An efficient TOPS imaging algorithm based on spectral analysis

The Terrain Observation by Progressive Scans (TOPS) mode solves the problems existing in the conventional ScanSAR mode by steering the antenna along the azimuth direction. However, the antenna steering introduces a serious azimuth signal aliasing both in time-domain and frequency-domain, thus traditional imaging algorithms are not available for the TOPS mode. In order to solve the azimuth signal aliasing, an efficient TOPS imaging algorithm based on spectral analysis (SPECAN) is presented in this paper, which is improved by sub-apertures division in the azimuth processing part. Only few FFTs and complex multiplications are used in the whole imaging processing, thus the algorithm has a high efficiency. What's more, in the final focused image, different ranges have the same azimuth interval and the azimuth image resolution is alterable according to the application requirements. Finally, some simulations are conducted to verify the validity of the proposed method.