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NARDA 8718B Stud Sensor User Manual

1. AT THE PROBE Operating the Meter ote All data will be lost when the memory is cleared 7 Once the correct probe temperature is displayed on the screen press F4 SAVE The meter will automatically return to the measurements screen 8 Alternately press F1 AUTO to return to the default auto correct mode Clearing the Memory If you determine that there is insufficient memory available to perform the desired logging task because much of the meter s memory has been used it will be necessary to empty the memory All data will be lost when the memory is cleared To download the current memory contents prior to clearing the memory you must connect the 8718B to your computer See Chapter 78 User s Software To clear the memory 1 Access the settings menu by following the procedure described in Accessing the Settings Menu Press 3 CLEAR MEMORY A screen will appear requesting that you confirm your request and warning that the stored information will be lost CLEAR MEMORY CLEARING THE MEMORY CAN NOT BE REVERSED CLEAR ABORT Press F1 CLEAR to clear the memory or F4 ABORT to return to the First Menu Screen without clearing the memory Press Esc to return to the measurements screen Chapter 15 Advanced Settings 91 92 Function Key Position The position of the commands for the function keys F1 F4 as described in this guide is for right hand operation Conventionally righ
2. USER S GUIDE Model 8718B Electromagnetic Radiation Survey Meter Safety Test Solutions an communications com pany P N 42983600 RevB 1 ote Return the Owner Registration Card for updates and your copy of the Applications Booklet Chapter 1 Introduction About the Model 8718B Your Model 8718B is a hand held battery powered meter designed to simplify the measurement of electromagnetic fields It can be used with any Narda 8700 Series probe The 8718B is an upgraded version of the original Model 8718 Although there are many enhancements the 8718B is most easily distinguished from its predecessor by the quick release style probe connector The meter enables you to perform both simple measurements and more demanding ones that require averaging and or data logging It can be mounted on a tripod and used with an optional fiber optic link for enhanced accuracy in certain applications Getting Started with the Model 8718B It is important to become familiar with the Model 8718B before you use it Chapter 2 explains the basic meter hardware Chapters 3 and 4 cover probe selection and basic operation The menu system which is the gateway to all the meter s advanced features is the subject of Chapter 5 It is strongly recommended that as a minimum you read Chapters 2 4 and preferably Chapter 5 thoroughly before you attempt to use the Model 8718B The advanced featu
3. Since stored data will be overwritten during the update process download any survey data that you want to save by following the directions described under Downloading Logged Data from the Meter Select Update Meter Firmware from the Update Meter Firmware menu Read the directions and click OK to continue or click Cancel to abort the update process Enter the password obtained from Narda and click OK Read the description of the three meter models Click Yes to update a Model 8718B meter Click No if your meter is a previously updated Model 8718 unit that currently has firmware version 3 0 or higher Click Cancel if the meter is a Model 8718 that has a firmware version lower than 3 0 These meters cannot be updated in the field The update process begins when you click either Yes or No as described above Do not interrupt the update process You should get a message box that the firmware has been updated in about three minutes at the recommended 9600 baud rate Click OK You can now use your updated meter Operating the Meter Communications with a Computer Application The Model 8718B can be connected to a computer for real time transmission of data via the meter s RS232 connector A limited number of the meter s functions can also be controlled remotely via the RS232 bus Checksum and Modulo Description Modulo 256 is the remainder of any number X divided by 256 As an example if the checksum is 1234 Mod
4. 1 43040934 WAQHOOSH 1 97 wove vio wavy 440 NO siuod9 5114110 HOLYTIIOSO ZIN Od YHOSNAS dwal zn NOIL93LOHd en YALHAANOO WMd ZHY OL 11 TOHLNOD BOVLIOA 1353350 Y3TIOULNOSOHOIN LHOd H 51909398 9015 AYG 30 ONY 911 sna Vivd 33H AG2 5919815 na 4 ASt sn 140d OW 179170 WOH 3549 14 HOLMS 19899 13 18 QVOIN 1 QvdAay 123 Appendix B Theory of Operation 1 2 124 Calibration is performed using the RS 232 port a voltage source and a computer PCB 1 is the primary circuit board within the meter The majority of the components are surface mount It is located ina heavily shielded area beneath the keypad Operating power from battery B1 is routed through Q3 and Q4 that form a momentary switch for the micro controller U5 U5 provides a control signal to the 5V 5V and 2 5V power supplies made up of U12 U13 and U14 The DC voltage output two voltages if a ultra broadband probe with a two channel amplifier is used from the field sensing probe is coupled through the A2 PCB into an input amplifier made up of U2 and then i
5. A screen will appear requesting that you assign two digit survey number to this logging run of data points Use the numeric keypad to enter the two digit number and then press F1 OK or ENTER Make note of this number so that you can later associate this survey number with the data points collected If you make a mistake press F2 CLR to clear the screen and enter a new survey number Operating the Meter ote It is important to move the probe vertically at a con stant rate to obtain an accurate spa tially averaged measurement NEW LOGGING RUN ENTER NEW REF NO __ OK CLR MENU QUIT Press F4 QUIT or F3 MENU if you change your mind The meter will automatically return to the measurement screen with new options available for the function keys 1121 11 9 27 5 1 00 START MAXR END QUIT Proceed to make measurements as normal To initiate making a spatially averaged measurement that will be logged hold the meter in one hand and the probe in the other with the head of the probe touching the ground Press F1 START while slowly moving the probe vertically at a constant rate of movement Keep your finger on the F1 key during this operation Strive for an interval of about ten seconds between starting and stopping the timer The displayed value will flash and the audio signal will sound every second as a timing aid When the probe reaches the height equal to the to
6. Example to set frequency for 27 12 MHz gt F0142712A7CR 3E 46 30 01 34 32 37 31 32 41 37 0D gt MO00CSCR ACR gt M000DDCR 3E 4D 30 30 30 44 44 0D gt 000 5 gt VOOOE6CR 3E 56 30 30 30 45 36 OD Response format 12 data bytes 6 data 6 units CSCR Last displayed value 6 characters units of last displayed value 6 characters exactly as displayed except squared and cubed symbols Note Superscript 2 or 3 are Hex 80 or Hex 81 respectively Response Example ASCII 0631 mW cm 58 Hex 2E 30 36 33 31 20 60 57 2F 63 6D 80 35 42 00 Appendix A Communications with a Computer 119 120 Command Characters G Read Max ASCII Hex H Reset Max ASCII Hex Display Averaging ASCII Hex Read Calibrated Probe Data ASCII Hex K Read Log Data ASCII Hex L Read Header setup data ASCII Hex Function SEND RESPONSE gt X000CSCR XXXXXXCSCR gt X000E8CR 6 data characters returned 58 30 30 30 45 38 OD exactly as displayed gt Y000CSCR ACR gt Y000E9CR 3E 59 30 30 30 45 39 0D gt Dr00CSCR ACR for minimum to 4 for maximum display averaging Example to set minimum display averaging 4 1 gt D100D5CR 44 31 30 30 44 35 OD gt POOOCSCR x xCSCR gt POOOEOCR 432 data bytes returned 50 30 30 30 45 30 00 gt LOOOCSCR x xCSCR gt LOOODCCR depends on size of log 4C 30 30 30 44 43 00 gt x xCSCR gt HOOODSCR 24 dat
7. Operating the Meter N ote The PAUSE feature can be useful when measuring the aver age value from cer tain rotating radars The effective mea surement technique requires you to pause during the pe riod of time when you are not in the beam of the radar Continue this technique for two or more revolutions de pending on the RPM to ob taina realistic average value of the field in the beam at your cation For details on this measurement technique see Radar Measurements in the Applications Booklet 2 You may continue to pause and start the averaging as many times as needed The time interval initially selected applies only to the measurement time 3 To end time averaging while PAUSED press F4 STOP To change the averaging interval 1 change the averaging interval once the current measurement interval has been completed or stopped press F4 QUIT To initiate a new time averaging interval use the menu system to select TIME AVG from the First Menu Screen 2 Proceed as previously described to select FIXED TIME from the averaging menu screen and then the new averaging interval Mode 2 Averaging Mode 2 averaging time averaging to meet the requirements of a specific standard requires two parameters to be properly set before being used The meter must be set to the correct standard for your application The meter must be set for a specific frequency because the aver
8. SAVE Save the data point or the new setting SEC Seconds used to define a logging interval SET Set the time date temperature or display contrast START Start averaging or data logging STNDS Standards access the menu of available exposure standards STOP Stop the current averaging run YES Yes the current probe selection is correct Proceed with zeroing process Chapter 5 Using the Menu System 33 34 Default Conditions Upon The Model 8718B is designed to automatically return to a basic set of operating parameters every time it is turned on Although in some cases this may require additional key strokes to set up the meter as desired this feature is designed to minimize the chance of making measurements while unknowingly having the meter incorrectly configured The table below lists the operating parameters that can be expected upon turn on Parameter Alarms Back Light Blank Out Cable Fiber Optic Data Logging Display Contrast Display Screen Lockout Probe Model Right Left RS232 Port Spatial Averaging Standard Temperature Correction Default Condition Last Used settings will be used OFF to conserve battery power OFF display will be active Last Used input will be active OFF Last Used setting will be in use Main Measurement Display Screen OFF keypad will be active Last Used probe model will be featured on the probe selection screen Last Used setting
9. Follow the instructions that appear on your screen The setup program places all of the program files ina directory on your hard drive called 8718B A new program group called RF Safety will be created Starting and Exiting the 8718B User s Program To start the 8718B User s Program 1 Click on Programs from the Start menu in Microsoft Windows 2 Select the 8718B User s Software icon The Main Menu Screen appears 3 Make sure you exit the 8718B User s Software before turning off your computer by selecting Exit from the File menu You can also double click on the Control menu box Do NOT use Ctrl Alt Del to exit the program Establishing Communications between the Meter and the Computer You must establish communications between the meter and the computer in order to enter change or view probe calibration information or to download data from the meter You can only view stored logged data using your computer 102 Operating the Meter narda Com S800 Maud CTS On ine Chapter 18 User s Software 103 ote The cable must be a RS232 serial cable with DB9 male connector end and a DB9 female connector on the other end Do NOT use a null modem ca ble since these are wired differently Note that certain older model computers have a 25 pin connector for a serial port that will require either an adapter or a different cable N ote Operation of a
10. MAIN MAXR MENU Chapter 4 Making a Measurement 21 4 Change the units if needed by pressing either F1 kHz F2 MHz or GHz N 5 Press F4 SAVE The probe correction factor will be ote displayed briefly if you are using a probe in memory and you will automatically return to the measurement screen See Using Probe Correction Factors on page 24 Alternate values can 6 From the Main Measurement Screen press F1 ALT to not be calculated at low frequencies for select the Alternate Measurement Display Screen standards with very high magnetic field To return to the Main Measurements Display Screen limits A greater than symbol gt is 1 From the Alternate Measurement Display Screen press shown under these F1 MAIN to select the Main Measurements Display conditions Screen 22 Operating the Meter N ote The Range Key only affects how the bar graph displays infor mation Bar Graph Ranges The Range key is used to control how the bar graph displays information The digital display is not affected and the meter automatically displays a digital value over the probe s entire measurement range There are four available settings AUTO HIGH MID and LOW The bar graph has 100 divisions You will probably find it convenient to use the AUTO setting most of the time but under a few conditions you may find one of the three fixed ranges useful The following table illustrates how the range setting w
11. corresponds directly with the indication on the bar graph of the display Under normal conditions the bar graph is in the AUTO mode which results in the bar graph using three 10 dB ranges to cover the entire dynamic range of the probe which is typically 30 dB Thus the recorder output would produce a sawtooth pattern if the measured field strength was slowly increased a linear fashion over the entire dynamic range of the probe For example the recorder output level with the 8718B bar graph range set to AUTO used with a probe with a full scale measurement range of 100 mW cm such as the Model 8723D would follow the table on the next page Chapter 17 Operation with a Data Recorder 99 ote The recorder output can be set to one of three fixed ranges by changing the bar graph range setting See Bar Graph Ranges on page 23 100 Field Strength Recorder Voltage Bar Graph 0 01 mW cm2 0 03 volts 1 of Full Scale 0 50 mW cm2 1 50 volts Half Scale 1 00 mW cm 3 00 volts Full Scale 1 01 mW cm 0 03 volts 1 of Full Scale 5 0 mW cm2 1 50 volts Half Scale 10 0 mW cm 3 00 volts Full Scale 10 1 mW cm 0 03 volts 1 of Full Scale 50 mW cm 2 1 50 volts Half Scale 100 mW cm 3 00 volts Full Scale gt 100 mW cm 4 2 4 5 volts The recorder output has an approximate 1 4 second RC time constant Operating the Meter 1 8 User s Software Description The 8718B User s Softwar
12. e Collect a series of up to 999 spatially averaged data points one at a time and automatically assign a reference number to each data point Both the average value and the maximum value at each location are stored The reference numbers can refer to either site plan locations or to a diagram of the industrial equipment being surveyed Each data point also has a time and date stamp e Automatically collect a series of data points at specific intervals of time for a specific time period Each data point also has a time and date stamp Format for Logged Data A record contains a header and one or more data points Each record is identified by a user defined two digit survey number and the time and date the survey was performed The header defines the serial number of the 8718B meter its calibration date the probe model used and a number of other settings These settings may include logging rate frequency correction averaging mode and averaging time If the probe used was selected from memory the header will also include the serial number of the probe and its calibration date Operating the Meter To initiate one of the three logging modes described N ote above 1 If you access the menu system from the Opening Menu Screen you will re 2 turn to that screen Once a probe has been selected and 3 zeroed the measure ment screen will re flect the logging mode that you have selected 6 T Access the
13. from the First Menu Screen new menu will appear offering two averaging modes The status of both modes will be shown TIME AVERAGING 1 FIXED TIME OFF 2 STANDARDS OFF ENTER NO TO TURN ON Press F4 OFF to turn either time averaging mode off and return to the measurements screen Chapter 9 Time Averaged Measurements 57 58 Mode 1 Averaging To initiate Mode 1 averaging fixed time averaging over any one of several specific time intervals 1 Press number 1 on the keypad to select FIXED TIME from the averaging menu screen Selecting Mode 1 averaging will automatically shut off Mode 2 averaging if it is on new menu screen will appear that offers four different averaging intervals 30 SEC 1 MIN 6 MIN and 30 MIN If an averaging interval had previously been selected and is currently active that selection will be flashing FIXED TIME AVERAGING 30 SEC 3 6 MIN 1 MIN 4 30 MIN OFF Press the number on the numeric keypad 1 4 that corresponds to the desired averaging interval and the meter automatically returns to the measurement screen with new options available for the function keys If you had accessed the menu system from the Opening Menu Screen you will return to that screen 1121 11 9 ISTID 27 5 MAX START MENU 4 At any time you can press F4 QUIT to turn the time averaging mode off and return to the normal measurements screen Operating the Meter 5 The meter
14. 37 7 17 81 85 Changing the Unit of Measure 38 Settings Advanced Clock setting the 88 Display Contrast adjusting 93 Function Keys right or left handed 92 Memory clearing the 91 Menu accessing the 87 Temperature Correction 89 134 Index Warranty Narda Safety Test Solutions Narda STS warrants each product of its manufacture to be free from any defect in material and workmanship for a period of one year from date of shipment to and return by the original purchaser All warranty returns however must first be authorized by a factory office representative The limit of liability under this warranty shall be to repair or replace any product or part thereof which proves to be defective after inspection by Narda STS This warranty shall not apply to any Narda STS product that has been disassembled modified physically or electrically damaged or any product that has been subjected to conditions exceeding the applicable specifications or ratings Narda STS shall not be liable for any direct or consequential injury loss or damage incurred through the use or the inability to use any Narda STS product Narda STS reserves the right to make design changes to any Narda STS product without incurring any obligation to make the same changes to previously purchased units This warranty is the full extent of obligation and liability assumed by Narda STS with respect to any and all Narda STS products Narda STS neither ma
