0 8 63 0 1 1000 0 0 16000 0 9 80 0 0 1250 0 0 20000 1 2 100 0 0 1600 0 0 125 0 0 2000 0 0 AC Output FLAT Frequency Response Nominal AC Output FLAT Nominal AC Output FLAT Nominal AC Output FLAT Frequency Hz Weighting dB Frequency Hz Weighting dB Frequency Hz Weighting dB 10 7 6 160 0 1 2500 0 0 12 5 6 2 200 0 1 3150 0 0 16 4 7 250 0 1 4000 0 0 20 3 5 315 0 0 5000 0 0 25 2 5 400 0 0 6300 0 0 31 5 1 7 500 0 0 8000 0 1 40 1 2 630 0 0 10000 0 1 50 0 9 800 0 0 12500 0 2 5 27 05 Model 812 User Manual A 5 AC Output FLAT Frequency Response 63 0 6 80 0 3 100 0 3 1000 1250 1600 0 0 0 0 0 0 16000 20000 0 3 0 5 125 0 2 2000 0 0 Model 812 User Manual 5 27 05 Detector Time
126. rnal power adaptor such as the PSAO017 or similar 1 18 Model 812 User Manual Alternatively you may use an external power source via pin 1 GND and pin 4 of the 5 pin connector To do this order cable 035 from Larson Davis The Model 820 accepts 7 16 Vdc 30 mA and is internally fused at 0 5 A 5 27 05 Memory Retention Certain safeguards have been included to prevent data loss An internal battery with a full charge will retain memory for 3 months with the instrument off The instrument will turn off when the usable battery capacity drops to 10 This will leave approximately 1 month of memory retention Before turning off four low battery messages will appear one every 16 seconds After 64 seconds the instrument turns itself off 5 27 05 Model 812 User Manual Caution Weak batteries should always be replaced Discharged batteries will cause memory loss and may leak and damage the Model 812 Always turn the instrument off and disconnect external peripherals before removing the internal battery Failure to do so may cause data loss Do not press ON while there is no battery in the SLM With the battery removed a capacitor will retain memory for several minutes during battery change The Model 812 will instantly turn off should the volt age drop to less then about 4 4 V An error message will be displayed at next power up Warning Power Failure Once the battery is installed the M
127. se threshold This sets the period for the interval history from 1 minute up to 99 59 A 1 second interval may also be selected by entering 00 00 76 Intv Time Sync No Yes Synchronizes start of interval with clock and daily history report If Yes Is entered the interval report will be started or restarted 1f already run ning at the start of each hour or minute depending on Intv duration 77 Intv Save Ln s No Yes Selects whether interval Ln s are stored The Ln s stored are those in effect items 55 60 at end of interval Model 812 User Manual 5 27 05 79 Intv Auto Stop No Yes If yes automatically stops instrument at the end of each interval for precise timing of series of manual measure ments Use R S key to restart Time History 80 87 H This third type of history is the most conventional The rms integrated level and if selected a maximum reading are stored in memory at the end of each time history period No 80 Prompt HIST Enable Entry No Yes Comment Time history report will be stored if Yes is entered Despite the Model 812 s large memory ensure antici pated requirements do not exceed available memory 81 Hist Resolution 0 1dB 1 0dB Normally all data is taken with 0 1 dB resolution 2bytes level Allows stor age of history with 1 dB resolution to conserve memory 1byte level
128. se transducer that should be handled with care Sensitivity Microphone Type mV Pa Bias 2540 Free field 14 5 Voltage Required 2541 377B41 Free field 44 5 Voltage Required 377A02 Free field 50 0 Prepolarized 377A20 Random 50 0 Prepolarized 2559 Random 12 9 Voltage Required 2560 377A60 Random 45 2 Voltage Required Table 1 1 Microphones for use with 812 Keep clean and protect from condensing moisture and water The microphone s ultra thin 1 8 Model 812 User Manual 5 27 05 diaphragm is covered by a protective grid which should not be removed in normal use Rain droplets or other foreign matter on the diaphragm may alter the microphones s response Please use a windscreen whenever possible Replace the desiccant cartridge when necessary 20 key membrane keypad Model 812 precision hand held Sound Level Meter with integral nose cone Powered internally by 9 volt cell or by an external battery or AC DC adapter WS001 3 1 2 inch windscreen An AC DC mini phone connector with pinout shown on page 4 10 A 5 pin cable connector with the pinout shown in fig Using cable CBL038 INT002 ure Figure 1 2 Note that this connector is used to and related software the 5 pin access external power connector is used both for external power and for the remote interface 2 TXD Transmitted Data fm 812 3 RXD Received Data to 812 4 External Battery to
