Low Sampling Rate Digital Dechirp for Inverse Synthetic Aperture Ladar Imaging Processing

The application of digital dechirp technology to Inverse Synthetic Aperture Ladar (ISAL) can greatly reduce the sampling rate burden on analog-to-digital converters. We address the disadvantage of signal sampling and imaging processing in linear frequency-modulated continuous waveform (LFMCW) ISAL systems and suggest a delay estimation method based on a reference channel to reduce the impact of echo delay error. Our method uses the strongest point in the scene as the scene center to estimate the delay and target distance via dechirped pulse compression. The reference channel data are also used to align the dechirped pulse signal and, in turn, reduce clock errors and ensure azimuth signal quality. To our knowledge, our experiment represents the first successful application of digital dechirp to ISAL systems. Experimental results confirm the applicability of our digital dechirp method to ISAL system in order to reduce sampling requirements.