Technique for organizing and coding serial binary data from a plurality of data lines for transmission over a single transmission line

Claim 2

A digital-data transmission apparatus for receiving at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate and for generating in response thereto a transmitter output signal for transmission over an output line, the apparatus comprising: a transmitter input circuit, connected to receive the system input signal, for generating a transmitter-input-circuit signal representing a sequence of transmitter-input-circuit bits determined by the sequence of data bits that the system input signal represents; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the transmitter-input-circuit bits, the transmitter output circuit comprising: transmitter frame-assembly means for organizing the transmitter-input-circuit bits into intermediate data words, each of which comprises a predetermined number of the transmitter-input-circuit bits; a transmitter complement unit for complementing alternate intermediate data words and generating a transmitter-complemented and uncomplemented intermediate data words; a coding unit responsive to the transmitter-complement-unit output for producing a coding-unit output signal representing transmitter code words that result from encoding the transmitter-complement-unit output in accordance with a code in which the imbalances of the majority of the unbalanced code words are opposite those of the code words that represent the complements of the data words that those unbalanced code words represent; and a transmitter for transmitting as the transmitter output signal a signal representing the transmitter code words that the coding unit produces.

Claim 3

A digital-data transmission apparatus as defined in claim 1 wherein each code word comprises 2M+1 bits, where M is an integer, and no more than M+1 bits of any code word have the same value.

Claim 4

A digital-data transmission apparatus as defined in claim 2 wherein M=2.

Claim 5

A digital-data transmission apparatus as defined in claim 3 wherein the code word for each intermediate data word is as follows: ______________________________________ Code Word Data Word ______________________________________ 01010 0000 10001 0001 10010 0010 11000 0011 01100 0100 10101 0101 ______________________________________

Claim 6

A digital-data transmission apparatus as defined in claim 4 wherein the transmitter comprises means for transmitting as the transmitter output signal an optical signal representing the transmitter code words that the coding unit produces.

Claim 7

A digital-data transmission apparatus as defined in claim 1 wherein the transmitter comprises means for transmitting as the transmitter output signal an optical signal representing the transmitter code words that the coding unit produces.

Claim 8

A digital-data transmission apparatus as defined in claim 6 wherein the transmitter input circuit: includes a sampling circuit for taking samples of the system input sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; includes a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and includes means for generating as the transmitter-input-circuit signal a signal whose contents are determined by the transmitter-filter output.

Claim 9

A digital-data transmission apparatus as defined in claim 1 wherein the transmitter input circuit: includes a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; includes a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and includes means for generating as the transmitter-input-circuit signal a signal whose contents are determined by the transmitter-filter output.

Claim 10

A digital-data transmission apparatus for receiving at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate and for generating in response thereto an optical transmitter output signal for transmission over a fiber-optic cable comprising: a transmitter input circuit, connected to receive the system input signal and including: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating a transmitter-input-circuit signal whose contents are determined by the transmitter-filter output; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the transmitter-input-circuit bits, the transmitter output circuit comprising: transmitter frame-assembly means for organizing the transmitter-input-circuit bits into intermediate data words, each of which comprises a predetermined number of the transmitter-input-circuit bits; a transmitter complement unit for complementing alternate intermediate data words and generating a transmitter-complement-unit output comprising the alternate complemented and uncomplemented intermediate data words; a coding unit responsive to the transmitter-complement-unit output for producing a coding-unit output signal representing transmitter code words that result from encoding the transmitter-complement-unit output in accordance with the following code: ______________________________________ Code Word Data Word ______________________________________ 01010 0000 10001 0001 10010 0010 11000 0011 01100 0100 10101 0101 00110 0110 01001 0111 01101 1000 10011 1001 ______________________________________ a transmitter adapted for coupling to a fiber-optic cable for transmitting over the fiber-optic cable, as the transmitter-output signal, an optical signal representing the transmitter code words that the coding unit produces.

