Digital communication system
First Claim
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1. A digital communication system for transmitting to a receiving side digital signals comprising first and second predetermined information symbols digitized in a predetermined time slot generated from a signal source, comprising:
- two signal transmission paths each having substantially different transmission time intervals between said signal source and an output of said receiving side,delay means inserted into at least one of said signal transmission paths for setting the delay time of information signals being transmitted via said two signal transmission paths at a predetermined fraction of said time slot,modulation means responsive to said digital signals for generating said information symbols by shifting carrier wave signal phases continuously twice by Δ
θ
/2 per 1/2 time slot with respect to first information symbols and continuously twice by -Δ
θ
/2 per 1/2 time slot with respect to second information symbols, anddemodulation means for combining said information signals received via said two signal transmission paths and for demodulating the original digital signal by delay detection,whereby a bit error rate of said system is brought near a minimum relative to said predetermined time slot.
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Abstract
The present invention provides two branches of a base station transmitter and a base station receiver, respectively, and inserts a delay circuit for ensuring a delay time difference between D and U waves required to obtain the best bit error rate for a DSK system, BPSK-RZ system, QPSK-RZ system or the like, into each system of the transmitter and the receiver, respectively, or into either the transmitter or the receiver of each system, thereby efficiently improving the bit error rate.
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Citations
15 Claims
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1. A digital communication system for transmitting to a receiving side digital signals comprising first and second predetermined information symbols digitized in a predetermined time slot generated from a signal source, comprising:
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two signal transmission paths each having substantially different transmission time intervals between said signal source and an output of said receiving side, delay means inserted into at least one of said signal transmission paths for setting the delay time of information signals being transmitted via said two signal transmission paths at a predetermined fraction of said time slot, modulation means responsive to said digital signals for generating said information symbols by shifting carrier wave signal phases continuously twice by Δ
θ
/2 per 1/2 time slot with respect to first information symbols and continuously twice by -Δ
θ
/2 per 1/2 time slot with respect to second information symbols, anddemodulation means for combining said information signals received via said two signal transmission paths and for demodulating the original digital signal by delay detection, whereby a bit error rate of said system is brought near a minimum relative to said predetermined time slot. - View Dependent Claims (2, 3, 4, 5)
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6. A digital communication system for exchanging between a base station and a mobile station digital signals comprising first and second predetermined information signals digitized in a predetermined time slot generating from a signal source, comprising:
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two signal transmission paths each having substantially different delay time intervals between said base station and said mobile station, delay means inserted into at least one of said two signal transmission paths for setting the delay time of information signals being transmitted via said two signal transmission paths at a predetermined fraction of said time slot, modulation means responsive to said digital signals for generating said information signals by shifting carrier wave signal phases continuously twice by Δ
θ
/2 per 1/2 time slot with respect to first information symbols and continuously twice by -Δ
θ
/2 per 1/2 time slot with respect to second information symbols, anddemodulation means for combining said information signals received via said two signal transmission paths and for demodulating the original digital signal be delay detection, whereby a bit error rate of said system is brought near a minimum relative to said predetermined time slot. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A digital communication system for transmitting to a receiving side digital signals comprising predetermined first and second information symbols digitized in a predetermined time slot generated form a signal source, comprising:
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two signal transmission paths each having substantially different transmission time intervals between said signal source and an output of said receiving side, delay means inserted into at least one of said signal transmission paths for setting the delay time of information signals being transmitted through said two signal transmission paths at a predetermined fraction of said time slot, modulation means responsive to said digital signals for generating information signals by shifting carrier wave signal phases twice by Δ
θ
/2 per 1/2 time slot based on a π
/2 DSK system with respect to binary information symbols, anddemodulation means for combining said information signals received via said two signal transmission paths and for demodulating the original digital signal by delay detection, whereby a bit error rate of said system is brought near a minimum relative to said predetermined time slot.
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13. A digital communication system for transmitting to a receiving side digital signals comprising first and second predetermined information symbols digitized in a predetermined time slot generated from a signal source, comprising:
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two signal transmission paths each having substantially different transmission time intervals between said signal source and an output of said receiving side, delay means inserted into at least one of said signal transmission paths for setting the delay time of information signals being transmitted via said two signal transmission paths at a predetermined fraction of said time slot, modulation means responsive to said digital signals for generating information signals by shifting carrier wave signal phases twice by π
/4 based on a π
/4 DSK system with respect to binary information symbols, anddemodulation means for combining said information signals received through said two signal transmission paths and for demodulating the original digital signal by delay detection, whereby a bit error rate of said system is brought near a minimum relative to said predetermined time slot.
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14. A digital communication system for transmitting to a receiving side digital signals comprising first and second predetermined information symbols digitized in a predetermined time slot generated from a signal source, comprising:
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two signal transmission paths each having substantially different transmission time intervals between said signal source and an output of said receiving side, delay means inserted into at least one of said signal transmission paths for setting the delay time of information signals being transmitted through said two signal transmission paths at a predetermined fraction of said time slot, modulation means responsive to said digital signals for generating BPSK-RZ signals identical in amplitude and phase to BPSK signals in a first T/2 intervals of respective time slots T and effectively 0 in amplitude n a second T/2 intervals, with respect to binary information symbols, based on a BPSK-RZ system, and ion demodulation means for combining said informat signals received through said two signal transmission paths and for demodulating the original digital signal by delay detection, whereby a bit error rate of said system is brought near a minimum relative to said predetermined time slot.
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15. A digital communication system for transmitting to a receiving side digital signals comprising first and second predetermined information symbols digitized in a predetermined time slot generated from a signal source, comprising:
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two signal transmission paths each having substantially different transmission time intervals between said signal source and an output of said receiving side, delay means inserted into at least one of said signal transmission paths for setting the delay time of information signals being transmitted via said two signal transmission paths at a predetermined fraction of said time slot, modulation means responsive to said digital signals for generating QPSK-RZ signals identical in amplitude and phase to QPSK signals in first T/2 intervals of respective time slots T and effectively 0 in amplitude in second T/2 intervals, with respect to binary information symbols, based on a QPSK-RZ system, and demodulation means for combining information signals received through said two signal transmission paths and for demodulating the original digital signal by delay detection, whereby a bit error rate of said system is brought near a minimum relative to said predetermined time slot.
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Specification