Patent Document ID: 4090173
Application ID: 05751505

Base Claim:
1. Vital digital communication system responsive to the selection of a desired command to be sent for encoding a corresponding message, transmitting and decoding the message to derive said command in a vital manner comprising: a transmitter including encoding means responsive to the selection of a desired command for generating and outputting said message, said message comprising a pair of multi-bit words, each word separated from other words by an identical multi-bit framing sequence, a second word of said pair complementary to a first word of said pair, the ratio of ones and zeroes in either said first or second word being constant, a receiver including vital decoding means responsive to the output of said encoder for identifying said framing bits and for identifying each word of said message, said vital decoding means including, means for sequentially producing multi-bit words in response to sequential receipt of said encoded words and means for checking that said sequentially produced multi-bit words are complementary to each other, said last-named means including, a multi-bit comparator for comparing said produced multi-bit word with a multi-bit pattern, said comparator sequentially emitting different outputs if sequential ones of said produced multi-bit words are complementary, said vital decoding means providing an output indicative of said command if, and only if, said sequentially emitted outputs are provided.

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Claim 7:
7. The apparatus of claim 1 wherein said vital decoding means includes a single central processor unit responsive to said message for producing an output distinctive of said message, and wherein said multi-bit comparator compares said produced multi-bit word comprising a check word provided by said central processing unit to validate the operations thereof.