AWOS System Description
Contents
1. 16 BELFORT instrument Proprietary Information Algorithm Flow Diagram for Visibility Sensor Sample the forward scattered light thirty seven 37 times each second in Phase I and Phase II Sample the illuminating LED power thirty seven 37 times each second as Pwr Subtract Phase Il from Phase to generate a one 1 second RevrAvg Add the one 1 second average to the Painting Average Adjust the average for power AvgRevr RevrAvgXTxPwrCal Pwr Where TxPwrCal is a calibration value Convert to Extinction Coefficient ExCo in inverse kilometers as AvgExCo f AvgRcvr Span Zero Where Span and Zero are calibration values AvgExCo available for polling by the DCP gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt gt Where DCP polling command is FL From ALS one 1 minute average ALS data available for polling by the DCP Where DCP Polling command is FE alia BELFORT instrument Proprietary Information 3 8 1 Ambient Light Day Night Sensor The Belfort Model 6300 Ambient Light Sensor ALS measures the luminance of a 6 cone of sky as required for day night determination The visibility sensor powers the ALS and communicates with the ALS through a five foot long cable by which the two sensors are connected The Ambient Light Sensor ALS continuously sa2. Battery Bracket J o Figis 22 80003 1 Battery Box 1 Fgl 23 800052 SolarPanel J 1 o Fies 24 80057 Solar Panel Mounting Kit 1 Figl4 25 ZXRPGI25 Weights Fig 26 ZX3827T34 NylonRope 1 Fg6 27 ZX4491K42 CapPlug Red 6 FiglO amp Figll 28 7x856 Solar Controller Figi6 29 SCP30SI5SDN__ Power Supply 1 Fg 30 ZXA8R84 Junction Box and circuit breaker 1 Figh7 31 80152 Battery backup power cable 1 Fig 32 80009 GroundCable 1 Figs6 amp IT 33 80090 LighmingRod 1 Fig5a E css 25 BELFORT instrument Proprietary Information a N pa No Wp Re Rn Rd Ro EO RN ph f ph f pd Rete 42 EPC 1026 77 Surge Suppressor 1 Fen 45 e00 DDR amp Power Supply 1 Sig 44 feo DDR Comm Cabe 1 meo 45 80659 RFO pi i o a 90001 Calibration Kit 47 80109 Obstruction Light and wiring Fig 5a o eee 48 80110 Base Transceiver 1 Figsa 49 somi Pressure VentKit 2 Figsa 50 80113 L ELDF Base Transceiver _ 2 Figsa 51 soe AME o a fo mea Table 2 Lowest Field Replaceable Components 6 BELFORT instrument Proprietary Information 3 0 Principles of System Operation Once every 5 seconds a proprietary digital message containing all the weather information and DCP system status is transmitted from the DCP to the HHDU and the DDR and DATU via a 464 MHz FM link This information is di
3. Wind Direction SCUSOE A gcc tice weal gna lates h ate Sete Anse tut hae is 21 System PO Wels to dra a a cate cep dai sea bu ant ada 21 System Software DESCHPHONS sia soro pad aaa AS ana Sa cp NU 22 DigiWx AGVISOL secoeosia asoini nien EEEE EEEE a aa 22 DIW Phone o eaen a E Ge a ad a a a a 22 DIWA Voice E E Eee O Ce ee 23 DCP configuration software ASOSDCP102 s sssssessssssesessssesesssereessseresssse 23 Applicable Documents amp List of ACTONYMS ceesceceseteeeeneeeesnneeeeteeeeeees 23 Applicable Documenta aaa aa aeaa cinta ase dana 23 WISE Ob ACEO VAS dat Bar vga dun eeitas bus a a tu pases eae 23 Tables DIST XC ONMOUTAMONS sta Dida Daiana Deda aaa 3 Lowest Field Replaceable Components cccccccccesseceeeeeeneeeeeeeeteeeeeneaaes 5 Figures amp Illustrations Interior and Exterior System Components ceessecessseceeseeeeeeeeeeeneeeeenees 2 Information PLOW seus smart nadar aa ns dA 7 Illustration of Data Interface Modes erre 9 Illustration of DCP Func Hens a a a 9 i BELFORT instrument Proprietary Information This page intentionally left blank ii BELFORT instrument Proprietary Information 1 0 Introduction 1 1 Purpose This manual has been prepared to identify the hardware components to the lowest field replaceable unit describe system hardware and software principles of operation and describe how they are integrated within the system 1 2 Scope This manual has b