15. Alarm Your Model 8718B is equipped with an audible alarm that emits sound through a tiny hole on the bottom of the meter The alarm sounds whenever the field strength exceeds the measurement range of the probe over ranges You can also set the meter to sound its alarm at a specific level and or turn on a variable tone mode Probe Test Sources Your Model 8718B is equipped with two RF sources for testing your probes The Test Source key will turn these sources on They will stay on for approximately 20 seconds A microwave waveguide window on the right side of the probe is used for testing high frequency probes A contact on the right side of the meter is used for testing low frequency probes Most probes have three test points on the head of the probe 4 Operating the Meter Strap and Tripod Mount A strap is provided on the underside of the Model 8718B It has a hook and loop closure to permit easy adjustment around your hand Behind the strap is a threaded connector used to secure the meter to a tripod Loosen the strap to access this connector Operation With a Computer To update probe calibration information or retrieve stored measurements you must connect your Model 8718B to a personal computer and use the User s Software provided by Narda See Chapter 18 User s Software Operation With a Recorder To obtain a continuous record of measurement over an extended period of time you can conne
16. First Menu Screen DATA LOG TIME AVG SPATIAL BAT LIFE Key Menu Options Chapter Log with time and date stamp Log spatially averaged values with time 1 and date stamp Continuous logging at various rates Turn fixed time averaging various 2 TIME ANG duration on or off Turn the spatial averaging mode used for 3 SRATIAL whole body averaging on or off 7 Check battery charge status and 4 BAT LITE estimated time remaining 12 Turn the back light on or off Select from all appropriate units of measure i e mW cm V m V m for the 5 UNITS probe in use Percent of Standard is the 6 only unit of measure for shaped frequency response probes Change the baud rate 6 RS232 Turn the RS232 port on or off Automatic 17 on for Model 8718B Menu is for Model 8718 only Show the model and serial number of the robe in use 7 PROBE 4 Select another probe and restart the zeroing process 8 NEXT Go to the Second Menu Screen 30 Operating the Meter Second Menu Screen COR FACT SETTINGS CABLE FO LOCKOUT Key Menu Options Chapter COR FACT Enter a numeric probe correction factor 4 SETTINGS Check or set the meter s internal clock time date Enter a value for temperature Used when the probe is separated from the meter and operating at a different ambient temperature Clear the memory of logged data S
17. allows you to enter another two digit survey number NEW LOGGING RUN ENTER NEW REF NO _ OK CLR MENU QUIT 16 Use the numeric keypad to enter a new two digit survey number and then press 1 or ENTER Again make note of this number so that you can later associate this survey number with the data points collected If you make a mistake press F2 CLR to clear the screen and enter a new survey number The meter will automatically return to the logged measurements screen 17 To end logging altogether and return to the standard measurement screen press F4 QUIT To initiate logging again at a later point use the menu system to select DATA LOG from the First Menu Screen Mode 3 Logging To initiate Mode 3 logging a series of data points automatically logged at specific intervals 1 From the main data logging screen press the number 3 on the keypad to select CONTINUOUS LOGGING from the logging menu screen 1 LOG WITH REF 2 LOG AVG WITH REF 3 CONTINUOUS LOGGING MEM Chapter 8 Data Logging 51 52 2 A screen will appear requesting that you assign two digit survey number to this logging run of data points Use the numeric keypad to enter the two digit number and then press F1 OK or ENTER Make note of this number so that you can later associate this survey number with the data points collected NEW LOGGING RUN ENTER NEW REF NO __ OK CLR MENU QUIT Anew menu screen will appear
18. are derived from the time and date that you downloaded the date The format is MDDHHmm SVY month day hour and minute 2 Exported files that have been converted to standard spreadsheet files have the same prefix as the original file with the suffix csv These files are automatically stored in the subdirectory labeled Ssdata 3 Exported files that have been converted to tab files standard ASCII text files commonly used in data base programs have the same prefix as the original file with the suffix txt These files are automatically stored in the subdirectory labeled Ssdata Chapter 18 User s Software 109 110 Three sample files were loaded on your hard drive when installed the User s Software There is a sample for each of the three modes of data logging Selecting a File to View To view stored surveys on your computer 1 Select View Stored Surveys from the Survey Data menu A dialog box will appear titled Open Survey File Normal downloaded survey files stored on the computer s hard drive will be listed in the table on the left Downloaded survey files are stored ina subdirectory labeled Svy You can change drives select which types of files are listed or change directories from this box Select the data file you want to view from the list of files by either double clicking on it or highlighting it and choosing OK A new window labeled Logged Survey Data will appear The file name will be shown to the rig
19. its alarm at 5 mW cm when using a Model 87210 probe which has a full scale measurement range of 20 mW cm set the alarm threshold to 25 you want to turn the variable tone alarm on or off do that next See Variable Tone Alarm on the following page When you are satisfied with all the alarm settings press ENTER and the meter will return to the measurement screen Operating the Meter ote The fixed and vari able tone alarms op erate independently of each other The meter can be set to have both alarms off either one of the alarms on or both alarms on If both alarms are turned on the variable tone rate will vary with the field strength un less the measured field strength ex ceeds the fixed alarm threshold The alarm will then sound a continuous tone Variable Tone Alarm 1 Use ON or F4 OFF to change the status of the fixed alarm The variable tone alarm constantly generates a series of tones that increase in frequency in direct proportion to field strength If you want to turn the fixed alarm on or off do that next See Fixed Alarm on the previous page When you are satisfied with all the alarm settings press ENTER and the meter will return to the measurement screen Chapter 10 Alarm Settings 69 70 Operating the Meter Using The RF Exposure Standards Feature Application The Model 8718B Meter is always set to reference a particular safety standard regulation or guidan
20. logged data with the User s Software 1 Select Clear Survey Data from the Survey Data menu A dialog box will appear titled Clear Survey Data It will ask to confirm that you want to clear the survey data from the meter s memory Click OK to clear the meter s memory of logged data If you make a mistake and want to restore the meter s memory Select Restore Survey Data from the Survey Operating the Meter Data menu dialog box will appear titled Restore Survey Data It will ask to confirm that you want to clear the survey data from the meter s memory 4 Click OK to restore the last survey data to the meter s memory To clear the meter s memory of logged data using the meter s menu system 1 Select 2 SETTINGS from the Second Menu Screen 2 Press CLEAR MEMORY will appear requesting that you confirm your request and warning that the stored information will be lost 3 Press F1 CLEAR to clear the memory or F4 ABORT to return to the First Menu Screen without clearing the meter s memory Diagnostics The password protected Diagnostics menu of the Users Software can be used if you experience a problem with your 8718B Narda may be able to troubleshoot the problem using the built in diagnostic tools of the Users Software Contact Narda if you believe the meter is not functioning properly Update Meter Firmware powerful feature of the Model 8718B is the ability to u
21. of the display 8 Press 8 NEXT to get to the Second Menu Screen 9 Press 2 SETTINGS 10 Anew screen will appear offering several options SETTINGS 1 CLOCK 4 RGT LEFT 2 TEMP 5 DISPLAY 3 CLEAR MEMORY 11 Press 3 CLEAR MEMORY A screen will appear requesting that you confirm your request and warning that the stored information will be lost CLEAR MEMORY CLEARING THE MEMORY CAN NOT BE REVERSED ABORT 12 Press F1 CLEAR to clear the memory or F1 ABORT to return to the First Menu Screen without clearing the memory Analog Output The 8718B Meter allows the user to output a DC voltage that is proportional to the instantaneous measured value When connected to a typical chart recorder it will provide a continuous analog record of the measured field strength See Chapter 17 Operation with a Data Recorder Operating the Meter Time Averaged Measurements Mode 1 Mode 2 Measurement Options The 8718B meter features two averaging modes Perform fixed time averaging over any one of several specific time intervals e Perform averaging to meet the requirements of a specific standard The averaging period is automatically set by meter Making Time Averaged Measurements To make time averaged measurements 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display Press number 2 on the keypad to select TIME AVG
22. resolution is approxi mately 1 4 second Press F1 START while slowly moving the probe vertically at a constant rate of movement uml ol guard wl 214 12 STD 39 5 MAX CF 1 00 START MAXR MENU QUIT Strive for an interval of about ten seconds between starting and stopping the timer The meter will beep every second as a timing aid When the probe reaches the height equal to the top of an adult s head about 6 ft 1 9 m press F1 again STOP umil oml l al iad nl 1121 11 9 ISIT D 39 5 111 STOP The meter will show the average value on the second line of the display and the maximum value on the left side of the third line of the display The bar graph will be indicating the instantaneous field magnitude in real time The averaging interval will be shown on the right side of the third line which can be useful in perfecting your spacial averaging technique wil om ol 81 9 15 AVERAGE 39 5 MAX 10 4 SEC START CLR MENU QUIT Chapter 7 Spatially Averaged Measurements 41 42 10 11 12 13 make another spatially averaged measurement press F1 START again To temporarily suspend the spatial average mode and make real time measurements press F2 CLR To make another spatially averaged measurement press F1 START again To end spatial averaging altogether press F4 QUIT The meter will automatically return to the standard me
23. status has changed to On Line Viewing or Changing Probe Calibration Data The 8718B knows the basic parameters of all 8700 series probes i e frequency range type of probe electric or magnetic field measurement range and standard calibration frequencies The term installed means that the meter has stored the calibration date and the correction factors for a specific probe Narda installs probes that are shipped at the same time as the 8718B Operating the Meter You can have maximum of six probes installed at any time Since the serial number of the probe is identified as well as the model number more than one probe of the same model number may be installed at the same time To view or change probe calibration data in the meter s internal 1 Establish communications between the meter and your computer as described in paragraph in Establishing Communications 2 Select Install Probes from the Install Probes menu The 8718B will beep to indicate that stored probes information has been retrieved The Probe nstallation Screen will appear on the computer The table in the top left hand corner lists the probes by model and serial number that have been installed in your Model 8718B A small box just below the table lists the total number of installed probes To simply view the details of any installed probe proceed to Viewing Installed Probes section If you have less than six probes installed an
24. will be incorrect for all data points after the pause feature was used 112 The fourth line shows the Ref Number that was entered by the user at the beginning of the survey the Record number and total number of records in the file and the Date and Start Time when the first data point was taken 2 The lower section of the window shows the measured data in both tabular and graphical form a The table on the left side of the screen displays up to eighteen 18 data points at one time The Data Point number will be a continuous sequence shown sequentially in the time the data points were taken The Field Strength is shown in the unit of measure used during the survey Mode 2 data a series of spatially averaged data points shows both the Average and Max or peak value for every data point Mode 3 data continuous logging mode shows the Time that each data point was taken The bar graph on the right side of the screen shows the same data listed in the table The title of the bar graph is Logged Data for Mode 1 data Spatial Average amp Max for Mode 2 data and Continuous Log for Mode 3 data The range of the vertical axis of the graph is automatically adjusted to accommodate the data The number of data points will also vary depending on the data with a maximum of thirty 30 displayed at one time The Scroll Back and Scroll Forward buttons are used when there are more than sixteen data points to view E
25. will continue to make real time measurements until you initiate making the time averaged measurement 6 Determine where you want to make the averaged measurement and place or hold the probe in the desired position For short intervals it may be practical to hold the meter in one hand and the probe in the other For longer intervals it is suggested that you place the probe on some form of non conductive stand so that it does not move At frequencies above 50 MHz the meter should be separated from the probe by a minimum of 12 inches 30 centimeters to minimize any interaction between the meter the probe and the electromagnetic field At the lower frequencies the measurement techniques are very different See Low Frequency Measurements in the Applications Booklet 7 Press F1 START when you are ready to begin the time averaged measurement 8 The averaged value is displayed on the screen and will flash each time it is updated one second intervals The meter will automatically stop at the end of the selected averaging interval 9 To end time averaging prior to the end of the averaging interval press F4 STOP 24 2 STD AVERAGE 39 5 MAX CF 1 00 PAUSE STOP 10 At the end of the averaging interval the meter will show the time averaged value and the averaging interval on the second line of the display The maximum value will be shown on the third line of the display The bar graph will be indicating the ins
26. 4 If more than three probes are in memory you will have to press F4 twice MORE then PROBE One of several screens that list all 8700 series probes will appear A8722D A8732D B8722D A8742D C8722D 087220 If you see the model of the probe you want to use press the appropriate number key The newer series probes are listed first If you do not see the model number you want use the 7 BACK or 8 NEXT keys to page forward and backward until you do Press the appropriate number key to select a probe model A new screen will appear specifying probe model number frequency range field type maximum measurement range and type of response flat or shaped If this information is correct press F1 If this information does not match your requirements you need to select another probe Press F2 and you will go back to the Select Probe screen to make another selection Operating the Meter ote Position the probe in the case with one test point pointed downward and the other two test points above the foam This will insure that the test points are not touching the foam 7 A8722D SNXXXXX 300kHz 50GHz E FLD 300 STD SHAPED YES NO Proceed with the probe zeroing process Zeroing the Probe The probe and meter must be zeroed together It is important that the probe is not exposed to radiated fields during the zeroing process The storage case is shielded and provides a convenient ze
27. 8700 8700B Series Probe 8718B lt 1 0 3m adapter cable P N 2178770 optional accessory A direct connection can be useful for certain low frequency measurements See Low Frequency Measurements in the Applications Booklet Chapter 5 Probe Selection 11 Probe Identification Narda 8700D series probes use the following labels and indicators Certified Calibration Date Label e Model Identification Label Field Type E or H SARDO FREDU MCW MELD Full Scale M urement Ran FULL SCALE BOLUS m0 STANDARD cale Measurement Range Model Number a Standards Shaped Probes Only eea n Harda Hauppauga Mae York 11788 Frequency Range PSSA GOES biade in LSA Serial Number OM E Color Band to Indicate the Full Scale Measurement Range 20 mW cm probes do not have a colored band e Calibration Label With Frequency Correction Factors T POWER DENSITY TT Wa FADO GORE CT ty MH FACTA Correction Factor Listed for Every Calibration Frequency Model Number and Serial Number 12 Operating the Meter 4 Making a Measurement Introduction This chapter will help you make measurements with your Model 8718B Information is included for turning the meter on selecting zeroing and testing a probe plus an explanation of the m
28. Screen Second Menu Screen Probe Selection Changing the Probe Model Connecting a Probe Entering a Probe Model Identifying a Probe Key Factors in Selecting a Probe Shaped Frequency Response Probes NNO 79 129 130 131 129 155 INDEX Probe Test Theory of Operation Sources 4 Meter functional description 121 Testing the Probe 23 Meter Circuits 122 Probe Zero Probe Designs 125 Causes of Zero Drift 82 Probe functional description 121 Checking for Zero Drift 82 User s Guide 1 2 Establishing a Zero Field 83 Shielding the Probe 84 User s Software Temperature Concerns 83 Description 101 Understanding the Zero Function 81 Data Window logged survey 110 Zeroing the Probe use 85 the Metar Zeroing ihe Prote Initial H Establishing Communications 102 Spatially Averaged Measurements Exporting Data 114 Spatial Averaging with the 8718B 40 File Format for Survey Data 109 Understanding Spatial Averaging 39 Firmware Update 115 Installing a Probe 106 Standards Feature a Installing the Software 102 Time Averaged Measurements Memory clearing the meter 114 Making Time Averaged Printing a Logged Data Record 113 Measurements 57 Probe Data Measurement Options 57 viewing or changing 104 105 Mode 1 Averaging 58 Removing a Probe 108 Mode 2 Averaging 61 Selecting a File to View 110 Starting and Exiting the Program 102 Tripod 5 System Requirements 101 Units of Measure Zeroing the Probe Available Units of Measure
29. a bytes sent use 48 30 30 30 44 38 0D definition table to decode bits Appendices Theory of Operation Overall Functional Description The meter is a portable battery operated instrument that forms a complete RF Radiation Survey System when used with an interconnected Narda 8700 Series probe Optionally the system may employ a fiber optic transmitter and cable between the probe and meter The survey system is designed to detect electromagnetic fields and to display the field level on the meter s Liquid Crystal Display LCD The probe detects the electromagnetic radiation and transmits a DC signal to the meter The meter processes the signal from the probe for viewing on the LCD screen The meter displays the field levels in various units of measure dependent on the field component detected and the characteristics of the probe used Probe Functional Description The probe senses the electromagnetic fields and develops a signal for transmission to the meter The probe has an isotropic sensing pattern so that the radiation may be sensed from any direction except through the handle Detectors in the probe sense the electromagnetic radiation present and apply signals to preamplifiers U1 and or U2 located within the probe Preamplifiers U1 and U2 amplify the signals from the detectors and route them to the meter via connector P1 Model 8718B Meter Functional Description The meter receives the signal s from the probe process
