Research And Design Of GPS Signal Acquisition And Tracking System Based On FPGA

Internet, mobile communication and satellite-based navigation are three most important industries in the information society of 21st century. Meanwhile, the technical level and the development course of GPS system represent the development status of the satellite navigational system in the whole world. At present, our country has already become a great user of GPS. The satellite navigation industry chain has basically been formed. Nevertheless, we have not gone deep into the core GPS technology, as the most important part of our GPS products are mostly import.Complex signal processing has to be done to synchronize the local signal with the received one when a GPS receiver works. How to acquire the satellite signal and keep track of it is one of the most important techniques in the GPS receiver technology. Many researchers have come up with lots of solutions on that question, but most of them are only on the theory level, and are difficult to apply them in a GPS receiver system to do the real-time processing.This theme has researched and designed a GPS signal acquisition and tracking system on FPGA based on the analysis of the algorithms existing. In that course, a GPS receiver module has firstly been designed and made using Nemerix Corporation's GPS chip group. It works stably and can be used as a GPS baseband signal processing research platform that outputs real-time GPS IF signal. Based on that, the article researches deeply on the GPS signal acquisition and tracking technique. Firstly, the article compares several GPS signal acquisition solutions, and determines to use the one called step forward correlation. Then analyzes the characteristics of tracking loop, and determines to make FLL and PLL work in turn to track the carrier and let the carrier assist the pseudo-code tracking. All of these solutions have finally been realized.The GPS signal acquisition and tracking system in this theme is realized by the operation of the hardware cooperating with the software. The hardware mainly realizes the functions of correlator that have high data rate and simple logic, and the software based on MicroBlaze processor mainly realizes the functions that have low data rate and complex logic. The article gives the detailed design and simulation result of the hardware circuit and detailed flow of the software design.This theme has finally realized the functions of the GPS signal acquisition and tracking system on FPGA, and the system has good performance. So it can be concluded that this design can satisfy the function and performance request of the system, may directly be used in the real-time GPS receiver system, and has established a foundation to design GPS receiver independently.The research of this theme has been supported by the Integrate Circuit Projects of Dalian Bureau of the Information Industry. The name of the item is "SOC Design of Allocation and Communication Functions Integrated". The harvest of this research will get tryout in the first half year of 2008.