Observation 7483531: Taurus-1 (44530)

Satellites & Observations Observations
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Regarding Observation 7483531 … why 52 frames acquired and yet no signal in waterfall?

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Given that there is no signal in waterfall, the pass is a low one and that the frames don’t have a pattern (for example a header that repeats), my guess is that these are noise frames, frames that were generated by the demodulator triggered by noise.

EDIT: I’ve just checked and it seems that all the frames have the “_g0” suffix, which means, correct me if I’m wrong, that they were generated by gr-satellites.

3

I’ve confirmed this with @SA2KNG.

@EA4GPZ can you take a look at this? I guess you will need an IQ file, right?

4

replay of the audio also gets a bunch of frames.
gr_satellites 44530 --wavfile satnogs_7483531_2023-04-28T16-21-54.ogg --kiss_out 7483531.kiss
52 correlate_access_code_tag_bb :debug: writing tag at sample 2202946
17 Could not parse telemetry beacon Error in path (parsing) -> beacon no subconstruct matched
kiss_satnogs.py -t 7483531.kiss results in: Found 47 frames.

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5

These are indeed false decodes. gr-satellites doesn’t check the CRC of Taurus-1 frames because the specs for the CRC were never published (or the frames don’t actually have a CRC; I don’t recall precisely). Therefore, the decoder will emit a frame as soon as the 32-bit syncword is detected. By default, up to 4 bit errors are allowed in the syncword detection. This can be modified with the --syncword_threshold parameter.

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6

Thanks guys. I guess this resolves my query; albeit a bit over my head.
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