Method and apparatus for locating and tracking a QPSK carrier

Pulse or digital communications – Receivers – Automatic frequency control

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Details

375326, 375329, 4551641, H04L 2706

Patent

active

056993854

ABSTRACT:
In a receiver for receiving a carrier modulated with data, there is provided a system for locating and tracking said carrier. The carrier is located by sweeping a frequency range containing said carrier. False lockup are inherent when a wide frequency sweep demodulator attempts to lock onto a carrier, and the system recognizes such lockups by monitoring data from a Viterbi error correction circuit. On false lockup, the system breaks the lockup and continues the sweep until the true data carrier is located and tracked.

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