[amsat-bb] Re: CAPE-2 over Cuba

Pavel Milanes Costa co7wt at frcuba.co.cu
Wed Dec 4 21:25:25 PST 2013

Hi Phil and others.

The last snapshoot of gqrx in the Csete ubuntu ppa is full of new 
features, among them is the ability to behave as a generic hamlib server...

Visit http://www.gqrx.dk (no affiliation, just a user...)

Configuring gqrx to accept connections is two click away and setting a 
new radio interface in Gpredict with the localhost and correct port 
setting makes the connection smooth..

Alex has provided an explanation about the doppler control moving the 
cursor in the spectrum rather than the center freq that makes the 
doppler tracking so easy...

The cursor keeps moving down with doppler even if you click/move it 
between the TLM/transpoder taking AO-73 as an example... good...

And you can push corrections at full speed, today I tested 100ms updates 
and works ok with funcube TLM...

About the audio... I have a kind of success today with the config 
decoding local 9600 bps in a local packet channel... not tested on sats 

The new gqrx has a "network audio broadcast" at one click away.

The I connect to the audio stream with nc and pipe the audio with sox to 
the second audio card that has soundmodem with 1k2, 4k8 and 9k6 modems 
on demand...

Alex mentions that the DireWolf team plan to make a "network sink" as a 
new feature in new versions... that will ease the things a lot...

listen or axlisten (depends of your source of ax25-libs/tools packages) 
serve as KISS raw packet visual aid and save them to a file also for later.

I said kind of success because sox sucks my CPU/RAM and appears to be a 
fight between sox and soundmodem some times... I have to tweak this a 

Alex Csete is doing a good job with SDR and linux, it's the only (nice 
GUI, native, easy and ham oriented, not just gnuradio) software for 
managing the RTL-SDR in linux, if I'm wrong please correct me. (I like 
having options!!!)

The only feature I miss is the save baseband as IQ in a file... for the 
moment only the audio...

I hope my english let your make an idea of my setup here...

73 de CO7WT, from Cuba.

El 04/12/13 19:33, Phil escribió:
> On 12/04/2013 11:24 PM, Pavel Milanes Costa wrote:
>> Hi to all...
>> Hard here is RTL-SDR + LNA + Gqrx + Gpredict for doppler
> Hello Pavel,
> Just wondering, how you interface Gpredict with Gqrx to control the
> tuning? Also, how are you interfacing Gqrx with your packet decoding
> software?

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