Pulse or digital communications – Receivers – Angle modulation
Patent
1994-05-05
1996-05-21
Chin, Stephen
Pulse or digital communications
Receivers
Angle modulation
375344, H04L 2722, H04L 2706
Patent
active
055197337
ABSTRACT:
A method and apparatus are provided for recovering and tracking the carrier in a QAM communication system, even under heavy interference conditions. A subset of fixed points is defined on an ideal constellation pattern for comparison to the data points in a received signal. The subset includes all of the points intersected by n radii (e.g., the four diagonals) of the constellation pattern. Additional points along the perimeter of the constellation pattern can also be provided in the subset. Data points received via a carrier are correlated with the fixed points of the subset in order to generate an error signal indicative of a phase difference between the fixed points of the subset and the received data points correlated therewith.
REFERENCES:
patent: 4587498 (1986-05-01), Bonnerot et al.
patent: 4958360 (1980-09-01), Sari
Patent Abstract of Japan, vol. 16, No. 465 (E-1270), Sep. 28, 1992, JP-A-04 165737, published Jun. 11, 1992.
A. Leclert, et al., "Universal Carrier Recovery Loop for QASK and PSK Signal Sets," IEEE Transactions on Communications, vol. COM-31, No. 1, Jan, 1983, pp. 130-136.
Sari, et al., "New Phase and Frequency Detectors for Carrier Recovery in PSK and QAM Systems, " IEEE Transactions on Communications, vol. 36, No. 9, Sep. 1988, pp. 1035-1043.
Godard, "Self-Recovering Equalization and Carrier Tracking in Two-Dimensional Data Communication Systems," IEEE Transactions on Communications, vol. COM-28, No. 11, Nov. 1980, pp. 1867-1875.
Chin Stephen
General Instrument Corporation of Delaware
Hoppin R. F.
Lipsitz B. R.
Phan Hai H.
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