Four state phase shift modulator, in particular for amplitude mo

Details Four state phase shift modulator, in particular for amplitude mo Four state phase shift modulator, in particular for amplitude mo

1990-05-15

1991-03-12

Grimm, Siegfred H.

Modulators

Phase shift keying modulator or quadrature amplitude modulator

Including logic element

375 39, 375 54, 375 67, H04L 2720, H04L 2736

Patent

active

049995901

ABSTRACT:
A QPSK modulator has a signal generator which generates four carrier outputs having respective phases of 0.degree., 90.degree., 180.degree., and 270.degree.. A four input phase selector is connected to the four outputs of the generator, has four modulator signal inputs, and has four phase shifted carrier outputs connected to an OR gate which provides the QPSK output signal. The generator comprises a source of signals in opposite phase coupled to two frequency dividers, each divider having two outputs of opposite phase. It also has two pairs of flip-flops whose outputs form the four outputs of the generator. The signal inputs of one pair of flip-flops are connected to the outputs of the first divider. The signal inputs of the other pair of flip-flops are connected to the outputs of the second divider. Variable capacitors are provided between the clock inputs of the flip-flops and ground. A 2.sup.2n QAM modulator can be formed with n QPSK modulators whose outputs are connected to the inputs of n attenuators followed by an adder.

REFERENCES:
patent: 3659202 (1972-04-01), Kaneko
patent: 3816657 (1974-06-01), Fletcher et al.
patent: 4206423 (1980-06-01), Nossen
Morais et al., "NLA-QAM: A Method for Generating High-Power QAM Signals Through Nonlinear Amplification", IEEE Trans. on Communications, vol. COM-30, Mar. 1982, pp. 517-522.

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