Study Of INSAR Echo Signal And System Simulation

Interferometric Synthetic Aperture Radar technique is a microwave remote sensing technique that can acquire high resolution digital terrain model. Computer simulation technique is very useful to deep understanding the interferometry theory, to testing the algorithm of processing interferometric data and system designing. After detailed analysis of the frequency domain expression of echo signals for a zero squint case, modified expression for a squint case is deduced. A simulation method for InSAR echo in two dimension frequency domain for both cases is presented, and radar foreshortening and beam squint angle is simulated. The presented method has sloved the problem of low efficiency in the time domain simulation method for distributed targets or real scene.Echo signal is processed using the Range-Doppler algorithm and Chirp-Scaling algorithm. Baseline decorrelation of InSAR system is verified by the experiment of distributed targets echo imaging. A combined doppler centroid estimation scheme and the newest doppler frequency rate estimation algorithm --Coherent Map Drift technique are analyzed. And the width of main lobe of the correlation function in the Coherent Map Drift algorithm is independent of the initial value, which is suitable for peak detection of correlation. Doppler parameter algorithms are tested using the range compressed data of single target. Real raw data is processed using the Range-Doppler algorithm. Flat-earth effect of interferogram is removed using the method based on frequency shift.A theoretical analysis is made for phase error sources (amplitude and phase errors of SAR system, phase and amplitude imbalance of I and Q channels and frequency modulation rate error), which affect the height measurement accuracy. And the phase error which is introduced by the error sources, at target position in the image, is derived. An elevation extraction method based on point target is proposed, which avoids the disadvantage of lack of quantification in distributed target simulation. Then, the presented method is used to simulation of the influence of different error sources on the interferometric phase and height measurement accuracy of targets.