Method of digital signal transmission
First Claim
1. A method of transmitting a digital signal, employing, in a transmission apparatus for transmitting digital data, a transmission signal having phase transition waveforms in respective continuous time slots of data, each phase transition waveform in each of the time slots having a varying rate of change of phase or at least one phase jump, wherein phase transition waveforms in any two time slots which are spaced apart from each other on a time axis by a prescribed number of time slots are identical to each other in shape irrespective of an information to be transmitted, the information to be transmitted being present in a phase difference between the phase transition waveforms in any two time slots spaced apart from each other on a time axis by the prescribed number of time slots.
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Abstract
A modulation method capable of high-speed or high-quality digital data transmission under a multipath fading transmission line such as a radio transmission in an urban area is a type of differential coding phase modulation and residues in the fact that the rate of change of phase varies, or the phase is discrete, but does not employ a phase transition waveform of a constant value in a time slot which is a smallest unit for transmitting one symbol of data as in conventional methods. Phase transition waveforms in respective time slots which are spaced apart from each other by prescribed time slots are identical varying waveforms or discrete waveforms, and entirely shifted from each other by an amount according to the data transmitted. A detecting method employed is a differential detection method using a delay line for delaying a signal for a time corresponding to the prescribed time slots. In the presence of multipath propagation, a plurality of kinds of detected outputs are produced according to the multipath propagation, and the detected outputs are combined by a filter after the differential detection, producing a diversity effect for improving bit error rate characteristics. This digital signal transmission method is capable of multiphase transmission and can increase spectrum utilization efficiency.
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Citations
22 Claims
- 1. A method of transmitting a digital signal, employing, in a transmission apparatus for transmitting digital data, a transmission signal having phase transition waveforms in respective continuous time slots of data, each phase transition waveform in each of the time slots having a varying rate of change of phase or at least one phase jump, wherein phase transition waveforms in any two time slots which are spaced apart from each other on a time axis by a prescribed number of time slots are identical to each other in shape irrespective of an information to be transmitted, the information to be transmitted being present in a phase difference between the phase transition waveforms in any two time slots spaced apart from each other on a time axis by the prescribed number of time slots.
Specification