Claim 11

A digital-data transmission apparatus for receiving at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate and for generating in response thereto an optical transmitter output signal for transmission over a fiber-optic cable comprising: a transmitter input circuit, connected to receive the system input signal and including: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating a transmitter-input-circuit signal whose contents are determined by the transmitter-filter output; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the transmitter-input-circuit bits, the transmitter output circuit comprising: transmitter frame-assembly means for organizing the transmitter-input-circuit bits into intermediate data words, each of which comprises a predetermined number of the transmitter-input-circuit bits; a transmitter complement unit for complementing alternate intermediate data words and generating a transmitter-complement-unit output comprising the alternate complemented and uncomplemented intermediate data words; a coding unit responsive to the transmitter-complement-unit output for producing a coding-unit output signal representing transmitter code words that result from encoding the transmitter-complement-unit output in accordance with the following code: ______________________________________ Code Word Data Word ______________________________________ 01010 0000 10001 0001 10010 0010 11000 0011 01100 0100 10101 0101 00110 0110 01001 0111 01101 1000 10011 1001 ______________________________________ a transmitter adapted for coupling to a fiber-optic cable for transmitting over the fiber-optic cable, as the transmitter-output signal, an optical signal representing the transmitter code words that the coding unit produces.

Claim 12

A digital-data transmission apparatus for receiving at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate and for generating in response thereto a transmitter output signal for transmission over an output line, the apparatus comprising: a transmitter input circuit connected to receive the system input signal and including: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating a transmitter-input-circuit signal whose contents are determined by the transmitter-filter output; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the contents of the transmitter-input-circuit signal.

Claim 13

A digital-data transmission apparatus for receiving at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate and for generating in response thereto a transmitter output signal for transmission over an output line, the apparatus comprising: a transmitter input circuit connected to receive the system input signal and including: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating a transmitter-input-circuit signal whose contents are determined by the transmitter-filter output; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the contents of the transmitter-input-circuit signal.

Claim 14

A digital-data transmission apparatus as defined in claim 10 wherein the transmitter comprises means for transmitting as the transmitter output signal an optical signal representing the transmitter code words that the coding unit produces.

Claim 15

A digital-data reception apparatus for receiving a receiver input signal representing a sequence of receiver-input-signal bits and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoding-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which the imbalances of the majority of the unbalanced code words are opposite those of the code words that represent the complements of the data words that those unbalanced codes represent; a receiver complement unit responsive to the decoding-unit output signal for complementing alternate receiver data words so as to generate a complement-unit output comprising a complement-unit output word associated with each receiver data word, every other complement-unit output word being the complement of its associated receiver data word, the remaining complement unit output words being identical to their associated receiver data words; and means for generating a receiver-input-circuit signal that represents contents determined by the complement-unit output; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the system output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 16

A digital-data reception apparatus for receiving a receiver input signal representing a sequence of receiver-input-signal bits and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoding-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which the imbalances of the majority of the unbalanced code words are opposite those of the code words that represent the complements of the data words that those unbalanced codes represent; a receiver complement unit responsive to the decoding-unit output signal for complementing alternate receiver data words so as to generate a complement-unit output comprising a complement-unit output word associated with each receiver data word, every other complement-unit output word being the complement of its associated receiver data word, the remaining complement unit output words being identical to their associated receiver data words; and means for generating a receiver-input-circuit signal that represents contents determined by the complement-unit output; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the system output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 17

A digital-data reception apparatus as defined in claim 12 wherein each code word comprises 2M+1 bits, where M is an integer, and no more than M+1 bits of any code word have the same value.

Claim 18

A digital-data reception apparatus as defined in claim 13 wherein M=2.

Claim 19

A digital-data reception apparatus as defined in claim 14 wherein the code word for each receiver data word is as follows: ______________________________________ Code Word Data Word ______________________________________ 01010 0000 10001 0001 10010 0010 11000 0011 01100 0100 10101 0101 00110 0110 01001 0111 01101 1000 10011 1001 01011 1010 11001 1011 00111 1100 10110 1101 01110 1110 ______________________________________

Claim 20

A digital-data reception apparatus as defined in claim 12 wherein the digital-data reception apparatus is an apparatus for receiving an optical signal as the receiver input signal.

