Raytheon Company

Richard W Burrier

Jerome Howard Pozgay

James T Hanson

Steven G Labitt

Leonard R Flumerfelt

Lisa F Kuegler

Gerald L Warner

A method and apparatus for frequency modulating a continuous wave signal is shown to comprise a voltage-controlled oscillator (VCO) having a first and a second control loop to maintain the carrier frequency of such VCO at a frequency determined by a crystal-controlled oscillator and to maintain the peak deviation of the FM modulation on such carrier frequency at a value equal to the deviation of the first Bessel null from the carrier frequency.

Apparatus and method for frequency modulation

A radar system having a radar transmitter and a radar receiver. The radar receiver includes a 'local' receiving station and a 'remote' located antenna station. A feedthrough nulling system is provided. The nulling system includes a 'remote' combiner for providing an feedthrough null residual signal representative of the difference in power between a signal received by the antenna station and a feedthrough nulling signal. A 'remote' downlink modulator, disposed at the antenna station, produces an optical signal representative of the feedthrough null residual signal. A 'local' downlink optical detector, disposed at either the receiver station or the transmitter, detects the optical signal representative of the feedthrough null residual signal. A variable attenuator-phase shifter is fed by a signal from the transmitter and the detected optical signal representative of the feedthrough null residual signal and changes the gain and phase shift of the signal from the transmitter in accordance with the signal detected optical signal to produce a replica of the transmitted signal with proper gain and phase shift to null feedthrough signals received at the antenna station. An 'local' uplink laser modulator, disposed at the receiver station or the transmitter, produces an optical signal representative of the replica of the transmitted signal with proper gain and phase shift to null feedthrough signals received at the receiving antenna station such fed signal. An 'remote' uplink detector, disposed at the antenna station, detects the optical signal produced by the uplink laser modulator, and produces the feedthrough nulling signal. A 'local' noise degeneration system is also provided.

Radar system

A calibration circuit includes a plurality of signal sources each of said signal sources having an output port and providing a signal having a known phase and a signal combiner circuit having a plurality of input ports and an output port with each of said input ports being coupled to a corresponding one of said signal source output ports. The calibration circuit further includes a switch having a common port and at least one branch port, said branch port being coupled to said output port of said signal combiner circuit and an analog to digital converter circuit having an input port coupled to the common port and an output port. The calibration circuit further includes a central processing unit coupled to the output port of said analog to digital converter and a summing circuit having a first input port coupled to said central processing unit, a second input port coupled to the output port of said analog to digital converter circuit and an output port.

Analog to digital converter calibration system and method of operation

An AWTSS is shown to be made up of an improved synthetic aperture radar (SAR) for generating radar maps with various degrees of resolution required for navigation of an aircraft and detection of ground targets in the presence of electronic counter-measures and clutter. The SAR consists, in effect, of four frequency-agile radars sharing quadrants of a single array antenna mounted within a radome on a 'four axis' gimbal with a sidelobe cancelling subarray mounted at the phase center of each quadrant. Motion sensors are also mounted on the single array antenna to provide signals for compensating for vibration and stored compensating signals are used to compensate for radome-induced errors. In addition, a signal processor is shown which is selectively operable to generate radar maps of any one of a number of desired degrees of resolution, such processor being adapted to operate in the presence of clutter or jamming signals.

Growing community of inventors

Chelmsford, MA, United States of America

Richard W Burrier