Time frequency processor for radar imaging of moving targets

Conventional radar uses the Fourier transform to generate a radar target image. Constraints on the use of Fourier methods requiring point scatterers to remain in their range cells and requiring Doppler frequency shifts for point scatterers to be stationary are impractical due to a moving object's inherent non-uniform motion and rotation. Time varying motion-induced Doppler frequency shift spectra represented with Fourier transform methods smears radar target image. Representing time-varying Doppler spectrum using joint time-frequency transform methods is desirable. Replacing conventional radar Fourier transform with a high resolution time-frequency transform, a 2-D range-Doppler Fourier image frame becomes a 3-D time-range-Doppler cube. By sampling in time, a time sequence of 2-D range-Doppler images with superior resolution can be viewed. Smears from time-variance of Doppler spectrum may be removed to enhance target image.