4. 4 inHg Yes Once each minute using the lower of average P1 and P2 calculate field pressure Pa using the equation Pa P 104 KH TR where P lower of average P1 and P2 K 0 008135 H difference in feet between the elevation of the pressure sensor Hz and the field elevation of the airport Ha T current 5 minute average temperature in degrees Rankin BELFORT instrument Proprietary Information Algorithm Flow Diagram for Pressure and Altimeter Setting Data Continued If Pais missing because Temperature is not available calculate Altimeter Setting AS using the equation AS P4N KHz 1 N where P lower of average P1 and P2 N 0 019263 1 N 5 25588 K 1 3126 104 5 and Hz Elevation of the pressure sensor in feet above MSL Once each minute calculate Altimeter Setting AS using the equation AS Pa N KHa 1 N where Pa Field Pressure N 0 190263 1 N 5 25588 K 1 3126 104 5 Ha Field elevation of he airport in feet above MSL Round AS to the nearest 0 01 inHg Midpoint values shall be rounded down Make sure the AS is within the allowable range more than 26 0 No inHg and less than 32 0 inHg Report Lower of If the DigiWx DCP unaveraged P1 and P2 Alert DigiWx being serviced If DCP IPC is down Yes Once a minute report Altimeter Setting AS as calculated mies BELFORT instrument Proprietary Information 3 7 Temperature Dew Point Sensor The temperature and humidity sensor is located
5. BELFORT instruvent 800 937 2353 www DIGIWX com BIJAN x Automated Weather Observing System AWOS System Description Proprietary Prepared in Response to FAA Automated Weather Observing System AWOS Requirements July 2005 Table of Contents System Description Paragraph Description 1 0 1 1 1 2 1 3 1 4 2 0 3 0 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 8 1 3 9 3 10 3 11 4 0 4 1 4 2 4 3 4 4 5 0 5 1 5 2 Table 1 Table 2 Figure 1 Figure 2 Figure 3 Figure 4 Page MTO QU UC Re l PURPOSE ahi stas5ts yaanaedls RREO RESID ea ER E RDNNNGOE ROVER A R AA AAA E RO RO PR l SCOPE assassina a A A da a l System Overview and Description sssessssesessssesesssereessseressssrressssreessseree l System Configuration sussa sino apra da as aaa Navies Satis cs 2 Lowest Level Field Replaceable Components Matrix 5 Principles of System Operations a a e na a 7 DATU ue e aita EEEE dad a awa AN aaa a 8 G EE E E REPEAT 9 DDR SS E A E T eas 9 R A E a undo cae era ese AO 10 INTC cite aro a a a aaeeate 10 Dual Barometer Sensors i iiss casais hankisocnccass chassibdevascasd aascasactessindevas tata 11 Temperature Dew Point Sensor ga ssa pasa sia needs tag u 14 Visibilty SENSOR eita Aslan od SL aires pu Og DER E 15 Ambient Light Day Night Sensor ccccccccessssecceeseeneeeeeseeaeeeeessneeeeeees 18 Wind Speed Sensor 22 Aisucssnsetenaaliungatiseedune dune wide dale 21
6. P enclosure Through DigiWx Advisor software and a Digital Data Receiver DDR the weather information and any NOTAMSs are communicated to users by Pilot Activated Unicom or an Endless Loop Dedicated Frequency ELDF on a dedicated VHF frequency An internet option and dial up voice modem allow remote users to access the information The system also reports weather conditions to pilots in the air through the DigiWx AWOS Hand Held Display Unit HHDU The pilot receives this information at ranges up to 10 miles from the airport In order to get the weather information the pilot only has to power up the hand held display and select the runway heading that he she will use In addition to alphanumeric readouts of the various weather parameters the hand held unit provides a graphical representation of the selected runway with the head tail and or cross wind components displayed thereon DigiWx system software design also incorporates plug and play simplicity for ease of installation and maintenance and an intuitive interface for ease of operation le BELFORT instrument Proprietary Information 1 4 System Configuration Figure la illustrates a typical DigiWx installation with all sensor options installed and the solar power option added Interior DigiWx Data Acquisition Exterior DigiWx Tower Terminal Unit Figure 1 Interior and Exterior System Components 2 BELFORT instrument Proprietary Inf