Claim 21

A digital-data reception apparatus as defined in claim 16 wherein the receiver output circuit comprises: a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit; and means for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 22

A digital-data reception apparatus as defined in claim 17 wherein: the code is one in which not all sequences of bits of the predetermined number are valid code words; the decoding unit includes means for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and the receiver input circuit includes means responsive to the complement-unit output and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 23

A digital-data reception apparatus as defined in claim 12 wherein the receiver output circuit comprise: a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit; and means for generating as the system output signal a signal representing contents determined by the

Claim 24

A digital-data reception apparatus as defined in claim 19 wherein: the code is one in which not all sequences of bits of the predetermined number are valid code words; the decoding unit includes means for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and the receiver input circuit include means responsive to the complement-unit output and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 25

A digital-data reception apparatus as defined in claim 12 wherein: the code is one in which not all sequences of bits of the predetermined number are valid code words; the decoding unit includes means for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and the receiver input circuit includes means responsive to the complement-unit output and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and, for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 26

A digital-data reception apparatus for receiving an optical receiver input signal representing a sequence of receiver-input-signal bits and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoding-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with the code employed by the coding unit and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; a receiver complement unit responsive to the decoding-unit output signal for complementing alternate receiver data words so as to generate a complement-unit output comprising a complement-unit output word associated with each receiver data word, every other complement-unit output word being the complement of its associated data word, the remaining complement-unit output words being identical to their associated data words; and means responsive to the complement-unit output and the validity signal to generate a receiver-input-circuit signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word; and a receiver output circuit, connected to receive the receiver-input-circuit signal and comprising a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit, for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 27

A digital-data reception apparatus for receiving an optical receiver input signal representing a sequence of receiver-input-signal bits and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoding-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with the code employed by the coding unit and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; a receiver complement unit responsive to the decoding-unit output signal for complementing alternate receiver data words so as to generate a complement-unit output comprising a complement-unit output word associated with each receiver data word, every other complement-unit output word being the complement of its associated data word, the remaining complement-unit output words being identical to their associated data words; and means responsive to the complement-unit output and the validity signal to generate a receiver-input-circuit signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word; and a receiver output circuit, connected to receive the receiver-input-circuit signal and comprising a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit, for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 28

A digital-data reception apparatus for receiving a receiver input signal and generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit, adapted to receive the receiver input signal, for generating a receiver-input-circuit signal that represents a sequence of receiver-input-circuit data bits determined by the contents of the receiver input signal; and a receiver output circuit, connected to receiver the receiver-input-circuit signal and comprising a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediate succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit, for generating as the output signal a bit that immediately precedes as the output signal a signal representing contents determined by the receiver-filter output.

Claim 29

A digital-data reception apparatus for receiving a receiver input signal and generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit, adapted to receive the receiver input signal, for generating a receiver-input-circuit signal that represents a sequence of receiver-input-circuit data bits determined by the contents of the receiver input signal; and a receiver output circuit, connected to receiver the receiver-input-circuit signal and comprising a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediate succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit, for generating as the output signal a bit that immediately precedes as the output signal a signal representing contents determined by the receiver-filter output.

Claim 30

A digital-data reception apparatus as defined in claim 23 wherein the receiver input circuit comprises: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoder-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which not all sequences of bits of the predetermined number are valid code words and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and means responsive to the decoder-unit output signal and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, contents determined by the receiver data word decoded therefrom and for each receiver code word that the validity signal indicates is not a valid code word, contents determined by the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 31

A digital-data reception apparatus as defined in claim 24 wherein the digital-data reception apparatus is an apparatus for receiving an optical signal as the receiver input signal.

Claim 32

A digital-data reception apparatus as defined in claim 23 wherein the digital-data reception apparatus is an apparatus for receiving an optical signal as the receiver input signal.

