| Since 1930s radar was invented, it has been used in many fields, especially in military detect, capture and track targets. 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 arbitray 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.Radar echo generator is used widely in radar performance measuring. This dissertation introduces the work principles, hardware circuit structure and application of a pint-sized multifunctional radar echo generator, which can generate various waveforms needed. We can modulate the Doppler frequency and adjust the time delay of the waveform to validate the performance the radar system. The device can also be used as a signal generator to provide the input of the other radar system.The primary work in this dissertation:1.Based on the analysis of direct digital synthesis(DDS), 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 Radar echo generator system based on DDWS and AD9857 is designed and implemented. The hardware design and debugging are finished.3.An asynchronous serial communication protocol based on RS-232C is designed to realize the data communication between the PC and the system.4.Debug the whole system including the application program, driver program and hardware; test the result of the system. |
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