Design of modified spectrum filter based on Mismatched Window for NLFM signal

In the radar field, Non-Linear Frequency Modulation (NLFM) signals are widely used. The conventional design method of side-lobe suppression filter for NLFM signal is based on the principle of stationary phase with the window functions and the modified spectrum algorithm. A new filtering technique of Modified Spectrum Filter based on Mismatched Window (MSFMW) algorithm is proposed in this paper. This method respectively designs the NLFM signal and the pulse compression filter based on different window functions. So the spectrum magnitude of the filtered waveform is proportional to the window function which is different from the one used for waveform design. The performance of the pulse compression can be modified by the different window functions. The simulation results demonstrate that the Ratio of Main-lobe peak to Side-lobe peak (RMS) can be increased by 0.8 ~ 7.7dB, without changing the main-lobe width.