Phase modulation scheme and apparatus

Details Phase modulation scheme and apparatus Phase modulation scheme and apparatus

1997-04-22

1999-11-16

Chin, Stephen

Pulse or digital communications

Transmitters

Angle modulation

332103, 332144, 455 42, 327254, H04L 2720, H03C 300

Patent

active

059870729

ABSTRACT:
In phase modulation of the quadrature signals of a multi-valued digital signal, when the signal state transition is .pi. [rad], the spectrum of a nonlinear amplifier extends beyond the transmission bandwidth, and the conversion distortion becomes conspicuous. A phase modulation apparatus includes a phase shifter (11) which receives a multi-valued digital signal, converts the digital signal into two quadrature signals such that a period for which the self phase shift amount of the digital signal on an orthogonal coordinate system becomes .pi./2 [rad] at the time of state transition of the digital signal is always obtained, and outputs the quadrature signals, a bandwidth limiting filter (12) which band-limits the outputs from the phase shifter (11), and a phase modulator (13) for phase-modulating the output from the bandwidth limiting filter (12). Since the state transition is .pi./2 [rad], extension of the spectrum beyond the transmission bandwidth is suppressed in a nonlinear amplifier, and the conversion distortion is relaxed.

REFERENCES:
patent: 5091919 (1992-02-01), Kuisma
patent: 5491457 (1996-02-01), Feher
patent: 5521559 (1996-05-01), Ichihara
patent: 5548253 (1996-08-01), Durrant

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