Claim 33

A digital-data reception apparatus for receiving a receiver input signal representing a sequence of receiver-input-signal bits and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoder-unit output signal representing receiver data words that result for decoding the receiver code words in accordance with a code in which not all sequences of bits of the predetermined number are valid code words and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and means responsive to the decoder-unit output signal and the validity signal to generate a receiver-input-circuit signal that includes: for each receiver code word that the validity signal indicates is a valid code word, contents determined by the receiver data word decoded therefrom and for each receiver code word that the validity signal indicates is not a valid code word, contents determined by the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the system output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 34

A digital-data reception apparatus for receiving a receiver input signal representing a sequence of receiver-input-signal bits and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoder-unit output signal representing receiver data words that result for decoding the receiver code words in accordance with a code in which not all sequences of bits of the predetermined number are valid code words and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and means responsive to the decoder-unit output signal and the validity signal to generate a receiver-input-circuit signal that includes: for each receiver code word that the validity signal indicates is a valid code word, contents determined by the receiver data word decoded therefrom and for each receiver code word that the validity signal indicates is not a valid code word, contents determined by the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the system output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 35

A digital-data reception apparatus as defined in claim 27 wherein the digital-data reception apparatus is an apparatus for receiving an optical signal as the receiver input signal.

Claim 36

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents the system input signal, of the system comprising: a transmission medium; a digital-data transmission apparatus, coupled to the transmission medium at the first location, for receiving the system input signal, for generating in response thereto a transmitter output signal, and for transmitting the transmitter output signal over the transmission medium, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receive the system input signal, for generating a transmitter-input-circuit signal representing a sequence of transmitter-input-circuit bits determined by the sequence of data bits that the system input signal represents; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the transmitter-input-circuit bits, the transmitter output circuit comprising: transmitter frame-assembly means for organizing the transmitter-input-circuit bits into intermediate data words, each of which comprises a predetermined number of the transmitter-input-circuit bits; a transmitter complement unit for complementing alternate intermediate data words and generating a transmitter-complement-unit output comprising the alternate complemented and uncomplemented intermediate data words; a coding unit responsive to the transmitter-complement-unit output for producing a coding-unit output signal representing transmitter code words that result from encoding the transmitter-complement-unit output in accordance with a code in which the unbalances of the majority of the unbalanced code words are opposite those of the code words that represent the complements of the data words that those unbalanced code words represent; and a transmitter for transmitting as the transmitter output signal a signal representing the transmitter code words that the coding unit produces; and a digital-data reception apparatus coupled to the transmission medium at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the transmission medium and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoding-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which the code employed by the coding unit; a receiver complement unit, responsive to the decoding-unit output signal for complementing alternate receiver data words so as to generate a complement-unit output comprising a complement-unit output word associated with each receiver data word, every other complement-unit output word being the complement of its associated receiver data word, the remaining complement unit output words being identical to their associated receiver data words; and means for generating a receiver-input-circuit signal that represents contents determined by the complement-unit output; and and means for generating a receiver-input-circuit signal that represents contents determined by the complement-unit output; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the receiver output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 37

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents the system input signal, of the system comprising: a transmission medium; a digital-data transmission apparatus, coupled to the transmission medium at the first location, for receiving the system input signal, for generating in response thereto a transmitter output signal, and for transmitting the transmitter output signal over the transmission medium, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receive the system input signal, for generating a transmitter-input-circuit signal representing a sequence of transmitter-input-circuit bits determined by the sequence of data bits that the system input signal represents; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the transmitter-input-circuit bits, the transmitter output circuit comprising: transmitter frame-assembly means for organizing the transmitter-input-circuit bits into intermediate data words, each of which comprises a predetermined number of the transmitter-input-circuit bits; a transmitter complement unit for complementing alternate intermediate data words and generating a transmitter-complement-unit output comprising the alternate complemented and uncomplemented intermediate data words; a coding unit responsive to the transmitter-complement-unit output for producing a coding-unit output signal representing transmitter code words that result from encoding the transmitter-complement-unit output in accordance with a code in which the unbalances of the majority of the unbalanced code words are opposite those of the code words that represent the complements of the data words that those unbalanced code words represent; and a transmitter for transmitting as the transmitter output signal a signal representing the transmitter code words that the coding unit produces; and a digital-data reception apparatus coupled to the transmission medium at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the transmission medium and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoding-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which the code employed by the coding unit; a receiver complement unit, responsive to the decoding-unit output signal for complementing alternate receiver data words so as to generate a complement-unit output comprising a complement-unit output word associated with each receiver data word, every other complement-unit output word being the complement of its associated receiver data word, the remaining complement unit output words being identical to their associated receiver data words; and means for generating a receiver-input-circuit signal that represents contents determined by the complement-unit output; and and means for generating a receiver-input-circuit signal that represents contents determined by the complement-unit output; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the receiver output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 38

A digital-data communication system as defined in claim 29 wherein each code word comprises 2M+1 bits, where M is an integer, and no more than M+1 bits of any code word have the same value.

