Spotlight SAR Data Focusing Based on Two-Step Processing Approach With Considering Correction Coefficients

Receiving more accurate information from an area in SAR images requires high-resolution imaging of that area. In order to achieve high resolution SAR images, spotlight imaging mode is used. Two-step focusing approach, is an efficient approach to eliminate doppler spectrum folding in spotlight mode and focus raw radar data. Relevant articles and references, have only used fast fourier transform and complex coefficient to eliminate data spectrum folding in implementing this approach. But in fact, eliminating the doppler spectrum folding in this approach, requires a series of correction coefficients in addition to fast fourier transform and complex coefficients, which in none of relevant references and articles, are not provided. In reality, the relevant references have only provided a general method of implementation of this approach and have omitted to provide these correction coefficients. Failure to consider these correction coefficients in the implementation of this approach, will cause distortions in the compressed signal. In this paper, the desired correction coefficients are extracted and the block diagram of signal processing is modified by using these coefficients. Also, simulations have been performed that shown the distortion due to not considering the correction coefficients. Implementing two-step focusing approach with considering correction coefficients is the main topic of this paper.