Roger K Ray

US Patent:

48993832, Feb 6, 1990

Filed:

Sep 8, 1987

Appl. No.:

7/094186

Inventors:

Charles W. Einolf - Murrysville PA
Harold B. Shutterly - Edgewood Boro PA
Shan C. Sun - Coral Springs FL
Russel W. Gonnam - Coral Springs FL
Roger E. Ray - Coral Springs FL
Karl C. Koch - Pittsburgh PA

Assignee:

Westinghouse Electric Corp. - Pittsburgh PA

International Classification:

H04L 708

US Classification:

380 48

Abstract:

The multiplexer in a multichannel, secure digital communication system repetitively embeds a sequence of byte length uniquely coded synchronizing signals in each of n successive frames of one channel of a multichannel, time multiplexed digital bit stream. Redundant protective relay data and associated parity check data are embedded in four of the n frames in a second, preferably adjacent channel, with the remaining of the n frames in the second channel containing additional of the uniquely coded synchronizing signals. The time multiplexed serial bit stream is transmitted to a remote station, preferably by fiber optic communications media. The most recent bits of the received serial bit stream equal in number to the number of bits spanned by the two channels in n frames are retained in n-1 serially connected serial in, serial out shift registers. Sixteen bit portions, a frame apart, of the retained most recent bits of the serial bit stream are applied to n serial in, parallel out shift registers. The parallel outputs of these shift registers corresponding to the frames of the two channels encoded with the synchronizing signals are compared with the sequence of uniquely coded signals stored in addresses in PROMs.