Abstract: To obtain good performance for detecting a moving target, the multi-channel SAR system always utilizes a long baseline. However, the radial velocity calculated by the interferometric phase presents ambiguous solutions. A radial velocity unwrapping method for a multi-channel SAR-GMTI system has been proposed in this paper. Based on the analysis of the relationship between interferometric phase of the mover and radar system parameters, the principle that the system velocity response can be altered by the variation of the wavelength and length of the baseline is revealed. The new method utilizes both the multi-baseline and multi-frequency to unwrap the radial velocity and performs better than the routine method. Synchronously, a numerical method is proposed for computing the precise radial velocity of the mover simply but effectively. Analysis and computer simulation demonstrates the validity of the method.

Key words: synthetic aperture radar (SAR), ground moving target indication (GMTI), velocity ambiguity