Raytheon Company

George R Spencer

James Williamson

Bernard J Thompson

Richard A Sparks

Paul G Crete

Malcolm E Skinner

Philip L Sullivan

Edward J Daly

Walter J Hicks

Ivor K Clements

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

An arrangement for reducing the effect of vibration-induced changes in phase of the first local oscillator in a tracking receiver wherein final detection is accomplished by a synchronous detector in a phase lock loop incorporating a voltage-controlled oscillator is shown to include a differentiator providing a control signal whenever a vibration-induced change occurs, such control signal being applied to cause the time taken for the voltage-controlled oscillator to regain proper phase is reduced to a minimum.

Phase lock loop circuitry

A frequency adjusting arrangement is disclosed whereby the frequency of a local oscillator, incorporating an Yttrium-Iron-Garnet filter as the frequency determining element, is controlled to follow a coded waveform having a bandwidth wider than the bandwidth of the circuit in which such filter is used.

A narrow band receiver is shown to include a double downconversion arrangement wherein the frequency of the second local oscillator is controlled to maintain the frequency of the second I.F. signals at a predetermined value.

Radar receiver

A monopulse receiver includes a monopulse antenna and arithmetic unit for providing a monopulse sum signal, S, an azimuth difference signal, y, and an elevation difference signal, p, an imbalance correction circuit to provide a first composite signal defined as (y+jp) and a second composite signal defined as (y-jp), wherein j is an indicator of being in quadrature with the monopulse sum signal, and for interleaving the first and the second composite signal for providing a composite difference signal, D, and a combiner for providing a third composite signal defined as [S+D] and a fourth composite signal defined as [S-D]. The monopulse receiver further includes a switch matrix, for feeding the third composite signal to a first amplifier channel and for simutaneously feeding the fourth composite signal to a second amplifier channel during a first interval of time and, alternatively, for feeding the third composite signal to the second amplifier channel and for simutaneously feeding the fourth composite signal to the first amplifier channel during a second interval of time to provide an output signal from each of the first and second amplifier channels, and a second switch matrix fed by each output signal from the first and second amplifier channels, to provide successively amplified third composite signals [S+D] at a first output line and successively amplified fourth composite signals [S-D] at a second output line. With this arrangement, the effects of phase and amplitude imbalances in the monopulse antenna and arithmetic circuitry are reduced.

Radar system and method of operating such system

A method of processing in a two-channel monopulse receiver and processor is shown to include the steps of: (a) forming composite signals equal to [S+(p+jy)] and [S-(p+jy)] where S in a monopulse sum signal and p and y are, respectively, pitch and yaw error signals; (b) alternately passing the composite signals through a two-channel amplifier; and (c) separating the components in the resulting amplified composite signals for conventional monopulse processing and smoothing to eliminate the effects of any imbalance (in phase or amplitude) between the channels in the two-channel amplifier.

Monopulse tracking apparatus and method of operating same

A three channel electronically tunable filter arrangement for selecting radio frequency signals to be processed in a monopulse receiver is disclosed. Each channel of the disclosed filter arrangement includes an yttrium-iron-garnet (YIG) filter disposed in a common structure so that the resonant frequency of each channel may be controlled by the magnetic field of a single electromagnet. Also disclosed is an alignment method whereby the response of the YIG filter in each channel may be independently adjusted to eliminate any substantial imbalance between channels as the strength of the magnetic field is changed to change the resonant frequencies of such filters.

Ganged radio frequency filter

A phase comparator suitable for integrated circuit fabrication is disclosed wherein each one of a pair of differential amplifiers periodically couples an input signal to the output of the comparator through a degenerative feedback arranged high gain amplifier selectively in accordance with a periodic reference signal. During one-half period of the reference signal, the input signal is coupled to the output of the comparator with a gain of substantially +1 and during the other half period of the reference signal the input signal is coupled to the output of the comparator with a gain of substantially -1. With such an arrangement the output voltage produced at the output of the phase comparator has an average value substantially proportional to the phase angle between the reference signal and the input signal. The use of a switched pair of differential amplifiers together with a degenerative feedback arranged high gain amplifier provides for a phase comparator suitable for integrated circuit fabrication.

Growing community of inventors

Needham, MA, United States of America

George R Spencer