7. RITHMS WIND ALGORITHMS ALTIMETER ALGORITHMS Figure 4 Illustration of DCP Functions 3 3 DDR Digital Data Receiver The DDR is a black box component with power switch AC adapter jack antenna and DB9 RS 232 serial port connector The DDR contains a receiver to receive data transmissions from 9 BELFORT instrument Proprietary Information the DCP and signal processing components to convert the received data into a serial ASCII data stream for input to the DATU s computer s Serial port interface 3 4 RIF The radio interface RIF is an analog audio processor that performs level control and compression on both radio to pilot activated computer and computer voice synthesizer to radio analog audio streams The RIF also keys the aviation base station radio in voice activated and endless loop configurations A microphone allows the transceiver to be used in a normal manner if required 3 5 MCIF The microphone click interface MCIF is both an audio pass through and digital processing device All audio signals between the RIF and the radio pass through the MCIF with no processing The MCIF processes radio squelch levels converting them to digital messages to the computer 10 BELFORT instrument Proprietary Information 3 6 Dual Barometer Sensors The dual barometric pressure sensors are located in the DCP enclosure and provide serial pressure data to the altimeter reporting algorithm The pressure se
8. data is not available 22 BELFORT instrument Proprietary Information 4 3 DigiWx Voice A separate program DigiWx Voice provides speech output through the CTAF Unicom radio upon demand from a pilot s radio DigiWx Voice is installed and configured at the Belfort factory There is no operator setup or configuration required 4 4 DCP Configuration software ASOSDCP102 ASOSDCP102 is a Belfort proprietary program that facilitates interactive dialog between the technician and the DigiWx DCP to enter and modifying local settings An automatic altimeter setting calibration program is also included All settings are password protected to prevent unauthorized changes 5 0 Applicable Documents amp List of acronyms 5 1 Applicable Documents FAA AC No 150 5220 16C Automated Weather Observing Systems AWOS For Non Federal Applications 5 2 List of Acronyms AC Alternating Current ALS Ambient Light Sensor AVG Average AWOS Automated Weather Observing System BIT Built In Test CTAF Common Traffic Advisory Frequency DATU Data Acquisition Terminal Unit DC Direct Current DCP Data Collection Processor DDR Digital Data Receiver DMM Digital Multi meter DSL Digital Subscriber Line DTMF Dual Tone Multi Frequency ELDF Endless Loop Dedicated Frequency EPROM Erasable Programmable Read Only Memory ExCo Extinction Coefficient in inverse kilometers FAA Federal Aviation Administration FBO Facility Base Operator FCC Federal Communica
9. een prepared to comply with the guidance and requirements of FAA Advisory Circular AC No 150 5220 16C and other referenced documents 1 3 System Overview and Description The DigiWx system is an FAA approved special configuration AWOS with dual pressure sensors and visibility sensors for reporting official altimeter settings and visibility measurements in addition to other advisory information It is a fully automated aviation weather observing and reporting system designed to support airborne and ground users The DigiWx system is modular and may be installed in a number of configurations see Table 1 A full DigiWx system consists of FAA approved barometric pressure sensors and a visibility sensor The system may contain additional advisory sensors such as wind speed wind direction temperature and humidity sensors mounted on a rugged aluminum tilt over tower Sensor readings are monitored and processed by a digital processor located in the DCP enclosure The processor uses sensor data to calculate the prevailing and gust wind components for pre programmed runway headings Depending on the system sensor configuration purchased the DigiWx system calculates the altimeter setting density altitude condensation altitude and dew point All of this information plus the speed and direction of prevailing wind and wind gusts current surface temperature and visibility are broadcast on UHF 464 MHz by a FCC licensed transceiver located in the DC
