Digital modulation method and digital communication system

Details Digital modulation method and digital communication system Digital modulation method and digital communication system

1998-02-06

2000-12-12

Pham, Chi H.

Pulse or digital communications

Systems using alternating or pulsating current

Angle modulation

375259, 332103, 329304, H04L 2700

Patent

active

061608556

ABSTRACT:
A digital communication method and system wherein in response to input 3-bit data, a phase and amplitude of a carrier signal are controlled so that a symbol at a given time is located at one of allowed signal points depending on the content of the symbol. The allowed signal points include six signal points where a phase shift equal to .+-..pi./4, .+-.2.pi./4, or .+-.3.pi./4 occurs relative to the signal point at which the immediately previous symbol was located and where the amplitude is equal to a first level, and also include two signal points where a phase shift equal to .+-.2.pi./4 occurs relative to the signal point at which the immediately previous symbol was located and where the amplitude is equal to a second level lower than the first level. The digital communication method and system allows for a transmitter which does require a high-performance power amplifier, and a simplified receiver circuit. In addition, high-speed transmission can be achieved without expanding the bandwidth and high-reliability transmission is possible even in an environment having bad radio wave propagation as is the case in mobile communication.

REFERENCES:
patent: 5402272 (1995-03-01), Nakatsu et al.
patent: 5663691 (1997-09-01), Kowalik et al.
patent: 5705958 (1998-01-01), Janer
patent: 5740204 (1998-04-01), Nagashima
patent: 5841815 (1998-11-01), Takizawa

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