Method for the processing of the reception signal of a deramp type synthetic aperture radar

摘要

A Deramp type radar used in synthetic aperture radar for radar imaging transmits coherently repeated linear frequency-modulated pulses and carries out a sort of pulse compression in reception by demodulation of the echo signals received by means of a frequency ramp that reproduces all or part of a transmitted pulse, and by a Fourier transform performed in range. The application to a Deramp type radar signal of a standard SAR processing is disturbed by the fact that, in this signal, the effectively demodulated part of an echo signal due to a target has a position with respect to this echo signal and a duration that are variable as a function of the distance from the target to the radar. The proposed method makes it possible to eliminate this disturbance by means of a particular choice of a common temporal support used for the demodulation of the signals of all the targets of the useful swath and a phase correction applied to the level of the pulse response of the image focusing filter of the SAR processing. Secondarily, a second phase correction can be applied to the complex reflection coefficients obtained for the dots of the image at the end of the SAR processing.