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[aprssig] Telemetry question

Heikki Hannikainen hessu at hes.iki.fi
Sat Aug 16 09:43:48 UTC 2008


   Hi,

On Fri, 15 Aug 2008, Alan P. Biddle wrote:

> Now, I would like to find out how to upload the data over RF into the system
> so that someone just going to a site such as APRS.FI will automatically see
> the data without the complicated URL.  Here is an example of what I am
> trying to do:
>
> http://aprs.fi/telemetry/VK5RAC-1
>
> I have asked about how to do that various places, and gotten answers such as
> "you can do that in the beacon message" or "you broadcast the parameters
> according to the APRS spec on RF," (Operator of APRS.FI.) or "you could do
> that with my unit's scripting language."  (Which in the last case does not
> yet exist.)   No doubt true, but not overly helpful if you don't really know
> what you are doing.  Ahem.

   I'm sorry about that - I'll try to answer in a more helpful method this 
time.

   As others pointed out, you need to send the equations and parameter 
names in an APRS message. You can send them from another APRS 
client/device/program than the actual device sending the telemetry, it 
just needs to be able to do APRS messaging (the one-liner "chat" messages 
you can read at http://aprs.fi/?c=message for example). I have to admit 
that aprs.fi had a bug here - it didn't allow updating another station's 
equations until today, but I've fixed that now.

   The telemetry device's callsign goes to the *destination* field of the 
message (not the AX.25 packet callsign, which can be just about anything, 
but the destination field of the messaging format). The PARMS/EQNS/UNIT 
message goes in the content of the text message.

   Start UI-view, or another program capable of sending APRS messages to 
other users, start a chat with the tracker which is sending the telemetry 
(click on Messages in UI-View32), and type in the EQNS/PARMS/UNIT 
messages.

> PARM.BATTERY,TEMP,,,,,,,,
> UNIT.VOLTS,DEGC,,,,,,,,
> EQNS.0,.109,0,0,1.96,-273,0,0,0,0,0,0,0,0,0
> BITS.00000000,NOTHING HERE....

   That should work. You can look at the raw packets received at aprs.fi, 
both yours and another station's which is sending these correctly, for 
example:

http://aprs.fi/?c=raw&call=VK5RAC-1

2008-08-16 09:00:42 UTC: VK5RAC-1>TLM,EYRE2-2,qAR,VK5ZEA::VK5RAC-1 :EQNS.0,0.5,0,0,0.1,0
2008-08-16 09:01:53 UTC: VK5RAC-1>TLM,EYRE2-2,qAR,VK5ZEA::VK5RAC-1 :PARM.Temp,Battery,TX
2008-08-16 09:03:06 UTC: VK5RAC-1>TLM,EYRE2-2,qAR,VK5ZEA::VK5RAC-1 :UNIT.Deg.C,Volts,PTT's

   The source callsign can be anything (the first VK5RAC-1 there), as long 
as the message destination (after the ::) is the telemetry station's call.

   - Hessu, OH7LZB





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