| Pulse stepped-frequency radar integrates advantages of pulse radar, pulse linear frequency modulation radar and frequency-agility radar. As one kinds of high range resolution radar, it can realize range resolution of cm or even mm order. Compared with other forms of high range resolution radar, the most important benefit that can be obtained from pulse stepped-frequency radar is that its receiver bandwidth is only the bandwidth of successive sampling and signal processing greatly. With the development of waveform generation technique and signal processing technique, pulse stepped-frequency radar attracts more and more attentions.This paper is mainly concerned about the design and realization of wide band stepping frequency radar signal source. The UWB-SAR signal design, digital waveform generate technology and the principle of DDS and the implementation of DDS chip AD9954 are the key points in this paper, which is detailed as following:1. UWB-SAR singal designSome konds of UWB-SAR signals in common use are studied in this paper and given more attention about the attrinute of the stepping frequency signal; Given some key parameter to stepping frequency based on the utilization of ground penerating radar.2. Digital waveform generate scheme designThe principle and feature of Direct digital waveform synthesis (DDWS) and Direct digital frequency synthesis (DDFS) are analysied in detail. The scheme based on the two kinds of technology and the merit and defect of the two kinds of technology are also studied in this paper.3. The implementation of high performance DDS chip AD9954 in wide band stepping frequency signal source.The principle and key feature of AD9954 are analysied in detail, the model and the configuration of AD9954 are also studied in this paper, some scheme of wide band stepping frequency signal source is presented, in the end the wide band stepping frequency radar signal source is realized based on DDS chirp AD9954 cascade qudrature modulator. |
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