Modulators – Phase shift keying modulator or quadrature amplitude modulator
Patent
1992-03-20
1993-01-12
Grimm, Siegfried H.
Modulators
Phase shift keying modulator or quadrature amplitude modulator
329306, 329316, 329323, 329341, 332119, 375 67, 375 84, 455 74, 455 83, 455 86, 455 93, 455110, 455143, 455144, 455337, H04B 140, H04L 2720, H04L 2722
Patent
active
051793601
ABSTRACT:
Upon transmission, when the digital transmission mode is set, an analog audio signal is A/D converted, the digital audio signal is coded, a first carrier is modulated by the coded signal and multiplied by a first multiplier, and the multiplied signal is sent to an orthogonal modulating and D/A converting circuit. When the analog transmission mode is set, a second carrier is modulated by the digital audio signal and multiplied by a second multiplier, and the multiplied signal is sent to the orthogonal modulating and D/A converting circuit. A signal of a frequency which is equal in both of the digital transmission mode and the analog transmission mode is given to the orthogonal modulating and D/A converting circuit. Upon reception, when the digital transmission mode is set, an output of an A/D converting and orthogonal demodulating circuit is frequency divided by a first frequency divider and demodulated and decoded. When the analog transmission mode is set, the output of the A/D converting and orthogonal demodulating circuit is frequency divided by a second frequency divider and demodulated. A frequency of a reference frequency signal is set to a common multiple of a coding rate of the A/D converter, the frequency of the first carrier, and the frequency of the second carrier, so that a necessary signal of each section can be easily formed from an output of a reference frequency signal generator.
REFERENCES:
patent: 4903257 (1990-02-01), Takeda et al.
Grimm Siegfried H.
Miller Jerry A.
Sony Corporation
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