Research On Key Technique And Hardware Design Of Chirp-uwb System

At present, both at home and abroad, the researches of Ultra-Wideband (UWB) focus on short-distance and high-speed application, scarcely touching upon medium or long distance applications. The wireless transmission technology based on the medium or long-distance UWB will further expanding the scope of UWB application, making its application form more flexible and its architecture more integrated. In particular, the strong technological superiority of anti-interference and capacity of covert communication make it very useful in the application of military, public security, fire safety, rescue and many other special occasions.Several of UWB system, the Chirp-UWB has unique advantage in the applications for medium or long-distance. But the current practical technique of Chirp-UWB is mostly used in the application of short-distance, low-speed and low-cost. So it is very useful to study the implement structure and the Key Technique of Chirp-UWB applications for medium or long distance.The main research contents include:Firstly, the techniques of Chirp-UWB signal generation. This thesis, studies on four signal generator programs:using analog VCO and its nonlinear correction technology, direct digital synthesis (DDS), DDS+PLL, DDS+mixer+frequency multiplier respectively, and gives detailed analysis of the performance of four programs used in the Chirp-UWB communication system. The results show that, DDS+mixer+frequency multiplier is a better Chirp-UWB signal generator programs that can generate a large bandwidth signal which combining analog signal processing technology and digital signal processing technology.Secondly, the techniques of Chirp-UWB signal sampling and processing. In this thesis, a program based on architecture of software radio is firstly studied, in which the signal is directly sampled by a high-speed ADC and then implements the digital signal processing program. Then, a program based on active spectrum compression and low-speed ADC sampling is given, which uses the character of signal that the time-domain multiply equals to frequency-domain correlative. This approach puts the extremely wideband Chirp-UWB signal compressed to a narrow-band signal in frequency domain, so as to avoid high-speed sampling and high-speed digital signal processing.Thirdly, the non-ideal factors of the Chirp-UWB system hardware design analyzed. Aim at a practical implementation structure of the Chirp-UWB, the thesis gives an analysis of the source of all non-ideal factors and their influence on system performance by setting up the mathematical model, and then gives the solutions or ideas to reduce or eliminate the impact of these factors.Finally, the thesis chooses the program of DDS+mixer+frequency multiplier to generate signal and the receive structure based on active spectrum compression and low-speed ADC sampling, designs the base band and RF circuit of Chirp-UWB receive and transmit system.