Feeding OGG files back into gr-satnogs flowgraphs


I am trying to do some offline testing with the gr-satnogs flowgraphs, using recorded .ogg files from the DB.
The “OGG File Source” block seems to work fine but I was not able to decode any AX.25 frames yet.
Does someone has a working example how to feed the ogg files back into GNU Radio without converting them to wav?

Thanks in advance!



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I think I do have something, but can’t access my PC today or tomorrow, unfortunately!

You need to connect the .ogg file source at the right block input, exactly where the sink was connected at receiving.

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Hi @DL4PD !

Thank you for the hint!
This is what I tried at first but until now without success.

Maybe I just choose the wrong satellites since I am uncertain which satellites can be used to test the gr-satnogs AX.25 decoder.
Do you have any recommendations?
Can I see from the DB which decoded data is uploaded from the gr-satnogs client and which is generated by gr-satellites or other sources?

Hm, yeah, I might also have a replay-decoder somewhere, but not on my laptop, and access to the PC is not possible today. Maybe I can find some time tomorrow!

An example from DB:

        "norad_cat_id": 44359,
        "transmitter": "",
        "app_source": "network",
        "schema": "",
        "decoded": "influxdb",
        "frame": "968870A6A0A660968C6CA48CB0E103F0ABCD0000005304CB009C6820324D5D570051000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000017003305E508090A880A7402530200000000000000000000000038810800000000167A01000000",
        "observer": "KB9JHU-EM69uf",
        "timestamp": "2019-08-09T08:43:14Z"

app_source is the tag to look for. "network" is from network and "sids" are third party forwarders!

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Finally I found two observations that work with FSK!

The following flowgraph can decode UNISAT-6 (FSK9k6 with AX.25 frames).

For some recordings where also data is available it still does not work and when it works the amount of frames does not match.

Here two selected recordings for testing:


I had to change Omega from 2 to 5 at the “Clock Recovery” block and I am still not sure what is the perfect gain in the “Quadrature Demod Filter”, for now it is set to 1.2.

I keep on trying to decode also other modulations. When they are available I will post them here.


AFSK1k2 with AX.25 frames was strait forward because the “OGG Sink” is located better.

Data from X-CUBESAT




Are you using the gr-satnogs dev branch?
It really is worth a try as there are a lot of improvements done!

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No, currently using the gr-satnogs main branch but I will give it a try!

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