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SenderBeacon.md

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As of version 0.2.6, a complete sender (aircraft) beacon message looks as follows:

FLRDF0A52>APRS,qAS,LSTB:/220132h4658.70N/00707.72Ez090/054/A=001424 !W37! id06DF0A52 +020fpm +0.0rot 55.2dB 0e -6.2kHz gps4x6 s6.01 h03 rDDACC4 +5.0dBm hearD7EA hearDA95

The first two groups are standard APRS:

FLRDF0A52>APRS,qAS,LSTB:/220132h4658.70N/00707.72Ez090/054/A=001424 !W37!
  • 'FLRDF0A52>': origin
    • 'FLRDF0A52': sender callsign (may include device ID)
  • 'APRS,qAS,LSTB:': source
    • 'APRS': software version (always "APRS")
    • 'qAS': q construct (not suited for beacon identifcation)
    • 'LTSB': receiver callsign
  • '/': position with timestamp follows
  • '220132h': timestamp in 24h notation UTC (22 hours, 1 minute, 32 seconds)
  • '4658.70N/00707.72Ez': position (WSG84) - see position precision enhancement below as well
    • '4658.70N': latitude (46 degrees, 58.70 minutes north)
    • '/': display symbol - table to use (primary symbol table)
    • '00707.72E': longitude (007 degrees, 07.77 minutes east)
    • 'z': display symbol - position in table "/" to use (house symbol)
  • '090/054': optional heading and speed ("000/000" indicates no data)
    • '090': heading (001 thru 360) in degrees ("090" = east)
    • '054': ground speed in knots
  • '/A=001424': altitude (1424 feet)
  • '!W37!': position precision enhancement
    • '3': latitude minutes third decimal digit (46 degrees, 58.703 minutes north)
    • '7': longitude minutes third decimal digit (007 degrees, 07.727 minutes east)

All subsequent groups are OGN specific sender details:

id06DF0A52 +020fpm +0.0rot FL000.00 55.2dB 0e -6.2kHz gps4x6 s6.01 h03 rDDACC4 +5.0dBm hearD7EA hearDA95
  • 'id02DF0A52'
    • 0x'06' = 0b'00000110': sender details (2 digit hex number encoding 8 bits)
      • 0b'0' = 'false': stealth mode boolean (should never be "1")
      • 0b'0' = 'false': no-tracking boolean (must ignore if "1")
      • 0b'0001' = '1':
      • 0b'10' = '2': address type - 01 ICA 02 FLR 03 OGN 04 P3I 05 FNT 0 RANDOM
    • 'DF0A52': sender address
  • '+020fpm': climb rate in "feet per minute"
  • '+0.0rot': turn rate in "half turn per 2 minutes"
  • 'FL000.00': optional flight level
  • '55.2dB': signal to noise ratio (5db are considered the lower limit for meaningful reception)
  • '0e': CRC error rate (>5 is considered unusable)
  • '-6.2kHz': frequency offset (should be constant thanks to GSM sync)
  • 'gps4x6': optional GPS signal quality
  • '4': horizontal accuracy (4 meters)
  • '6': vertical accuracy (6 meters)
  • 's6.01': optional FLARM software version
  • 'h03': optional FLARM hardware version (hex)
  • 'rDDACC4': optional FLARM device ID
  • '+5.0dBm': optional power ratio ⚠️ unconfirmed
  • 'hearD7EA hearDA95': optional other FLARM devices received by this device
    • 'hearD7EA': receiving FLARM device with ID ending "D7EA"
    • 'hearDA95': receiving FLARM device with ID ending "DA95"