129. se w Battery m Note Those items marked with are standard included accessories L Software SWW SLM UTIL SWW SLM LINK EXCXXX SWW ENV 20 SWW REM SWW NMS SWW ACS LT 5 AC Out black e DC Out red lason Davis WEB Page CCS009 Soft Case INTOO2 12 4 Conductor CBLO34 6 L A Shielded gt 001 Desktop Computer To nextSIM CBLo40 12 Battery to CBLO35 4 Ea power 820 11 L 1 PSAO001 alligator clips CBL116 1 5 CBLO77 6 optional gt ge 3 lantan Camniitar Figure 1 4 System Diagram 1 16 Model 812 User Manual 5 27 05 Battery Installation To insert the 9 volt battery in the Model 812 remove the battery cover at the lower left side of the instrument by sliding it out as shown in Figure 1 5 Figure 1 5 Remove Battery DoorRemove Battery Door 5 27 05 Model 812 User Manual With the battery door removed drop the battery into the opening in the case as shown in Figure 1 6 making certain that the battery is aligned with the positive and negative electrodes as shown on the graphic inside the battery compartment Figure 1 6 Inserting Battery Internal battery life is approximately 16 hours Refer to the description in Chapter 2 of this manual for additional battery information The cable CBL116 SLN serial connectivity kit which allows connection of the 820 to a PC or modem provides the connection of an exte
130. several speeds used Slow The time constant is 1 second 1000 ms This is the slowest and is commonly used in environmental noise mea surements Fast The time constant is 1 8 second 125 ms This is a less commonly used weighting but will detect changes in sound level more rapidly Impulse The time constant is 35ms for the rise and 1 5 sec onds 1500 ms for the decay The reason for the double con stant is to allow the very short signal to be captured and displayed The oscillatory movement of a mechanical system generally taken to be solid It is used as a broad desciptor of oscilla tions Model 812 User Manual 5 27 05 Wavelength 1 Wavenumber k The distance between peaks of a propagating wave with a well defined frequency It is related to the frequency through the following equation where is the sound speed and f is the frequency in Hz It has the dimensions of length A number that is related to the wavelength of sound and is used to compare the size of objects relative to the wave length or the time delay in sound propagation It is related to wavelength through the following equation 21 2 A where is the wavelength c is the sound speed f is the fre quency in Hz and o is the radian frequency It has the dimensions of inverse length Yearly Average Sound Level YDNL Lygn The Day Night Average Sound Level for each 5 27 05 day is averaged over the entire
131. specific applications Among those used are Frontal incidence Free Field The microphone has been adjusted to have an essentially flat frequency response when in a space relatively free of reflections and when pointed at the source of the sound Random incidence The microphone has been adjusted to have an essentially flat frequency response for sound waves impinging on the microphone from all directions Pressure The microphone has not been adjusted to have an essentially flat frequency response for sound waves imping ing on the microphone from all directions Model 812 User Manual C 9 What a microphone measures A microphone detects more than just sound The motion of a microphone diaphragm is in Microphone Guidelines cont response to a force acting on it The force can be caused by a C 10 number of sources only one of which are we interested sound Non sound forces are 1 direct physical contact such as that with a finger or a raindrop 2 those caused by the movement of air over the diaphragm such as environmental wind or blowing 3 those caused by vibration of the micro phone housing and 4 those caused by strong electrostatic fields Rules 1 Do not permit any solid or liquid to touch the microphone diaphragm Keep a protective grid over the diaphragm 2 Do not blow on a microphone and use a wind screen over the microphone to reduce the effect of wind noise 3 Mount microphones so their body is not subject
