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VCP2 for tail biting decoding.

Niraj Ghanekar
Prodigy 85 points

Hi,

I am using 6670 VCP2 for tail biting decoding. Few of the test cases are failing. I am using one pass method in which I am applying prefix and postfix to my input data. However in VCP2 document for 6670 it is said that branch metrics that need to be provided for VCP2, should be of length (F+C). So my question is from where I can get extra branch metrics for length C?

Shall I repeat the same branch metric again i.e. of frame length F.

 

Thanks & Regards,

Niraj

  • 0
    Guru 13202 points

    Hello,

    Repeating metrics is generally good idea. The only point is how much data to repeat. Repeating whole frame will do the job, but at expense of work load. You don't need that much. Limited amount of data, called training sequence is required. Actual length depends on code constraint length. I attach a file I was provided some time ago. It's just six page long and easier to pick up the idea, than from my ugly words. Hope that helps.

    tailed bit Encoder.pdf