The Weight Spectra of Some Short Low-Rate Convolutional Codes

This paper reports the results of a computer analysis of the distance properties of some of the best known rate 1/2, 1/3, and 1/4 codes to constraint length 14. The data include the truncated weight distributions of the codewords belonging to the incorrect subset which specifies the performance of the Viterbi algorithm as well as the minimum asymptotic growth rate of the weights of unmerged codewords which has been conjectured to be related to the length of error events produced by Viterbi decoders.