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Enhanced radar range resolution

  • US 9,103,918 B2
  • Filed: 11/29/2012
  • Issued: 08/11/2015
  • Est. Priority Date: 11/29/2012
  • Status: Active Grant
First Claim
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1. An improved method of operating radar hardware/software apparatus mounted on a moving airplane and used to implement radar image tracking of a ground region of interest and including a transmitter to emit pulse trains torward said region, a receiver to receive return pulses from said region, and a processor to process the return pulses, the transmission and recipt being via one or more antennas and in different frequency bands, the method improvement comprising implementation of a synthetic aperture radar (SAR) imaging method, comprising:

  • receiving a plurality of return pulses acquired by said radar, wherein each radar return pulse is generated in response to a corresponding radar transmission pulse reflected from objects within said region of interest;

    operating the apparatus to process each of the radar return pulses by combining them with a sinusoid, to reduce the radar return pulses to a baseband frequency;

    operating the apparatus to deskew each radar return pulse to remove effects of its corresponding radar transmission pulse;

    operating the apparatus to determine a maximum likelihood estimate (MLE) of residual motion parameters for a dominant scatterer on the ground relative to the airborne radar, based on the deskewed radar return pulses thus defining a target item;

    operating the apparatus to correct for errors in inertial navigation system measurements based on the MLE residual motion parameters;

    operating the apparatus to convolve each radar return pulse with its corresponding radar transmission pulse to generate a range compressed image for each radar return pulse;

    operating the apparatus to generate an original sub-band range profile image for each radar return pulse and its corresponding radar transmission pulse based on the corresponding range compressed image that has been corrected for residual motion; and

    operating the apparatus to combine the sub-band range profile images to obtain a combined range profile image of the target item.

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