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daniestevez / gr-satellites

GNU Radio decoder for Amateur satellites
GNU General Public License v3.0
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Error when using OPS-SAT satyaml based decoder #201

Closed N6RFM closed 3 years ago

N6RFM commented 3 years ago

Hi Dani,

When running a satyaml or norad ID based decoder for OPS-SAT, the following error is given. Have to quit the flow graph. Any suggestions? Tks, Bob

gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 2, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 22, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 5, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 11, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 2, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 28, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 11, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 5, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 13, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 15, interleave = 1, RS code (255, 223) gr::log :ERROR: decode_rs0 - Wrong Reed-Solomon message size. size = 30, interleave = 1, RS code (255, 223)

daniestevez commented 3 years ago

Hi Bob,

Actually this is normal (but annoying, I reckon). In one of the updates to the Reed-Solomon decoder I introduced these error logs when the decoder gets a message of the wrong size. Nothing bad happens. The message is just dropped. The difference is that before it was dropped silently.

This causes this annoying problem with OPS-SAT because OPS-SAT uses Reed-Solomon frames inside AX.25. Since AX.25 is not a very good protocol, it will produced many false decodes that are sent to the Reed-Solomon decoder and then dropped by it. A good solution to prevent this would be to check the packet size before sending it to the Reed-Solomon decoder.

I'll leave this open in case I have some time to do it.

N6RFM commented 3 years ago

Thanks Dani for keeping this open.

Perhaps only here, but these streaming error messages really overflow the console output.
In the meantime, I've suppressed these by adjusting the gr::log Error message output at the user level.

Best,

Bob

daniestevez commented 3 years ago

I think that a good way to solve this would be to add a "PDU length filter" block that takes as parameters a minimum length and a maximum length and drops PDUs that don't satisfy the restrictions. Using -1 for maximum length would have the semantics of "unlimited".

N6RFM commented 3 years ago

Great idea Dani. Will be happy to test when ready. Cheers.

daniestevez commented 3 years ago

I have just pushed a commit that should fix this problem. If possible, please give this a try, since I don't have an OPS-SAT recording at hand at the moment.

daniestevez commented 3 years ago

I'm closing this, since I want to release v3.7 soon and this is on the list of issues to be closed for release. If the problem persists, please re-open this issue.