30. ach time you click on one of these buttons you advance or go back by sixteen data points The New Record and Old Record buttons allow you to go back and forth between different records within the same file Each survey is a different record identified by the Run Ref Number that was entered by the user at the beginning of the survey Operating the Meter f The up and down keys to the right of Increment or Decrement By are used to determine how many records you advance or go back every time you click on the Prev previous Record and Next Record buttons The small window to the right of the arrows indicates the current setting To view another survey file 1 Select Load Survey File from the File menu to close the current logged data window and view another logged data file A dialog box will appear titled Open Survey File Normal downloaded survey files stored on the computer s hard drive will be listed in the table on the left Downloaded survey files are stored ina subdirectory labeled Svy You can change drives select which types of files are listed or change directories from this box 2 Select the data file you want to view from the list of files by either double clicking on it or highlighting it and choosing OK 3 The new Logged Survey Data window will appear To return to the Main Menu Window 1 To leave the Logged Survey Data window and return to the Main Menu Window click the Close button Printing a Logge
31. ack Light and Battery Status Application for Back Light The liquid crystal display LCD on the Model 8718B Meter provides high contrast in bright outdoor lite However LCD s do not generate any light and can be difficult to read in low light conditions The LCD on the 8718B contains a high brightness back light that can be turned on whenever it is needed The only disadvantage to using the back light is that it consumes much more energy than the meter circuits and significantly reduces operating time between battery charges Controlling the Back Light To turn the back light on or 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display 2 Press 4 to select from the First Menu Screen A new screen will appear that indicates both battery status and back light status nnll I LIGHT 19109 1 1 5 TIME 18HRS ION OFF 3 Press F3 ON or F4 OFF to turn the back light on or off as required 4 Press the ESC key to return to the First Menu Screen Press it again to return to the measurements screen Chapter 12 Back Light and Battery Status 75 76 Battery Capacity The Model 8718B Meter uses a custom rechargeable battery Under normal conditions the battery provides about 20 hours of use before it must be recharged The two features on the 8718B that significantl
32. acuate the area immediately if RF field levels in excess of the applicable standard are observed Operating the Meter 5 Using the Menu System General The menu system allows you to store data and to select various operating modes It is accessed by pressing the appropriate function key that corresponds to MENU on the bottom line of the display screen The menu is comprised of two menu screens and several sub menus Press the number on the keypad that matches the number on the menu to make your selection Instructions or sub menus appear when one of the basic menu options is selected Press the Help key or refer to the appropriate chapter of this guide for detailed instructions The following keys are used to move through the various menu options and to set measurement parameters Function Most menu options are offered on the fourth Keys bottom line of the display Simply press the F1 F4 function key that matches the marking just below the display Numeric Used to make a selection where options are Keys listed on several lines of the display Often 0 9 multiple options are listed in two columns Used to input a specific value or range frequency data logging interval time and date Press the ENTER key after entering numeric Key value to complete the selection process ESC key Press the ESC key to return to the previous screen without making a selection Chapter 5 Using the Menu System 29
33. aging time in many standards is frequency dependent For example IEEE C95 1 1999 specifies a six minute averaging period for Controlled Environments from 3 kHz to 15 GHz Above 15 GHz the averaging period decreases to ten seconds at 300 GHz based on a logarithmic function Chapter 9 Time Averaged Measurements 61 62 set the meter for a specific frequency 1 Press F4 FREQ from the measurement screen new screen will appear to allow you to enter a frequency FREQUENCY __ GHz CORRECT FACTOR 1 00 kHz MHz GHz SAVE Enter the frequency that you want to use for the time averaged measurements Make sure you fill in all four positions If you make a mistake just enter more digits until correct For greater accuracy use the units that allow the larger number For example enter 10 00 kHz not 00 01 MHz Change the units if needed by pressing either 1 kHz F2 MHz or F3 GHz Press F4 SAVE The meter will automatically return to the measurement screen If the probe used is a probe in memory the frequency that you have set will be displayed on the right side of the third line of the display The meter will also automatically correct the readings for probe frequency deviation The meter does this by using the closest calibration frequencies above and below the selected frequency to calculate and apply an appropriate correction factor This new correction factor is briefly shown on the second line o
34. ain measurement screen of the meter Some general information is also included about measurement surveys precautions you should observe and the use of probe correction factors Getting Started Press the On power key The meter model serial and firmware version will be displayed briefly After a few seconds the Opening Menu Screen will appear CALIBRATION DATE CAL DATE 09 01 98 e Indicates date the meter CAL DUE 09 01 99 CALIBRATION DUE DATE was last calibrated Indicates recommended CONNECT PROBE NOW date for next calibration To Make Measurements 1 Select the probe you want to use and connect it to the meter N ote 2 Proceed as directed in Entering the Probe Model See Chapter 5 To access the meter s menu system to perform some other Using the Menu function System for details 1 Press F4 MENU The First Menu Screen will appear on features and operation See Chapter 5 Using the Menu System Chapter 4 Making a Measurement 13 ote The single most im portant thing you must do is tell the 8718B meter which probe you are using 14 Entering the Probe Model Narda s 8700 Series system is completely modular all 8700 series meters work with all 8700 series probes The single most important thing you must do is tell the 8718B meter which probe you are using The Model 8718B has the basic characteristics of every 8700 Series probe stored in its internal memory All you have to do is selec
35. al measured value e Unit of measure is always STD for shaped frequency response probes CALCULATED FIELD STRENGTH Displays field strength in mW cm that has been calculated from the STD reading using the referenced PROBE FREQUENCY CORRECTION CF 1 00 indicates no correction factor is being applied e CF indicates 0 61mW cm MAIN MAXR MENU 10 00 GHz FREQ standard and the indicated frequency Change to the Go to the First Alternate Menu Screen Measurement Display Screen F4 Allows you to enter the numeric value that is being applied A frequency displayed here indicates that the meter is applying a correction factor based on the stored calibration data for the specific probe in use or change the frequency that you are correcting for probe frequency deviation Alternate Measurement Display Screen Flat Probes The Alternate Measurement Display Screen for flat frequency response probes is the same as the screen for shaped frequency response probes except as indicated below CALCULATED PERCENT OF STANDARD Displays percent of standard that has been calculated from the field strength reading using the referenced standard and the indicated frequency mi mil onl nnl untl 6 26 mW cm2 FIELD STRENGTH e Indicates actual measured value e Unit of measure can be changed by going to the First Menu Screen 25 2 STD 10 00 GHz
36. and the amount of memory already used The bar graph is a rough indicator of remaining memory capacity as a percentage of total Capacity nid AVAILABLE MEMORY 10kB AVAIL 15kB USED MENU QUIT A record contains a header and one or more data points To estimate the approximate number of data points and records logging runs that can be stored with the available memory 1 Allocate 33 bytes for each header separate header is used for each record Allocate 7 bytes for each data point from Mode 1 and Mode 3 logging Allocate 14 bytes for each for each spatially averaged data point from Mode 2 logging More memory is used in this mode because both average and peak values are stored Determine whether there is sufficient available memory to perform the desired task If there is proceed with logging as described above If you determine that there is insufficient memory to perform the desired task because much of the meter s memory has been used it will be necessary to empty the memory Press F4 QUIT To download the current memory contents you must connect the 8718B to a computer See Chapter 18 User s Software Chapter 8 Data Logging 55 7 discard the contents the meter s memory once the contents have been downloaded or without saving the information access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line
37. asurement screen If you had accessed the menu system from the Opening Menu Screen you will return to that screen To initiate spatial averaging again at a later point use the menu system to select SPATIAL from the First Menu Screen Operating the Meter 8 Data Logging Mode 1 Logging Options The 8718B Meter features several methods of collecting data The basic choices are Logging Data with the Meter The logged data stored in the meter is downloaded to a computer at a later date using the User s Software where it can be viewed and printed The data can also be exported in spreadsheet or database formats for further processing Continuous Output to a Computer Data collection if any is performed by the computer Analog Output An analog voltage is continuously available for use with a Chart Recorder or A D converter Logging Data The 8718B has three logging modes to collect field strength measurements store the data in the meter s memory and later export the data to a personal computer via the RS232 port on the top of the meter The three logging modes are e Collect a series of up to 999 data points one at a time and automatically assign a reference number to each data point The reference numbers can refer to either site plan locations or to a diagram of the industrial equipment being surveyed Each data point also has a time and date stamp Chapter 8 Data Logging 45 Mode 2 Mode 3 44
38. ations that the probe may have drifted enough to require correction e Whenever the negative zero drift exceeds 0 1 of full scale of the probe the words RE AUTO ZERO will flash on the top line of the display This will replace the bar graph Operating the Meter 12 1 STD 27 5 1 00 ALT MAXR MENU FREQ e Whenever the meter continues to show low level values and never seems to get back to a zero field condition positive zero drift is a possibility This can be confirmed by shielding the probe to see if the meter goes back to a zero reading See Shielding the Probe on the following page for suggested methods Temperature Concerns It is important to allow the meter and probe to become conditioned to the ambient temperature before attempting to zero the system This is especially important when the meter and probe have been transported or stored at a different temperature such as in a vehicle for example Diode sensor based probes require only a few minutes to stabilize The thermo couple sensors used in microwave band and ultra broadband probes may require 15 20 minutes to stabilize Establishing a Zero Field It is important to zero the probe while the probe is not exposed to a significant RF field level For accuracy the field level should be lower than the lowest value that the probe is capable of reading If previous measurements have indicated that the ambient field lev
39. attery B1 Communications Band Electric Field Probes The LCD is a self contained display and meter circuit assembly The display has four lines with twenty characters per line Each character is a 5 x 7 dot matrix The display is backlit for improved visibility under low light conditions It connects directly to PCB 1 The keypad has 22 keys It is shielded in aluminum and connects directly to PCB A1 The battery pack is a custom package consisting of six individual NiCd cells It has a rated output of 7 2 volts with a capacity of 7 2 Ah The battery pack contains an over current protection device It connects directly to PCB 1 Probe Designs The probes used with the Model 8718B meter measure either the electric field or the magnetic field Some have a flat frequency response others have a shaped frequency response see Chapter 3 Probe Selection All 8700 series probes have square law characteristics that provide an accurate summation of field levels present from multiple frequency sources All probes are internally coated with a thin film high resistive coating The film is on the order of 0 5 M per square inch and provides a shield against electrostatic charges All 8700 series probes utilize a preamplifier in the handle to amplify the detected signals from the sensors This eliminates probe to meter cable modulation The probe amplifiers are connected to the probe elements by inflexible monolithic resistive leads This prevent
40. ce The 8718B uses the referenced standard in two ways e The Alternate Measurement Display Screen displays additional information about the instantaneous measurement at a particular frequency See Alternate Measurement Display Screen on page 20 e Time averaged measurements are made to conform to the referenced standard at the specified frequency Checking or Changing the Standard To determine which standard the 8718B is currently set to reference 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display 2 Press number 8 NEXT to select the Second Menu Screen 3 Press number 6 to select STNDS A screen will appear that specifies the current standard The specific level or tier will be specified for standards with more than a single tier Chapter 11 Using the RF Exposure Standards Feature 71 Many standards have more than one tier IEEE C95 1 1999 establishes different Maximum Permissi ble Exposure MPE levels and averaging times for Controlled Environments and for Uncontrolled Envi ronments 72 C1915 1191919 CONTROLLED ENVIR OK STNDS 5 Press 1 OK to continue using this standard as reference without change To change the standard or tier that the 8718B references 6 Press F4 STNDS A new menu screen will automatically appear that lists several major international standard
41. ct a data recorder to the smaller jack located on the left side of the meter See Chapter 17 Operation with a Data Recorder Chapter 2 Understanding Your Model 8718B 5 ote The keys on the 8718B must be firmly depressed to per form their function and give a tactile feedback when prop erly depressed Keypad The Model 8718B has four groups of keys distinguished by their color Function keys green Numeric keys yellow Special Function keys white Power keys blue green Power Keys Two power keys are used to turn the Model 8718B On and Off Use the four function keys F1 F4 to select the options displayed on the bottom line of the display screen directly above the F1 F2 and F4 markings In afew cases the options will be spelled out on the display Operating the Meter Numeric Keypad Esc Auto Zero Help Test Source Range Enter Use the numeric keypad to enter number data into the Model 8718B You also use the numeric keypad to select a numbered option list
42. ctions oriented at right angles This provides for the independence of probe orientation relative to the polarization of the field These probes operate from 300 kHz to 50 GHz Two distinct sets of isotropic sensors are used to cover this very broad bandwidth The output from each set of detectors is processed separately by separate amplifier circuits in the probe handle The two signals are summed within the 8718B meter Models include the Model 8741D that has a flat frequency response and the x8722D series that have shaped frequency response characteristics In the lower frequency region below 1500 MHz a dipole with diode detector and both distributed and discrete components are used Three orthogonally mounted conductive dipoles each terminated in diode detector form the low frequency detection circuit These diode detectors are operated in their square law region This region is defined as that in which the DC diode current is proportional to the square of electric field tangential to the dipole The elements that are used in the higher frequency region are thin film thermocouples They provide true square law output and function in two modes Between 1 5 and 12 GHz they are resistive dipoles As a resistive dipole each probe contains three mutually perpendicular elements Above 12 GHz it utilizes the phase delay of a traveling wave to produce additional output In this mode the dipole is aligned along the Poynting Vector with the cold
43. d Data Record To print a copy of the Logged Survey Data window that you are viewing 1 Select Print Screen from the File menu The information will print automatically 2 To print very large records with many data points it is suggested that you export the data and use another program Chapter 18 User s Software 113 114 Exporting Data To export a logged data file for use in a spreadsheet program 1 Select Make Spreadsheet csv File from the Export menu A dialog box will appear titled Make Spreadsheet csv File The file selected to be exported drive will be listed in the table on the left The default directory for exported survey files is Ssdata which is a subdirectory under 8718B You can select any drive and directory to export your file from this dialog box Click OK to convert the file and store it in the selected location To export a logged data file for use in a word processor or text editor program 1 Select Make Tab txt File from the Export menu A dialog box will appear titled Make Tab txt File The file selected to be exported drive will be listed in the table on the left The default directory for exported survey files is Ssdata which is a subdirectory under 8718B You can select any drive and directory to export your file from this dialog box Click OK to convert the file and store it in the selected location Clearing the Meter s Memory To clear the meter s memory of
