Demodulators – Amplitude modulation demodulator – Having specific distortion – noise or other interference...
Patent
1984-06-22
1986-03-04
LaRoche, Eugene R.
Demodulators
Amplitude modulation demodulator
Having specific distortion, noise or other interference...
329109, 329124, 375 39, 375120, 455214, H03D 318, H03K 902, H04L 512, H04L 2502
Patent
active
045742448
ABSTRACT:
A quadrature amplitude modulation (QAM) demodulator system has in-phase and quadrature channel detectors receiving local oscillator signals which must be in precise phase quadrature relationship with each other. The in-phase and quadrature channels each have analog-to-digital converters with n output bits, where n is greater than m, the number of bits required for the data output for each channel. The n-m less significant bits in one channel are used to derive a signal indicating the deviation from a true quadrature relationship between the local oscillator signals. The error signal controls an adjustment of the phase of one of the local oscillator signals, to bring about the precise quadrature relationship required for accurate demodulation.
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patent: 4458356 (1984-07-01), Toy
patent: 4464770 (1984-08-01), Maurer et al.
Hamann H. Fredrick
LaRoche Eugene R.
Mis D. C.
Rockwell International Corporation
Sewell V. Lawrence
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