DIGITAL COMMUNICATION SYSTEM INCLUDING AN ERROR CORRECTING ENCODER/DECODER AND A SCRAMBLER/DESCRAMBLER

摘要

An error correction code data communication system of the present invention has a transmitter and a receiver. The transmitter includes an encoder for adding a correction code to a data signal to be transmitted and a scrambler for randomizing the data signal. The receiver includes a descrambler for descrambling the data signal randomized by the scrambler, and a decoder for correcting a code error by means of the error correction code. The transmitter in accordance with the present invention comprises a random signal generator for generating a random signal in a repetitive pattern having a predetermined period. The scrambler includes circuitry which modulo 2 adds an output of the random signal generator to both a data signal inputted to the encoder and a data signal outputted from the encoder. The receiver comprises a random signal generator for generating a random signal in the same pattern as the signal generated by the first-mentioned random signal generator. The descrambler includes circuitry which modulo 2 adds an output of the second-mentioned random signal generator to both a data signal inputted to the decoder and a data signal outputted from the decoder. The receiver further comprises monitoring circuitry for monitoring a code error in the decoder, and circuitry for setting up synchronization of the second-mentioned random signal generator in response to an output of the monitoring circuitry in such a manner as to reduce the code error. The invention dispenses with the need for a special synchronizing bit and permits descrambling without enhancing data errors developed in the transmission path.