Research On Key Technology Of Locata System And Transmitter Module Design Of System Tranceiver

LOCATA is a kind of new land pseudo satellite positioning system, which was jointly developed by the University of New South Wales, Australia (UNSW) and LOCATA company. The performance of this system has been tested in a variety of experimental environments.Stage research results and number of patent applications hace been achieved, with high positioning accuracy, scalability, good environmental adaptability, etc. In the case of scenes where GPS satellite navigation system has poor performance, such as valleys, tunnels and "urban canyons", underground car parks and other places, LOCATA can improve the quality of services within the regional location as a ground enhanced system of satellite navigation system. In the specific area which has high positioning accuracy requirements, such as mines, military areas, etc., LOCATA can also be an independent network, providing high-precision positioning services for users in these regions. In addition, within the shopping malls, office buildings, apartments, LOCATA can also provide better location service than the existing satellite navigation system. Compared with the traditional pseudo-satellite positioning system, LOCATA positioning system has many advantages. Currently, the research about LOCATA is still rare in China. To this end, research on the prototype system of LOCATA has been carried out. The main study of this thesis is focused on the aspects of system transceiver port and the design of its transmitter module. The main work of this thesis is as follows:First of all, the performance of LOCATA system using transmit diversity techniques to combat multipath effect is studied. LOCATA system uses spatial-frequency diversity to obtain considerable diversity gain. Through simulation this thesis verifies the performance of transmit diversity for enhancing the signal availability and reducing the error rate. In addition, research on the pseudo-satellite transceiver networking layout and near-far problem is also studied.Then, the time synchronization technology of LOCATA system -TimeLoc is studied. The key to the technology is the utilization of direct frequency synthesis DDS technology to eliminate the influence caused by internal clock deviation between each transceivers, this thesis also focuses on here.Next, the architecture of system transceiver LocataLite is studied, and then a design scheme of its transmitter module is proposed. The design of LocataLite’s transmitter module can be divided into two parts. The first part is FPGA-based digital signal processing section, this part implements the generation and control of the transmitted signal, and the design and simulation is based on Xilinx ISE14.6. The second part is the RF front-end section, by selecting appropriate hardware modules, to do pre-launch processing on the baseband digital signal. The performance of hardware modules and the correctness of this design are verified by experimental tests.Finally, the research work of this thesis is summarized and a prospect to the future work is provided.