10. ems are supplied with one Hand Held Display Unit A solar power option is available for all configurations and is denoted by appending SP to the above designators Details of the configurations in the shaded boxes above are listed as examples BELFORT instrument Proprietary Information BNT H Dual Barometer DCP wall mount Handheld Receiver HHDU B Al Dual Barometer DCP Tower Mount HHDU DigiWx Advisor FBO BV A3 Dual Barometer DCP Visibility Tower Mount HHDU DigiWx Advisor FBO Dial In BW A V1 Dual Barometer DCP Tower Mount Wind Speed and Direction Temperature and Dewpoint HHDU DigiWx Advisor Al A2 A3 or A4 DigiWx Voice on UNICOM BWV A V2 Dual Barometer DCP Tower Mount Wind Speed and Direction Temperature and Dewpoint HHDU Visibility DigiWx Advisor Al A2 A3 or A4 DigiWx Voice on Dedicated VHF 4 BELFORT instrument Proprietary Information 2 0 Lowest Level Field Replaceable Components Matrix The following table illustrates the lowest possible field replaceable unit FRU PARTS LIST Di feo nstraction Manual J o po o o o 2 feos HADU User Mama J o Oooo o o oS 3 6795 01 Hand Hield Recsiver 1 Fig 18 22168 Chanm 1 f Fee 6794 01 DCP Enclosure Asy 1 Fes Fig 10 Fig 11 Fig 10 Fig 11 Fig 12 Fig 12 Fig 5a Fig 5 7 10 lI 12 14 16 17 18 Fig 5a Fig 5a ZX1324U2 Cap End 2 Figio amp Figil 20 ZX1242DPCHR EyeStrap Fig 21 80003
11. f an AC powered 12VDC supply is used the battery is maintained by a charge controller built into the DCP Diagnostics on both supply channels are conducted by the DCP once a minute he BELFORT instrument Proprietary Information 4 0 System Software Descriptions 4 1 DigiWx Advisor The DigiWx Advisor is a Belfort proprietary software program that provides a PC based graphical display of local weather data collected from the base DigiWx Weather Station The data can be viewed on the DATU terminal at the airport FBO or if the optional Web Service has been installed on the web for pre flight planning purposes and general airport operations The DigiWx Advisor has an event manager capability that provides visual alerts of important possibly critical weather conditions such as high density altitude or excessive cross wind component The program captures all weather conditions to support aircraft accident or incident investigations All historical data is saved subject only to limitations of hard disk space If the Internet option has been installed current data is also be transmitted to a central site where it is saved in a master database with on line and off line backups for data safekeeping Historical data saved at the master database is retained indefinitely 4 2 DigiWx Phone The DigiWx Phone program is an optional feature that can be added to the DigiWx Advisor software It provides the capability to automatically answer a phone line and
12. f six 6 active boxcars is less than sixty 60 seconds coast the last one 1 minute average Is a one 1 minute average available current or coasted No ALS NA yes New one 1 minute average passed to the Visibility Sensor and made available for polling by the DCP Where DCP Polling command is FE 19 BELFORT instrument Proprietary Information 20 BELFORT instrument Proprietary Information 3 9 Wind Speed Sensor The wind speed sensor generates a pulse with the frequency proportional to the wind velocity This pulse frequency is sampled once a second by the DCP and processed to construct the 2 minute average and gust information along with sensor health and data quality determinations Reported wind speed is rounded to the nearest knot 3 10 Wind Direction Sensor The wind direction sensor measures wind direction from 001 to 365 degrees and communicates with the DCP using a 7 bit gray code The direction is sampled once a second and the 2 minute running average is computed every 5 seconds Sensor health and data quality algorithms are also computed Reported wind direction is rounded to the nearest 10 degrees 3 11 System Power System power is made available to the DCP through a power wire harness that is connected to an 115VAC powered 12VDC power supply and or a 12VDC deep discharge lead acid battery The battery may be maintained by a solar cell and charge controller I
