Multilevel data transmission system
AssigneeNippon Electric Co., Ltd.
InventorsShin'Ichi Koike, Hiroshi Fujimoto
Life of this patent
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Abstract
An improved multilevel code transmission system for transmission of a data signal in the form of an N-level code signal based on a partial response shaping employs a special differential coding prior to partial response shaping on the transmitter side and, on the receiver side subsequent to partial response decoding, a differential decoding corresponding to the differential coding. The system is characterized in that each pair of input, parallel binary codes is so arranged that only the most significant bit is different from each other and the remaining bits are represented by the same binary codes, and in that only the most significant bit is affected by the differential coding and decoding.
Claims11
A multilevel code transmission system for transmission of a data signal in the form of a 2N-1 level code signal based on a partial response shaping, where N is an integer greater than two, comprising:
- a transmitter including
- means for providing said data signal in the form of parallel binary codes;
- means for monitoring each pair of input parallel binary codes representing N-i and i levels, where i represents all positive integers smaller than N of said N-level code signal, wherein each pair of input parallel binary codes is so arranged that only the most significant bit is different from each other and the remaining bits are represented by the same binary codes;
- means for delivering an output parallel binary code representing i level when the level monitored by said monitoring means is N-i or i and the most significant bit last monitored by said monitoring means is a binary one, and for delivering another output parallel binary code representing N-i level when the level monitored by said monitoring means is N-i or i and the most significant bit last monitored by said monitoring means is a binary zero;
- means for converting the outputs of said delivering means to said 2N-1 level code signal based on the partial response shaping, said converting means including an adder for carrying out modulo-N addition between the outputs of said delivering means and a delayed signal, a delay circuit for delaying the output of said adder by twice the clock time period for data transmission to deliver said delayed signal, and a subtractor for subtracting said delayed signal from the output of said adder to deliver said 2N-1 level code signal;
- and
- means for amplitude modulating said 2N-1 level code signal thereby to transmit the modulated signal to a receiver;
- and a receiver including
- means for applying a coherent demodulation to said transmitted modulated signal thereby to deliver discriminated parallel binary codes;
- means for carrying out modulo-N addition between said discriminated parallel binary codes and said N, thereby to regenerate said output parallel binary codes;
- means for monitoring each pair of said regenerated input parallel binary codes;
- and
- means for regenerating one of said parallel binary codes which represents i-level when the level monitored by the last mentioned monitoring means is N-i or i and is equal to the N-i or i level last monitored by the last mentioned monitoring means, and for regenerating another of said input parallel binary codes which represents N-i level when the level monitored by the last mentioned means is N-i or i and is different from the N-i or i level last monitored by said last mentioned monitoring means, thereby to regenerate said data signal in the form of parallel binary codes.
In a multilevel code transmission system for transmission of a data signal in the form of a 2N--1 level code signal based on a partial response shaping, where N is an integer greater than two, a transmitter comprising:
- means for providing said data signal in the form of parallel binary codes;
- means for monitoring each pair of input parallel binary codes representing N-i and i levels, where i represents all positive integers smaller than N of said N-level code signal, wherein each pair of input parallel binary codes is so arranged that only the most significant bit is different from each other and the remaining bits are represented by the same binary codes;
- means for delivering an output parallel binary code representing i level when the level monitored by said monitoring means is N-i or i and the most significant bit last monitored by said monitoring means is a binary one, and for delivering another output parallel binary code representing N-i level when the level monitored by said monitoring means is N-i or i and the most significant bit last monitored by said monitoring means is a binary zero;
- means for converting a part of the input parallel binary codes and the outputs of said delivering means to said N-level code signal based on the partial response shaping, said converting means including an adder for carrying out modulo-N addition between the outputs of said delivering means and a delayed signal, a delay circuit for delaying the output of said adder by twice the clock time period for data transmission to deliver said delayed signal, and a subtractor for subtracting said delayed signal from the output of said adder to deliver said 2N-1 level code signal;
- and
- means for amplitude-modulating said N-level code signal thereby to transmit the modulated signal to a receiver.
In a multilevel code transmission system for transmission of a data signal in the form of a 2N--1 level code signal based on a partial response shaping, where N is an integer greater than two, a receiver comprising:
- means for applying a coherent demodulation to a transmitted modulated signal thereby to deliver discriminated parallel binary codes;
- means for carrying out modulo-N addition between said discriminating parallel binary codes and said N, thereby to regenerate output binary codes;
- means for monitoring each pair of said regenerated output parallel binary codes;
- and
- means for regenerating an input parallel binary code representing i-level when the level monitored by the monitoring means is N--i or i and is equal to the N--i or i level last monitored by the monitoring means, and for regenerating another input parallel binary code representing N--i level when the level monitored by the monitoring means is N--i or i and is different from the N--i or i level last monitored by said monitoring means, thereby to regenerate said data signal in the form of parallel binary codes.
Dependencies are inferred from the claim text.