Abstract: A method for reducing adaptive beam forming computation resources for estimating and updating a model of unwrapped beam weights. The optimal beam pattern weights of an antenna array are estimated using an adaptive beamforming algorithm. An initial model is created for either magnitude or phase components of the optimal beam pattern weights computed from the adaptive beamforming algorithm estimates. For each time step, a measurement of optimal beam pattern weights is estimated, using a reduced set of data comprising 5-20% of first samples of signal reference data. New beam pattern weights are computed using a magnitude Kalman filter (KF) and/or phase KF, wherein the computation resources required to obtain the new beam pattern weights are reduced by 80 to 90% over an adaptive beam forming algorithm.

Abstract: A method for correcting a synthetic aperture radar (SAR) antenna beam image comprising: collecting SAR data, forming an uncorrected image, isolating a pixel value from the uncorrected image, performing an inverse image formation on the isolated pixel value to convert the isolated pixel value into a phase history, calculating actual isolated pixel value location in the uncorrected image, computing range loss, antenna beam, and phase corrections for the isolated pixel value, interpolating range loss corrections, antenna beam pattern corrections, and phase corrections in the phase history, applying the interpolated corrections to the isolated pixel value phase history thereby forming a corrected phase history, converting the corrected phase history back into a corrected image, replacing the corresponding uncorrected pixel value in the uncorrected image with the corrected isolated pixel value, and repeating this process for all uncorrected pixel values thereby providing a corrected SAR image.

Abstract: Various technologies for mitigating distortion in coherent image products generated from SAR data are described herein. Synthetic aperture radar (SAR) datasets generated based upon SAR returns from first and second passes of a SAR platform over a scene are received. The SAR datasets can be co-notched at matching sample indices to improve coherence of SAR images generated from the datasets. Windowed SAR data is generated by applying independent windows to subsets of each of the datasets to reduce sidelobe levels of their image impulse responses. Coherent image products are generated based upon the windowed SAR data, wherein an image quality of the coherent image products is improved as compared to coherent image products generated based upon the SAR datasets.

Abstract: Various technologies for mitigating interference artifacts in multi-pass synthetic aperture radar (SAR) imagery are described herein. First and second phase histories corresponding to first and second SAR passes over a scene are processed in image and phase-history domains to correct for spatially-variant and constant phase offsets between the phase histories that can be caused by known and unknown variations in motion of a SAR platform between passes. Data samples from one phase history can then be replaced with data samples from the other phase history to remove artifacts and distortions caused by sources of interference in the scene.

Abstract: Various technologies for mitigating interference in stretch-processed SAR imagery are described herein. Stretch-processed SAR data is received at a computing device. The stretch-processed (or deramped) SAR data is then reramped, thereby removing frequency-variant components of narrowband interference signals in the deramped data. A frequency-domain transform is executed over the reramped data to generate a spectral characteristic of the reramped data. A spectral notch filter is applied to frequency bands corresponding to the peaks of the spectral characteristic in order to filter out the narrowband interference signals. An inverse frequency-domain transform can then be executed over the filtered spectral characteristic to return to a phase-history representation of the SAR data. The phase history resulting from the inverse frequency-domain transform is a ramped phase history, which can then be deramped prior to use in connection with generating images of the scanned scene.

Abstract: The various technologies presented herein relate to reducing and/or filtering undesired artifacts in a SAR image, wherein the artifacts are generated by RF interference resulting from a communication signal being included in a radar return which also comprises radar clutter. The radar return is separated into two subapertures, a first subaperture comprising radar clutter only, and a second subaperture comprising radar clutter and the communication signal. The communication signal is extracted from the second subaperture and reapplied to the initially received radar return. Reapplication of the communication signal to the radar return enables any undesired artifacts arising from the communication signal to have their return strength reduced or minimized, while maintaining any desired radar returns in the SAR image.