Error detection and correction in signal transmission by use of convolution codes

Digital error correcting coding techniques involving the sensing of conditions under which the decoder is operating. In one aspect a monitoring device counts the ones in the decoding decision and in certain parity checks corrected by those decisions. In another aspect the code is supplemented such that one actual decoding error can create a number of apparent errors or ones, which enables early detection of conditions beyond the capability of the decoder. In another aspect fades are detected in combination with a decoding logic capable of acting upon the whole set or any group of nonfaded elements in the decoding set.