A De-Chirp Processing Method for Wide-Band Stepped-Frequency Chirp Signals

A de-chirp processing method was introduced for stepped-frequency chirp signals(SFCS) in the application of ISAR.In this method,de-chirp operation was performed on each sub-chirp pulse signal,the resulted time-domain data was shifted along time-axis according to the frequency step and the slope of sub-chirp signal,and then combined altogether coherently.Finally IFFT was performed on the combined time-domain data to get a range profile corresponding to each burst of pulses with much higher resolution achieved than single chirp does.Comparison between the proposed method and the sub-aperture method based on matched filtering,as well as simulations were presented to show the effectiveness of the method.