Research And Realization Of High-precision GPS Timing And Snapshot Data Acquisition System

As the era of electronic information technology dawns, high-precision time transfer system not only plays an important role in research areas such as national defense and aerospace exploration, but also has such a wide range of applications in communication system, electric power system and wireless sensor network. How to make the time synchronization system achieving higher precision more safely and reliably become a research hotspot.This subject is based on the study of digital monitoring receiver using GPS module.Using highly accurate time that GPS satellites provide, we realize the synchronization of receivers and acquisition of snapshot data for computing Time-Difference-Of-Arrival(TDOA).The main work of this dissertation is the research and realization of high-precision time transfer system based on GPS and its snapshot data acquisition. Firstly, the relevant technology of GPS timing is introduced. By analyzing the characteristic of precise one-pulse-per-second(1PPS) signal from GPS and the short-term frequency stability of crystal oscillator, we design a high-precision GPS timing module and a time stamping unit that combine baseband data with time information from digital monitoring receiver.This dissertation also analyzes the factors affected the accuracy of GPS timing, and designs an anti-interference mechanism for 1PPS signal to keep the timing system steadily.With the aid of DDR2 memory caching technology and the dual FIFO Ping-Pong caching technology, this dissertation realizes a variable-speed and varialbe-length snapshot data acquisition system. This system can cache and acquire baseband data with seventeen kinds of variable bandwidth from 1kHz to 20 MHz.In order to optimize the function of this GPS timing system, we design three trigger modes including timing trigger, level continuous trigger and burst single strigger.We use the short-time burst signal detector and the level detector with different detector types including Sample, Peak, Average, RMS. Finally, through the system of joint test,the correctness of snapshot data is proved. By the correlative TDOA algorithm calculations, the final timing error with intermediate frequency data is below 50 nanoseconds.This system can be applied to the monitoring of wireless spectrum management system to reconnoiter and combat the illegal radio, interference sources, to keep the electromagnetic environment harmonious and orderly.