13. in the naturally aspirated enclosure mounted near the top of the sensor tower This sensor provides digital information to the DCP for use in the temperature dew point humidity and density altitude algorithms 14 BELFORT instrument Proprietary Information 3 8 Visibility Sensor The Belfort Model 6000 forward scatter visibility sensor including the Belfort Model 6300 day night sensor operates in the polled mode The DCP requests data once a minute and the 6000 responds with an ASCII data string including status of the visibility and day night sensors a one 1 minute average extinction coefficient ExCo and the ALS reading in footlamberts The DCP then calculates visibility using the relationships Visibility 6213712 X 3 0 Exco Daytime in miles Ln 00336V V Exco Night Time in miles DCP Flow Diagram for Reported Visibility Once each minute poll VS Non for daytime ExCo and ALS Valid Mark NA background illumination D ata values Valid Data Determine Day Night status Day to Night lt 0 5 fl Night to Day gt 3 0 fl Calculate one 1 minute visibility in miles Day 0 62137X3 0 ExCo Night Ln 00336V V ExCo If Day Night indeterminate use Daytime visibility Store one 1 minute visibility value rounded to nearest 0 1 mile in ten 10 minute array replacing oldest value if any 15 BELFORT instrument Proprietary Information DCP Flow Diagram for Reported Visibility c
14. ks the VHF transceiver with the PC and the RIF 5 An aviation VHF base station Technisonics TLC 100 Interconnect cables adapters and power supplies The DATU provides the user interface for all modes of operation other than the Hand Held Display Unit HHDU These interfaces are DigiWx Advisor display available locally and through an Internet link DigiWx Voice available through a pilot request a dedicated frequency endless loop audio broadcast telephone dial in request 8 BELFORT instrument Proprietary Information Figure 3 Illustration of Data Interface Modes 3 2 DCP Data Collection Processor The DCP is located on the sensor tower and collects processes and communicates the weather and system status information It also contains the 2 barometric pressure sensors and battery charging circuitry for the backup battery supply The 464 MHz transceiver listens before transmit and has automatic alternate channel capability SENSORS DCP EM TRANSCEIVER WIND DIRECTION POWER MANAGEMENT 464 MHZ WIND SPEE 464 MHZ TRANSCEIVER TEMPERATURE SYSTEM STATUS ALGORITHMS HUMIDITY SENSOR STATUS ALGORITHMS VISIBILITY DATA QUALITY ALGORITHMS DAY NITE HEAD WIND CROSSWIND ALGORITHMS PRESSURE 1 DENSITY ALTITUDE ALGORITHMS PRESSURE 2 CONDENSATION ALTITUDE ALGORITHMS VISIBILITY ALGO
15. mples background illumination calculates ten 10 second averages and once 1 a minute calculates a one 1 minute average from the ten 10 second averages Ifa valid one 1 minute average is calculated this information is made available for a polling request by the Visibility Sensor VS Ifa valid one 1 minute average is not calculated the output is marked NA and will deliver a null when polled Algorithm Flow Diagram for ALS Sensor Make ambient light measurements as fast as possible from one 1 cycle per second to two hundred 200 cycles per second depending on illumination level Once every ten 10 seconds calculate a ten 10 second boxcar average If a valid ten 10 second average is available set the boxcar count to six 6 Yes Six 6 valid boxcar averages available for one 1 minute average calculation No Or If a valid ten 10 second average is not available set the boxcar count to last count less one 1 Five 5 or less valid boxcar averages available for one 1 minute average calculation Once every ten 10 seconds determine if at least five 5 active boxcar averages are available yes Once every ten 10 seconds calculate one 1 minute average No Yes 18 BELFORT instrument Proprietary Information Algorithm Flow Diagram for ALS Sensor Continued If the time since last availability of 75 o
