Unequal error protection of PCM signals by self-orthogonal convolutional codes

Abstract

In the PCM (pulse-code modulation) transmission system discussed, the influence of bit errors on the demodulated signal-to-noise ratio differs in the erroneous bit position. The demodulated signal-to-noise ratio can be improved when the PCM signals are protected so that the decoded bit error rate in more important bit position may be lower. Assigning a different number of orthogonal check sums to each information bit of self-orthogonal convolutional code provides a different error protection capability to each information bit. The author presents an unequal error protection self-orthogonal convolutional code with different error protection capability for each information bit, and discusses the condition that makes the demodulated signal-to-noise ratio of PCM signals maximum. >