Design And Implementation Of Transceiver Baseband For Local Area Wireless Time Synchronization System

The local wireless time synchronization system is a system that is applied to the visible range and eliminates the clock difference between the two places based on the principle of two-way pseudo-code ranging to realize time synchronization.The system has the advantages of high precision,flexibility,and no influence from atmospheric delay.Therefore,the application and technology of local wireless time synchronization systems are becoming more and more extensive,and they are widely used in scientific research,communication measurement,and electric power transportation.The baseband signal processing unit is a key component of the local wireless time synchronization system.The main application technologies and principles include wireless time synchronization technology,code division multiple access technology,and two-way pseudo code ranging principle.In this thesis,the system structure of baseband ranging signal is designed firstly.The basic methods and key algorithms of transmitting and receiving baseband signals are studied.The hardware experimental platform based on FPGA+DSP architecture is designed and built.The design and implementation of the baseband of the two-way pseudo-code ranging principle was carried out.Finally,the two-way wireless time synchronization system was tested and the test results were analyzed.The specific contents of this thesis are as follows:1.The two-way pseudo-code ranging and time synchronization methods are studied.Then the basic methods of baseband signal transmission and reception in wireless time synchronization system are analyzed.2.The key technologies of transceiver baseband signal transmission and reception are studied.The system structure and information frame format of the ranging signal are designed,and the performance of the generated signal is analyzed.At the same time,the carrier loop and the code loop are studied.The error and accuracy of the carrier loop and the code loop are analyzed respectively.Finally,the loop structure and loop parameters are optimized.3.Introduce a well-established two-way time synchronization hardware and software platform.The software implementation based on FPGA+DSP architecture is divided into modules,which realize the generation and reception of baseband signals respectively.The receiving processing unit mainly includes tracking loop,pseudorange processing,clock difference calculation and time synchronization.Finally,a hardware test platform is designed,the combined delay is calibrated,and the results of single pseudorange,clock difference and two-way time synchronization test are analyzed.In the static state,the one-way pseudorange transmission delay stability of the radio frequency direct connection system is better than 0.18ns(1?),in which the ranging measurement deviation is better than 2.12 ns,and the mean ranging stability is 0.91ns(1?).Before calibration of combined time delay,the deviation between the pseudo-range calculated clock difference and the counter measured clock difference is-5.6ns.