[amsat-bb] FO-29 transponder block diagram

Pedro Converso pconver at gmail.com
Wed Nov 1 05:08:54 UTC 2017

Hello Dany,

Try perhaps to check if your results match others tracking applications.

I do use http://amsat.org.ar/pass or http://amsat.org.ar/pass.exe with
wispdde driver or HDSDR.

Using last 2 combinations, I follow LO-19 constant carrier receiving CW and
software follows right on frequency, using either an FT-736 or FT-897.

To calculate Xmt & Rcv Dopplers, I take into account instant satellite
velocity related to user ground station, always using the latest TLEs.

We can share formulas to calculate both Dopplers if that helps.

Best 73, LU7ABF, Pedro

On Mon, Oct 30, 2017 at 6:53 PM, Dani EA4GPZ <daniel at destevez.net> wrote:

> 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
> http://destevez.net/2017/10/wsjt-x-and-linear-satellites-part-ii/)
> 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:
> http://www.jarl.org/English/5_Fuji/systeme.gif
> However, I need something similar to this:
> https://funcubetest2.files.wordpress.com/2010/11/funcube_
> rf_board_block_diagramv2-1_pa3weg_open-1.pdf
> 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?
> 73,
> Dani EA4GPZ.
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