The Design And Implementation On The Accurate Positioning System Of Mobile Phone

The construction of mobile monitor and positioning system that takes advantage of mobile communication networks has broad market prospects. It is easy to maintain, and it can cover all the areas that the mobile phone signals can reach. The system is very suitable to be apply to the applications such as 110, 119, 120 alarming and command systems and the scheduling of vehicles and vessels. But at present, there are still many difficulties and problems in the development of mobile phone positioning service.The foundation of mobile phone positioning is adjusts the mobile phone's transmitting power basing on the base station's control state. Along with the distance between mobile phone and the base station increases, the transmitting power increases too, and vice versa. This means that the base station knows about the distance between mobile phone and itself. Once the mobile phone is power on, then the mobile network switching center has preliminarily positioning your mobile phone already. Of course, this preliminarily positioning information can not satisfy the requirement of mobile phone location positioning. To meet the requirement of accurate positioning, we still need to add many steps. In the alarming and command systems, we need to find out mobile phone user's location actively. We can not waiting the user send out the positioning request passively. The objective of this thesis is to probe the mobile phone user's location by measurement unit by inspire mobile phone emit signals actively. In the project, we use SIEMENS TC35i to dial a mobile phone, after receives the dialing request, the mobile phone will emit acknowledge signal actively. We can measure the signal intension of the acknowledge signal. The measurement unit we use adopts a directional antenna. There are differences of signal intension in different directions, so we can probe the mobile phone user's position actively. Because our measurement unit is installed on a car, so it has good mobility, by several times of measure, we can identify the location of mobile phone user.We designed hardware circuit to down-conversion and demodulation the GSM mobile phone signal. To achieve the positioning function, we designed software code to accomplish the identification of base station clock signal and mobile phone user's acknowledge signal. At the same time, we also adopt CC1100 to construct the short distance wireless communication network, and realize the data communication between the probe machine and PC. To make the operator operating the probe machine conveniently, we adopt the pronunciation module (ISD4004) to report the result of signal analysis to the operator directly.It aims to seek the active location methods how to locate mobile phone in emergency system. Accurate positioning system of mobile phone using the approach of detecting signals actively is proposed in this paper. The system we put forward can positioning the mobile phone user actively, need not wait the user emit positioning request passively. The system that can implement such function is especially needed by emergency system (such as police organizations). Further more, the precision of our system has been improved. By testing, the system's precision of positioning mobile phone user is about 10 meters.