Importance

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Abstract

A vehicle-mounted passive synthetic aperture system for locating a source 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 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 that is proportional to the difference between the respective ranges from the first and second antennas to the source of the received radiation when the received radiation is radiated spherically from its source. The signal processor is coupled to the receiver for processing the phase difference signal in combination with the measured speed of the vehicle to determine the range and direction from the vehicle to the source of the electromagnetic radiation. 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