Two basic functions would be neccessary.
One: show call sign and position of received stations (and hopefully track)
Two: Topofusion sends instructions to TNC (terminal node controller) to transmit location
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The logs from USAPhotoMaps include:
1.) Instructions to TNC:
These look like this and this may not be a complete set of instructions I just copied and pasted a group I recognized (not sure what they all do but it is probably in the APRS Protocol):
cmd:BEACON EVERY 15
BEACON Â was EVERY 0
cmd:MMONITOR Â was ON
cmd:ECHO ON
ECHO Â Â was ON
cmd:HID OFF
HID Â Â Â was OFF
cmd:MYCALL KE7MWY
MYCALL Â was TEST
cmd:UNPROTO APZUSA VIA WIDE1-1,WIDE2-1
UNPROTO Â was APO422 VIA WIDE1-1,WIDE2-1
cmd:BTEXT =3600.75N/11505.10W-270/000
BTEXT Â Â was =3506.84N/-11546.71Wk270/016
cmd:MONITOR ON
MONITOR Â was OFF
cmd:BEACON EVERY 15
BEACON Â was EVERY 15
2.) GPS Location information - these look like this
$GPRMC,192714,A,3506.7533,N,11448.8119,W,17.8,269.6,120908,13.0,E,D*0ABTEXT =3506.75N/-11548.82Wk186/020
3.) APRS Packets received - THese look like this
AD6NH>APU25N,ONYX,WA7RAT-12*,WIDE2:@121929z3350.99N/11752.79W_207/003g005t068r000p000P000h76b10120/PHG61604/Anaheim WX {UIV32}
N6BG-9>SVQTTT,N7ZEV-3,WIDE1,WA7RAT-12*,WIDE2:`+,gm{u>/";q}
N6BG-9>SVQTTT,VEGAS,WIDE1*,WIDE2-1:`+,gm{u>/";q}
K7YMA-6>STUSVU,W7DXJ-1,WA7RAT-12*,WIDE2:`*?s ?iv/]"5B}=
K1GGS-9>S6QQQY,N7ZEV-3,WIDE1,WA7RAT-12*,WIDE2:`+`ZnIpR/]":P}=
N5UIS-9>S6PXWS,N7ZEV-2,N7ZEV-3,WA7RAT-12*,WIDE3:`+ap*:k/"3r}TinyTrak3
W7DXJ-2>APTW01,WA7RAT-12*,WIDE2-1:_09130032c225s002g000t087r000p000P000h29b09769tU2k
N7ZEV-3>APN383,WA7RAT-12*,WIDE2-1:!3619.06NS11534.32W#PHG3962/W3,NV3 Angel Peak north of Las Vegas, NV.
W7DXJ-2>APTW01,WA7RAT-12*,WIDE2-1:!3429.56N/11416.35W_WXTrak
K1GGS-9>S6QPXS,N7ZEV-3,WIDE1,WA7RAT-12*,WIDE2:`+`eo^0R/]":]}=
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I will try to dig down and learn more about TNC Commands. Not sure what I will be able to come up with as I really dont know much about software commands.
Hope this helps. Ed.