ax25_callsigns.py

#!/usr/bin/env python
#
#   Print out AX25 dst/src callsigns, and packet path from a SatNOGS HexTDump
#
#   Example: python ax25_callsigns.py "AE 90 64 B0 A0 9A 60 9C 6E A6 96 86 40 E1 03 F0 00"
#
import codecs
import sys


def extract_callsign(data):
    _dst = data[:6]
    _dst_flags = data[6]
    _dst_chars = []
    for x in _dst:
        _dst_chars.append(x>>1)
    
    _dst_ssid = (_dst_flags & 0b00011110) >> 1


    _src = data[7:13]
    _src_flags = data[13]
    _src_chars = []
    for x in _src:
        _src_chars.append(x>>1)
    
    _src_ssid = (_src_flags & 0b00011110) >> 1

    print(f"DST: {bytes(_dst_chars).decode()}-{_dst_ssid} SRC: {bytes(_src_chars).decode()}-{_src_ssid}")

    if (_src_flags & 1) == 0:
        # Address extension bit set!
        _repeater = data[14:20]
        _repeater_flags = data[20]
        _repeater_chars = []
        for x in _repeater:
            _repeater_chars.append(x>>1)
        
        _repeater_ssid = (_repeater_flags & 0b00011110) >> 1
        
        print(f"Layer 2 Repeater: {bytes(_repeater_chars).decode()}-{_repeater_ssid}")
        if (_repeater_flags & 0x80) != 0:
            print("Packet has been repeated.")
        else:
            print("Packet has NOT been repeated.")



data = sys.argv[1]

#print(f"Source Data: {data}")

_data = data.replace(' ', '')
_data_bytes = codecs.decode(_data, 'hex_codec')
#print(_data_bytes)

extract_callsign(_data_bytes)