[amsat-bb] FO-29 transponder block diagram

Dani EA4GPZ daniel at destevez.net
Mon Oct 30 21:53:15 UTC 2017

Hi all,

A few days ago I have transmitted and recorded a (low-power) FT8 signal
through the FO-29 linear transponder to test some Doppler correction
algorithms I'm developing (see

After Doppler correction, I'm left with a linear frequency drift both in
my downlink signal and in the satellite CW beacon. However, the drift
rate of my signal and the beacon are different. Specifically, my signal
drifts 1.26 times faster than the beacon. I suspect that this drift is
due to one of the local oscillators in FO-29.

To understand this better, I need to look at a block diagram of the
FO-29 linear transponder. The best I've found is this:


However, I need something similar to this:


Since I need to see the frequencies of all the local oscillators
involved in the transponder and CW beacon.

Is there a more detailed block diagram for FO-29 or does anyone know
something about this information?


Dani EA4GPZ.

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