GPS System Modeling And Simulation Technique

Global Position System (GPS) offers us highly precise position, speed, and time information all-day in any weather. As GPS is getting more and more important in military and civil use, it has a good application foreground. The extension of the application area of GPS brings forward more requirements to the performance and precision of GPS receiver. Therefore, for various application systems, we need to verify if the performance and precision of the receiver satisfy the requirements. It has merits like short cycles, high benefits, no venture, repeatability, and controllability when we adopt system simulation method instead of expensive physics experiments and practicality experiments. In this paper, the GPS navigation positioning system simulation method is intensively studied.Firstly, a series of reference systems, related to GPS navigation positioning system, such as timing system, reference frame and force model system, are discussed in detail. These three systems make up of the simulation theory base. Secondly, the GPS satellite circulating orbit is simulated, according to the position, speed, acceleration and the rate action factor of acceleration, given by GPS satellite broadcast star calendar. Because of the huge influence of GPS error on simulation effect, the error simulation method is studied intensively. The errors simulated include troposphere error and ionosphere error. At present, there are many models to select. After some comparison, we choose two models which are fit for simulation, EGNOS troposphere error model and Klobuchar ionosphere error model. Then we carry out star choosing arithmetic, transformation from geography coordinates system to earth coordinates system, user position obtaining, fake distance equation solving and simulation information solving. Finally, the simulation software of GPS navigation positioning system is compiled.