Modulators – Phase shift keying modulator or quadrature amplitude modulator
Patent
1989-02-09
1990-03-20
Mis, David
Modulators
Phase shift keying modulator or quadrature amplitude modulator
332104, H03C 500, H03K 710
Patent
active
049104748
ABSTRACT:
An improved circuit for generating phase and amplitude modulated signals in a modem. A first circuit (161) generates a first signal (163) using a 1200 Hz carrier (160) and an input data stream (162). This signal (163) is generated at the rate of 7200 samples per second. The first signal (163) is then sampled by a sampler (164) at a 3600 Hz rate (165). The sampled signal (166) contains both a 1200 Hz signal and a 2400 Hz signal. A bandpass filter (43) selects a 1200 Hz or a 2400 Hz center frequency. The resulting output (44) is a selectable 1200 Hz or 2400 Hz signal which is generated using only the data sampling points necessary to generate the first, 1200 Hz signal (163).
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Nash Randy D.
Sweitzer Steven R.
Tjahjadi Taruna
Hayes Microcomputer Products, Inc.
Mis David
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