Research And Design Of Signal Generator With Multi-mode Based On CPLD And DDS

In the area of modern military communication and detection technology, in order to enhance the anti-interference ability of the active wireless detective system, outputting variety of modulation signal from the system's transmitter is required. At present, most research on signal's interference is at the research of signal frequency, including frequency hopping and spread spectrum signal. Or increased the complexity of the signal content and enhance applications of pseudo-random signal etc when encoding the signal.However, it is rarely to design a signal generator with changing modulation of signal, which is enhancing anti-interference ability of the signal. Therefore, the thesis is based on direct digital frequency synthesis technology, using the advanced CPLD control technology, Flash data storage technology, and software radio thinking, designs a kind of multimode signal generator which can changing modulation pattern of transmit signal, according to setting model in conditions of continuous-time.The thesis introduces the significance of research projects and the analysis of the current related technologies.It submited the basic idea and technical indicators of the multi-mode signal generator. Meanwhile, it demonstrated the method of engineering realization. Paper has offered an idea of system with a core of DDS (Directi Digital frequency Synthesis). This system is stored multi-mode signals in the Flash and outputted real-time coded signal,modulating signal through digital circuits design and under the control of CPLD system. The thesis displays related technology and principles, involving DDS principles, the realization of multi-mode signals switch, hardware design choices and the frame structure of system. According to the technical indicators, the paper does research on the DDS signal generator; ? design the control system with CPLD and Flash as well as peripheral circuits. Finally, VHDL language is programmed to design the timing controller.The thesis does research on the control software of the system. The project designed the control software of UFM storage,Flash storage and signal generating. The paper presents the programming of signal tuning word and mode switching. It designed generating software of Chirp signals, BPSK signals, FSK signals, pseudo-random signals of 4 steps M sequence and systems management software of multi-mode signal switching.At last, the paper shows the experiment of hardware testing and the data analyses of software. Finally, it summarized the project.