Raytheon Company

Paul G Crete

James Williamson

George R Spencer

William C Brown, Jr

Philip L Sullivan

A circuit for compensating for frequency modulation on a radar signal is disclosed. The disclosed circuit includes an adaptive narrow band filter in the feedback path of a phase-locked detector, such filter having a bandwidth which is narrower than the frequency range of the signal being compensated, and means for detecting the amplitude of such signal. The invention herein described was made in the course of, or under a contract or subcontract thereunder, with the Department of Defense.

Frequency adjusting arrangement

Automatic control circuitry for maintaining the frequency of a first local oscillator in a radar receiver at a predetermined offset frequency with respect to the frequency of either transmitted signals from a radar transmitter or echo signals from a target is disclosed. The disclosed circuitry operates as a discriminator when the frequency of the first local oscillator is different from the predetermined offset frequency and as a 'phase lock' loop when the frequency of the first local oscillator is the same as the predetermined offset frequency.

Automatic frequency control circuitry

An improved automatic frequency control arrangement for a missile-borne inverse receiver is shown to include a reference oscillator and a voltage-controlled oscillator with control means for the latter, such means including a frequency-to-voltage converter responsive to the difference frequency between the two oscillators so that the latter may produce a signal representative of the Doppler shift frequency of a target. A starting circuit is also shown to ensure that the frequency of the reference oscillator is always lower than the frequency of the voltage-controlled oscillator.

Radar receiver local oscillator control circuit

Circuitry for compensating for the effects of changes in ambient temperature on an automatic gain control arrangement in a missile-borne receiver is shown to include an operational amplifier responsive only to the level of the output signal from an automatic gain detector and amplifier, such end being effected by using temperature sensitive elements in the input and feedback circuits of the operational amplifier.

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Chelmsford, MA, United States of America

Paul G Crete