Research Of A Portable Radio Direction Finding System

Radio direction finding is a technique to find the direction of arriving wave bymeans of special method based on the combination of direct antenna and receiver,which has found wide applications in multiple areas such as communication spying,radar spying, radio measurement/control and radio frequency spectrum management.This thesis mainly researches on a radio direction finding system based on a mechanicalservo antenna, aiming at developing a portable one with strong functions includingpositioning.The thesis summarizes the development of a portable engineering prototype ofradio direction finding system, which the author joined in, including the design of thetotal system and all the constitutive units, system debugging and performance testing;the detail is as follows.(1) Through analyzing the characteristics of various directing antennas, a schemeof high accuracy direction measuring system is designed, which finds direction ofarriving wave based on direction variation of the antenna driven by a servoelectromotor.(2) The total system and all the constitutive units are designed, including themechanical servo antenna, the ultra-high-frequency receiver, automatically directionfinding circuit and the man-machine interactive interface. The thesis describes theconfiguration of every units, the assignment and realization of various techniquespecifications, type selection of some key parts and chips, as well as design andmanufacture of circuits of these units.(3) Considering the frequency band of the system is rather wide, the author pay agreat attention to design of frequency synthesizer. After presenting the design idea, thethesis discusses the type selection of some key devices as well as its affection to theperformance of the whole system.(4) For the sake of convenience and human-like behavior in practical applicationsof the system, the interface of the results display and man-machine interactive operationis aboratively designed.The engineering prototype is successfully developed and tested, the results showthat the performance of the system reaches the expectation..