44. d in classified environments The majority of the 8700 series probes have four inch 10 cm diameter heads The minimum measurement distance for these probes is about 4 inches 10 cm from the outside surface of the probe Measurements made at closer distances can result in inaccurate readings due to capacitive coupling The Models 8721D 8723D and 8725D have two inch 5 cm diameter heads that can be used as close as 2 inches 5 cm from the source to the outside of the probe These probes are ideal for the measurement of waveguide leaks Similarly the Model 8781D has a one inch 2 5 cm diameter head with a flexible shaft that is designed for locating leaks in densely packaged microwave systems Shaped Frequency Response Probes The goal in designing and manufacturing a traditional flat frequency response probe is to make the probe equally responsive to energy at every frequency within its rated frequency range In contrast Narda s patented shaped frequency response probes are designed and manufactured so that their sensitivity mirrors a particular standard as closely as possible For example many of the major standards in the world set limits for maximum exposure at the lowest frequencies of 100 mW cm2 These same standards typically limit exposure in the VHF region to 1 mW cm and to 5 10 mW cm in the microwave region A shaped frequency response probe designed for such a standard is 100 times more sensitive in the VHF region t
45. d want to install a probe you can proceed as described in Installing a Probe If you already have six probes installed you must first remove one or more probes to make room Proceed to the Removing Installed Probes section Viewing Installed Probes To view the information on a specific probe that has already been installed 1 Goto the Probe Installation Screen 2 Highlight the model and serial number of the probe that you want to view from the list in the Installed Probes box The calibration information for that specific probe will appear 3 leave the Probe Installation window and return to the Main Menu Screen click the Close button Chapter 18 User s Software 105 ote Probe Models 8782D and 8782 are unique low frequency elec tric field probes that feature a range switch on the probe to cover a total of 60 dB The 8782 series probes must be en tered as two sepa rate probes since there are two differ ent full scale mea surement ranges dependent on the switch on the probe that the meter can not control or know the status of and each range has dif ferent calibration factors N ote A correction factor greater than 2 0 or less than 0 5 will not be accepted and will automatically be changed to one of these values Narda probes never have a correction factor outside of this range for any frequency within their rated fre quency range 106 Installing a Probe You may have a maximum
46. e about its axis and using the mean value to determine the correction factor If you rotate the probe around its axis and use the mean value ellipse ratio can be eliminated as a source of uncertainty e Isotropic response is the error that occurs when the probe is pointed in different directions It includes the ellipse ratio plus some additional uncertainties Although the probes pick up energy from all directions they are most accurate when pointed at the source of energy Generally speaking the isotropic response is no greater than the ellipse ratio providing that the probe is pointed towards the source e Calibration uncertainty represents another 0 5 dB e The Model 8718B meter has a maximum uncertainty of 3 A good rule of thumb is that the total uncertainty is no greater than 3 dB when correction factors are not used providing that the probe is pointed at the source of energy There are other issues related to field perturbation that can be more significant sources of uncertainty See Field Perturbation in Measurement in the Applications Booklet Making a Measurement Refer to the Applications Booklet for both general and specific information on making measurements Precautions When making measurements of electromagnetic fields a potential exists to expose yourself to excessive levels Approach the source of energy slowly and begin making measurements from a distance at which low field levels exist Be prepared to ev
47. e is a Windows based program that performs three basic functions Probe Calibration Data The User s Software is used to enter probe calibration information into the memory of the Model 8718B Data Retrieval The User s Software is used to download data collected with the Model 8718B with one of its three data logging modes Diagnostics and Upgrades The User s Software is used to provide meter diagnostics and to load firmware updates into the meter The User s Software for the Model 8718B is supplied on a compact disk It should be permanently installed on the hard drive of a personal computer System Requirements In order to install and operate the User s Software successfully your system must meet the following minimum requirements An IBM or 100 compatible personal computer with 4 MB of RAM 1 MB of hard drive space Microsoft Windows 3 1 Windows 95 Windows 98 Windows NT or later A printer supported by Microsoft Windows required for printing reports ACD ROM drive A mouse A cable to connect the computer to the 8718B Supplied Chapter 18 User s Software 101 Installing the User s Software To set up the program 1 Turn the computer and start Microsoft Windows type WIN at the DOS prompt if your computer doesn t start Windows automatically 2 Insert the User s Software into your CD ROM drive The CD starts automatically and the 8718B menu screen appears 3
48. e probe is subjected to If the two components are operating in different ambient temperature environments the 8718B can be set to Chapter 15 Advanced Settings 89 90 correct for the temperature differential The amount of error that can occur when the meter and probe are operating at different temperatures depends on the particular probe design as well as the temperature differential The maximum error that can occur is about 1 per degree Centigrade for diode probes and about 0 1 per degree Centigrade for thermocouple probes The change may either increase or decrease the meter reading from the true value depending on the probe model To correct for a significant temperature differential 1 Access the settings menu by following the procedure described in Accessing the Settings Menu 2 Press 2 to select TEMP A new screen will appear that shows the current mode The default mode is Auto Correct TEMP CORRECTION IS SET FOR AUTO OK SET 3 Press F1 OK to continue with the same setting without change 4 Press F4 SET to either set or change to a specific probe temperature 5 Ifthe meter was set for a specific temperature and you want to return to the auto correct mode press F1 AUTO 6 Anew screen will appear that shows two underscored lines where the probe ambient temperature should be entered Use the numeric keypad to enter the temperature of the probe in degrees Centigrade TEMP CORRECTION 15
49. e probe is separated from the meter and operating at a different ambient temperature Clear the memory of logged data Set the function keys for right or left handed operation Adjust the contrast of the display Accessing the Settings Menu To access the Settings menu 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display Press 8 NEXT to select the Second Menu Screen Press 2 to select SETTINGS A new screen will appear that offers five choices SETTINGS 1 CLOCK 4 RIGIT LIE F T 2 TEMP 5 01 3 CLEAR MEMORY Chapter 15 Advanced Settings 87 Setting the Clock To check and or change the time and date 1 3 Access the settings menu by following the procedure described in Accessing the Settings Menu Press 1 to select CLOCK A new screen will appear that displays the time on the left side of the screen and the date on the right The time is in 24 hour format i e 13 30 equals 1 30 P M The date format is MM DD YY TIME IS DATE 15 1131 12 02 27 98 24HR FORMAT MM DD YY SET SET Press the Esc key to return to the First Menu Screen without making any changes To set the time 1 88 Press F1 SET The display will change to show four underscored lines where the new time must be entered DATE IS 02 27 98 24HR FORMAT MM DD YY SAVE Enter the new time in 24 hour format using the numeric
50. e the F1 F2 or F3 legends If more than three probes are in memory they can be found by pressing F4 MORE 4 Press the appropriate function key and the probe model and serial number will be displayed on the second line of the screen If this is correct press Enter 5 Anew screen will appear specifying probe model number serial number frequency range field type maximum measurement range and type of response flat or shaped If this information is correct press F1 If this information does not match your requirements you need to select another probe Press F2 and you will go back to the Select Probe screen to make another selection A8742D S N 00001 300kHz 3GHz 600 STD SHAPED YES NO 6 Proceed with the probe zeroing process See Zeroing the Probe on page 17 Chapter 4 Making a Measurement 15 ote You must return to the Opening Menu Screen and repeat the probe selection and zeroing process if you want to change probes Press 7 Probe from the First Menu Screen and then press F4 RESTART 16 To use a PROBE that is NOT IN MEMORY 1 2 If you haven t already press F1 MEASURE The model number of the last probe used will be displayed on the second line of the display If you want to use the same model probe press Enter SELECT PROBE MODEL A8722D SNXXXXX OR SELECT FROM LIST 87XX 87XX 87XX PROBE If you want to use a different model probe select PROBE by pressing F
51. e timer During this interval of time the meter takes a large number of measurements The results are presented as both an average value and a peak value Effective measurement technique requires you to simply move the probe slowly from toe to head while the timer is running Although this technique may not be specifically called out a particular exposure standard it is technically sound and much more accurate than averaging a series of measurements It is anticipated that future updates of the major standards will reflect this automatic technique now that the survey equipment makes it practical To make spatially averaged measurements 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display 2 Press the number 3 on the keypad to select SPATIAL from the First Menu Screen SPATIAL AVERAGING MODE 15 ON 3 Press F1 ON 4 The meter will automatically return to the measurement screen with new options for the function keys If you had accessed the menu system from the Opening Menu Screen where the calibration dates are shown you will return to that screen 5 Holding the meter in one hand and the probe in the other touch the head of the probe to the ground Operating the Meter ote It is important to move the probe vertically at a con stant rate to obtain an accurate spa tially averaged measurement N ote The averaging time
52. easurement interval has been completed or stopped press F2 CLR if the averaged value is displayed Once the meter is displaying real time values the frequency menu is accessed by pressing F3 FREQ Proceed as previously described to set the meter to a new frequency Operating the Meter 10 Alarm Settings N ote If you access the menu system from the Opening Menu Screen you will re turn to that screen Once an alarm set ting has been made the alarm function will be initiated once the meter is placed into the measure ment mode Alarm Description The Model 8718B Meter is equipped with an audible alarm that emits sound through a tiny hole on the bottom of the meter The alarm sounds automatically whenever the field strength exceeds the measurement range of the probe or over ranges The meter can also be set to sound its alarm at a specific level and or to sound a variable tone indication of field strength Controlling the Alarm Functions To make changes to the audio alarm settings 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display Press 8 NEXT to go to the Second Menu Screen Press 5 ALARM to access the alarm menu A new menu will appear that allows you to Turn the audio alarm on or off e Set the alarm threshold in terms of percent of full scale of the probe in use 1 to 99 Turn the variable tone a
53. ed on the display screen Special Function Keys Six special function keys enable you to perform specific functions Returns you to the previous menu In a few cases you must enter a selection rather than use the Esc key Enables you to automatically zero the meter and probe Displays a help screen that explains your options Turns on the built in low frequency and high frequency probe test sources for approximately 20 seconds Locks in a specific measurement range for the bar graph The digital display is not affected The meter automatically displays a digital value over the probe s entire measurement range See Bar Graph Ranges on page 23 Stores data you entered with the numeric keypad Confirms an option you selected from a menu screen Chapter 2 Understanding Your Model 87186 7 Operating the Meter 5 Probe Selection FREQUENCY RANGE POWER DENSITY OR FIELD STRENGTH ELECTRIC FIELD VERSUS MAGNETIC FIELD Introduction The 8700 series RF measurement system offers a very broad selection of probes The factors that you should consider in selecting the probe or probes best suited for your task are described in this section Key Factors in Selecting a Probe The probe frequency range should include the frequencies of all the emitters to be surveyed at one time The measurement range of the probe should be adequate for the field levels that you anticipate i e do you expect strong fields or weak fi
54. efault correction factor value of 1 0 CF 1 0 is automatically entered in the table to minimize measurement error in case the user fails to enter a value Operating the Meter Probe Installation Screen ATIE Miehs alleen Probes THEM ic Se Probebht 5 Full Sesh Facies Faas ESTO blaima 6 Probe Typa hejig Herdal E EC SH mms Hapen eed Prota Ente CH Date m maihi dep pe Dun monlhidaptpoar Chapter 18 User s Software 107 108 10 11 Enter any special calibration frequencies on the extra lines provided and enter the appropriate calibration factors Delete any standard calibration frequencies that were not used Click on the Install Probe button A dialog box will appear asking you if you are sure you want to install the probe Click on OK The program will automatically send the calibration information to the meter via the modem and cable The program will then verify that the probe has been successfully installed in the meter by reading the meter s memory The model number and the serial number of the probe just installed will now appear in the table of Installed Probes To leave the Probe Installation window and return to the main menu click the Close button Kemoving Installed Probes To remove a specific probe from the meter s memory 1 First view an installed probe as de
55. el is very low the probe can be zeroed without shielding This is often the case in a typical office environment It is recommended that the ambient field level be at least 30 dB below the full scale measurement range of the probe When it is necessary to zero a probe in higher field areas the probe must be shielded Chapter 14 Probe Zero 83 ote The Electric Field At tenuator can not be used to zero mag netic field probes 84 Shielding the Probe The probe must be shielded from significant RF fields whenever it is zeroed with the meter This is to establish a zero reference for the field There are four ways to shield the probe during zeroing e Use the Model 8713B Electric Field Attenuator supplied with the meter This conductive fabric is the same material that is used in RF protective clothing The attenuator should be put over the head of the probe and closed off around the neck of the probe above the handle using the hook and loop fastener band e Use the shielded storage case Place the probe in the case and close the lid carefully on the cable with the meter outside the case Be careful not to move the probe while zeroing takes place On probes with low frequency test points you can create static which will give inaccurate results although this is less of a concern with the new 8700D series probes e Use aluminum foil to shield the head of the probe Fully wrap the head of the probe and close it around the nec
56. elds Probes give more accurate and more stable readings when they are not used at the extreme low end of their sensitivity range Therefore if you anticipate measuring very weak fields select a probe with a lower power full scale measurement range to get greater sensitivity In contrast higher power probes give additional safety margins especially at microwave frequencies where field strength can change rapidly with a small change in distance to the source Select a probe with a higher power full scale measurement range if you anticipate measuring high level fields Most standards recommend that you measure both electric E and magnetic H fields below 300 MHz due to the possibility that measurements may be made in the near field Since most experts agree that the electric field poses a greater danger at lower frequencies due to induced and contact currents that can occur the electric field is normally measured first Higher frequency measurements are normally made of only the electric field since measurements will generally be made in the far field Chapter 5 Probe Selection 9 FLAT RESPONSE OR SHAPED FREQUENCY RESPONSE SIZE AND MINIMUM MEASUREMENT DISTANCE 10 Flat response probes are the most common Narda s patented shaped frequency response probes read out in Percent of Standard and are particularly useful in complex multi signal environments where exposure limits are different for the various emitter frequencies an
57. ent as many times as needed by entering a new value When you are satisfied with the setting press F4 SAVE The meter will return to the First Menu Screen Press Esc to return to the measurements screen Operating the Meter 16 Operation with a Fiber Optic Link Description Narda fiber optic link transmitters are compatible with all 8700 series probes and the Model 8718B meter The meter has a built in fiber optic receiver compatible with the HP Versatile Link type plastic cables and connectors The fiber optic transmitter connects directly or via a short cable to the probe A fiber optic cable connects the 8718B to the transmitter The transmitter contains a rechargeable battery that provides both power for its own circuitry and to operate the amplifier in the probe Full system calibration is maintained because each of the components in the system meter fiber optic transmitter and probe are independently calibrated The fiber optic transmitter converts the analog DC voltage out of the probe amplifier to a series of pulses The pulse rate is directly proportional to the probe output Application The fiber optic link provides total isolation between the meter and the probe which is often desirable when making low frequency measurements At frequencies below 50 MHz and especially below 10 MHz there is significant interaction between the field the individual making the measurements and the survey equipment There is als
