MESSAGE SCRAMBLER FOR PCM COMMUNICATION SYSTEM

摘要

A message to be transmitted in binary form over a signal channel to a remote terminal is scrambled by being passed through an Exclusive-OR gate which logically combines its bits in pseudo-random fashion with bits of a quasi-aperiodic code sequence to generate a scrambled binary message; a similar Exclusive-OR gate at the receiving terminal logically combines the bits of that scrambled message with corresponding bits from a like quasi-periodic code sequence to reproduce the original message. The circuits delivering the two code sequences are concurrently reset, at irregular intervals, by a predetermined succession of code combinations transmitted over the channel.