132. ssure level is L 2019g 201og 50000 20 4 699 94 0dB 20 10 Calibrators often use a level of 94 dB so they generate a sound pressure of 1 Pascal If the sound pressure level 76 3 dB then the sound pres sure is 76 3 20 3 815 6 2 185 20 10 10 20 10 20 10 20 0 0065 0 13 Energy Average Loy The value of a steady sound measured over a fixed time period that has the same sound energy as C 16 Model 812 User Manual 5 27 05 Sound Power W the actual time varying sound over the same period This descriptor is widely used It is a fixed average See Sound Pressure Impulse The value of an impulsive sound The reading will depend on the time weighting applied Unweighted Peak The peak value of a sound with a meter that has flat frequency weighting and a peak detector Weighted Peak The peak value of a sound with a meter that has a frequency weighting other than flat and a peak detec tor The sound power emitted by a sound source It is measured in Watts Sound Power Level PWL L The logarithmic form of sound power It is also expressed by Sound Speed c attachment of the word decibel to the number The loga rithm is taken of the ratio of the actual sound power to a ref erence sound power which is 1 pico watt Sound power level cannot be measured directly but can only be deduced through measurements of sound intensity or sound pressure around the source The e
133. surements Measures FAST SLOW Unweighted PEAK Weighted PEAK Impulse Loy Lpop Losna Dose Projected Dose TWA Sel Lae Lmax Lmin Ln and more User selectable dose exchange rate criterion thresh old and reference duration Measures and stores more than 40 000 different DOSE combinations in a single measurement Allows comparisons of different DOSE standards using the same data Complete data logging capabilities with 64 kB stan dard memory Passby event data such as time duration Lmax Leg SEL integrated about 10 dB of the maximum Time history sampling periods are user selectable from 1 second up to one sample every 255 seconds Quartz clock calendar system for data annotation Calibration from front panel using an appropriate calibration source Easy one step reset of measurement Battery level indication Standard 9V internal alkaline battery life of more than 16 hours or external power using Larson Davis cable CBL035 for longer measurements RS 232 computer interface standard All functions fully programmable Comes complete with PC SWW SLM UTIL software for data retrieval and translate binary files to ASCII format Other PC soft ware also available 5 27 05 Model 812 User Manual Large two line 32 character high contrast LCD dis play e Small 33cm x 7 5cm W x 2 5cm D 13 x 3 x 1 HWD and lightweight 370g 13 oz including microphone and battery Rugged ABS case with
134. t column and the rationale why you do 5 27 05 Model 812 User Manual it with other cautions and comments are shown in the right column For example Microphone Polarization Voltage is preset by Larson Davis at 200 volts Should this parameter be incorrect the Model 812 will not calibrate correctly Step 1 Check the microphone polarization by looking at setup parameter 43 To do this turn on the Model 812 press site Modify 4 and 3 and Enter The following display will appear Especially important information is shown in italics for example To access items 48 50 Overall Exchange Rate Overall Threshold Overall Criterion press the Y key Features The Larson Davis Model 812 meets the requirements of the American National Standards Institute ANSI 51 4 International Electrotechnical Commission IEC 651 and 804 1985 standards for Type 1 accuracy and offers the following features Dynamic range of more than 110 dB for error free measurements Impulse measuring range greater than 100 dB e Standard microphone allows measurements typically between 30 and 140 dB A in one range Optional microphones allow measurements as low as 20 dB or as high as 190 dB A Mic bias is user selectable 0 28 and 200 V 1 4 Model 812 User Manual 5 27 05 Selectable A and C frequency weightings for hearing protector applications Multiple detectors provide simultaneous RMS and PEAK mea
