Improved Design of Orthogonal Discrete Frequency-Coding Waveform Based on Modified Genetic Algorithm for MIMO-SAR

Synthetic aperture radar (SAR) is a good-proven remote sensing technique; but, single antenna SAR systems cannot provide at the same time wide-swath and high-resolution imaging. Multi-Input Multi-Output (MIMO) radar can be used to form a synthetic aperture for high resolution imaging. To successfully utilize the MIMO synthetic aperture radar (SAR) system for practical imaging application, the orthogonal waveform design plays a critical role in image formation. Focusing on the SAR application, a definition for synthetic integrated side-lobe level ratio (ISLR) is proposed. The autocorrelation peak side-lobe level ratio (A-PSLR) of discrete frequency-coding waveform with fixed frequency pulses (DFCW_FF) is very large. Replacing the fixed frequency pulses with linear frequency modulated (LFM) pulses can lower the A-PSLR. Changing between the up -and down-chirp waveform can improve ISLR. In this paper modified genetic algorithm is proposed to numerically design orthogonal discrete frequency-coding waveform with linear frequency modulated (DFCW_ LFM) and search optimal sequences for up and down chirp waveform. The simulation results show that the proposed algorithm is effective for the design of DFCWs signal used in MIMO-SAR.