Time Sidelobe Correction of Hardware Errors in Stretch Processing

To obtain high-range resolution profiles of a target, stretch processing is often used when the required instantaneous bandwidth (sampling rate) is not available. Hardware errors introduce amplitude and phase distortions to radar signals that increase the time sidelobes (TSLs) of the dechirped returns. Calibration and digital correction of the transmitter and receiver hardware errors are required to obtain acceptably low TSLs. Prior work on calibration focused on providing conceptual frameworks without experimental detail. We implemented a complete TSL calibration procedure by modifying a technique from the literature and described the experimental setup that we used to study TSL behavior. We obtained an average TSL value of -55 dB for a waveform bandwidth of 512 MHz and instantaneous bandwidth of 15 MHz, when the same calibration data measurements were used in TSL correction. We also showed that TSL performance remained stable with an average TSL of -48 dB for 16 hr after calibration in a laboratory environment and with varying pulse lengths.