Modulators – Phase shift keying modulator or quadrature amplitude modulator
Patent
1995-07-18
1996-07-09
Mis, David
Modulators
Phase shift keying modulator or quadrature amplitude modulator
332144, 332149, 375298, 375308, H03C 100, H03C 300, H04L 2720
Patent
active
055348289
ABSTRACT:
A digitized quadrature modulator receives an I-channel input digital signal and Q-channel input digital signal, and quadrature modulater the I-channel and Q-channel input digital signals by digital signal processing. The modulator has a digital filter (504) for shaping the spectrum of the I-channel and Q-channel input digital signals to provide I-channel and Q-channel output signals. The output signals have a predetermined phase shift between the I-channel and the Q-channel so as to compensate a phase difference based upon the quadrature modulation by the digital signal processing. Complementers (505a, 505b) for taking the complement of the I-channel and Q-channel output signals to provide I-channel and Q-channel complement signals. A multiplexer (505c) multiplexer the I-channel and Q-channel output signals from the digital filter and the I-channel and Q-channel complement signals from the complementers to provide a quadrature modulated output signal.
REFERENCES:
patent: 4644565 (1987-02-01), Seo et al.
patent: 5459749 (1995-10-01), Park
"A VLSI Architecture for a High-Speed All-Digital Quadrature Modulator and Demodulator for Digital Radio Applications", Samueli et al, IEEE Journal on Selected Areas in Communications, vol. 8, No. 8, Oct. 1990, pp. 1512-1519.
"QPSK Modulator with Digital Signal Wave from Synthesis", Kikuchi et al, Proceedings of Japanese Electron. Commun. Conference, 2297, 1986, pp., 10-30.
"A Multipurpose Modulator ASIC for Digital Communication", Okada et al., Proceedings of Japanese Electron. Inf. Commun. Conference, B-401, 1994; p. 401.
Okada Takashi
Shirato Tadashi
Mis David
Nippon Telegraph and Telephone Corporation
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