Range Cell Migration Correction by Fractional Fourier Transform in Synthetic Aperture Radars

Abstract

One of the important parameters in Synthetic Aperture Radars (SARs) is image resolution which is defined in two dimensions, azimuth and range. Two techniques named pulse compression and Range Cell Migration Correction (RCMC) help us to achieve high resolutions. Generally, the transmitted pulse in SAR is a Linear Frequency Modulation (LFM) which is typically compressed by matched filter. As Fractional Fourier Transform (FrFT) is able to eliminate the quadratic phase term, compressing the LFM signal by FrFT has been introduced in literature. Since the Range Cell Migration (RCM) is a quadratic term, it can also be corrected by FrFT, a fact not considered earlier. In this paper, a novel algorithm is proposed where in addition to pulse compression, the RCM is corrected by the FrFT. The simulation results are presented to show the advantages of the proposed algorithm compared to the conventional Range-Doppler Algorithm (RDA) according to Integrated Side-lobe Ratio (ISLR), Peak to Side-lobe Ratio (PSLR) and Impulse Response Width (IRW) criteria.