Research And Realization Of GNSS Satellite Signal Simulator

In recent years, the technology of satellite navigation has developed rapidly. It has been widely used in various areas. In order to improve the performance of navigation and position receiver, a satellite signal simulator with sufficient precision, which can simulate different environments signals and be used for quantitative evaluation, is very essential. Therefore, the research for simulator has a very important role.The function of the GNSS (i.e.Global Navigation Satellite System) satellite signal simulator is to simulate the GNSS satellite signals for all kinds of actual environments. Because of the sensitivity and complexity of this technology, there are few open references, also the research of simulator has needed to understand the whole GPS system. So the development is very difficult. In this area, some foreign countries start earlier and have achieved great progress, but domestic research starts later. So the GPS system can be referred to develop our own satellite navigation system.In this thesis the GPS satellite signal simulator is used as a reference to realize the multi-channel GPS satellite signal simulator. The position principles of satellite navigation are firstly introduced, then the GPS signal structure and navigation message is described, also the principles of the direct sequence spread spectrum communication system and the pseudorandom sequence's generation is researched, still the direct digital frequency synthesis technology and over-sampling shaping filter is discussed. On this basis, a signal processor method is proposed, in which computer transfers the data packets to the the module for baseband digital signal processing, then the signal flows through the digital upconvert module, and is transmitted to GPS receiver. And the FPGA design of the baseband signal processor part is achieved, and the correctness of the FPGA design is verified, and the storage structure of the data packets is optimized, also the multi-channel GPS satellite signal simulator is realized.