Pulse or digital communications – Receivers – Automatic frequency control
Patent
1994-07-22
1997-12-09
Chin, Wellington
Pulse or digital communications
Receivers
Automatic frequency control
375376, 375340, 375326, 329307, 4551641, 455256, H04L 2706
Patent
active
056967977
ABSTRACT:
An apparatus and accompanying method for demodulating with baseband Doppler frequency shift compensation. An RF section (20) down-converts received data communication signals (12) to baseband. A/D converters (24, 26) digitize I, Q quadrature baseband signal components. Phase (32) and frequency (50) tracking loops reside on a common digital ASIC substrate (28). A complex multiplier (30) rotates digitized baseband signals by a digitized oscillation signal, producing Doppler shift compensated signals. The phase tracking loop (32) estimates data and generates a pure phase error signal from which data modulation and Doppler shift compensation influences have been removed, which drives a frequency discriminator (52) that identifies either clockwise or counterclockwise phase rotation for each symbol (18). An integrator (54) combines identification results over a burst and a numerically controlled oscillator (56) adjusts the digitized oscillation signal frequency in a constant frequency step. This adjustment takes place once for each burst.
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"VLSI-Implemented High Speed Digital Burst Modem-Applications For Satellite Video TDMA and Wireless LAN" by Yoichi Matsumoto, Kiyoshi Kobayashi, Tetsu Sakata, Kazuhiko Seki, Shuji Kubota and Shuzo Kato for 0-7803-1825-0/94 1994 IEEE.
Bucher William Alexander
Gross Joel Lloyd
Jones Clay Garlen
Kirschenmann Mark Alan
Chin Wellington
Fliegel Frederick M.
Luther William
Motorola Inc.
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