Simulation Of GPS Signal And GPS Offline Signal Analysis

With the development of the Global Navigation Satellite System GNSS, mostly strongcountries all over the world have built Satellite Navigation System for themselves, such as GPS,GLONASS, Galileo and Compass. One of the critical characteristics of Satellite NavigationSystem is the signal quality. The performance of satellite navigation system depends on thequality of satellite signal, and it also reflects the working state and electricity performance ofsatellite’s load. GNSS signal quality evaluation is of significant importance in the design andoperation of the satellite navigation system. Therefore, many countries attach great importance toGNSS signal quality evaluation. In the meantime, the monitoring and analysis laboratories ofnavigation signal have been set up in the building process of satellite navigation system,such asGPS, Galileo and Compass.The thesis is mainly divided into two parts. The first part analyze some modulatetechnologies widely used in the GPS signal system, including the Time-Multiplexed BOCadopted in the GPS modernization from two aspects, power spectrum density and autocorrelationfunction. Then the second part analyze two kinds of real GPS signal：signal in the base band andmonitoring receiver. The thesis presents different signal quality evaluation’s parameters and theresults of real signal evaluation.Signal in the base band is evaluated in the aspects of time field, frequency field,modulation characteristics and autocorrelation characteristics. In details, we mainly analysis theeye diagram in time field, the power spectrum density using the methods of Welch periods,thescatter and the autocorrelation peak et al.Signal in the monitoring receiver is evaluated in the aspects of stability, coherency andmultipath error. The stability of GNSS signal is judged by pseudorange stability and carrierstability using Least Squares. Coherency between codes and carrier weighs the comparativelytwitter’s degree between them, and it’s of vital importance to the measurement of distance andpseudorange smoothing by carrier phase. Using the equation exported from the arithmetic calledCode Minus Carrier, the multipath error on L1and L2can be estimated for all the samples ofdual frequency GPS data.With the technique of Matlab, the results of evaluation are elaborated in the end. Theseresults validate the methods’ correctness and feasibility and will have an instructive meaning forensuring the continuity and reliability of GNSS signal.