58. environment for the probe as before 2 Press the Auto Zero key This will automatically touch up the zero and correct for any drift in a few seconds Measurement Display Screens There are two display screen options e The Main Measurement Display Screen The Alternate Measurement Display Screen Main Measurement Display Screen The Main Measurement Display Screen shows a maximum value on the third line of the display The Alternate Measurement Display Screen provides frequency specific real time information instead of a maximum value Operating the Meter MAXIMUM VALUE Main Measurement Display Screen Shaped Probes FIELD STRENGTH e Indicates actual measured value e Unit of measure is always STD for shaped frequency response probes BAR GRAPH e Indicates approximate field strength 100 segment three 10 1 10 dB ranges PROBE FREQUENCY CORRECTION CF 1 00 indicates no correction factor is Indicates the maximum value that has occurred since you began making 27 5 MAX CF ALT MAXR MENU measurements or being applied since resetting the e CF X XX indicates maximum using the numeric value that F2 MAXR _1 is being applied The unit of measure is F1 F3 frequency displayed the same as for the Change to the Go to the First here indicates that the instantaneous value Alternate Menu Screen meter is applying a shown on the line Measurement correction factor above Displa
59. es the signal s and provides a visual display of the levels detected The signal s received from the probe at PROBE connector J1 is routed to amplifier U2 Amplifier U2 amplifies the signal s from the probe and generates a signal to drive the A D converter U3 The output of the A D converter is routed to microprocessor U5 that drives the LCD Appendix B Theory of Operation 121 122 The meter also contains built in self testing facilities for checking the condition of the batteries the operation of the probe and for zero adjustment of the probe The meter provides a means for automatically zero adjusting the meter and probe When in an operating mode and the probe is in a zero field the operator presses the Auto Zero key to begin the auto zeroing routine The 8718B meter uses a unique digital method to set the zero reference The meter provides a means of testing whether the probe is operational using built in test signal sources The test is used to prove that the probe is operational by generating upscale indications on the Model 8718B meter a High Frequency Test Source A 10 5 GHz nominal oscillator and waveguide aperture for illuminating the probe Power output is capable of producing an upscale indication on the meter of approximately 0 75 mW cm2 3 dB b Low Frequency Test Source An external test point provides a 10 kHz nominal signal at the unit and test points on the probe to excite each low frequency element a
60. et the function keys for right or left handed operation Adjust the display contrast 15 CABLE FO Select between the standard probe cable input and the fiber optic receiver 16 LOCKOUT Lock the keypad so that settings will not accidentally be changed To release press ENTER and ESC together 13 ALARM Turn the audio alarm on or off Set the alarm threshold in terms of percent of full scale of the probe in use 1 to 99 Turn the variable tone alarm on or off 10 STNDS Check or set the standard that is referenced for various measurement options 11 BLANK Blank the display and lock the keypad To release press ENTER and ESC together 13 BACK Return to the first menu screen Chapter 5 Using the Menu System 31 32 Menu Commands The following is a list of menu commands that are shown on the fourth line of the display and selected by using the four function keys F1 F4 AUTO ABORT BEGIN CABLE CANCEL CONT CLEAR CLR DISCARD END FO FREQ GHz HR kHz LEFT LOG Auto returns the meter to the normal automatic temperature correction mode Abort clearing the memory Begin confirms that the meter is ready to perform time averaging to meet the requirements of a specific standard Cable changes the meter input from fiber optic receiver to the standard cable input Cancel making the selection and return to the pr
61. evious menu Continuous initiate logging for an undefined interval Clear the memory of logged data Clear the screen and return to making real time measurements Discard this data point without storing it End the logging run or averaging interval Fiber Optic changes the meter input from the standard cable input to the fiber optic receiver Frequency change or enter a frequency GHz used to enter a frequency Hours used to define a logging interval kHz used to enter a frequency Left set menus for left handed operation Log the current measured value Operating the Meter MAIN Main switch to the Main Measurement Display Screen MAXR Maximum Reset reset the maximum value to the instantaneous value MEASURE Measure begin the measurement process by selecting and zeroing the probe MEM Memory display the available memory MENU Menu access the First Menu Screen MIN Minutes used to define a logging interval MHz MHz used to enter a frequency NO No the current probe selection is incorrect Return to the menu to make another selection OFF Off turn special mode off OK OK continue with the same setting ON On turn special mode on PAUSE Pause during data logging or time averaging QUIT Quit special mode and return to the standard measurement screen RESTART Restart the probe selection and zeroing process RGT Right set menus for right handed operation
62. f the display after you press F4 SAVE before the meter automatically returns to the measurement screen Operating the Meter To initiate Mode 2 averaging averaging to meet the requirements of a specific standard 1 sure that the meter is set for the correct standard or change it if needed See Chapter 11 Using the Standards Feature 2 Make sure the meter is set to the correct frequency for the measurement you are making See page 64 3 Press number 2 on the keypad to select STANDARDS AVG from the averaging menu screen Selecting Mode 2 averaging will automatically shut off Mode 1 averaging if it is on 4 A new screen will appear stating that averaging has been enabled in accordance with a specific standard AVERAGING ENABLED 9 5 111 11191919 LEVEL CONTROLLED BEGIN CANCEL OFF 5 Press F3 CANCEL to return to the initial time averaging menu screen to make another selection or press F4 OFF to turn time averaging off and return to the standard measurement screen 6 Press F1 BEGIN to automatically return to the measurement screen with new options available for the function keys 6 26 mW cm2 11 5 MAX 10 00 GHz START MENU FREQ QUIT Chapter 9 Time Averaged Measurements 63 N ote If you access the menu system from the Opening Menu Screen you will re turn to that screen Once a probe has been selected and zeroed the mea surement screen will re
63. flect the averaging mode that you have selected 64 10 11 The meter will continue to make real time measurements until you initiate making the time averaged measurement Press F1 START when you are ready to begin the time averaged measurement The averaged value is displayed on the screen and will flash every second each time it is updated The meter will automatically stop at the end of the averaging interval which was determined by the standard and the frequency To end time averaging prior to the end of the averaging interval press F4 STOP 8 71 mW cm AVERAGE 11 5 MAX 10 00 GHz PAUSE STOP At the end of the averaging interval the meter will show the time averaged value on the second line of the display and the maximum value on the third line of the display The bar graph will be indicating the instantaneous field strength in real time tL avant 8 71 mW cm AVERAGE 11 5 MAX 10 00 GHz START CLR MENU QUIT 12 To make another time averaged measurement at the same frequency press F1 START again Operating the Meter ote The PAUSE feature can be useful when measuring the aver age value from cer tain rotating radars The effective mea surement technique requires you to pause during the pe riod of time when you are not in the beam of the radar Continue this tech nique for two or more revolutions depending on the RPM to obtain a re alistic avera
64. for function key location will be in use OFF to conserve battery power OFF Last Used standard will be referenced OFF the meter will sense ambient temperature and automatically correct Operating the Meter Time Averaging Unit of Measure Chapter 5 Using the Menu System OFF Last Used unit of measure will be in use if previous and current probe both have flat or shaped frequency response If current probe is shaped unit will be of STD If current probe is flat and previous probe was shaped then unit will be mW cm 35 36 Operating the Meter 6 Units of Measure Available Units of Measure The 8718B Meter allows you to quickly select any unit of measure that is appropriate for the probe in use The available units of measure depend on whether the probe is designed to measure the electric field or the magnetic field It also depends on whether the probe has a flat frequency response or a shaped frequency response The available units of measure for the various types of probes are Field Frequency Component Response Units of Measure mW cm2 W m2 V m Electric Flat V2 m pem mW cm W m N Magnetic Flat Alm A m pJem ote Electric Shaped Percent of Standard Percent of Standard Magnetic Shaped Percent of Standard is the only unit of measure available for shaped fre quency response probes Shaped probes have fre quency response curves designed to
65. ge value of the field in the beam at your loca tion For details on this measurement technique see Ra dar Measurements in the Applications Booklet Chapter 9 13 14 To temporarily suspend the time average mode once the current measurement interval has been completed or stopped and make real time measurements press F2 CLR To make another time averaged measurement under the same conditions press F1 START again To end time averaging altogether and return to the standard measurement screen once the current measurement interval has been completed or stopped press F4 QUIT To initiate time averaging again at a later point use the menu system to select TIME AVG from the First Menu Screen To temporarily pause during a time averaged measurement Time Averaged Measurements To temporarily suspend time averaging press PAUSE The word PAUSED will appear on the fourth line of the display To resume time averaging and complete the measurement press F1 START 8 71 mW cm AVERAGE 10 00 GHz PAUSED STOP 11 5 MAX START You may continue to pause and start the averaging as many times as needed The time interval determined by the standard and the frequency applies only to the measurement time excludes time when PAUSED To end time averaging while PAUSED press F4 STOP 65 66 To change the frequency 1 To change the frequency once the current m
66. ging at the end of this interval To stop logging earlier or when set to an indeterminate period of time press F3 END Chapter 8 Data Logging 53 54 10 screen will appear requesting that you assign another two digit survey number to the new logging run Use the numeric keypad to enter the two digit number and then press F1 OK or ENTER Again make note of the number for later use If you make a mistake press F2 CLR to clear the screen and enter new survey number The meter will automatically return to the logged measurements screen NEW LOGGING RUN ENTER NEW REF NO _ OK CLR MENU QUIT To begin another logging run at a different rate or for a different duration e Press MENU Press the number 1 the keypad to select DATA LOG from the First Menu Screen and proceed as previously described To end logging altogether and return to the standard measurement screen e Press F4 QUIT To initiate logging again at a later point use the menu system to select DATA LOG from the First Menu Screen Memory Capacity To determine the remaining memory of the 8718B meter 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display 2 Press the number 1 on the keypad to select DATA LOG from the First Menu Screen Operating the Meter Press F2 A screen will appear showing the approximate amount of available memory
67. han at the lowest frequencies The result is that energy from all sources within the probe s rated frequency range are not only summed in terms of RMS power but are also weighted in direct proportion to a particular standard s frequency dependent exposure limits Operating the Meter ote It is important to un derstand that each shaped frequency re sponse probe model is designed to conform to a par ticular standard The readout on the 8718B is shown in terms of Percent of Standard The full scale of Narda s shaped probes is typically either 300 or 600 of a standard This permits measurements of exposure environments where the weighted field strengths range from as high as three to six times the maximum permissible exposure MPE level to environments where the levels are less than one percent of the MPE Connecting a Probe Connect a cable with a quick release eight pin connector to the connector at the top of your Model 8718B This cable will be either 1 a short adapter cable for attachment to older style 8700 series probes with integral cables or 2 a 4 ft 1 2m long cable with a quick release connector on both ends for use with the 8700 D series probes The D series probes have a quick release eight pin connector that allows the probe to attach directly to your 8718B or be used with a cable 8700D Series Probe Direct Connection 8700D Series Probe 4 1 2m cable Model 8744 04 supplied
68. haped frequency response probe has been selected e Flat Frequency Response Probes This display mode instantly converts the measured value to a percent of the referenced exposure standard at a particular frequency e Shaped Frequency Response Probes This display mode instantly converts the measured value shown in Percent of Standard to an equivalent power density value at a particular frequency The use of the Alternate Measurement Display Screen also introduces an automatic correction for probe frequency deviation for probes in memory The option to change display screens is only available when other options such as spatial averaging data logging or time averaging have not been turned on To use the Alternate Measurement Display Screen 1 sure that the 8718B is set to the correct exposure standard See Chapter 11 Using the Standards Feature 2 Press F4 FREQ from the Main Measurements Display Screen Anew screen will appear to allow you to enter a frequency 3 Enter the frequency that you are measuring You must fill all four positions If you make a mistake just enter more digits until correct For greater accuracy use the units that allow the larger number For example enter 10 00 kHz not 00 01 MHz Operating the Meter Alternate Measurement Display Screen Shaped Probes BAR GRAPH e Indicates approximate field strength 100 segment three 10 1 10 dB ranges IELD STRENGTH e Indicates actu
69. have a single conductive test point that is used to simultaneously test all three sensors A microwave window on the right side of the probe is used for testing high frequency probes Hold the probe parallel to the right side of the meter and position the probe head against the test window so that one of three arrows on the probe is pointing towards the window These arrows indicate the location of the three sensors inside the probe A deflection of any magnitude on the bar graph is acceptable Repeat for the other two sensors to insure that the probe is working correctly Ultra broadband probes contain both high frequency and low frequency sensors These probes require six checks three high frequency and three low frequency Using Probe Correction Factors All probes have a certain amount of frequency sensitivity Frequency sensitivity is the amount of deviation from the correct measured value that a probe yields at various frequencies Obviously the smaller the deviation the better But since a certain amount of frequency deviation is unavoidable the more frequencies that you calibrate the probe at the better At each calibration frequency you have a correction factor Multiplying the reading on the meter by a correction factor marked on the handle of a Narda 8700 Series probe compensates for the probe s frequency sensitivity The Model 8718B is unique because it can perform this task automatically Correction factors can be u
70. highly proactive policy on environmental protection and conservation of natural resources This service is available to our customers at no charge At the end of this product s effective life cycle it may be returned to Narda for proper disposal Appendix C Maintenance 131 152 Appendices Audio Alarm Alarm Description 4 67 Controlling Alarm Function 67 Fixed Alarm 68 Variable Tone Alarm 69 Back Light 75 Bar Graph 23 Battery Accuracy of Battery Status Indicator 77 Battery Capacity 76 Charger description 3 130 Charger line cord options 3 131 Checking Battery Status 76 Rechargeable Management Program 131 Clock 88 Communications with Computer 117 Correction Factors 24 Data Logging Format for Logged Data 44 Memory Capacity 54 Mode 1 Logging 46 Mode 2 Logging 48 Mode 3 Logging 51 Options 43 Data Recorder operation with Description 5 56 99 Output Level 99 Display Blanking 80 Display Screens measurement Alternate 20 Main 19 Index INDEX Fiber Optic Link operation with Application Controls and Indicators Setting the Meter System Checks Keypad Function Keys Numeric Keypad Power Keys Special Function Keys Keypad Lockout Maintenance Calibration Battery Charger and Line Cord Options Rechargeable Battery Program Replacement Parts Measurements Getting Started Entering a Probe Model Making a Measurement Precautions Uncertainty Memory Menu System Commands Default Conditions First Menu
71. ht at the top of the window Logged Survey Data Window The Logged Survey Data window is comprised of two parts 1 The header section at the top of the window defines the equipment that was used to make the survey a b The first line shows the meter model number serial number Cal Date and calibration Due date The model number serial number Cal Date and calibration Due date of the probe used are shown on the second line Line three identifies whether or not probe frequency correction PROBE CORRECTION was used during the survey Probe correction can be in the form of a frequency that was entered or a numeric correction factor Operating the Meter fo Logged ayey iste Logged Survey Data Screen Den Siew Fis METER PHASE PORE CORRECTION Poet 2 EA m _ CE wr __ _ _ T E M Oi _ i 1 Chapter 18 User s Software 0804 Col Date Bur Sy 01015 Cal Daw Due Conection Feder 1 2 of 2 Gaim Stan Tene 1621 Spatial Ma gt iar EF EL ee Field Strength of STO vs Data Point 1 111 ote If you used the PAUSE feature dur ing continuous log ging the time shown for each data point
72. ill affect the bar graph For simplicity a probe with a full scale rating of 100 mW cm is used as an example Range Measurement Range AUTO As the field level increases the bar graph automatically switches between three ranges 0 01 to 1 1 to 10 and 10 to 100 HIGH 1 to 100 MID 0 1 to 10 LOW 0 01 to 1 If you exceed the upper limit of either the MID or LOW range the bar graph will be replaced with the message RANGE OVERLOAD The digital display will continue to show the correct value If you exceed the full scale measurement range of the probe the word OVERLOAD will appear Testing the Probe Your Model 8718B is equipped with two RF sources for testing probes Press Test Source and both sources will stay on for approximately 20 seconds A contact on the right side of the unit is used for testing low frequency probes and the low frequency section of ultra broadband probes Most probes have three test points around the head of the probe Position the probe so that one of the test points touches the contact on the meter You should Chapter 4 Making a Measurement 23 N ote A probe that does not show a move ment of the bar graph for all three or six tests may be damaged and should not be used to make measurements 24 get a deflection on the bar graph but the amount of deflection is not important Repeat for the other two test points to insure that the probe is working correctly The D series magnetic field probes
