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.