possible bug/feature in Convolutional Coding about komm

[dchutchings]

apologies - I should have read the documentation for komm.ConvolutionalStreamDecoder more carefully. So I am only noting here a difference in functionality with the Matlab Communications Toolbox implementation of Convolutional Coding and giving example code.

"... The output stream has a delay equal to kτ, where k is the number of input bits of the convolutional code..."

[rwnobrega]

Thanks a lot for your feedback!

But in fact this exact same functionality is implemented by MATLAB when 'TerminationMethod' is set to 'Continous'. See:

>> % MATLAB R2015a
>> convolutional_decoder = comm.ViterbiDecoder( ...
   'TrellisStructure', poly2trellis(3, [7 5]), ...
   'TracebackDepth', 10, ...
   'TerminationMethod', 'Continuous', ...
   'InputFormat', 'Hard');
>> convolutional_decoder.step([1 1 1 0 0 0 0 1 1 0 0 1 0 0 0 1 0 1 1 1]')'
ans =
     0     0     0     0     0     0     0     0     0     0
>> convolutional_decoder.step(zeros(2*10, 1))'
ans =
     1     0     1     1     1     0     1     1     0     0

This matches exactly the example in komm.ConvolutionalStreamDecoder documentation.

Alternatively, you may also want to take a look at komm.TerminatedConvolutionalCode, and use .encode and .decode methods.

[dchutchings]

Cheers Roberto,
my mistake. I'd missed the 'trunc' that was in my previous Matlab code using vitdec. You're absolutely right and I should have used the terminated form for equivalence in komm.

I'd like again to express my appreciation to you for developing this package, which I'm now planning on switching to in my Digital Communications course.

[rwnobrega]

I'm glad to hear that. Reports, patches and suggestions are always welcome. I'm closing this issue.