TRANSMISSION OF ADDITIONAL SIGNALS VIA LINE ENCODED DIGITAL TRANSMISSION SYSTEMS BY EMPLOYING RANDOM SIGNALLING OPPORTUNITIES

摘要

TRANSMISSION OF ADDITIONAL SIGNALS VIA LINEENCODED DIGITAL TRANSMISSION SYSTEMS BYEMPLOYING RANDOM SIGNALLING OPPORTUNITIESAbstract of the DisclosureAt a transmitter of a digital transmission system which usesa redundant transmission code to transmit data, at least one predeterminedcode combination which occurs randomly in the encoded data is selectivelymodified, to form a predetermined code violation, in dependence upon anadditional signal which is to be transmitted. At a receiver, thepredetermined code violation is detected and corrected to reproduce theadditional signal and the data. By selection of appropriate codecombinations and violations more than one additional signal can betransmitted. The arrangement is particularly suitable for transmission ofadditional signals, which may comprise protection switching signals or adigital voice channel signal, via fiber optic transmission links using2AMI encoding.- i -