Difference webpage and ogg decoding by gr_satellites

SatNOGS Software
1

Hi!

I tried using gr_satellites to decode the .ogg file for observation 7109702.

There are 432 frames listed in the data tab on the page. However, when using gr_satellites, I was only able to decode 308 frames. Could this discrepancy be due to the lossy compression of the .ogg file?
I searched this issue, and it seems it might be due to lossy compression. But I’m not certain. Am I correct?

2

Hi,
you’re right, you cannot get 100% replication of the results. sometimes you can get a few new frames, but the count is usually lower.
One big difference is the complex float type that the live udp stream contains, and the int16 that the ogg/wav contains.
(for fsk) It also has a different path of quadrature demodulation and automatic frequency tracking.
Have a look at the different flowgraphs to see how this all works in satnogs-flowgraphs

3

Thanks for your kind explanation!!

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