Precoded and polarity‐controlled 3B‐2T code transmission systems
Kenji Ohue, Noriaki Yoshikai, Haruo Yamaguchi · Electronics and Communications in Japan (Part I Communications) · 1982
Abstract In realizing block polarity controlled 3B‐2T code transmission systems, suppression of burst error occurrence due to block polarity control for BSI is the most important problem. This system is more efficient then the conventional AMI code transmission and 4B‐3T code transmission systems. This paper describes a new polarity‐control method, PPC, which makes it possible to eliminate burst errors, and the 3B‐2T code transmission system construction using this method. The proposed polarity‐control burst error elimination is realized by precoding and decoding for polarity indicating signal sequence, and inserting dummy bit at the head of polarity‐control block. The characteristics of twenty‐four 3B‐2T code conversion rules and the four optimum 3B‐2T code conversion rules with average error extension rate 1.6 and average parity detection rate 1.0 are shown. Moreover, word synchronization at demodulation is achieved by detecting the ternary illegal word and its average synchronization detection digit length is shown to be 16. The optimum polarity control block length for an 800 Mbit/s coaxial PCM transmission system is determined to be 32 digits, considering SN degradation caused by waveform distortion due to low‐frequency‐cutoff, timing information disappearance and scapegoat bit insertion which are introduced to satisfy BSI condition.