Abstract：Considering the blind recognition of (n,1,m) convolutional codes at high bit error rate, a novel method based on modified Walsh-Hadamard Transform (WHT) is presented. First, the original issue is equivalent to the blind recognition of several 1/2 rate convolutional codes, and a system of linear equations for generating polynomial coefficients is established. Disadvantages of the existing methods based on WHT are analyzed, after which a more robust decision threshold is deduced, with a reduction in computational complexity by limiting the range of roots, and then the code length is recognized while the correct solution vector is found. Finally, the generator polynomial matrix of (n,1,m) convolutional codes is obtained by combining the generator polynomial of the equivalent 1/2 rate convolutional codes. The simulation results verify the effectiveness of the proposed method, which has a better performance when comparing to the traditional method.
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