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RE: AO40 telemetry tutorial?



Mark Hammond wrote:

At MA30, it should be working fine with S5 signal over noise.  AO40rcv can 
deal with VERY rapid doppler changes...

One thought...did you turn the volume UP enough?  On my former sound card 
(SB 16), I had to turn the volume up until the program complained about 
being too loud, then back it down just below that.  I got the best decoding 
that way.  With my SB Audigy, the level is less fussy.

What center frequency are you using?  Mine does better at about 1200-1300 Hz...

Another thought--do you have any strange equalizer/sound effects software 
running?

Wayne replies:

I get audio out of the FT-847 data jack which is independent of the radio's volume control.  I had the sound card's "line in" gain at a setting that works well with several PSK-31 programs.  I will try cranking up the sound card's "line in" gain.  My waterfall display was probably a bit more faint that the example screen shot on the AE4JY web page.

Center frequency was about 1100 Hz most of the time.  I did try different center frequencies and didn't see any difference in the way it decoded.  I'm pretty sure I don't have any equalizer effects enabled.  The sound is integrated in the mother board, and doesn't really have any "sound effects" features.

I didn't look at the AO40rcv help file.  I should do that.

The squint angle was less than 15 degrees at the time (MA20-25).  There was no perceptible fading, and the beacon was more than 5 S-units above the noise level.

I tried decoding telemetry blocks with auto Doppler tuning (via SatPC32) enabled and disabled.  Even when Doppler tuning was enabled, the RX frequency rarely incremented in the middle of a block.

My first attempt to decode telemetry wasn't successful, but it was overall a successful test of my new G3RUH dish/feed, DEM preamp, and G-5500B rotors.  With my old BBQ dish and dipole feed, I never heard the sidebands that are a few kHz on either side of the beacon.  And the noise floor dropped more than 1 S-unit when the transponder abruptly shut off at MA29.6.  New schedule, I guess!  The final bonus this morning was working French Guiana for satellite country #109 (my second "new one" on AO40).

Wayne Estes W9AE
Mundelein, IL, USA


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