[amsat-bb] AO40 telemetry tutorial?

[Estes Wayne-W10191 <W10191@xxxxxxxxxxxx>]

This morning I tried to decode AO40 telemetry for the first time using AO40rcv.  I never got any "CRC good" blocks out of 25 blocks monitored.  This was around MA30.  AO40rcv appeared to stay "synced" during each "read block" cycle.  I had the AO40rcv AFC on, and the Doppler seemed to be changing about 6 Hz per second.  Is that within the AFC tuning capability of AO40rcv?

I'm sure the signal was strong enough.  The beacon was 5+ S-units above my noise level.  The bottom part of the signal waveform was 2 lines (20 dB I think) above the noise level.  I'm extracting the audio from my FT-847 data jack, and the audio interface works fine for PSK-31.  It does have isolation transformers.  The spectrum and waterfall display looked similar to the screen shot on AE4JY's web page.

I did go to this site, but didn't find anything that solves my problem:

http://ao40.homestead.com/TelemFAQ.html <http://ao40.homestead.com/TelemFAQ.html> 

Is there a tutorial that describes how to decode AO40 telemetry?  Things like:
	Configuration of AO40rcv
	Tuning requirements (maximum rate of change in Doppler shift)
	Interpreting the waterfall display
Interpreting the data

Thanks in advance.

Wayne Estes W9AE
Mundelein, IL, USA



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