The Design And Realization Of Signal Generator For Chirp UWB Wireless Communication System

Ultra-Wideband (UWB) technology is a research focus of the field of wireless communications in recent years. For its advantages of low complexity, strong anti-jamming ability, high capacity, high resolution of multipath, UWB technology has wide application prospect in communication, radar and wireless location fields. Compared with the traditional UWB technology, UWB technology based on chirp spread spectrum has not only the advantages of UWB, but also has the advantages of small peak to average power ratio, long transmission distance. In 2007,chirp spread spectrum technology that has become one of IEEE 802.15.4a Physical Layer Standards proves its development potential.The thesis mainly studies the design and realization of a Chirp UWB signal generator for Chirp UWB communication system. The thesis first introduces the basic principles of Chirp UWB, including the features in time domain and frequency domain, pulse compression theory and CSS. Then it analyses the principle and the merits and demerits of the generation method of Chirp UWB. According to project requirement, we propose a scheme using Phase Locked Loop (PLL) to generate Chirp UWB signal on the basis of active generation of Chirp UWB signal. The scheme improves the incoherence of each pulse initial phase in active generation of Chirp UWB signal. Besides, the initial frequency and the bandwidth of Chirp UWB signals is flexibly controled by changing the paremeters of the sawtooth signals which are injected into PLL, and the data rate can reach 2Mbps. The problem of low data rates in DDS method is overcome by this scheme. Then, the principle of this scheme has been deduced and the feasibility of it has been verified by Matlab simulation. Finally, according to the scheme, signal generator circuit is realized, parameters index and communication system of Chirp UWB are tested. The results show that the design of Chirp UWB signal generator reached the requirement of the project, and it has some good characteristic, for instance, simple structure, low cost, great extensibility and flexibility, and high transmission rate.