Digital communication system
AssigneesFumio Ikegami, Mitsubishi Denki Kabushiki Kaisha
InventorsFumio Ikegami, Susumu Yoshida, Tsutomu Takeuchi, Sirikiat Ariyavisitakul
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Abstract
The present invention provides a communication system which employs a signal whose carrier phase is shifted by a constant amount .DELTA..theta. per time slot in correspondence to each symbol (1 or 0) transmitted, and the phase shift is performed by .DELTA..theta./2 (or -.DELTA..theta./2) in the first 1/2 time slot and further by .DELTA..theta./2 (or -.DELTA..theta./2) in the second 1/2 time slot thereby to improve the bit error rate in multipath propagation.
Claims8
A digital communication system for transmitting binary information symbols, including a first information symbol and a second information symbol, through a transmission medium formed by a multipath channel wherein each path has a substantially different transmission time, the digital communication system being capable of improving symbols comprising:
- transmitting means for generating and transmitting through said transmission medium a phase shift keyed transmission signal which, in correspondence with the binary information symbols sent out at a predetermined time slot, shifts a phase of an information signal by .DELTA..theta./2 for each 1/2 time slot two times in succession for said first information symbol, and shifts the phase by -.DELTA..theta./2 for each 1/2 time slot two times in succession for the other information symbol;
- receiving means for receiving the transmitted signal transmitted through said transmission medium;
- and
- demodulating means for dividing a signal received by said receiving means into two signals delaying, by 1/2 time slot, one of the two signals to obtain a delayed signal, multiplying the delayed signal by the other one of said two signals to obtain a product signal and integrating said product signal to obtain the original binary information symbol.
In a digital communication system for transmitting binary information symbols, including a first information symbol and a second information symbol, through a transmission medium formed by a multipath channel wherein each path has a substantially different transmission time, a method of improving bit error rate, comprising the steps of:
- transmitting through said medium a phase shift keyed transmission signal which, in correspondence with the binary information symbols sent out at a predetermined time slot, shifts a phase of an information signal by .DELTA..theta./2 for each one-half time slot two times in succession for said first information symbol, and shifts the phase by -.DELTA..theta./2 for each one-half time slot two times in succession for the other information symbol;
- receiving the transmitted signal;
- dividing a received signal into two signals;
- and
- delaying by one-half time slot, one of said two signals to obtain a delayed signal, multiplying the delayed signal by the other one of said two signals to obtain a product signal and integrating said product signal to obtain the original binary information symbol having an improved bit error rate.
Dependencies are inferred from the claim text.