[aprssig] Why do stations send telemetry parameter messages to themselves?

[Lynn W Deffenbaugh (Mr)]

Read chapter 13 of aprs101.pdf.  It describes the "On-Air Definition of 
Telemetry Parameters" which are specially formatted messages (PARM, 
UNIT, EQNS, BITS) sent via APRS message format packets from a station to 
itself.   The T datatype only carries values, not the definitions of how 
to interpret those values.

As for RXTLM-1, technically that would be an Alternate Net identifier of 
RXTLM since it doesn't start with AP.   You can read about these on Page 
15 of chapter 4 in aprs101.pdf.

The -1 would be a Generic APRS Digipeater Path also discussed on page 15 
in chapter 4 of aprs101.pdf.   The -1 would technically be the same as a 
WIDE1-1 path.

However, that said, I suspect that the RXTLM-1 is actually not meaning 
that but is being mis-used by some software somewhere.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32



On 11/14/2024 4:15 PM, John Gorkos wrote:
> I'm back into the deep, ugly guts of parsing the full APRS-IS stream, 
> and I keep seeing messages like this:
>
>
> EL-OK1BY>RXTLM-1,TCPIP,qAR,OK1BY::EL-OK1BY:UNIT.RX Erlang,TX 
> Erlang,RXcount/10m,TXcount/10m,none1,STxxxxxx,logic
> ER-F5ZVB>RXTLM-1,TCPIP,qAR,F5ZVB::ER-F5ZVB :UNIT.RX Erlang,TX 
> Erlang,RXcount/10m,TXcount/10m,none1,STxxxxxx,logic
> KI0AU-1>APMI06,TCPIP*,qAC,T2BC::KI0AU-1 
> :UNIT.C,Pkt,Pkt,Volts,Volts,N1,N2,N3,N4,N1,N2,N3,N4
> GM7AFE>APMI01,TCPIP*,qAS,MB7UZL::GM7AFE 
> :UNIT.Pkt,Pkt,Pcnt,Volts,Volts,Off,On,On,On,Hi,Hi,Hi,Hi
>
> Why are stations wrapping telemetry parameter messages in APRS 
> Messages and then sending them to themselves?  At least they're not 
> asking for acknowledgements.  Can anyone explain this behavior and 
> what it's intended to do, versus just using a :T telemetry message, 
> per spec?
>
> While we're at it, what does the RXTLM-1 tocall tell me?  Clearly 
> something to do with Receive Telemetry (i.e. erlang values, etc).
>
>
> Thanks de AB0OO
> John Gorkos
>
>
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