Importance

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Abstract

A vehicle-mounted passive synthetic aperture system for locating sources of electromagnetic radiation having a given wavelength .lambda.. The system includes first and second receiving antennas, a phase sensitive receiver and a signal processor. The first and second antennas are mounted to a vehicle and spaced apart from each other in the principle direction of motion associated with the vehicle. The first and second antennas respectively provide first and second received signals in response to a wavefront of electromagnetic radiation having the given wavelength .lambda.. The phase sensitive receiver is coupled to the first and second antennas and responds to the first and second received signals by providing a phase difference signal that indicates a phase difference .phi. between the wavefronts of the radiation of the given wavelength received by the respective first and second antennas when the received radiation is radiated spherically from its source. The speed of the vehicle also is measured. The signal processor processes the phase difference signal in combination with the measured vehicle speed to provide imaging signals for an object-space display of an image of the source of the electromagnetic radiation in relation to the location of the vehicle. The image is displayed. The system of the present invention effectively uses the motion of the vehicle to synthesize an aperture. The synthesized aperture is long relative to the spacing between the receiving antennas (which spacing is limited by vehicle size) so that angular resolution is greater than that of a fixed antenna system with a baseline length equal to the spacing between the receiving antennas of the present system.

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First Claim