High resolution imaging on distributed SAR using joint space-time-frequency method

Spaceborne distributed SAR is comprised of several satellites flying in constellation stereo geometry, which has advantages in imaging of ground moving targets. Especially in single-transmitter-multiple-receivers (STMR) mode, it can obtain higher resolution than single SAR. Comparing with the complex images of ground static scattering points, the deviation of Doppler center frequency of each moving target leads to differences in relative frequency shift. However, those differences cannot be accurately estimated using conventional interferometric phase technique, which would consequently degrade the performance of the image obtained via spectral synthesis technology. To solve this problem, a novel moving target imaging method via joint space-time-frequency is presented by combining space-time parameter estimation, time domain BP (Back Projection) algorithms and spectral synthesis techniques together. The presented method is testified by analyzing the estimate precision of frequency shift and the resolution of image in computer simulations.