Suppressed carrier automatic gain control circuitry
AssigneeMotorola, Inc.
InventorsLansing M. Carson, Neil E. Welter
Life of this patent
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Abstract
An automatic gain control (hereinafter referred to as AGC) circuitry is used in conjunction with a Costas loop detector to provide positive gain control during the acquisition and tracking modes of the operation of a receiver. The circuitry includes circuitry for deriving a noise estimate signal from one channel of the Costas loop and circuitry for subtracting the noise estimate signal from the data and noise signal combination in the other channel of the Costas loop for providing the automatic gain control signal to prevent false locking.
Claims3
In a receiver of the type adapted to receive suppressed carrier signals such as a receiver with a Costas loop configuration, wherein the incoming signal is decomposed into in-phase and quadrature phase components and processed in two channels to obtain data output, and wherein an automatic gain control signal is obtained and used to provide an automatic gain control feedback signal for stabilizing the amplitude level of data output and the loop gain, the improvement which comprises means for deriving a noise estimate signal from one channel and means for subtracting the noise estimate signal from the data and noise signal combination in the other channel to derive the automatic gain control signal and prevent false locking of the receiver.
Dependencies are inferred from the claim text.