[amsat-bb] Re: Cal Poly Satellite, CP4 Beacon Help

Mike Rupprecht mail at mike-rupprecht.de
Wed Jul 23 21:55:49 PDT 2008

Hi Tim,

i think MixW isn't very useful for decoding CP4 telemetry. You can't see the real byte values with MixW (only ASCII chars).

There are two ways to get the telemetry:

1. Use MixW with option TNC emulation (needs an driver to loop back on serial ports) -> see MixW documentation
2. Use an TNC in KISS mode an log the incoming data to a file

It's not so easy to get the right frequency because CP4 is jumping around some times. If you use an TNC you must be very fast to adjust the correct receiving frequency. CP4 is sending a short CW sequence before the telemetry. Tune you receiver at this moment so that the audio frequency of this cw signal is 2200Hz.. The following two beacons should be now decoded with your TNC.

If you record the beacons you can play around with MixW. There is an option - Custum AFSK - where you can set the two AFSK frequencies manually.

73, Mike

Betreff: [amsat-bb] Re: Cal Poly Satellite, CP4 Beacon Help
Gesendet: Do, 24. Jul 2008
Von: Tim Tuck<tim.tuck at penrith.net>

> Jason Anderson wrote:
> [snip]
> > Satellite Link Information
> > ------------------------------
> > Frequency: 437.325Mz
> > Modulation: FSK (but uses LSB cheat to make AFSK)
> > Radio Mode: LSB (neccesary for LSB cheat)
> > Baud Rate: 1200
> > Beacon rate: 1 beacon/minute (maybe change to 5 minutes if satellite
> changes mode)
> >
> >   
> Hi James,
> Happy to help with this but I'm a little confused as to what I should 
> set MixW to decode your data since I have 5 possible forms of 1200 baud 
> to set it to which are....
> Standard 1200/2200 Hz
> Zero Crossing 600/1200 hz
> Zero Crossing 1200/2400 Hz
> satellite PSK
> FX469: 1200\1800 Hz
> I'm new to telemetry gathering, and I 'm currently collecting packets of 
> DelpiC3 with great success but they made it easy with their own program.
> regards
> Tim
> -- 
> VK2XTT :: QF56if :: BMARC :: WIA :: AMSAT 
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