Automatic frequency controller

Details Automatic frequency controller Automatic frequency controller

1996-03-25

1998-03-31

Mullen, Thomas

Telecommunications

Receiver or analog modulated signal frequency converter

Signal selection based on frequency

375344, H04B 118

Patent

active

057349720

ABSTRACT:
A pilot signal (a signal having known phase information and a prescribed length) is inserted at a prescribed time interval in a signal transmitted from a transmitting end to a receiving end. An arc tangent operation circuit (22) performs an operation for arc tangent of the pilot signal in a received signal to obtain a phase of the pilot signal. A phase error operation circuit (24) determines for a phase error between the known phase information previously held in a memory (23) and an output from the arc tangent operation circuit (22). A linear approximation circuit (25) takes an output from the phase difference operation circuit (24) as a linear function of time, and linear-approximates the output. A frequency error operation circuit (26) obtains for a frequency error from a slope of an output from the linear approximation circuit (25). In response to the obtained frequency error, control of an oscillation frequency of a variable frequency oscillation circuit allows rapid automatic frequency control with high accuracy.

REFERENCES:
patent: 3919651 (1975-11-01), Le Mouel
patent: 3919653 (1975-11-01), Le Mouel
patent: 5495506 (1996-02-01), Shoji
patent: 5579346 (1996-11-01), Kanzaki

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