Claim 39

A digital-data communication system as defined in claim 30 wherein M=2.

Claim 40

A digital-data communication system as defined in claim 31 wherein the code word for each data word is as follows: ______________________________________ Code Word Data Word ______________________________________ 01010 0000 10001 0001 10010 0010 11000 0011 01100 0100 10101 0101 00110 0110 01001 0111 01101 1000 10011 1001 01011 1010 11001 1011 00111 1100 10110 1101 01110 1110 11010 1111 ______________________________________

Claim 41

A digital-data communication system as defined in claim 29 wherein the transmission medium comprises a fiber-optic cable.

Claim 42

A digital-data communication system as defined in claim 33 wherein the transmitter input circuit includes: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating as the transmitter-input-circuit signal a signal whose contents are determined by the transmitter-filter output.

Claim 43

A digital-data communication system as defined in claim 34 wherein the receiver output circuit comprises: a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit; and means for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 44

A digital-data communication system as defined in claim 35 wherein: the code is one in which not all sequences of bits of the predetermined number are valid code words; the decoding unit includes means for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and the receiver input circuit includes means responsive to the complement-unit output and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 45

A digital-data communication system as defined in claim 34 wherein: the code is one in which not all sequences of bits of the predetermined number are valid code words; the decoding unit includes means for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and the receiver input circuit includes means responsive to the complement-unit output and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 46

A digital-data communication system as defined in claim 33 wherein the receiver output circuit comprises: a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-input-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit; and means for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 47

A digital-data communication system as defined in claim 29 wherein the transmitter input circuit includes: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating as the transmitter-input-circuit signal a signal whose contents are determined by the transmitter-filter output.

Claim 48

A digital-data communication system as defined in claim 39 wherein the receiver output circuit comprise: a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit; and means for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 49

A digital-data communication system as defined in claim 40 wherein: the code is one in which not all sequences of bits of the predetermined number are valid code words; the decoding unit includes mean for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and the receiver input circuit includes means responsive to the complement-unit output and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 50

A digital-data communication system as defined in claim 39 wherein: the code is one in which not all sequences of bits of the predetermined number are valid code words; the decoding unit includes means for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and the receiver input circuit includes means responsive to the complement-unit output and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 51

A digital-data communication system as defined in claim 32 wherein the receiver output circuit comprises: a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit; and means for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 52

A digital-data communication system as defined in claim 43 wherein: the code is one in which not all sequences of bits of the predetermined number are valid code words; the decoding unit includes means for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and the receiver input circuit includes means responsive to the complement-unit output and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and, for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 53

A digital-data communication system as defined in claim 29 wherein: the code is one in which not all sequences of bits of the predetermined number are valid code words; the decoding unit includes means for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and the receiver input circuit includes means responsive to the complement-unit output and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and, for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated as a valid code word.

Claim 54

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents of the system input signal, of the system comprising: a transmission medium; a digital-data transmission apparatus, coupled to the signal medium at the first location to receive the system input signal, for generating in response thereto a transmitter output signal and for transmitting the transmitter output signal over the signal medium, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receiver the system input signal and including: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and (3) the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating a transmitter-input-circuit signal whose contents are determined by the transmitter-filter output; and a transmitter output circuit, connected to receiver the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the contents of the transmitter-input-circuit signal; and a digital-data reception apparatus coupled to the signal medium at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the signal medium and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit, connected to receive the receiver input signal, for generating a receiver-input-circuit signal that represents a sequence of receiver-input-circuit data bits determined by the contents of the receiver input signal; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the system output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 55

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents of the system input signal, of the system comprising: a transmission medium; a digital-data transmission apparatus, coupled to the signal medium at the first location to receive the system input signal, for generating in response thereto a transmitter output signal and for transmitting the transmitter output signal over the signal medium, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receiver the system input signal and including: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and (3) the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating a transmitter-input-circuit signal whose contents are determined by the transmitter-filter output; and a transmitter output circuit, connected to receiver the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the contents of the transmitter-input-circuit signal; and a digital-data reception apparatus coupled to the signal medium at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the signal medium and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit, connected to receive the receiver input signal, for generating a receiver-input-circuit signal that represents a sequence of receiver-input-circuit data bits determined by the contents of the receiver input signal; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the system output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 56

