Modulators – Amplitude modulator – Nonlinear device controlled by modulating signal
Patent
1987-05-08
1988-04-05
Grimm, Siegfried H.
Modulators
Amplitude modulator
Nonlinear device controlled by modulating signal
332 22, 332 23R, 375 39, 375 54, 375 67, H04L 2720
Patent
active
047361700
ABSTRACT:
An unbalanced quarternary phase-shift keying modulator provides relatively higher signal power for one of two signal information channels. The carrier to be modulated is split into two equal-amplitude, equal-phase portions, each of which is applied to a biphase modulator. Each of the information signals is also applied to one of the biphase modulators, for producing two equal-amplitude, phase modulated carriers, each biphase modulated by one of the information signals. The modulated carriers are applied to the ports of a quadrature hybrid coupler which is other than a 3 dB (equal-amplitude) coupler. In one embodiment, the coupler is a 7 dB coupler. The modulated carrier applied to the through port of the coupler appears with reference amplitude and phase at the output of the hybrid. The modulated carrier applied to the other or coupled port appears at the output with relatively reduced amplitude and a relative phase shift. In one embodiment, the phase shift is 90.degree.. The resulting sum signal is quarternary keyed by the information signals. Waveguide and microstrip unbalanced couplers are described.
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"Conventional and New Applications for the Quadrature IF Microwave Mixer", by Neuf et al., Microwave Journal, Jan. 1973, pp. 99-109.
Technical Note "Modulator Highly Suppresses Carrier and Harmonics", by Torok, Microwaves, Nov. 1978, p. 96.
"Symmetrical Coupler Reduces Phase Error", by Ho et al., Microwaves, Apr. 1981, pp. 82-84.
Aubert Donald E.
Wu You-Sun
Berard Jr. Clement A.
Grimm Siegfried H.
Meise William H.
RCA Corporation
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