System, method and computer program product for reducing quadratic phase errors in synthetic aperture radar signals

A system for reducing quadratic phase errors in synthetic aperture radar signals from a plurality of range lines where each range line includes a plurality of azimuth positions, the system comprising:

• an autofocus processor for receiving a plurality of slow-time samples representing radar signals for a plurality of azimuth positions for a plurality of range lines,
• wherein the autofocus processor is adapted to identify a plurality of corrected samples and an initial quadratic phase error coefficient based upon the slow-time samples,
• wherein the autofocus processor is adapted to process the corrected samples according to a superresolution signal processing technique to thereby obtain a plurality of estimated Doppler frequencies for a plurality of point scatterers at each range line,
• wherein the autofocus processor is adapted to reconstruct a true signal for each range line based upon the plurality of estimated Doppler frequencies, and
• wherein the autofocus processor is adapted to obtain a correction to the initial quadratic phase error coefficient based upon the corrected samples, the true signals and the initial quadratic phase error coefficient.

A computer program product of reducing quadratic phase errors in synthetic aperture radar signals from a plurality of range lines where each range line includes a plurality of azimuth positions, the computer program product comprising a computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program portions comprising:

• a first executable portion for receiving a plurality of slow-time samples representing radar signals for a plurality of azimuth positions for a plurality of range lines;
• a second executable portion for identifying a plurality of corrected samples and an initial quadratic phase error coefficient based upon the slow-time samples;
• a third executable portion for processing the corrected samples according to a superresolution signal processing technique to thereby obtain a plurality of estimated Doppler frequencies for a plurality of point scatterers at each range line;
• a fourth executable portion for reconstructing a true signal for each range line based upon the plurality of estimated Doppler frequencies;
• and
• a fifth executable portion for obtaining a correction to the initial quadratic phase error coefficient based upon the corrected samples, the true signals and the initial quadratic phase error coefficient.