Hello,
I want to decode a never-ending data stream using VCP2 on C6474. The data I need to decode is encoded without resetting the state metrics, so we can consider it as one long message. I have to decode this frame by frame using the state metrics continually. The implementation that I have found and been able to use decodes only a frame of some length. When I use this for my problem, the first and last some bits are corrupted.
I read the documents and the example codes, but I could not make it work in this way. Moreover, I could not understand what the traceback length is, how to change it, where the state metrics are stored, how to use the sliding window concept, etc. Combining these with the lack of DSP programming experience and enough coding/decoding/Viterbi knowledge, I cannot develop any reasonable solution.
I have found a workaround but it is not theoretically proven. To decode a frame of length n bits, I feed the decoder by adding redundant m bits from each of the previous and the next messages. So when I decode (m + n + m) bits, the middle n bits are the desired message without any corruption. Is this reasonable? Even if it is, the redundancy is really high since m should be at least the traceback length. Since the constraint length is 7 and coding rate is 1/2, the redundancy is 5*7*2*2 symbols per a frame of 250 decoded bits (per second). So I am after a more proper way.
Any suggestions and comments would be much appreciated.