Pulse or digital communications – Spread spectrum – Direct sequence
Patent
1986-06-09
1988-10-11
Buczinski, Stephen C.
Pulse or digital communications
Spread spectrum
Direct sequence
328155, 375 97, H04L 2540, H04L 2706
Patent
active
047776404
ABSTRACT:
A modem receiver circuit comprises one or more phase jitter canceling circuits for reducing sinusoidal components of phase jitter in a telecommunications channel. The receiver circuit automatically tracks multiple sinusoidal frequency components and jitter components varying slowly in amplitude and frequency. Each phase jitter canceling circuit is responsive to a phase angle error signal, which is scaled by an adaptive gain constant and appropriately signed. The corrected error signal is passed through a second order loop filter which contains an accumulator with a jitter frequency estimate. The output is integrated into an estimate of the phase of the sinusoidal jitter, which is converted into an estimate of the jitter angle by using a sine lookup table. The resulting estimated jitter component angle is added to the carrier loop phase angle estimate to derive a total receiver phase estimate. The circuit provides rapid acquisition of an accurate initial estimate for the jitter component. It also decouples the operation of the jitter canceling circuitry from the existing carrier phase loop circuitry to avoid harmful interactions.
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J. D. Harvey, "Carrier Phase Estimation and Phase Jitter Suppression for Data Modems," Conference: Colloquium on Phase-Locked Techniques, London, England, Mar. 26, 1980, pp. 4/1-4/7.
Hayes Jack L.
Turner Michael D.
Buczinski Stephen C.
Motorola Inc.
Wallace Linda J.
Warren Charles L.
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