A method and system for processing radar data from a movable platform comprising passing a radar signal through a low noise amplifier; down converting the signal to a lower frequency; filtering out harmonics; sampling using A/D converter at or above Nyquist frequency; determining a scene center; performing a two stage averaging scheme of the received signals with a variable window function based upon the velocity, acceleration of the platform and scene center; coherently averaging N pulses to create an average pulse; performing an inverse Fourier transform; compensating to the scene center by multiplying by a complex exponential based upon GPS and inertial navigational system; summing the average pulses using a low pass filter; repeating the determination of an average pulse for a time period that is less than the Nyquist sample time interval to generate second average pulses; and performing a 2D inverse Fourier transform to obtain SAR image.