The Research Of Ultra-Wideband Signal In Optical Fiber Communication System

In the technology of wireless communication, the technology of Ultra-Wideband(UWB) is great popular because of its advantage, such as communicating without carrier,strong resistance of anti-interference, high speed of transmission, large capacity of systemand so on. But due to its low consumption and the ultra wide band, it is unable to realizelong distance transmission, which constraints the scope of its application. UWB over fibertransmission (UWB over fiber) system can effectively solve the problems of the shortdistance of UWB signal transmission. UWB signal can be transmitted to in fiber by director indirect modulation, so that it can extend the transmission distance of the UWB signal,and realize high-speed and long-distance transmission.This thesis makes a study of the UWB technology and its characteristics，andestablishes UWB over fiber system model. On the basis of it, the thesis simulates theUWB signal in optical fiber transmission characteristics, generates the Gaussian waveformUWB signal and the first-order differential Gaussian waveform UWB signal on printedcircuit board. The specific work is as follows:(1) The simulation generates UWB signal modulated by BPSK, based on the study ofthe theoretical of UWB technology. Considering the cost consideration, a low-cost of850nm vertical cavity surface emitting laser (VCSEL) is adopted on the premise of systemperformance, and the direct modulating is used to modulate UWB signal to the fiber.(2) Set up UWB optical fiber transmission system based on multimode fiber. In orderto realize the communication among the ultimate consumers, the transmitting terminal andreceiving terminal have the advantage of high mobility. An amplifier module is designedto compensate the sender path attenuation of UWB signal. In this thesis, ADS andOptiSystem are used for system design. Simulation results show that UWB signaltransmission distance can be extended from the original under10m to about200m in theUWB over fiber system which transmits UWB signal by optical fiber, it expandes thecoverage of UWB signal, provides a practical reference.(3) This thesis designs a simple circuit which can generat Gaussian waveformgenerating circuit and a first-order differential Gaussian waveform UWB signal, and the corresponding printed circuit board is produced by PROTEL software. After debuggingand measurement, the circuit achieves a gaussian waveform and first order differentialwaveform. The circuit has the advantages of simple structure, low cost and goodpracticability.