135. ts internal firmware is designed to accom modate changing regulations and to overcome sound measurement problems While the Model 812 is the size of a dosimeter it may also be used as an environmental noise monitor offering features which will ensure qual ity measurements for many years We invite you to read this manual to get the most out of your new Larson Davis sound level meter 5 27 05 Model 812 User Manual About This Manual This manual has 10 chapters and 4 appendices covering the following topics Chapter 1 Introduction Overview of this user manual and the Model 812 s functions and measurement capabilities Chapter 2 Overview to Model 812 Understanding the keyboard and screen turning the instrument on and off and checking the battery voltage Chapter 3 Calibration Using a reference to calibrate the instrument and its importance Chapter 4 Quick Start Setting parameters using function keys and using numbers and other charac ters Chapter 5 Performing a Measurement Reading the Data taking a measurement and becoming familiar with the function keys Chapter 6 Timed Measurement Using the timer for unattended readings setting additional parameters and using the password lock Chapter 7 History Functions Setting parameters for history settings interval passby time history and daily history Chapter 8 Parameters A complete listing of all parameter items and an explanation of their
136. tup parameters 92 RMS Histogram No Yes Prints histogram of overall rms levels 93 Lowest Level 0 255 RMS Histogram lowest printed level 94 Highest Level 0 255 RMS Histogram highest printed level 95 Histogram Resl 1 8 1 2 1 0 2 0 5 0 10 Spacing in dB between histogram entries 96 Peak Histogram No Yes Prints histogram of overall peak lev els 97 Lowest Level 0 255 Peak Histogram lowest printed level 98 Highest Level 0 255 Peak Histogram highest printed level 99 Histogram Resl 1 0 2 0 5 0 10 Spacing in dB between histogram entries 100 UwPk Histogram No Yes Prints histogram of overall unweighted peak levels 16 Model 812 User Manual 5 27 05 101 Lowest Level 0 255 UWPk Histogram lowest printed level 102 Highest Level 0 255 UWPKk Histogram highest printed level 103 Histogram Resl 1 0 2 0 5 0 10 Spacing in dB between histogram entries 107 INTV Report No Short Long Prints interval report 108 Lowest Rec 0 65535 Starting interval record number of printout 109 Highest Rec 0 65535 Ending interval record number of printout 110 HIST Report No Yes Prints time history report 111 Lowest Rec 0 gt 999999 Starting history record number of printout 112 Highest Rec 0 gt 999999 Ending history record number of printout 5 27 05 Model 812 User Manual 8 17 Model 812 User Manual 5 27 05 Memory
137. ty in great part to a flexible setup More than 160 parameters and options can be selected to tailor the Model 812 to any measurement Four prepro grammed setups for standard applications are in mem ory One may use these as blueprints for modifications Itis also possible to store up to 3 other setups in memory for later recall Along with downloadable setups from software this truly makes the Model 812 a myriad of instruments in one In this chapter we will review the following Parameter access keys R mec Learn to store and retrieve complete setups from the various memory registers e List all parameters with a short explanation Parameter Key Access Review Entering and Exiting the Setup Menu Some setup items may be changed while the Model 812 is running but parameters influencing data integrity require a memory Reset ALL Step 1 Enter the setup by pressing The following 5 27 05 Model 812 User Manual 8 1 will appear Step 2 exit back to the main screen press Step Return to the setup menu Press Locating Parameters When in the setup menu the arrow keys allow move ment from one parameter to another One may also use a function key or directly index to the appropriate param eters Step 1 From the Setup menu press Y one parameter Press Y to go to the next parameter Step 2 When the arrow keys are used in conjunction with the Shift key SHIFT the Model 812 will take you to the
138. urements are always easily available from the keypad The display now reads an C weighted slow average reading of 84 5 dBC re 20 uPa The level is also shown on a semi analog bar graph Parameters 39 43 affect these values and parameters 45 47 effect the Current SLM The Lmin and Lmax for the current reading at the current time are dis played in the first screen Notice that the current sound pressure level continues to read in the upper left corner and fluctuates Note that even in the stop mode the Model 812 continues to monitor SPL while in this window Notice the space beneath 88 4 in this screen The are in an area where six fields of information are available Respectively with the controlling parameter these are listed to the left If these param eter values have been triggered the will appear to indicate that the record contains information related to that occurrence 5 27 05 These values may be checked at any time while the mea surement is being taken or final readings after the mea surement has been completed Be careful not to bump or drop the instrument as the results of the reading will be affected Step 4 Press the key again for the second screen In this example the measurement is running Notice the figure is in motion Step 5 v key for the third screen Step 6 Step7 The next screen addresses the Alarm time and current te