73. isplay and unlock the keypad These are the two dark blue keys Operating the Meter 1 4 Probe Zero Understanding the Zero Function The purpose of zeroing the probe and meter is to set the meter to indicate a zero field strength when there is no measurable field strength The Narda 8700 series survey system maintains measurement accuracy under all conditions by insuring that all probes always provide true RMS Root Mean Squared indications of field strength Diode detectors which are used in many of Narda s electric field probes are always operated in the square law region Since the diodes are not operated in a saturated mode to insure accuracy in multi signal Conditions the survey system must be zeroed The Model 8718B establishes the zero reference as a small positive voltage inside the meter This zero offset allows the use of only positive voltages while handling both positive and negative zero drift While it is difficult to distinguish between a positive zero drift and the presence of an actual field a negative indication on the meter must be due to zero drift This is indicated on the display by a flashing negative sign between the field strength value and the unit of measure on the second line of the display umh oml l onl l nl 1121 19 15 27 5 1 00 ALT MAXR MENU FREQ Chapter 14 Probe Zero 81 82 Causes of Zero Drift All sensors have a change in output that is a function
74. junctions oriented tangential to the electric field Each of the three mutually orthogonal elements contains four resistive dipoles with the cold junctions oriented at right angles Appendices This provides for the independence of probe orientation relative to the polarization of the field The instantaneous charge distribution on adjacent cold junction elements produces a potential difference across the thin film resistive thermocouples and a resultant dissipation of energy in these films As the frequency increases the phase difference between the potentials developed in adjacent junctions also increases the open circuit voltage Low Frequency The Model 8764D operates from 100 kHz to 300 MHz It contains Electric Field three orthogonal displacement energy sensors with diode Probes detectors This unique design has much lower impedance than traditional dipole designs The major advantage is the greatly reduced interaction between the meter and probe the human body making the measurements and the field The Model 8782D uses an active antenna design to accurately measure fields as low as 3 kHz over 60dB dynamic range Low Frequency These probes are responsive to the H Field component Each Magnetic Field of the three mutually perpendicular coils in every probe has a Probes diameter of 3 5 inches 8 9 cm consists of multiple turns and is series resonated somewhat below the low frequency end of the band The RF curren
75. k of the probe about half way down If the probe has metallic low frequency test points these must be insulated from the aluminum foil One way to do this is to use electrical tape to cover the test points The other solution is to use a wide elastic band around the head of the probe over the test points The elastic band can easily be moved to use the 8718B s built in low frequency RF test source Alternately use an aluminum can e Use your body to shield the probe from the source of energy Operating the Meter Zeroing the Probe While Use The meter and probe are initially zeroed before the meter is allowed to go into the measurement mode If you determine that significant drift may have occurred it is simple to fine tune the zero See Checking for Zero Drift on page 82 To zero the probe while in use 1 Shield the probe using one of the methods described in Shielding the Probe 2 Press the Auto Zero key The meter will correct for any probe drift in about eight seconds The meter will then automatically return to the measurements screen Chapter 14 Probe Zero 85 86 Operating the Meter 1 5 Advanced Settings Description The Settings menu is used to control several features of the Model 8718B that need to be accessed infrequently The options available under the Settings menu are e Check or set the meter s internal clock time date Enter a value for temperature This feature is used only when th
76. kes nor authorizes any person to make any other guarantee or warranty concerning Narda STS products Safety Test Solutions an B communications company USA 435 Moreland Road Hauppauge NY 11788 Tel 1 631 231 1700 Fax 1 631 231 1711 E Mail NardaSTS L 3COM com www narda sts com GERMANY Sandwiesenstrasse 7 D 72793 Pfullingen Tel 49 7121 9732 777 Fax 49 7121 9732 790 E Mail support narda sts de www narda sts de
77. keypad If you make a mistake simply enter more numbers until the correct time has been entered Press F2 SAVE to save the new time Operating the Meter Proceed to setting the date if required Alternately press the Esc key to return to the First Menu Screen Press Esc again to return to the measurements screen To set the date 1 Press F3 SET The display will change to show six underscore lines where the new date must be entered TIME IS DATE 15 1131 1412 24HR 2 Enter the new date in DD MM YY format using the numeric keypad If you make a mistake simply enter more numbers until the correct time has been entered Press F4 SAVE to save the new time Proceed to setting the time if required Alternately press the Esc key to return to the First Menu Screen Press Esc again to return to the measurements screen Temperature Correction This feature is only used when the meter and probe are operating at significantly different ambient temperatures This situation can occur when the meter is located indoors and the probe is outdoors Either a probe extension cable or a fiber optic link system is normally used for such applications Temperature correction circuitry is used in the probe and there is atemperature sensor located inside the meter To achieve the highest level of accuracy it is important that the sensor inside the meter sense the ambient temperature that th
78. larm on or off AUDIO ALARM SETTINGS FE 185 15 ON 25 OFF ON OFF ON OFF Chapter 10 Alarm Settings 67 If you change to an other probe with a different full scale measurement range the alarm threshold will also change A setting that is often used with shaped fre quency response probes is 50 of Standard set the alarm for one of the 8722 series probes which have full scale measure ment ranges of 300 of standard calculate the threshold setting by dividing the de sired alarm level by the full scale value In this case 50 300 16 66 Set the alarm thresh old to 17 and the alarm threshold will be 51 of Standard when using a 8722 series probe 68 The left side of the display gives the status of the fixed alarm It indicates whether the fixed alarm is either on or off and the current alarm threshold setting in terms of percent of full scale of the probe in use 1 to 99 The right side of the display indicates whether the variable tone alarm is either on or off The bottom line of the display indicates which function key F1 F4 is used to turn the two alarms on or off Fixed Alarm 1 Use F1 ON or F2 OFF to change the status of the fixed alarm Use the numeric key pad to enter a two digit alarm threshold number This number is equal to the percent of full scale of the measurement range of the probe in use For example to set the meter to sound
79. les 1 CS two digit checksum 2 ASCII Hex characters NOTE The gt is NOT included in the checksum calculation 2 CR one digit camage return 13 or 0D 3 x data 4 r range 5 gt ASCIl gt 3E B General send format 1 gt letter 0 0 of digits in data data CS CRI 2 All characters are sent and received as capital letters don t send lower case letters unless one is specifically requested 3 Checksum CS is always sent or received as a hexadecimal value e g A7 BC 2E etc 4 Data is always sent or received as a decimal value 118 Appendices Command Characters Function To Change or initiate the following C D F Auto Zero ASCII Hex Read Clock ASCII Hex Where Correction Factor ASCII Hex Frequency ASCII Hex Clear All Survey Data ASCII Hex Read Field Strength ASCII Hex SEND RESPONSE gt A000CSCR ACR gt A000D1CR ACR 41 30 30 30 44 31 OD 41 0D gt C000CSCR SMHXDNYCSCR gt C000D3CR 3E 43 30 30 30 44 33 0D S seconds in BCD format M minutes in BCD format H hours in BCD format X N A D day of month in BCD format N month in BCD format Y year 00 99 in BCD format CS two byte checksum CR carriage return gt E003xxxCSCR ACR Example to set CF to 1 53 xxx 153 gt E00315371CR 3E 45 30 30 33 31 35 33 37 31 OD gt FOr4xxxxCSCR ACR 0 for kHz 1 for MHz or 2 for GHz Note is in binary not ASCII
80. ly the distance from the antenna but the height above the ground traditional method of making _ spatially averaged measurements is to use storypole storypole is a non conductive pole often wooden equal in height to an average adult with distance marks equally spaced along its length Measurements are made alongside the storypole at each height and then mathematically averaged The height and spacing of each measurement varies from standard to standard For example the IEEE 95 1 1999 standard specifies measurements from 0 centimeters ground level to 200 centimeters in 20 centimeter increments Some exposure standards such as Canada s Safety Code 6 require that measurements be averaged across two dimensions vertically and horizontally Modern wireless communications sites make this manual technique more difficult than ever since field levels at many sites particularly multi user sites are constantly varying For example paging systems go on and off and the number of cellular channels in use is constantly changing Thus a series of measurements made at varying heights can vary more as a function of time than location Chapter 7 Spatially Averaged Measurements 39 40 Spatial Averaging with the 8718B The Model 8718B uses time to quickly make precise spatially averaged measurements With the 8718B set for spatial averaging press the F1 function key to start the timer Pressing the same key again stops th
81. menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display Press the number 1 on the keypad to select DATA LOG from the First Menu Screen A new menu will appear presenting the three logging modes If any of the three logging modes is currently active the line showing that option will be flashing 1 LOG WITH REF 2 LOG AVG WITH REF 3 CONTINUOUS LOGGING MEM To review the available memory before beginning to make logged measurements press F2 MEM A screen will appear showing the approximate amount of available memory and the amount of memory already used The bar graph is a rough indicator of remaining memory capacity as a percentage of total capacity See Memory Capacity at the end of this chapter for information on how to determine the number of additional measurements that can be stored ml om l nl AVAILABLE MEMORY 10kB AVAIL 15kB USED MENU QUIT Press Esc to return to the logging menu screen To turn off the logging feature press F4 QUIT Chapter 8 Data Logging 45 46 Mode 1 Logging To initiate Mode 1 logging a series of data points with a reference number assigned to each data point 1 Press the number 1 on the keypad to select LOG WITH REF from the logging menu screen A screen will appear requesting that you assign a two digit survey number to this logging run of data points Use the numeric keypad to ente
82. mimic a particular exposure standard See Chapter 3 Shaped Frequency Response Probes Chapter 6 Units of Measure 37 Changing the Unit of Measure To change the unit of measure that the meter is set 1 58 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display Press the number 5 on the keypad to select UNITS from the First Menu Screen A screen will appear that offers the available units of measure for the probe in use 1 mW cm 2 2 W m 3 V m Press the number key on the keypad that matches the desired unit of measure For example pressing 1 selects mW cm as the unit of measure This unit of measure is available for all probes with a flat frequency response The meter will automatically return to the measurement screen If you had accessed the menu system from the Opening Menu Screen you will return to that screen Operating the Meter 2 Spatially Averaged Measurements Understanding Spatial Averaging The major standards concerned with human exposure to radio frequency radiation specify maximum exposure levels averaged over the whole body The co linear dipole antenna arrays that are very common in modern wireless communications systems for example have multiple lobes close to the antenna The field strength typically varies by 6 7 dB along the length of an array Therefore the measured value is highly dependent on not on
83. n of charge level This is because there is very little voltage difference over a broad range of charge levels The battery status indicator on the 8718B is reasonably accurate when indicating charge levels of more than 80 or less than 20 Unfortunately indicated charge levels greater than 20 but less than 80 are only very rough estimates It is a characteristic of these batteries to get a large voltage increase with only a brief charging period if one starts with a battery that is completely discharged However under such conditions the battery has very little capacity and the voltage drops quickly in use Since the status indicator circuits measure battery voltage this can lead to erroneous indications of charge level when the meter is first turned on This false indication will only occur when the batteries do not receive a complete charge The battery should be charged for a minimum of eight hours but ideally only when the status indicator shows a level of less than 20 The back light can be turned on to speed up the discharge process when desired These batteries obtain a maximum charge when charging takes place with batteries close to fully discharged Chapter 12 Back Light and Battery Status 77 78 Operating the Meter 5 Keypad Lockout Display Blanking Description The Lockout feature disables the keypad to prevent inadvertent changes in operation This feature can be useful while climbing and or if the me
84. n older model 8718 meter that has been upgraded to Version 3 0 firmware is different The default condition upon meter turn on for the RS232 port is off to con serve power The RS232 port must be turned on from the meter menu 104 To establish communications between the meter and the computer Use the supplied computer cable to connect between the RS232 connector on the meter and a COM port COM 1 or COM 2 of your computer 2 Start the User s software The Main Menu Screen shows the COM port and baud rate settings Check that the COM port setting matches the location of the cable Note the baud rate setting The default setting is 9600 baud 3 Change the baud rate and or COM port if desired by selecting the ComPort pull down menu and selecting the desired rate and or COM port The User s Software indicates the communications status Prior to establishing communications the CTS Clear To Send indicator will be black and the words Not On Line will be shown below the indicator 4 Turn the Model 8718B 5 Once the meter has finished booting up press F4 MENU on the meter to access the First Menu Screen 6 Press 6 RS232 to select the communications port menu 7 Check that the baud rate on the meter is set to the same as the User s Software The meter setting will be the same as the last time the meter was used 8 Check that the CTS indicator on the computer screen has turned red and the
85. nd produce an upscale indication on the meter The amount of deflection will vary depending on the model probe being used When the Test Source key is depressed U5 and part of U1 and Q1A within the meter generate test signals that are sensed by the probe causing the level displayed on the LCD to move upscale If no change in reading is observed either the probe or the meter may be defective The test source automatically shuts off after twenty seconds The test must be performed with the meter in the correct location relative to the meter Model 8718B Meter Circuits The 8718B is comprised of five main assemblies printed circuit boards PCB A1 and A2 keypad S1 LCD display D1 and the battery pack B1 This section provides an overview of the 8718B circuits There no adjustable components i e potentiometers or variable resistors used within the 8718B Appendices YOLOANNOO 262 59 YOLOANNOD Odo 93915 HOLO3NNOD 83980938 MOQNIM 1531 2 9 01 2 4 1534 ZHY OL YHOLOANNOO 390 a 1451 1 2 anon in 2190 EERIE a webera 42019 98148 IPPON vrO sn SN TOHLNOO 585 54 ven l 1081409 ASWHLNOO 91901 amo snob zn vin OL 1
86. nput into the Analog to Digital converter U3 U3 s digital output is applied to the micro controller U5 The on board data bus is used to drive the LCD display The data bus interfaced with latch U8 static Random Access Memory RAM and Time of Day U10 and the program memory U11 The LCD module receives input from the data bus along with a contrast control input from U8 through U2A R2 and R21 The LCD back light control is provided from P O Q4 which is controlled by U5 The address bus circuit is made up of U5 U10 U11 and the glue logic circuit comprised of U4 U7 and parts of U1 U6 and U4 The circuit provides RS 232 interfacing through U8 which also controls A2U2 the RS 232 UART The 10 GHz test source is controlled by U8 in conjunction with Q2 and Q3A Micro controller U5 also provides Pulse Width modulated PWM signals that are used by the 8718 The 10 kHz source control is provided by U5 s PWM along with U1 A PWM line and Q1 drive the audible alarm circuit A PWM line and U1 and U2 also control the Recorder Output This small circuit board primarily handles input output I O functions for the meter It is located in a shielded area behind the probe connector A2 contains the RS232 circuit and interfaces with the charger jack the recorder output jack the probe and fiber optic inputs and the high frequency test source 2 connects to 1 a filtered connector mounted on 1 Appendices LCD Display D1 Keypad 1 B
87. o the possibility that the probe and meter will be at different electrical potentials which can result in a false indication of what is actually a scalar field See Low Frequency Measurements inthe Applications Booklet for additional information Chapter 16 Operation with a Fiber Optic Link 95 96 The fiber optic link system also allows the meter and probe to be separated by up to 50 meters One application is surveying towers A skilled climber carries the probe while the person actually making the measurements remains on the ground Controls and Indicators The fiber optic transmitter has the following controls and indicators Control Function Indication BAT Test Tests Battery Charge LED 1 OFF Turns Battery Off LED Off ON Turns Power On LED Off CAL 1 Tests Channel 1 Meter mid scale 2 NORM Normal Operation Variable Level CAL 2 Tests Channel 2 Above mid scale a The battery is considered charged when above 15 0 Vdc Setting the Meter The meter has two input ports to receive information from probes e The standard probe cable input e The fiber optic receiver input Only one input can be in use at any time The default input upon turn on is the last input port used It is important to remember this if you switch back and forth between using the standard input and the fiber optic receiver Operating the Meter set the meter to use the fiber optic receiver input 1 Access the menu sys
