Generalized Range Doppler Reconstruction Algorithm for Multistatic Along-track SAR Constellations

Abstract:
Multi-channel SAR signal reconstruction algorithms are sensitive to geometrical errors arising from relevant separations between channels, and their performance naturally decreases with increasing resolutions and swath widths. This paper proposes a two-step signal reconstruction method for spaceborne large along-track baseline multistatic SAR constellations operated with a pulse repetition frequency (PRF) under the Nyquist rate. The suggested algorithm first applies a bulk polychromatic reconstruction in wavenumber domain and then compensates the residual range variance in range-Doppler domain. This simple modification helps to reduce overall phase errors in the reconstruction process of the analysed case with respect to algorithms in the literature by easily one order of magnitude. The performance of the algorithm is verified by showing the results in point target simulations for a multistatic X-band constellation with a resolution of about 15 times the carrier wavelength.