GMTI and GMTIm via Fractional Fourier Transform and GLRT in SAR

In synthetic aperture radar (SAR) signal processing, the images of the moving targets are displaced and unfocused due to their unknown motion parameters. Therefore, different methods have been suggested for ground-moving target indication (GMTI) and ground-moving target imaging to detect the moving targets and estimate their motion parameters. In this article, noting the linear frequency modulation of the SAR-transmitted signal, we propose a method that employs the fractional Fourier transform (FrFT) as a tool for signal detection and signal parameter estimation. Specifically, for the detection of the SAR echo signal, the generalized likelihood ratio test (GLRT) is derived by means of the FrFT. The proposed detector is further modified to possess the constant false alarm rate (CFAR) property. The performance of the proposed method and its effectiveness in SAR imaging for moving targets are evaluated through simulations and examples.