A digital-data communication system as defined in claim 46 wherein the receiver output circuit comprises: a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit; and means for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 57

A digital-data communication system as defined in claim 47 wherein the receiver input circuit comprises: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoder-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which not all sequences of bits of the predetermined number are valid code words and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and means responsive to the decoder-unit output signal and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, contents determined by the receiver data word decoded therefrom and, for each receiver code word that the validity signal indicates is not a valid code word, contents determined by the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 58

A digital-data communication system as defined in claim 48 wherein the transmission medium comprises a fiber-optic cable.

Claim 59

A digital-data communication system as defined in claim 47 wherein the transmission medium comprises a fiber-optic cable.

Claim 60

A digital-data communication system as defined in claim 46 wherein the receiver input circuit comprises: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoder-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which not all sequences of bits of the predetermined number are valid code words and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and means responsive to the decoder-unit output signal and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, contents determined by the receiver data word decoded therefrom and, for each receiver code word that the validity signal indicates is not a valid code word, contents determined by the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 61

A digital-data communication system as defined in claim 51 wherein the transmission medium comprises a fiber-optic cable.

Claim 62

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents the system input signal, of the system comprising: a transmission medium; a digital-data transmission apparatus, coupled to the transmission medium at the first location, for receiving the system input signal, for generating in response thereto a transmitter output signal, and for transmitting the transmitter output signal over the transmission medium, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receive the system input signal, for generating a transmitter-input-circuit signal representing a sequence of transmitter-input-circuit bits determined by the sequence of data bits that the system input signal represents; and a transmitter output circuit, connected to receiver the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the contents of the transmitter-input-circuit signal; and a digital-data reception apparatus, coupled to the transmission medium at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the transmission medium and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit, connected to receive the receiver input signal, for generating a receiver-input-circuit signal that represents a sequence of receiver-input-circuit data bits determined by the contents of the receiver input signal; and a receiver output circuit, connected to receive the receiver-input-circuit signal and comprising a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit, for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 63

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents the system input signal, of the system comprising: a transmission medium; a digital-data transmission apparatus, coupled to the transmission medium at the first location, for receiving the system input signal, for generating in response thereto a transmitter output signal, and for transmitting the transmitter output signal over the transmission medium, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receive the system input signal, for generating a transmitter-input-circuit signal representing a sequence of transmitter-input-circuit bits determined by the sequence of data bits that the system input signal represents; and a transmitter output circuit, connected to receiver the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the contents of the transmitter-input-circuit signal; and a digital-data reception apparatus, coupled to the transmission medium at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the transmission medium and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit, connected to receive the receiver input signal, for generating a receiver-input-circuit signal that represents a sequence of receiver-input-circuit data bits determined by the contents of the receiver input signal; and a receiver output circuit, connected to receive the receiver-input-circuit signal and comprising a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit, for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 64

A digital-data communication system as defined in claim 53 wherein the receiver input circuit comprises: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoder-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which not all sequences of bits of the predetermined number are valid code words and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and means responsive to the decoder-unit output signal and the validity signal to generate as the receiver-input-circuit signal a signal that includes: for each receiver code word that the validity signal indicates is a valid code word, contents determined by the receiver data word decoded therefrom and for each receiver code word that the validity signal indicates is not a valid code word, contents determined by the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word.

Claim 65

A digital-data communication system as defined in claim 54 wherein the transmission medium comprises a fiber-optic cable.

Claim 66

A digital-data communication system as defined in claim 53 wherein the transmission medium comprises a fiber-optic cable.

