Re: [amsat-bb] Observed AO-40 FEC coded telemetry ?

[Phil Karn <karn@xxxxxxxx>]

JJ1WTK, Kazu Sakamoto wrote:

> The waterfall pattern is so interesting. After the conventional A block,
> the many peaks around 1600Hz turned broad ones. I think it means the
> scrambler in the onboard FEC encoder works well.

Yes, I used the CCSDS-standard scrambler in my encoder. It sits between 
the Reed-Solomon outer and convolutional inner codes. I originally tried 
to avoid scrambling, but I found that it significantly improved symbol 
tracking in the demodulator when the data consisted of lots of binary 
zeroes.

Phil



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