16. nsors are sampled once every 10 seconds and 1 minute averages are constructed The 2 averages are compared and the lower is used to compute field pressure If the pressures differ by more than 0 04 inHg the pressure is reported missing The altimeter algorithm calculates and reports altimeter setting and density altitude The altimeter setting is rounded to the nearest 0 01 inHg The following flow chart describes the algorithm for calculating Altimeter Setting data Algorithm Flow Diagram for Pressure and Altimeter Setting Data Cache raw instantaneous Every 2 seconds request data for use by calibration SSS 0 SSSSSSSSSSSSSSSSSSSSSSSSSSSSS 5 O pressure data from sensor 1 functions and routines and sensor 2 P1 and P2 Every 10 seconds insert the most recent pressures data into the P1 and P2 6 element circular averaging buffers If data not available insert NA into that position Once every minute if the number of valid entries equals 6 calculate the 1 minute averages for P1 and P2 Ifa data point is missing or the buffer is not full output NA Yes 11 BELFORT instrument Proprietary Information Algorithm Flow Diagram for Pressure and Altimeter Setting Data Continued 12 Once every minute calculate the altimeter setting from the average pressure data for P1 and P2 as follows Il Are both 1 minute P1 and P2 Yes average pressures available a Do the average values differ by more than 0 0
17. ontinued On startup report NA until all ten 10 elements are filled and a ten 10 minute harmonic can be calculated Subsequently report NA if less than 8 valid elements are present in the array I Calculate and report variable visibility if the ten 10 minute average is greater than three 3 miles all ten 10 array elements gt gt gt gt Incorporate in the METAR output are filled and the element to element differences and sign reversals exceed threshold values gt gt gt gt The Visibility Sensor samples light forward scattered from the sample volume 37 times each second as Phase I and 37 times each second as Phase II A synchronous rectifier detects the difference from an arbitrary zero Also the power of the illuminating LED is sampled in the same way The one 1 second and average differences are converted to Extinction Coefficient in inverse kilometers as a function of the difference span and zero factors The Extinction coefficient is converted to visibility using the formula V 3 ExCo in kilometers and then converted to units of choice Every 30 seconds the ALS is polled by the Visibility Sensor and the one 1 minute average information is stored in a buffer available through the Visibility Sensor as a response to an FE poll The Visibility Sensor is polled once each minute by the DCP for the one 1 minute average visibility and the 30 second average ALS data
18. ormation The system is modular and may be deployed in a number of configurations depending on the sensors selected the mounting method and the output options as shown in the following table DigiWx Sensor and Data Distribution Configurations Sensor Configurations DCP DCP DCP Dual Baro Tower Dual Baro Wind DCP Dual Baro Tower Mount Sock Mount DCP DCP Dual Baro Mount Wind Speed Wind Speed and Wind Speed and Data Distribution Dual Baro Wall Dual Baro Tower Tower Mount eP Direction Direction pee and Direction Options Mount Mount Visibility T Temperature and Temperature and emperature and Day Night Dew point Dew point Dew point Visibility with Visibility with Day Night Sensor Day Night Sensor Code BNT B BV W V S Handheld HHDU H BNT H B H BV H BW H BWV H BWS H DigiWx Advisor FBO Al BNT A1 B Al BV Al BW AI BWV AI BWS Al DigiWx Advisor FBO A2 BNT A2 B A2 BV A2 BW A2 BWV A2 BWS A2 Internet DigiWx Advisor FBO Dial A3 BNT A3 B A3 BV A3 BW A3 BWV A3 BWS A3 In DigiWx Advisor FBO A4 BNT A4 B A4 BV A4 BW A4 BWV A4 BWS A4 Internet Dial In With DigiWx Voice UNICOM vi BNT A V1 B A V1 BV A V1 BW A V1 BWV A V1 BWS A V1 Or DigiWx Voice VHF V2 BNT A V2 B A V2 BV A V2 BW A V2 BWV A V2 BWS A V2 Table 1 DigiWx Configurations DigiWx Voice requires the presence of one of the DigiWx Advisor modules Al A2 A3 or A4 All syst
