Research On Technique Of Galileo Satellite Navigation System IF Signal Simulation

With the Global Navigation Satellite System being used widely, studying navigation satellite signals is becoming a hot spot. Navigation satellite signals simulation is able to simulate a variety of satellite signals in real environment. It plays a crucial role in the varieties of tests of receivers’ performance, and it can reduce the development cost and improve development efficiency of receivers. Under this background, the paper is going to study the simulation of the IF(Intermediate Frequency) signal of Galileo satellite navigation system, and to derive the mathematical model of the Galileo satellite IF signal, and to propose the framework of the IF signal simulation, and to establish every model in the simulation of information level and signal level. After the simulation, Galileo satellite IF signal is generated, and its correctness is also verified.The paper mainly studys the simulation technology of IF signal of Galileo satellite navigation system, and it simulates the Galileo intermediate frequency signal in the real environment. Firstly, it derives mathematical model of the Galileo satellite IF signal in detail, and the model includes mathematical models of launching satellite signal and propagating satellite signal in the space and RF front-end processing of receiver. Then the paper raises the structure of the IF signal simulation, including information level simulation and signal level simulation.In the information level simulation, it derives mathematical models of the satellite clock error, ionospheric delay and tropospheric delay, which have greater impacts on the accuracy of pseudorange observation, and it also derives mathematical models of position, velocity and acceleration of the satellite. Based on the study of Galileo navigation message model and measurement model, it achieves the simulation of information-level model, and then it verifies the navigation message data and observation data. In the signal level simulation, it studies the principle of spread spectrum modulation, subcarrier modulation and carrier modulation, and simulates the model of pseudo-code generation and signal modulation. Then the initial Galileo satellite IF signal is generated. Based on the analysis of the basic principles of noise generation, sampling and quantization, it simulates the models of them, and then the Galiloe IF signal is added noise, sampled and quantized. By comparing the effects of different intensity noise, different sampling rates and different quantization bits on the signal, it determines the noise intensity, sampling rate and quantization bits used in the simulation in the paper. After the above processing, Galileo satellite digital IF signal is generated. By analyzing the time domain and frequency domain waveforms, it can conclude that the simulated signal is correct.Finally, by comparing the results of signal acquisition, tracking and position resolution processing of the software receiver and the navigation message data and observations data of information level simulation, it can conclude that the simulated Galileo satellite IF signal is correct, and the simulating program is reasonable.