Hi everyone, Is it possible to modify the *traceback depth* of the built-in *CC Decoder Definition*? It appears unable to recover errors I have introduced during puncturing/depuncturing, returning values with bit errors still present.
I am trying to decode a PDU I originally convolutionally encoded using the *FEC Async Encoder* block with the default 1/2 rate, K=7, 79/109 *CC Encoder Definition* in 'terminated mode'. I then perform async puncturing using a custom block I wrote to achieve 2/3 and 3/4 code rates, followed by the corresponding async depuncturing block, which inserts zeroes in previously punctured positions. I then attempt to decode the depunctured code using the *FEC Async Decoder *block with the default 1/2 rate, K=7, 79/109 *CC Decoder Definition* in 'terminated mode'. Without puncturing (rate = 1/2) decoding works perfectly. I have confirmed the puncture/depuncture behaviour is correct, so it appears that the decoder just isn't looking back far enough when performing Viterbi decoding. I haven't been able to find an obvious way to modify the decoder's traceback depth... *SSE2 Viterbi* decoding methods like that used in *DVB-T* and *802.11* actually already modify their traceback depth to accommodate puncturing. Anyone have any advice? Ideally I'd make the default cc encoders/decoders work since they perform the necessary flushing of bits for fixed length packets, rather than modifying the SSE2 versions to do the same. Big thanks in advance for any help! Cheers, Justin
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
