Researches On Techniques Of The Capture Of GSM Aerial Signal And Mobile Position Location

With the development of technology and market of digital mobile communication, GSM acts as an important role in people's communication manner. However criminals also use GSM handset as the assistant tool of their crimes, which damage the security of our country and society badly. So we need an effective interception and location technology of GSM system to strike the crimes.Based on this background, a project is present to capture the aerial signal of GSM system and locate the target mobile stations. As part of the work of the project, the algorithms of baseband are realized in form of fixed-point and implemented on DSP. The techniques of mobile position location are also discussed in the thesis.In the thesis, the system architecture is presented firstly .The relevant aerial interface characters of GSM are introduced here also. Then some needed algorithms for baseband signal processing are given, including channel equalization and system synchronization . Based on these, the implementation of both hardware and software are presented.Further more, the method of time of arrival (TOA) estimation is analyzed in the thesis, which is the key technique for mobile position location (PL) .Our system uses TDOA method to locate the mobile stations. The precision of the PL is depend upon the performance of the TOA algorithms .There is nearly no public literature about TOA estimation method that can be practically implemented on GSM system. A method is presented in the thesis and the result of the simulation shows some good performance.