An algorithm for identifying rate (n-1)/n catastrophic punctured convolutional encoders

It is known that both Viterbi and sequential decoding of convolutional codes can be greatly simplified by employing punctured convolutional codes, which are obtained by periodically deleting a part of the bits of a low-rate convolutional code. Even if the original low-rate convolutional code is noncatastrophic, some deleting maps may result in rate (n-1)/n catastrophic punctured encoders. An algorithm is presented to identify such encoders when the original rate 1/b encoder is antipodal. The major part of the algorithm solves a linear equation of /spl nu/+1 variables, where /spl nu/ is the constraint length of the original rate 1/b code.