Modulators – Phase shift keying modulator or quadrature amplitude modulator
Patent
1992-01-27
1992-12-29
Pascal, Robert J.
Modulators
Phase shift keying modulator or quadrature amplitude modulator
375 53, H03C 500
Patent
active
051755149
ABSTRACT:
A digital modulator includes a signal source for a digital baseband signal and a signal source for carrier phase information. The digital baseband signal is converted into amplitude information of an I phase, a Q phase, an I' phase and a Q' phase by a mapping circuit. The carrier phase information is converted into four phase information with phases shifted by shift registers to be out of phase by .pi./4 from each other. The digital modulator includes four ROM, each ROM outputting a multiplication result of the corresponding amplitude information and carrier signal based on the corresponding one of the four amplitude information as a higher order address and the corresponding one of the four phase information as a lower order address. These outputs are added to each other in a digital manner and then converted into an analog signal which is supplied as a modulated signal.
REFERENCES:
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patent: 4910474 (1990-03-01), Tjahjadi et al.
patent: 5077757 (1991-12-01), Cahill
Yongacoglu et al., "Differential Detection of GMSK Using Decision Feedback", IEEE Transactions on Communications, vol. 36, No. 6, Jun. 1988, pp. 641-649.
Murota et al., "GMSK Modulation for Digital Mobile Telephony", IEEE Transactions on Communications, vol. com-29, No. 7, Jul. 1981, pp. 1044-1050.
Iinuma Toshinori
Kosaka Akio
Yoshimoto Mitsufumi
Michaelson Peter L.
Pascal Robert J.
Sanyo Electric Co,. Ltd.
Tottori Sanyo Electric Co. Ltd.
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