Interferometric radar compressive sensing imaging with direct downsampling

An experiment of direct downsampling on echo signals from a moving train by a Ku-band interferometric noise radar was successfully conducted and high-resolution ISAR images were reconstructed through compressed sensing (CS). The radar transmitted stepped-frequency chaotic noise signals (SF-CNSs) covering a total bandwidth of 4.02GHz by 20 subpulses with a frequency step of 200MHz and each subpulse is of 220MHz bandwidth. Benefitted from the random characteristics of the transmitted waveforms, just simple uniform downsampling is required for applying CS to reconstruct radar images. In the Experiment, 10MHz and 1MHz sampling rates were used far less than the Nyquist rate required for recovering a signal of 220MHz bandwidth by ordinary approach. From the obtained interferometric phases (InPhes) along the train body, we also observed the micro-motion (m-M) phenomenon of the train which was reported previously.