Observation 392599: CAS-4A (42761)


#1

Regarding Observation 392599

Hi can someone tell me whats decoded in this CW?


#2

That happens when there is noise! :wink:


#3

yes, I know but I was wondering what data is transmitted in this CW. satnogs does a bad job decoding, maybe there needs to be a notch filter or make the band pass smaller but when I play this cw audio back and use a CW decoded I get a better decode.

bj1sl dfh aaa hir rrv rmm rui tri r6i rkk rtn uun rvm tvt 6tr ttt ttt kib ttt mtt iur camsat camsat

what do the set of 3 letters mean?


#4

I have seen no spec’s for CAS4A/B CW telemetry anywhere, however, DK3WN once made a decoder, maybe he can help you.
http://www.dk3wn.info/p/?page_id=75524

Using Audacity you can easily (well, not that easy) decode it manually, the first beacon starting at timestamp 2:14 reads:
bj1sk dfh aaa rtr rrr utr ruv trm r6i rkk rtn uui rii ttn mcr ttt ttt 4rb ttt mtt vrr camsat camsat
Pasting this into DK3WN’s CW decoder gives:


#5

We indeed using a very steep band-pass. This steep filter however, is a headache for even tiny drifts… CW maybe quite easy to decode for a human but is very difficult in an automated way. There is no framing structure, no encoding, thus is quite difficult to discriminate between a valid and an invalid decode. I try to improve the decoder, but if you have better ideas feel free contribute them!


#6

I understand. Even the CW decoder has to be told where the signal is. This is a great system either way. Looking forward to future development. For me I am trying to get a better antenna acquisition setup. I sure wish i could just buy the SatNOGS rotator from a builder.


#7

pretty cool Jesper, thanks for sharing.