| With the development of modern electromagnetic countermeasure technology ,the modern radar is in condition of austere electromagnetic countermeasure . In this condition, modern radar should advance the capability of high accuracy ,multifunctional and anti-jamming . A method of advance the capability is use the technology of array radar and transmit wideband radar signal of linear frequency modulation(LFM). 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.In this dissertation,general analysis the system of Direct Digital Synthesizer (DDS) on the basis of radar theory and pulse compression theory . A digital waveform generator for a radar sysytem has been implemented, which can generate dual-resolution pulse compression signals with 200MHz/2.5MHz bandwidth working at 200MHz carrier.By tested,the system run steadied and generate high-quality waveform which can delayed with ps precision and phase adjusted. The primary work in this dissertation:(1) Base on the theory of wideband digital array radar and Direct Digital Synthesis, analyzed the influence of the delyed error and phase error of radar signal.(2) DDS system is presented, and the theoretical analysis and practical implementation of the system is discussed in details.(3) wideband digital array radar(WDAR)generator system based on AD9858 is designed and tested. The test results indicate that meet system requests. This dissertation gives a full analysis of the LFM signals generation based on DDS technology and some conclusions are also presented. |
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