Data Acquisition, Research And Analysis On Galileo E1 Signal

Galileo system, which is the European navigation satellite system, together with the modernization of Global Positioning System has recently become the hot points of navigation's research. The new modulation technique binary offset carrier(BOC) modulation used by Galileo system, which has reduced the obstructions of signals and improved the capability of positioning, has become the main technique of modern navigation satellite system. The Galileo E1 signal is highly valued as it shares the same frequency domain with GPS L1 and is designed for civil use. Now Galileo system has lunched low satellites named GIOVE-A and GIOVE-B for test, which are under good operation. This paper simulated and acquired the real Galileo E1 signal broadcasted by GIOVE-A. Other works, including data processing are also implemented.High precision Galileo signal, as the data source of signal decoding and positioning, is the premise of the study of Galileo system. As a result, the simulation of real Galileo E1 signal is of great importance for the generation of the simulation platform used for the study of high dynamic Galileo receiver. Now the related researches are lacked internally. This paper presented two different methods for the simulation of Galileo E1 IF digital signal with adjustable carrier-to-noise ratio, simulation time and Doppler. The signal generated was of the characteristic of Galileo E1 signal through the data analysis and the test of acquisition and can be used for the positioning of Galileo receivers.The front-end of Galileo receiver is the data acquisition module. In this paper we acquired the data broadcasted by GIOVE-A through down-sampled module, serial-to-parallel module and sampling and quantizing module. The reliable data is for later use of data processing.The data processing module, performing signal acquisition, pull-in, signal tracking and decoding of navigation data, is the core module of Galileo software receiver. In this paper we implemented the data processing of real signal through a series of improved algorithms which are used only for Galileo E1 signal and are different with the ones used for GPS data processing.The serial search in time domain and FFT search in frequency domain, used by traditional acquisition, is of little use for real Galileo E1 signal. This paper presented a multi-periodic FFT search and reserved BOC modulation algorithm based on the characteristic of autocorrelation and cross correlation function, which takes the characteristic of Galileo signal and BOC modulation into account. The algorithm was approved by the data simulation as it could improve the effect of the acquisition of real Galileo signal.The traditional tracking algorithm is also of little use for Galileo E1 signal. This paper presented an improved algorithm using the very early and very late tracking loop based on the traditional tracking loop and BOC modulation. The results show this new tracking loop can work more efficiently for the Galileo E1 signal and the acquisition of navigation data.Galileo E1 signal has the different navigation data format with GPS L1 signal. This paper discussed the data format of Galileo E1 signal and the method about how to decode the navigation data from the data generated by the tracking loop to get the navigation message. The data analysis shows that the data decoded from the tracking loop is correct and reliable and can be used for later positioning.This paper solved the core problems caused by the BOC modulation of Galileo system through the simulation and data processing of real Galileo E1 signal. It can prove the reliable algorithms and data sources for the Galileo software receiver as an important reference which provides the reliable guarantee for the study of Galileo positioning algorithm.