Research on the Chirp Signal Echo Processing Based on DDS

摘要

For the advantage of high range resolution and low power, the radar usually use the linear frequency modulated continuous waveform. With the development of electronic technology, the operating bandwidth of radar is also growing. In broad bandwidth, to realize the linear modulated waveform using VCO is difficult. It requires additional circuits to detect the linearity of VCO, and feed it back to the control system. Then do the correction to the control signal of VCO. Since the digital controllability of DDS, it can provide highly linear modulated waveform without additional correction circuits. In this paper, through studying the broadband chirp source system of radar based on DDS technology and analyzing the error model of the system, a method that selecting the ADC sampling rate accordance with the speed of linear FM frequency agile is proposed. It reduces the system errors caused by the discontinuous chirp signals. Simulation results show that this method can effectively solve the interference problem brought by the discontinuity of DDS chirp signal.