General Lfm Signal Based On Dds Technology System

With the development of modern digital technology and VLSI, the method of digital waveform synthesis of the pulse compression signals is now widely used in radar systems. The waveform generated using digital systems is of strict coherence, repetitiveness, high stability and programmability, which can also easily realize the waveform parameter agility and generate arbitrary waveforms in order to meet the urgent needs for anti-interference and strong viabilities of radars under modern EW environment. Thus, further researches on digital waveform generation are of much importance recently. The primary work in this dissertation: (1) This dissertation compares the differences and similarities between direct digital waveform synthesizer(DDWS) and direct digital frequency synthesizer (DDFS). A DDS system is presented, and the theoretical analysis and practical implementation of the system is discussed in details. (2) A LFM signal generator system based on AD9858 is designed and implemented. The test results indicate that output harmonics are low and spurious signals are below –40dB, the ripple in passband below 1dB and pulse compression RMS meet system requests, which precedes the requests of the radar system. The generator is now taking part in radar system tests. This dissertation gives a full analysis of the LFM signals generation based on DDS technology and some conclusions are also presented.