Probability distribution of digital sum variation for bimode pulse transmission code

Abstract

A variety of coding types are proposed to improve the information transmission efficiency for a digital relay and transmission system. Quantitative estimation is required to clarify coding effectiveness with respect to the frequency region of timing waveform sampling characteristics and the time region of intercode interference based on low‐frequency cutoff. Formerly, various calculations were proposed to use the power spectrum for the former purpose and no consideration was given to the latter. This paper explains how to calculate the probability distribution of digital sum variations to estimate pulse transmission code performance in the time region. Since there are instances where the digital sum variations do not reach a desired state as a result of dc component suppression, the transition probability matrix cannot be determined. The transition probability matrix is then determined by introduction of a new parameter called the state vector, whereby the probability distribution can be calculated. Distribution probabilities for the 4B‐3T code digital sum variation are calculated as a practical application of calculation methods. Error rate performances considering these distributions are shown. These calculation methods may permit the estimation of pulse transmission code performance in conjunction with the power spectrum formerly used for the estimation of transmission code performance.