[Discuss-gnuradio] FEC: Convolutional Encoder Gnuradio and Matlab: different results

[Emanuel.Staudinger]

Hi together,

 

I’m using the FEC Async Encoder with the CC Encoder Definition. Input/Output are unpacked and I use the terminated behavior. In Gnuradio the polynomials for the CC Encoder Definition are defined on a base of 10, and not as octals like in MATLAB, right?

 

I tried the following: 1 bit with ‘1’ as input to the FEC Async Encoder and the same in MATLAB to check the response of the encoder. The results don’t match. No matter if I use different constraint lengths, rates or polynomials.

e.g. in Matlab: K = 7, 1/R=2, Polynomials (octal) [171,133] and Gnuradio Polynomials (10-base) [121,91] give completely different outputs.

 

No matter what I do, e.g., using octal representation in Gnuradio, or changing the polynomials’ positions in the specified vector, gives me a result which matches.

 

Did anyone compare results before? Any clues?

Regards,

Emanuel