Hughes Aircraft Company

Samuel C Reynolds

Donald C Chang

Kar W Yung

Yi-Chi Shih

Frank A Hagen

Victor S Reinhardt

Stanley S Chang

Joseph G Gurley

Paul A Toth

A system (36, 98) for determining the linearity of an RF detector (46, 106). A first technique involves combining two RF signals from two stable local oscillators (38, 40) to form a modulated RF signal having a beat frequency, and applying the modulated RF signal to a detector (46) being tested. The output of the detector (46) is applied to a low frequency spectrum analyzer (48) such that a relationship between the power levels of the first and second harmonics generated by the detector (46) of the beat frequency of the modulated RF signal are measured by the spectrum analyzer (48) to determine the linearity of the detector (46). In a second technique, an RF signal from a local oscillator (100) is applied to a detector (106) being tested through a first attenuator (102) and a second attenuator (104). The output voltage of the detector (106) is measured when the first attenuator (102) is set to a particular attenuation value and the second attenuator (104) is switched between first and second attenuation values. Further, the output voltage of the detector (106) is measured when the first attenuator (102) is set to another attenuation value, and the second attenuator (104) is again switched between the first and second attenuation values. A relationship between the voltage outputs determines the linearity of the detector (106).

Detector power linearity requirements and verification techniques for

A technique for near-field tomographic imaging using a multiple-receiver correlating interferometer. A target object or scene to be imaged is located in a near-field or Fresnel region of a receiver system. The target object radiates or reflects a signal that is sensed by a plurality of antennas. The received signals are correlated using conventional correlation algorithms. An image pixel for a focal point is then computed by correcting a differential time delay between a signal emitted at the focal point and received at first and second antennas. The system is focused on the target object by correcting a phase term of the correlation algorithms. The phase term is corrected by multiplying the correlation algorithms by a phase factor. A peak correlated value is developed when the focal point is at the target object location. A series of snapshots is generated from data produced by the focussing process, as the focal point is moved through the scene. The snapshots are successively superimposed, using tomographic techniques, to form a high resolution image map. The system achieves extremely high resolutions, rivalling those of synthetic aperture radar.

Passive microwave near-field tomographic imaging system and method

A radiometer system is disclosed, the system incorporating a cylindrical parabolic reflector and a plurality of radiation sensors disposed along the focal line of the reflector in a minimum redundancy array. Digital processing circuitry is connected to the output of the sensors for digitally processing signals using a cross-correlation signal processing and fast Fourier transform circuitry to generate image signals, the system providing reduced weight and increased signal integration time. Several embodiments of the system are disclosed including analog and digital versions having a multiplicity of antenna configurations.

Radiometer system incorporating a cylindrical parabolic reflector and

The polystatic correlating radar includes a plurality of radar receivers which receive a signal reflected from an object from one or more radar signal transmitters. Signals received from the plurality of receivers are cross correlated to provide high resolution of the angular location, range, and radial velocity measurements, as well as tangential velocity measurements for close targets.

Polystatic correlating radar

A correlator apparatus that simultaneously delays two time-varying input signals using just a single transmission line, with the signals being connected to opposite ends of the line. Directional couplers spaced along the transmission line extract delayed versions of the two input signals, for correlation by a bank of correlators, to produce a correlation envelope for the two signals. The apparatus is substantially less massive than prior apparatus of this kind and can be easily constructed and aligned.

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Los Angeles, CA, United States of America

Samuel C Reynolds