Claim 67

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents the system input signal, of the system comprising: a transmission medium; a digital-data transmission apparatus, coupled to the transmission medium at the first location for receiving the system input signal, for generating in response thereto a transmitter output signal and for transmitting the transmitter output signal over the transmission medium, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receive the system input signal, for generating a transmitter-input-circuit signal representing a sequence of transmitter-input-circuit bits determined by the sequence of data bits that the system input signal represents; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the contents of the transmitter-input-circuit signal; and a digital-data reception apparatus, coupled to the transmission medium at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the transmission medium and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoder-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which not all sequences of bits of the predetermined number are valid code words and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and means responsive to the decoder-unit output signal and the validity signal to generate a receiver-input-circuit signal that includes: for each receiver code word that the validity signal indicates is a valid code word, contents determined by the receiver data word decoded therefrom and for each receiver code word that the validity signal indicates is not a valid code word, contents determined by the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the system output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 68

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents the system input signal, of the system comprising: a transmission medium; a digital-data transmission apparatus, coupled to the transmission medium at the first location for receiving the system input signal, for generating in response thereto a transmitter output signal and for transmitting the transmitter output signal over the transmission medium, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receive the system input signal, for generating a transmitter-input-circuit signal representing a sequence of transmitter-input-circuit bits determined by the sequence of data bits that the system input signal represents; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the contents of the transmitter-input-circuit signal; and a digital-data reception apparatus, coupled to the transmission medium at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the transmission medium and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoder-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with a code in which not all sequences of bits of the predetermined number are valid code words and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; and means responsive to the decoder-unit output signal and the validity signal to generate a receiver-input-circuit signal that includes: for each receiver code word that the validity signal indicates is a valid code word, contents determined by the receiver data word decoded therefrom and for each receiver code word that the validity signal indicates is not a valid code word, contents determined by the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word; and a receiver output circuit, connected to receive the receiver-input-circuit signal, for generating therefrom as the system output signal a signal determined by the contents of the receiver-input-circuit signal.

Claim 69

A digital-data communication system as defined in claim 57 wherein the transmission medium comprises a fiber-optic cable.

Claim 70

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents the system input signal, of the system comprising: a fiber-optic cable; a digital-data transmission apparatus, coupled to the fiber-optic cable at a first location, for receiving the system input signal, for generating in response thereto an optical transmitter output signal, and for transmitting the optical transmitter output signal over the fiber-optic cable, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receive the system input signal and including: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; and a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and (3) the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating a transmitter-input-circuit signal representing a sequence of transmitter-input circuit bits determined by the transmitter-filter output; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the transmitter-input-circuit bits, the transmitter output circuit comprising: transmitter frame-assembly means for organizing the transmitter-input-circuit bits into intermediate data words, each of which comprises a predetermined number of the transmitter-input-circuit bits; a transmitter complement unit for complementing alternate intermediate data words and generating a transmitter-complement-unit output comprising the alternate complemented and uncomplemented intermediate data words; a coding unit responsive to the transmitter-complement-unit output for producing a coding-unit output signal representing transmitter code words that result from encoding the transmitter-complement-unit output in accordance with the following code: ______________________________________ Code Word Data Word ______________________________________ 01010 0000 10001 0001 10010 0010 11000 0011 01100 0100 10101 0101 00110 0110 01001 0111 01101 1000 10011 1001 01011 1010 11001 1011 00111 1100 10110 1101 01110 1110 11010 1111; and ______________________________________ a transmitter optically coupled to the fiber-optic cable for transmitting over the fiber-optic cable, as the transmitter-output signal, an optical signal representing the transmitter code words that the coding unit produces; and a digital-data reception apparatus, coupled to the fiber-optic cable at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the fiber-optic cable and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoding-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with the code employed by the coding unit and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; a receiver complement unit responsive to the decoding-unit output signal for complementing alternate receiver data words so as to generate a complement-unit output comprising a complement-unit output word associated with each receiver data word, every other complement-unit output word being the complement of its associated data word, the remaining complement-unit output words being identical to their associated data words; and means responsive to the complement-unit output and the validity signal to generate a receiver-input-circuit signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and, for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word; and a receiver output circuit, connected to receive the receiver-input-circuit signal and comprising a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit, for generating as the system output signal a signal representing contents determined by the receiver-filter output.

