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ACoff2's avatar
ACoff2
Icon for New Contributor rankNew Contributor
6 years ago

Viterbi IP - BER estimate error number

I am using the Viterbi decoder ip (altera_viterbi_ii) in a project.

I am encoding a count variable using a convoluational encoder. I then passing this through the Viterbi decoder block. The data out of the decoder matches my input data into the encoder, so I am confident it is working correctly.

I then turned on the BER (bit error rate) option of the decoder and rerun the test above. I am still getting the correct output from the decoder, so I know its functioning correctly however the BER error number increases by 2 each cycle.

Does anyone have any insight into what might be wrong?

4 Replies

  • CheepinC_altera's avatar
    CheepinC_altera
    Icon for Regular Contributor rankRegular Contributor
    6 years ago
    Hi, I would like to apologize for the delay in response. It seems like I encounter some issues with notification reaching my mailbox. Sorry for the inconvenience. As I understand it, you have some inquiries related to the Viterbi IP BER estimator. To ensure we are on the same page, just would like to check with you if you are observing this behavior in Modelsim simulation? If yes, would you mind to share with me a simple test design with simulation files which could replicate similar observation. I would be great if you could share with me some screenshots or illustration so that I can have a better understanding of the observation. Thank you very much. Please let me know if there is any concern. Thank you. Best regards, Chee Pin
  • CheepinC_altera's avatar
    CheepinC_altera
    Icon for Regular Contributor rankRegular Contributor
    6 years ago
    Hi, Sorry for the delay. I have run simulation with you attached file and able to observe the incremental numerr for decoder instance 1 and 2. As I understand it, how the BER estimator works is by re-encoding the decoded data and then perform comparison. If there is error at the decoder output, there is a possibility that it might lead to more error after the encoder within the Viterbi IP. This will lead to much high estimated BER at the output. To help to further narrowing down the issue, would you mind to perform a comparison of your convolution encoder's output against golden reference ie Matlab. This is to help isolating any potential issue at the encoder output prior feeding into the Decoder IP. Please let me know if there is any concern. Thank you. Best regards, Chee Pin