Re: [Discuss-gnuradio] Convolutional Code output does not match polynomial

On Tue, Sep 1, 2015 at 2:55 PM, bob wole <bnwole@gmail.com> wrote:

I am trying channel coding in gnuradio. I am using convolutional encoder with K=7 and R=1/2 with polynomials [109, 79] (default). However I am not getting the expected result. I input a known bit sequence, single frame using head block, and observe the output of the encoder using file sink. The output I think is not correct according to the given polynomials. Input bit stream is

http://pastebin.com/thsYtLFG

I am getting this output

http://pastebin.com/P42QNjiE

However, I am expecting (in hex)

00    00    E3    32    63    D7    4B    FA    D3 ......

 I have attached the flowgraph I am using for this purpose. I did a dry run by drawing a diagram of the encoder and inputing  initial two bytes. Diagram of the encoder is also attached. I also used MATLAB script to test and found that my dry run output matches with MATLAB but not with Gnuradio output. I also played with the endianness but could not get the desired result. Maybe I am doing something wrong in configuring the encoder?

Also another thing I noticed is that in QA codes of gr-fec I found

import fec_swig as fec
import blocks_swig as blocks

I think this should be

from gnuradio import fec, blocks

Am I right? I am using gnuradio 3.7.8.

--

Bob

I am still waiting to get a reply on this. Anyone else verified the output of the convolutional encoder?


--

Bob