139. urposes Press the 3 or Kid Modify and 6 and Press to change the serial number enter the correct numbers and press Enter Seat the microphone fully in the calibrator cav ity If possible both units should be at the same temperature and stationary so that hand vibra tions are not transmitted to the SLM Press c to exit calibration setup Then activate the calibrator by pressing the button on its side Press the and on the Model 812 This display indicates the current sensitivity off set and will be blinking between two settings Model 812 User Manual Refer to the specific instructions accompanying your calibrator for accomplishing this step Pressing the a will check calibra tion pressing the v will change it 3 3 Step 10 Pressingthe v key willinitiate a calibration change Do that now Step 11 To Reset the Model 812 for re calibration press SHIFT and Step 12 Press Enter Reset is complete and the instru ment will return to the calibration mode Step 13 To leave the calibration mode press 3 4 Model 812 User Manual In this screen an error message initially prompted for a reset see step 12 to reset The difference between the current and the last calibration is 0 dB If the level is not stable enough for proper cali bration the Model 812 will exit the calibration mode without changing its calibration level The c indicates t
140. whose value is selected from a few possible choices are displayed with the current setting inside square brackets To make a selection Step 1 Press and then the 4 and 0 keys Step 2 Confirm change with Enter Step 3 Cancel change by pressing before Enter Error Messages Entry errors will be noted by a warning message For example Verify the correct entry format Learning to Store and Retrieve Setup Memory The current setup parameters can be stored internally in two ways for later recall 4 Model 812 User Manual 5 27 05 Intwo RAM random access memory registers In one EEPROM register electronically erasable pro grammable read only memory Setups stored in RAM occupy the same memory as the data 64 KB They may be lost if battery power is removed for more than a few minutes One set of param eters at a time can be stored in the EEPROM Parameters in the EEPROM register are secure even if the batteries are disconnected since the EEPROM does not require bias voltage to maintain its state A minimum of 5 000 STORE operations are possible with the EEPROM Storing a Setup The Model 812 must be stopped and memory reset to store to the EEPROM Step 1 Press GHIFD an 5 27 05 Model 812 User Manual Remember to reset memory press SHIFT Enter The EEPROM register is the default In this instance the title of the measurement is TECH WRIT
141. y 8 17 Data time history eese 7 3 Date gic S 8 8 De output specifications A 8 Decibel ntes tenet md C 3 Department of Defense level 52 2 m alse Aen C 5 Detector iei unici 8 11 C 5 Display digital aida A 10 Duration measurement C 9 Dynamic range 1 5 E EEPROM REGISTER i e eme e aera 8 5 Environment effects of Temperature A 7 enda B 31 messages and warnings B 31 Error Checking Dia it B 23 Exceedance 8 14 Exceedance History 8 14 Exchange Rate 8 12 gloSsary cseteris C 5 Exchange Rate Factor glossary uei eee et C 5 Exposure Factor gloSsary i eene C 5 F suas Saas C 6 acOUStiQ us ie C 6 geometric A C 6 Formatting Conventions 1 3 Free field C 6 Frequency band pass filter C 7 A ner Mense C 6 Hz rad sec C 7 Frequency Weightings Index 1 specifications A 4 frequency weightings 1 5 H Histogram variables x nre e B 29 Histogram Reports
