COMPUTATIONALLY EFFICENT RADAR PROCESSING METHOD AND SYTEM FOR SAR AND GMTI ON A SLOW MOVING PLATFORM

摘要

A method and system for processing radar data obtained from a platform which is subjected to non-uniform movement, the distance the platform travels during the formation of an image comprising an aperture; the system comprising software programming for performing a subroutine for building up an average pulse representing a single point on the aperture; the subroutine comprising the steps of inputting radar data from a radar antenna; passing the radar signal through low noise amplifier to reduce impact of electronic noise from the radar system; down converting the signal with a mixer to obtain a lower frequency; filtering out harmonics from the higher frequency range; sampling the radar data using an analog to digital converter at least at Nyquist down range frequency; based upon the IF of the radar; determining a scene center (center of SAR imagery) for the purpose of motion compensation; performing a two stage averaging scheme of the received signals with a variable window function; determining a window function based upon the velocity and acceleration of the platform and scene center; the window function comprising a first stage window; coherently averaging N pulses together to create an average pulse; performing an inverse Fourier transform; compensating to the scene center by multiplying by a complex exponential based upon both the GPS and inertial navigational system; summing the average pulses using low pass filter; the software programming operating to repeat the step of building up an average pulse a first predetermined number of times for a time period that is less than the Nyquist sample time interval; the software programming operating to repeat the step of building an average pulse for a predetermined number of times to generate a second predetermined number of average pulses; the software programming operating to perform a two dimensional inverse Fourier transform to obtain SAR image; outputting the SAR image on a display screen; and a display for displaying the outputted SAR image.