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g4klx / MMDVMHost

The host program for the MMDVM
GNU General Public License v2.0
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Fix trellis decoder/encoder bit order #778

Closed alexernst closed 1 year ago

alexernst commented 1 year ago

The trellis decoder and encoder are both working with reverse bit order. After this change I'm able to decode data packets with trellis encoding from my Hytera successfully.

Fix #744

shawnchain commented 1 year ago

I'm wondering if this PR will break other radio's data decoding ? The ETSI TS 102 361-1 describes the DMR rate 3/4 trellis code logic, and I think the original MMDVM code looks just fine.

alexernst commented 1 year ago

It won't break anything. Here it is only used to try to fix errors in received data packets. MMDVMHost is simple decoding/encoding datarate 3/4 packets and tries to fix errors. As decode and encode use the same bit order it didn't mattered.

I only noticed it because I needed the decoded debug output.

iddq commented 1 year ago

@alexernst Thank you! https://github.com/g4klx/MMDVMHost/issues/744