88. obe model that the meter is currently set to 1 2 4 Press MENU The First Menu Screen will appear Press 7 PROBE A Screen will appear that shows the model number and basic characteristics of the probe The probe serial number is shown for probes selected from memory 8712D SN 12345 300MHz 50GHz 20 mW cm RESTART Press F1 OK key to return to the First Menu Screen Press Esc to return to the Measurement Display Screen To change to another probe without turning the meter off 1 2 Press F3 MENU The First Menu Screen will appear Press 7 PROBE A screen will appear that shows the model number and basic characteristics of the probe Press F4 RESTART to return to the Opening Menu Screen Press F1 MEASURE and begin the probe selection process Measurement Uncertainty The uncertainty of any measurement includes several factors related to the probe and meter e Frequency response or frequency sensitivity is typically 1 dB to 2 dB from about 25 to about 55 The correct use of correction factors can greatly reduce the amount of uncertainty associated with frequency response Chapter 4 Making a Measurement 27 28 Ellipse ratio is 0 75 dB or better depending on the model of the probe The ellipse ratio is the ratio of readings that occur when one rotates the probe around the axis of its handle Narda calibrates its probes by rotating the prob
89. of temperature In a probe it is both the thermal coefficient of the detector and the gain of the probe amplifier that determine how much a probe drifts over temperature Thermal compensation Circuitry in the probe is used to minimize the impact of temperature change Thermocouple detectors have the lowest thermal coefficient but their very low level output requires much more amplifier gain than diode sensors especially in electric field probes Therefore Narda probes with the greatest amount of thermal drift are the microwave band electric field probes which all use thermocouple sensors The lower frequency electric field probes use diodes and require much less gain Narda magnetic field probes use thermocouples but the circuit requires lower gain than the electric field probes The other possible cause of zero drift can occur when a probe is subjected to a very high field level and then is moved to an area with a very low field The high field heats the sensor and can cause drift However this type of drift normally corrects itself within a few minutes Many competitive diode sensor probes exhibit drift for another reason reaction to infrared light on the diodes Narda probes do not have this problem Narda uses special diodes with an integral light shield photographic paper inside the probe cover and a combination anti static shield and blackout coating on the inside of the probe cover Checking for Zero Drift There are two indic
90. of six probes installed in the 8718B at any time If you have six probes installed and want to install another probe you must first remove a probe See Removing Installed Probes To add a probe to the meter s memory 1 Click on the New Probe button The Select Below dialog box will appear Select the model number of the probe you want to install from the list of files by either double clicking on it or highlighting it and choosing OK Each standard Narda 8700 series probe has a separate file that defines its basic characteristics The file names are simply the model number of the probe preceded by the letter p The window will now show the model number of the probe selected its basic characteristics frequency range full scale measurement range field type and response flat or shaped and the standard calibration frequencies will be entered in the table on the right Enter the five digit serial number in the highlighted box in the center of the window Enter the calibration date by highlighting the box to the right of legend Enter Cal Date This date is shown on the handle of the probe Hit the Tab key on the computer The Calibration Due date is automatically calculated as one year after the calibration date Enter a different calibration date if you are using a different calibration cycle Enter the correction factor for each calibration frequency of the probe by highlighting the default value of 1 0 A d
91. p of an adult s head about 6 ft 1 9 m press F1 again STOP Chapter 8 Data Logging 49 50 10 11 12 13 14 wml onl nl l 1121 1 15 27 5 11 STOP A screen will appear that indicates the average and maximum values of the reading that has been temporarily stored in memory and the number of the data point The first data point will be 001 DATA POINT 001 1 STD AVG STD MAX DISCARD Press F1 SAVE to permanently log this data point into the meter s memory with its associated data point number The meter will automatically return to the logged measurement screen Press F3 DISCARD to erase the data point from the meter s temporary memory The meter will automatically return to the logged measurement screen and display real time values Press F1 START again to begin the second spatially averaged data point It will automatically be assigned data point 002 providing that you had saved the first data point If you had elected to discard the first data point then this point will be designated data point 001 Press either F1 SAVE or F3 DISCARD Continue to record up to 999 spatially averaged data points in this manner Both the average and maximum values will be saved and will be associated with a specific data point number Operating the Meter 15 To end this logging run and begin a new run press END The screen will appear that
92. pdate its Operating software or firmware in the field The password protected Update Meter Firmware menu of the User s Software is used to update the firmware Narda may periodically offer new firmware to correct problems and or to add new features The update process uses the meter s memory to temporarily store files during the update process All logged data will be lost Therefore itis very important to download any data that you want to save prior to updating the firmware Chapter 18 User s Software 115 ote Download any data that you want to save prior to upgrading the firmware All stored data will be lost during the up date process N ote Do not interrupt the update process If the process is inter rupted the firmware file may become corrupted The meter will be inoper ative and will have to be returned to Narda for repair 116 To update the meter s firmware 1 10 Turn your meter Observe the firmware version number which is displayed briefly about three seconds after you turn the meter on The meter can be updated if the firmware version is 3 0 or higher Stop if the firmware version is lower than 3 0 these meters cannot be updated in the field Establish communications between the meter and your computer as described in Establishing Communications is very important that make good connections at both ends of the cable used to connect the meter to your computer
93. r Cod outline Storage Case 32542703 Probe Extension Cable 87744 04 Electric Field Attenuator 8713B Computer Cable 87239000 User s Software 990125 CD ROM User s Guide 42983600 Insulated Tripod Handle 21797900 Optional Accessory Tripod Adapter 32595900 Optional Accessory Battery Charger and Line Cord Options The Model 8718B contains a rechargeable battery The meter is supplied with either a 115 volt 50 60 Hz or a 230 volt 50 60 Hz charger The 115 volt charger plugs directly into the style of wall outlets common to North America The 230 volt charger has an IEC receptacle and is supplied with any one of nine different power cords that meet virtually all international requirements The table on page 117 identifies the power cord by its outline Appendices MAJOR USE COUNTRIES PART NUMBER Continental Europe 89707000 Australia amp NewZealand 89707001 U K amp lreland 89707002 Denmark 89707003 India 89707004 Israel 89707005 Italy 89707006 U S Canada amp Japan 89707007 Switzerland b 4 J 2 89707008 Kechargeable Battery Management Program The Model 8718B contains a rechargeable nickel cadmium battery that must be recycled or disposed of in compliance with applicable federal state or local environmental regulations Narda maintains a rechargeable battery management program in keeping with its
94. r the two digit number and then press F1 OK or ENTER Make note of this number so that you can later associate this survey number with the data points collected If you make mistake press F2 CLR to clear the screen and enter a new survey number NEW LOGGING RUN ENTER NEW REF NO __ OK CLR MENU QUIT Press F4 QUIT or F3 MENU if you change your mind The meter will automatically return to the measurement screen with new options available for the function keys 1121 15 27 5 1 00 LOG MAXR END QUIT Proceed to make measurements as normal To log the value of the point currently being measured and displayed on the second line of the display press F1 LOG Operating the Meter 6 A screen will appear that indicates the value of reading that has been temporarily stored in memory and the number of the data point The first data point will be 001 DATA POINT 001 STD DISCARD 7 Press F1 SAVE to permanently log this data point into the meter s memory with its associated data point number The meter will automatically return to the measurement mode 8 Press F3 DISCARD to erase the data point from the meter s temporary memory The meter will automatically return to the measurement mode 9 Press F1 LOG again to log the second data point It will automatically be assigned data point 002 providing that you had saved the first data point If yo
95. res in Chapters 6 though 17 can then be referred to as required Chapter 18 covers the use of the User s Software Introduction User s Guide Updates This User s Guide was thoroughly reviewed for accuracy prior to publication Corrections to this guide necessitated by errors or omissions or by minor revisions to the meter firmware will be covered in the README file enclosed with the User s Software The README file is available at any time from the HELP menu within the User s Software Equipment Supplied Your Model 8718B is supplied with e Meter Battery Charger Power Supply e Power Cord 230 volt chargers only e Storage Case e Probe Extension Cable Model 8744 04 e Electric Field Attenuator Model 8713B e User s Software CD ROM Computer Cable e User s Guide Using this Guide with a Model 8718 The Model 8718 can be upgraded to take advantage of most but not all of the improvements incorporated into the Model 8718B The upgrade includes some minor hardware changes and the installation of the Version 3 0 firmware that is described in this guide There are only a few differences in the operation of a Model 8718 upgraded with Version 3 0 firmware versus the new 8718B Those differences are noted in this guide Operating the Meter 2 Understanding Your Model 8718B N ote NiCad batteries should be fully dis charged lt 20 indi cation before recharging Charge for a minimum of 8 hours See Checking Ba
96. ro density environment To zero the probe 1 Place the probe the storage case careful not to move the probe while zeroing takes place on probes with low frequency test points you can create static which will give inaccurate results When you are ready press the ENTER key The screen will say ZEROING The meter will beep and the main measurement screen will appear in about 15 seconds after zeroing is completed If you get a message that the probe could not be zeroed the most likely causes are The probe is not connected properly Check the connector and retry The meter is set for a fiber optic input and you are using the standard cable input or vice versa Turn the meter off Turn the meter back on and press F4 MENU to access the menu system Press 8 NEXT to get to the Second Menu Screen Press 3 CABLE FO to the probe input status Press F1 OK if it is correct or F4 to select the alternate Then press Esc to return to the Opening Menu Screen Chapter 4 Making a Measurement 17 ote See Chapter 12 Probe Zero for additional infor mation on the char acteristics of the survey system including the causes of zero drift 18 The field strength is not low enough Move away from the RF field source use the storage case to zero the probe e The probe is damaged Try another probe To reconfirm the zero while the instrument is in use 1 Establish a zero density
97. s FCC 97 IRPA ANSI 82 ACGIH UK NEXT 5 99 6 US DOD 7 8 7 Press the number on the keypad that matches the desired standard For standards with only a single tier 8 Anew screen will appear that lists the complete standard number Operating the Meter N ote Changing the level referenced ona multi tier standard does NOT change the characteristics of a probe ie a probe rated at 600 of oc cupational limits al ways yields an output in Percent of the Oc cupational limits 9 10 Press F1 OK to begin using this standard as reference Alternately press F4 STNDS to select another standard For standards with two or three tiers 11 12 13 14 A new screen will appear that lists the complete standard number at the top of the display The available tiers will be listed below the basic standard FCG REGULATIONS 9 7 1 OCCUPA L CONTRL D D 2 GEN ENTER NO TO SELECT Press the number on the keypad that matches the desired tier The screen will change so that only the standard and the selected tier are shown with two options available for the function keys FCG REGULATIONS OCCUPA L CONTRL OK Press F1 OK to begin using this standard and tier as a reference Alternately press F4 STNDS to select another standard Chapter 11 Using the RF Exposure Standards Feature 73 74 Operating the Meter 12 B
98. s cable modulation from affecting the signal derived from the elements Each instrumentation amplifier consists of three distinct sections two analog and one digital The 876xD series probes operate from 300 kHz to 3 GHz They use three sensors supported along mutually orthogonal axes Each sensor consists of a dipole diode combination The dipoles are approximately 8 cm in length The broad beam width is achieved through the capacitive divider effect of the dipole diode combination Some linearity correction is provided for field levels that approach full scale A patented circuit design maintains RMS detection over the entire dynamic range of the probe Appendix B Theory of Operation 125 Microwave Band Electric Field Probes Ultra broadband Electric Field Probes 126 The 872xD series probes operate from 300 MHz to gt 50 GHz They contain resistive thermocouples distributed along the length of the dipole The spacing prevents resonance over the operating frequency range of the probes The dipole may be viewed as a group of series connected small resistive dipoles or as a very low resonant circuit Element sensitivity decreases with frequency At frequencies above12 GHz the dipole begins to align along the Poynting Vector with the cold junctions oriented tangential to the electric field This is the traveling wave mode of operation Each of the three mutually orthogonal elements contains four resistive dipoles with the cold jun
99. scribed in Viewing Installed Probes Click on the Remove Probe button A dialog box will appear asking you to confirm that you want to remove a probe from the meter s memory Click OK The probe will automatically be removed from the meter s memory The model number and the serial number of the probe just removed will disappear from the table of Installed Probes To leave the Probe Installation window and return to the Main Menu Window click the Close button Operating the Meter Downloading Logged Data from the Meter To download data from the meter 1 Establish communications between the meter and your computer described in Establishing Communications 2 Select Download New Survey from the Survey Data menu A dialog box will appear that reminds you to make sure that the 8718B is menu and not measurement mode 3 Click OK The message Downloading please wait will flash on the computer screen 5 Once the data has been downloaded the Downloading please wait message will stop flashing and a dialog box will appear The dialog box specifies the file name that has been given to the downloaded data and its location on your hard drive Make note of this information and click OK File Format for Survey Data Data files can have one of three forms identified by the suffix in the file name 1 file name will be an eight digit number with a SVY survey extension The eight digits
100. sed e When there is only a single emitter being surveyed e When there are multiple emitters all operating at the same frequency this is often the case with industrial equipment Operating the Meter e When there are multiple emitters with frequencies that are close to each other and the nearest calibration frequencies have very similar correction factors Correction factors should NOT be used e When the frequencies of the emitters are diverse N ote Do not use correction factors in a broadband Correction factors may vary considerably and there is no way to determine the distribution of energy from the various emitters It is more accurate not to use a correction factor under these conditions See Measurement Uncertainty on page 27 multi emitter environ use a correction factor for a probe in memory ment 1 Press F4 FREQ the measurement screen new screen will appear to allow you to enter a frequency Enter the frequency for which you want to correct readings Make sure you fill in all four positions If you make a mistake just enter more digits until correct For greater accuracy use the units that allow the larger numbers For example enter 10kHz not 00 01 MHz Change the units if needed by pressing either F1 kHz F2 MHz or F3 GHz Press F4 SAVE The meter will automatically calculate the correction factor for the frequency you have entered from the two closest correc
101. t handed people hold the probe in their right hand and the meter in their left hand The choice of function key location for the START and LOG commands is particularly important because it is often desirable to press these keys without looking at the meter This situation occurs during spatial averaging data logging and time averaging The four function keys on the Model 8718B allow for easy operation with your thumb and the raised area around each key makes it easy to be certain that your thumb is in the correct location The START and LOG functions are always operated with the F1 key for right hand operation The 8718B allows you to change to eft handed operation with a few keystrokes When set for eft handed operation the START and LOG functions will be operated with the F4 key The functions normally associated with the F4 key are then operated with the F1 key The meter will remain set the same way upon turn on and can only be changed by following the procedure described below To check or change the function key location 1 Access the settings menu by following the procedure described in Accessing the Settings Menu 2 Press 4 select RGT LEFT A new screen will appear that shows the current mode FUNCTION KEYS ARE SET FOR RIGHT HANDED OPERATION Operating the Meter 3 Press F1 OK to continue with the same setting without change The meter will return to the First Menu Screen Press Esc to return to the meas
