Satellite frequency doppler correction

[Tomasz Blazej]

Hi All

I would like to use linrad to receive LEO satellites in adaptive polarization mode in the 70cm band. Satellites rotate and the polarity changes which causes unimpeded fading for proper reception and decoding of the signal.

I have a cross yagi antenna and soon a two channel sdr Afedri. 

"Generator" of frequency feeds and changes I imagine will be the program Gpredict.

 It can control the frequencies of many trx, and also do it via UDP. 

Is it possible to combine these two programs (linrad and gpredict) to get doppler correction for each satellite ? How to do it ? Will Linrad be a panadapter for gpredict ?

73! with best regards

Tomek SP5LOT

[Leif Asbrink]

Hi Tomek,

There is an AFC in Linrad:
http://www.sm5bsz.com/linuxdsp/afc/meteor.htm
http://www.sm5bsz.com/linuxdsp/afc/lock.htm

You might compile from source with extra_w3sz.c renamed users_extra.c
to be able to control the frequency by writing the desired frequency
into a file which Linrad would read and use to set the frequency.
The default update rate is 0.25 seconds.

I never used this myself, but this might be useful for SSB or other
modes that do not have a distict carrier.

73

Leif

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[Tomasz SP5LOT]

It seems to be a breakneck path, but doable. 

Too bad it's not simpler.

AFC seems to be able to keep up with changes in satellite frequencies

73

Tomek SP5LOT