Claim 71

A digital-data communication system for receiving at a first location at least one system input signal representing a sequence of data bits that occur at most at an expected maximum data rate, for transmitting the information content thereof to a second location, and for producing at the second location a system output signal representative of the contents the system input signal, of the system comprising: a fiber-optic cable; a digital-data transmission apparatus, coupled to the fiber-optic cable at a first location, for receiving the system input signal, for generating in response thereto an optical transmitter output signal, and for transmitting the optical transmitter output signal over the fiber-optic cable, the digital-data transmission apparatus comprising: a transmitter input circuit, connected to receive the system input signal and including: a sampling circuit for taking samples of the system input signal at a sampling rate that exceeds the expected maximum data rate and for generating a sample signal representing a sequence of sample bits determined by corresponding successive samples; and a transmitter filter responsive to the sample signal for generating a transmitter-filter output that comprises, for each given sample bit, an associated transmitter-filter output bit whose value is that of the majority of the given sample bit, the sample bit that immediately succeeds the given sample bit, and (3) the transmitter-filter output bit associated with the sample bit that immediately precedes the given sample bit; and means for generating a transmitter-input-circuit signal representing a sequence of transmitter-input circuit bits determined by the transmitter-filter output; and a transmitter output circuit, connected to receive the transmitter-input-circuit signal, for generating as the transmitter output signal a signal representing contents determined by the transmitter-input-circuit bits, the transmitter output circuit comprising: transmitter frame-assembly means for organizing the transmitter-input-circuit bits into intermediate data words, each of which comprises a predetermined number of the transmitter-input-circuit bits; a transmitter complement unit for complementing alternate intermediate data words and generating a transmitter-complement-unit output comprising the alternate complemented and uncomplemented intermediate data words; a coding unit responsive to the transmitter-complement-unit output for producing a coding-unit output signal representing transmitter code words that result from encoding the transmitter-complement-unit output in accordance with the following code: ______________________________________ Code Word Data Word ______________________________________ 01010 0000 10001 0001 10010 0010 11000 0011 01100 0100 10101 0101 00110 0110 01001 0111 01101 1000 10011 1001 01011 1010 11001 1011 00111 1100 10110 1101 01110 1110 11010 1111; and ______________________________________ a transmitter optically coupled to the fiber-optic cable for transmitting over the fiber-optic cable, as the transmitter-output signal, an optical signal representing the transmitter code words that the coding unit produces; and a digital-data reception apparatus, coupled to the fiber-optic cable at the second location, for receiving, as a receiver input signal representing a sequence of receiver-input-signal bits, the signal transmitted by the transmitter over the fiber-optic cable and for generating a system output signal representative of the corrected contents of the receiver input signal, the reception apparatus comprising: a receiver input circuit comprising: receiver frame-assembly means for organizing the receiver-input-signal bits into receiver code words, each of which comprises a predetermined number of the receiver-input-signal bits; a decoding unit responsive to the receiver frame-assembly means for producing a decoding-unit output signal representing receiver data words that result from decoding the receiver code words in accordance with the code employed by the coding unit and for generating, in response to each receiver code word, a validity signal that indicates whether that receiver code word is a valid code word; a receiver complement unit responsive to the decoding-unit output signal for complementing alternate receiver data words so as to generate a complement-unit output comprising a complement-unit output word associated with each receiver data word, every other complement-unit output word being the complement of its associated data word, the remaining complement-unit output words being identical to their associated data words; and means responsive to the complement-unit output and the validity signal to generate a receiver-input-circuit signal that includes: for each receiver code word that the validity signal indicates is a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from that receiver code word and, for each receiver code word that the validity signal indicates is not a valid code word, receiver-input-circuit data bits determined by the complement-unit output word associated with the receiver data word decoded from the last receiver code word that the validity signal indicated was a valid code word; and a receiver output circuit, connected to receive the receiver-input-circuit signal and comprising a receiver filter responsive to the receiver-input-circuit signal for generating a receiver-filter output that comprises, for each given receiver-input-circuit data bit, an associated receiver-filter output data bit whose value is that of the majority of the given receiver-input-circuit data bit, the receiver-input-circuit data bit that immediately succeeds the given receiver-input-circuit data bit, and the receiver-filter output data bit associated with the receiver-input-circuit data bit that immediately precedes the given receiver-input-circuit data bit, for generating as the system output signal a signal representing contents determined by the receiver-filter output.