19. splayed directly by the HHDU and decoded by the DDR and passed to the DATU as an ASCII string The information is then parsed by the DATU and made available to various users through on screen displays synthesized voice audio information via pilot activated Unicom endless loop synthesized voice audio information via dedicated frequency Unicom telephone dial in via an audio modem and if available through an Internet link Figure 2 displays this information flow e Wi f ION F 7 eH IDITY So 7 Par e Yi UTY i EN i s eo NIGH i gt if PRESSURE EEE Vv pf RE P A e d MH TRANSCEIVER F A SINS N x E Es AUTOMATED hd Di gt N VISTA n Sp 2 e i Pay LJ ENDLE LOC TE s 2 FREQUEN ELC y Lome ced z L a DDR NT TA DE A GA a Figure 2 Information Flow 27s BELFORT instrument Proprietary Information 3 1 DATU Data Acquisition Terminal Unit and Peripheral Devices The DATU consists of 5 basic modules 1 A digital data receiver DDR that links the sensors and DCP to the PC based user interface 2 A PC and peripherals meeting at least the following requirements Dell Optiplex GX270 PC Minimum of 128MB RAM 20GB Hard Drive 1 GHz Pentium Processor Windows XP Home Edition Voice Modem V 92 Sound Card Sound Blaster Compatible Network Interface Card NIC 1OMB Minimum Monitor 3 A radio Interface RIF that links the MCIF with the PC 4 A Microphone Click Interface MCIF that lin
20. tion Commission FRDF Facility Reference Data File FRU Field Replaceable Unit FSDO Flight Standards District Office Hg Mercury HHDU Hand Held Display Unit 293 BELFORT instrument Proprietary Information ICAO International Civil Aviation Organization ID Identification INOP Inoperative KT Knots LED Light Emitting Diode LRU Lowest Replaceable Unit MCIF Microphone Click Interface MHz MegaHertz million Hertz MOU Memorandum of Understanding MSL Mean Sea Level NAVAID Navigational Aid NIST National Institute of Standards and Technology NOTAM Notice To Airmen OMM Operations and Maintenance Manual RAF Regional Airway Facilities REL HUM Relative Humidity RIF Radio Interface RPM Revolutions Per Minute T1 T carrier 1 digital transmission line 1 544 Mbps 24 voice channels UHF Ultra High Frequency UNICOM Universal Integrated Communications System VAC Volts Alternating Current VDC Volts Direct Current VDD Version Description Document DigiWx Configuration Baseline Document VDU Video Display Unit VHF Very High Frequency VS Visibility Sensor 24 BELFORT instrument Proprietary Information
21. will deliver current conditions as speech output In order for the telephone answering and reporting system to function a modem capable of voice output must be installed If this option is installed the modem will be configured at the Belfort factory The DigiWx Phone program will answer a call on the telephone line connected to the modem The program will usually answer before the second ring at the modem The caller may hear three 3 or more rings depending upon the variables in the public telephone switching network Once DigiWx Phone has answered the call the program will query the database to retrieve the most current reading The program will generate speech output into the modem for Airport name NOTAM message if any current winds and gusts altimeter visibility if sensor is installed temperature dew point relative humidity density altitude and condensation altitude The program will repeat the current conditions and will then terminate the call and hang up the phone line Stale data threshold A stale data threshold is pre configured at the Belfort factory If the most current data reading is older than the current clock time minus the stale data threshold interval no weather parameters will be shown and Current data not available will be output instead of the date and time In the event that the stale data threshold has been exceeded the speech message output will consist of the airport name and the phrase Current
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