142. y ettet tpe pei t e toate A 10 Digital Display Resolution eee eee enne A 11 Display Bareraph eerte te ete iter ei tea A 11 Real time Clock Calendar eese nnne ennemis A 11 Runetime Clock id eee as A 11 Standards Met Rt eee e meom died A 11 Power S pply caia cada ne meii A 12 Dimensions Weight with Microphone Preamplifier and Battery A 12 Serial Port Interface Remote Control B 1 Model INT002 Interface Cable eese B 2 Daisy Chain Addressing otenn itn eee ene B 3 App C App D Comtm andsu x det set teet ete to ucla b History Oriented Commands Mode eee eere Read Variables essere Other Read Group Read Programming Setting Parameters mienite a a eiat Numeric Parameters esee Indexed Parameters Character String Template Parameters Query Parameters Histogram Reports sse Tailored Report eene e Error Checking History Records secet enmt Types History caet oue tie daga
143. y the options use the a or keys and the display will remain for five seconds before returning to automatic scroll This option allows you to access the printer setup status This option will return you to the Printout Parameters and will start with the printer type selection The v key will access item 89 of the Printout Parameters This option allows you to tailor your own report changing the set tings of parameter items 89 112 but imputting the entries in items 177 200 After the printout is complete the values will revert back to factory settings 10 3 Model 812 User Manual 5 27 05 APPENDIX Specifications This Appendix contains the specifications for the Model 812 in the following order Type Reference Direction Measurement Ranges Reference Level Frequency Weighting Detector Time Weightings Effects of Temperature Effects of Humidity Limits of Temperature and Humidity Microphone Extension Cables Positioning of Instrument and Observer for Best Mea surements ACand DC Outputs Reference Frequency Stabilization Time Microphone Electrical Impedance Functions Measured DataStorage 5 27 05 Model 812 User Manual A 1 Data Communications Digital Display Digital Display Resolution Display Bargraph Real time Clock Calendar e Run time Clock Typical Noise Floors Standards Met Power Supply e Dimensions Weight with Micropho
144. year It is calculated as fol lows 365 Lian 10log 10 i 1 Ldn 10 Model 812 User Manual C 19 C 20 Model 812 User Manual 5 27 05 APPENDIX Warranty Customer Satisfaction A Total Customer Satisfaction Larson Davis Inc LD guarantees Total Customer Satisfaction If at any time you are not completely satisfied with any LD product LD will repair replace or exchange it at no charge except as otherwise provided in this Limited Warranty The employees of LD strive to provide superior unmatched customer service Should you find yourself dissatisfied with any LD product for any reason consult a LD Application engineer or local representative distributor to discuss your situation B Purchase Price Refund Limited Warranty LD warrants to the original purchaser the Buyer that unless otherwise expressly specified in writing by a LD officer all LD products shall be free of defects in material and workmanship for a period of two 2 years from date of original purchase In furtherance of LD s commitment to Total Customer Satisfaction LD will for a period of one 1 year from date of original purchase refund 100 of the customer s purchase price for any LD product with which the buyer is not completely satisfied subject to the exceptions contained in Paragraph J of this Limited Warranty The option of a refund may be selected during this one 1 year period in lieu of repair replacement or exchange of the produ
145. yy hh mm ss C3 Calibration Mode Manual Auto C4 Cal Status OK Bad B 28 Model 812 User Manual 5 27 05 C101 Cal Variables 1 4 all variable values Time History Variables Brackets in the syntax indicate optional characters and operands Syntax Response H istory var no time var Example H2 Peak level in current record HI RMS Level nnn n dB H2 Peak Level nnn n dB H3 Run Time of Sample calc hhhhh mm hh mm ss mm ss ss H4 HISTORY BARGRAPH Histogram Table Variables Brackets in the syntax indicate optional characters and operands Table e 1 RMS 2 Peak e 3 Unweighted Peak Default is last used table or RMS Syntax Response T able var_no table table_var 5 27 05 Model 812 User Manual B 29 Example The table number is optional Will RMS current bin level 1 Level of current bin nnn n dB T2n Count of samples nnnnnc c or M for Kilo or Mega 3 n Percent of total nnn nn T5 n Prints the accumulated timer for the current level bin hhhhh mm ss s a Where n equals the table number 1 RMS 2 Peak amp 3 UnWeighted Peak Print Commands Brackets in the syntax indicate optional characters cr carriage return lf line feed Syntax Response P rint print_no cr 1f

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