102. t induced by the field dissipates power in the thermocouple elements heats the hot junctions and provides a DC output voltage proportional to the square of the induced current Circuitry is added to minimize high frequency out of band responses typical in many H field probe designs Appendix B Theory of Operation 127 128 Appendices Maintenance General The Model 8718B requires very little maintenance No operator adjustments are required The electronic circuitry is contained in a very rugged aluminum housing However this housing is not watertight and should not be immersed in water The LCD display and the case may be cleaned using a damp cloth Do not use any type of detergent or solvent Calibration The Model 8718B is calibrated before it is shipped Narda recommends that the Model 8718B be calibrated every two years Narda will perform this calibration for a nominal charge The meter is completely tested using Automated Test Equipment ATE as part of the calibration service Keplacement Parts None of the parts within the meter are considered user serviceable The table below contains the model numbers and part numbers of the accessories supplied with the 8718B and available as optional accessories Appendix C Maintenance 129 150 Description Part Number Comments Battery Charger 115 volt 84156000 Battery Charger 230 volt 84156001 Supplied with 230 Powe
103. t the correct model number and the meter automatically sets the correct scales The Model 8718B can also store the specific calibration details for up to six probes This includes the probe serial number calibration date and the calibration factors marked on the handle of the probe Probes with this additional detail stored in the meter are referred to as probes in memory Putting probes into memory has several advantages e It makes it easier to select a probe e Data that is downloaded after using a data logging mode will include a record of the probe s calibration date and its serial number e It makes using frequency correction much easier Probes are put into the meter s memory using a personal computer e By Narda on the day of shipment for all probes shipped at the same time as the meter e By you at any time when you use the User s Software supplied by Narda and a personal computer Refer to Chapter 18 User s Software for detailed information regarding computer operations Operating the Meter To select from the PROBES IN MEMORY 1 If you haven t already press F1 MEASURE 2 The model number and the serial number of the last probe used will be displayed on the second line of the display If you want to use the same probe press Enter SELECT PROBE MODEL A8722D SNXXXXX OR SELECT FROM LIST 87XX 87XX 87 MORE 3 If you want to use a different probe look for the model number in the positions abov
104. tantaneous field strength in real time Chapter 9 Time Averaged Measurements 59 If you access the menu system from the Opening Menu Screen you will re turn to that screen Once a probe has been selected and zeroed the mea surement screen will reflect the averaging mode that you have selected 60 11 12 13 wml nl sued ial 2 4 1 2 ISTID AVERAGE 10 4 CLR MENU QUIT 319 5 START To make another time averaged measurement over the same interval press F1 START again To temporarily suspend the time average mode once the current measurement interval has been completed or stopped and make real time measurements press F2 CLR To make another time averaged measurement over the same interval press F1 START again To end time averaging altogether and return to the standard measurement screen once the current measurement interval has been completed or stopped press F4 QUIT To initiate time averaging again at a later point use the menu system to select TIME AVG from the First Menu Screen To temporarily pause during a time averaged measurement 1 To temporarily suspend time averaging press PAUSE The word PAUSED will appear on the fourth line of the display To resume time averaging and complete the measurement press F1 START 2 4 2 1 00 PAUSED STOP 91 15 START
105. tem by pressing the function key that corresponds to the legend below MENU on the bottom line of the display Press 8 NEXT to select the Second Menu Screen Press 3 to select CABLE FO A new screen will appear that shows the current input status PROBE INPUT STATUS CABLE ON FIBER OPTIC OFF OK FO Press F1 OK to continue with the same input without change The meter will return to the First Menu Screen Press Esc to return to the measurements screen Press F4 FO to change to the fiber optic receiver input The meter will return to the First Menu Screen Press Esc to return to the measurements screen To set the meter to use the cable input 6 Access the CABLE FO menu as previously described A screen will appear that shows the current input status PROBE INPUT STATUS CABLE OFF FIBER OPTIC ON OK CABLE Press F1 OK to continue with the same input without change The meter will return to the First Menu Screen Press Esc to return to the measurements screen Chapter 16 Operation with a Fiber Optic Link 97 98 8 Press F4 CABLE to change to the cable input The meter will return to the First Menu Screen Press Esc to return to the measurements screen System Checks To insure that the entire system meter fiber optic transmitter and probe are functioning properly 1 Set the 8718 to use the fiber optic receiver input as previously described Connect the probe to the fiber op
106. ter is left unattended during a long data logging session The Blank feature both disables the keypad and blanks the display This feature can be useful if the meter is left unattended during long data logging session Keypad Lockout To lock the keypad 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display 2 Press number 8 NEXT to select the Second Menu Screen 3 Press 4 to select LOCKOUT 4 The meter will automatically return to the measurements screen and the keypad will be locked Only the Off key will respond to commands individually To unlock the keypad 5 Simultaneously depress both the Enter and Esc keys to unlock the keypad These are the two dark blue keys Chapter 13 Keypad Lockout and Display Blanking 79 80 Display Blanking and Keypad Lockout To both blank the display and lock the keypad 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display 2 Press number 8 NEXT to select the Second Menu Screen 3 Press 7 to select BLANK 4 The meter will automatically return to the measurements mode but will be blank The keypad will also be locked Only the Off key will respond to commands individually To both activate the display and unlock the keypad 5 Simultaneously depress both the Enter and Esc keys to both activate the d
107. that offers five different logging rates 1 SEC 10 MIN 1 MIN 10 HR and 2 HR LOGGING RATE 10 MIN 1 SEC 4 10 HR 10 MIN 5 2 HR OFF 4 Press the number on the numeric keypad 1 5 that corresponds to the desired logging rate 5 A new menu screen will appear The numeric keypad and the function keys are used to define the duration of time to be logged CONTINUOUS LOGGING RATE 10 MIN DURATION __SEC MN HR SEC MIN HR CONT Operating the Meter 6 log for a specific interval of time enter a two digit number on the keypad If you make a mistake entering a number simply continue entering numbers until the correct value is displayed Then press either F1 SEC F2 MIN or F3 HRS and the meter will automatically return to the measurement screen with new options available for the function keys log for an indeterminate interval of time until you tell the meter to stop or the memory is filled press F4 CONT The meter will automatically return to the measurement screen with new options available for the function keys 1121 11 15 27 5 1 00 LOG MAXR MENU QUIT 8 Proceed to make measurements as normal To initiate logging press F1 LOG The meter will beep every time a data point is recorded 1121 1 1 27 5 1 00 LOG END QUIT 9 Ifa specific interval of time had been selected the meter will automatically stop log
108. tic transmitter Connect a fiber optic cable between the meter and the fiber optic transmitter Check the battery charge level in the transmitter by turning switch 51 BATT TEST ON to BATT TEST Verify that the green LED is illuminated which signifies that the battery is adequately charged for operation If the LED fails to illuminate charge the transmitter overnight A full battery charge takes approximately 16 hours Set S1 to the ON position and S2 to the NORM position Zero the 8718B using the standard procedure Move 52 CAL1 NORM CAL2 to the CAL1 position The meter should read 45 55 of the full scale rating of the probe The actual error from the combination of the 8718B and the fiber optic transmitter is less than 3 Move 2 to the CAL2 position The meter should read approximately 25 higher than the CAL1 position The exact value is not critical Set S2 to the NORM position to begin making measurements providing that all the system checks were successfully completed Operating the Meter 1 Operation with a Data Description The Model 8718B provides an output signal that can be connected to a data recorder to provide a continuous record of measurement over an extended period of time The recorder output is available via the smaller of the two jacks located on the left side of the meter The output is always on Output Level The recorder output ranges from 0 0 volts to 3 0 volts The level
109. tion factors that were stored when you put the probe in memory The calculated numeric value will be displayed briefly before the meter automatically returns to the measurement screen See page 64 for a more complete description The frequency that you are correcting for will be displayed on the right side of the third line of the display Chapter 4 Making a Measurement 25 To use a correction factor for probe memory 1 Press MENU The First Menu Screen will appear DATA LOG TIME AVG SPATIAL BAT LIFE COR FACT SETTINGS CABLE FO LOCKOUT 3 Press 1 COR FACT Ascreen will appear that shows the correction factor 4 Use the correction factors on the handle of the probe to determine the appropriate correction factor and then use the numeric keys on the meter to enter this value Enter a three digit number ignoring the decimal point and rounding to two digits to the right of the decimal point If you make a mistake just enter more digits until correct For example to enter a correction factor of 1 22 simply enter 1 2 and then 2 while a correction factor of 0 94 is entered as 0 9 and 4 5 Press Enter to save this correction factor The meter automatically returns to the measurement screen 6 The numeric correction factor will be displayed on the right side of the third line of the display in the form CF Operating the Meter Checking Changing the Probe Model To check the pr
110. ttery Status in Chapter 12 General Description It is important to be familiar with the Model 8718B before you use it This section includes descriptive data keyed to highlighted illustrations to help you locate the various features of the meter The descriptions not only identify the features but tell you how they are used Battery Charger and Power Cord The battery charger and power cord are used to recharge the battery within the Model 8718B To recharge the meter first connect the cable of the battery charger to the larger jack on the left side of the meter Make sure the plug is fully inserted into the jack Connect the power cord to the wall outlet The battery will be fully charged in about 8 hours The indicator light on the charger illuminates during charging A full charge will give you about 20 hours of operation approximately 6 5 hours if back lighting is used The charger can also be used to power the Model 8718B when it is to be operated for periods beyond the capacity of the battery Chapter 2 Understanding Your Model 8718B 3 Probe Connection To make measurements you must use your Model 8718B with a compatible probe Connect the cable of the probe to the probe connector located at the top of the unit If you use a fiber optic link the probe connects a fiber optic transmitter A fiber optic cable connects the transmitter to the rectangular fiber optic jack on the left side of the meter Audio
111. u had elected to discard the first data point then this point will be designated data point 001 10 Press either F1 SAVE F3 DISCARD The meter will automatically return to the logged measurements screen 11 Continue to record up to 999 data points in this manner 12 To end this logging run and begin a new run press F3 END The screen will appear that allows you to enter another two digit survey number NEW LOGGING RUN ENTER NEW REF NO __ OK CLR MENU QUIT Chapter 8 Data Logging 47 48 13 14 Use the numeric keypad to enter a new two digit survey number and then press F1 OK or ENTER Again make note of this number so that you can later associate this survey number with the data points collected If you make a mistake press F2 CLR to clear the screen and enter a new survey number The meter will automatically return to the logged measurements screen To end logging altogether and return to the standard measurement screen press F4 QUIT To initiate logging again at a later point use the menu system to select DATA LOG from the First Menu Screen Mode 2 Logging To initiate Mode 2 logging a series of spatially averaged data points with a reference number assigned to each data point 1 From the data logging screen press the number 2 on the keypad to select LOG AVG WITH REF from the logging menu screen 1 LOG WITH REF 2 LOG AVG WITH REF 3 CONTINUOUS LOGGING MEM
112. ulo 256 of 1234 is 210 The two ASCII digits to be transmitted as the checksum would be D and 2 the decimal hex conversion of 210 An equivalent calculation is to convert the sum to Hex and transmit the two lowest digits The Hex of 1234 is 4D2 therefore the digits to transmit are ASCII D and 2 Computer to Model 8718B Message Format The first character in any message is the gt This allows the Model 8718B to synchronize to the computer Upon detection of the gt character the 8718B will e Set itself to listen mode thereby eliminating the possibility of a bus contention problem e Reset its character counter to allow storage of succeeding characters in an internal buffer The next characters s is selected from the functions listed in Command Character Function table Appendix A Communications with a Computer 117 Command Characters Function gt A000CSCR AUTO ZERO gt CO00CSCR READ CLOCK TIME DATE gt Dr00CSCR Display averaging change r 1 2 3 4 low to high display averaging gt E003XXXCSCR SET CF Correction Factor gt FOr4xxXXCSCR SET FREQ X is DATA ris kHz MHz GHz 0 2 r 1 MHz r 2 GHz gt HOO0OCSCR SEND HEADER 24 bytes of data gt 000 DUMP PROBE DATA 432 bytes of data gt LOOOCSCR DUMP LOG DATA gt VO00CSCR READ displayed VALUE Last displayed value 6 bytes units 6 bytes gt X000CSCR READ MAX Command Characters Function Communications Protocol A Ground Ru
113. urements screen 4 Press F4 LEFT or F4 RGT to change to the alternate setting for function key menu position The meter will return to the first menu screen Press Esc to return to the measurements screen Adjusting the Display Contrast The LCD display is set at the factory for the best contrast under typical conditions The user can adjust the contrast to optimize visibility under specific lighting conditions To adjust the display contrast 1 Access the settings menu by following the procedure described in Accessing the Settings Menu 2 Press 5 to select DISPLAY A new screen will appear that shows the current setting The adjustment range is from 0 9 with 0 the lightest setting and 9 the darkest setting DISPLAY CONTRAST CURRENT SETTING 6 O0 L IGHT 9 DARK OK 3 Press F1 OK to continue with the same setting without change The meter will return to the First Menu Screen Press Esc to return to the measurements screen Chapter 15 Advanced Settings 93 94 Press F4 SET to change the display contrast setting The screen will change to show both the current setting and display an underscore where the new setting is entered DISPLAY CONTRAST 16 NEW SETTING Use the numeric keypad to enter a single digit from 0 9 with 0 for the lightest setting and 9 the darkest setting The contrast will change as soon as the numeric value is entered You may continue to experim
114. y Screen based on the stored F4 calibration data for the F2 Allows you to enter specific probe in use Reset the or change the Maximum Value to frequency that you the current Field are correcting for Strength displayed probe frequency on the second line deviation Main Measurement Display Screen Flat Probes The Main Measurement Display Screen for flat frequency response probes is the same as the screen for shaped frequency response probes except as indicated below wml nul ill FIELD STRENGTH gt 6 26 mW e Indicates actual 11 5 MAX CF 1 00 measured value e Unit of measure can be ALT MAXR MENU FREQ changed by going to the First Menu Screen Chapter 4 Making a Measurement 19 ote The Alternate Mea surement Display Screen should only be used for single frequency measure ments or where all emitter frequencies are close and the ex posure standard has the same limits Re fer to Using Probe Correction Factors on page 24 20 Alternate Measurement Display Screen The Alternate Measurement Display Screen is very similar to the Main Measurement Display Screen with one difference This display mode is used to show frequency specific real time information on the third line of the display instead of a maximum value It should be used only for single frequency or narrow band measurement applications The information that is shown depends on whether a flat frequency response probe or a s
115. y increase the current draw and therefore reduce the operating time are the back light and the RS232 serial port It is for this reason that the default condition upon turn on for both these features is off Operating time with the back light on is about 6 5 hours This is normally sufficient for a full day of measurements but it is a factor that must be considered Checking Battery Status To check the battery status 1 Access the menu system by pressing the function key that corresponds to the legend below MENU on the bottom line of the display 2 Press 4 to select BAT LITE from the First Menu Screen A new screen will appear that indicates both battery status and back light status LIGHT 9 0 113 TIME 18HRS ION OFF 3 The bar graph indicates the approximate charge level of the battery The charge level is also shown as a numerical percentage on the left side of the third line of the display The estimated operating time under the current operating conditions is shown on the left side of the bottom line of the display Turning the back light on for example reduces the operating time significantly Operating the Meter 4 Press the ESC key to return to the First Menu Screen Press it again to return to the measurements screen Accuracy of Battery Status Indicator The characteristics of Ni Cad rechargeable batteries make it difficult to provide a truly accurate indicatio

NARDA 8718B Stud Sensor User Manual

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