Improved RD imaging method based on the principle of step-by-step calculation

Abstract

RD (Range Doppler) imaging algorithm is a classical SAR imaging algorithm. The algorithm has simple principle and strong universality. It is widely used in multiple flight platforms or multi-mode SAR imaging. The basic idea of the classical RD algorithm is to realize the two-dimensional imaging of SAR through two matched filters: range compression and azimuth compression, combined with range migration correction. In the process of quadratic matched filtering,. there are a lot of basic FFT operations. Especially in the process of azimuth compression,. it is necessary to carry out FFT calculation along the "slow time" axis of the range to multiple resolution units. The processing time of this step is related to the observation range,. range resolution and FFT transform points. In the application of high resolution imaging,. the higher the azimuthal resolution is within the same observation range,. the more times of azimuthal FFT transformation is needed,. and the longer the operation time of the imaging processing system is. Using the principle of step-by-step calculation,. the FFT operation of a complete sequence is divided into multiplication and addition operations of multiple sequences which can be calculated step by step. In order to save the whole operation time of the imaging processing system and improve the efficiency of RD imaging operation,. the simple sequence multiplication and addition operation process is evenly distributed to the imaging data preparation process,. and the preprocessing function of azimuth FFT operation is realized by using the data preparation time.