Design method of parameters for pulse doppler signal to nullifying the interference of negative frequency

This paper describes how the negative-frequency portion of the pulse doppler (PD) radar signal´s spectrum extends into positive frequency and causes interference in signal processing. A novel design method of the parameters of pulse doppler signal is presented to nullifying this interference. The key idea of nullifying the interference is to place a null of the negative-frequency portion´s sidelobes to the place where the interference exists. This method encounters the problem of frequency aliasing in conventional process of PD signal and it no longer works. An improved filtering process is proposed to solve this problem. Some computer simulation results are presented to illustrate the performance of the proposed parameters designing method and the improved filtering process.