defining a convolutional code c=b G of size n through a rate k/n code, where b is a binary sequence of length k and G is a variable polynomial code generating matrix G of size k by n; defining a matrix HT of size n by (n???k) which represents the syndrome-former of the convolutional code defined so that G HT=0; defining a matrix (HT)???1 of size (n???k) by n which represents the left inverse of HT