The Research And Implementation Of Navigation Satellite Payload Software Simulation System

With the development of satellite navigation and position technology, satellite navigation has been produced a profound impact on the whole world people’s production and life. Currently, the USA GPS system due to early deployment time, high position coverage, leading-edge technology and high position accuracy, is ahead in the field of satellite navigation, while China’s Bei Dou satellite navigation system is also developing rapidly. Combing the principles of satellite communication, satellite navigation and position theory and computer simulation theory, this paper proposed and established a relatively complete software simulation platform for satellite navigation. According to the configuration of the GPS system, the simulation platform contains the monitoring station member, the injection portion of the ground station, the uplink and downlink transmission channel, the satellite part, the receiver portion of the ground and so on, these portions correspond to the actual structural members in the GPS system, and the sub-function processing modules in each sections correspond to the function modules in the reality.In the simulation platform functionality, the paper discusses all the module function in the payload satellite navigation simulation system in detail, including the generation of the baseband signal, the signal conversion, filtering, etc., and discusses based on parallel FFT’s code phase acquisition algorithm and the Early-Late lead-lag pseudo-code code tracking loop. It also analyzes the effects of ionosphere and troposphere in channel environment on satellite signal, and its error correction is generated by the Klobuchar and Hopfield models.In the simulation framework, the paper discusses the message response mechanism and signal transmission mechanism those based on TCP/IP underlying transport protocol within the platform in detail. It also discusses the interactive control mechanisms between members within the simulation system and the design of advance the simulation process. Finally, the efficiency of signal processing modules within the platform was compared with the actual modules.Previous studies on satellite navigation simulation are mostly against only the generation and processing of partial block signals. While this paper propose a simulation platform which function is relatively intact and with high authenticity. Today, our country’s Bei Dou navigation system hardware is improving, the construction of hardware system is extremely complex, and its development and maintenance are costly. On the contrary, software simulation is very flexible and saving funds. Meanwhile, the design of a complete signal generation algorithm is the basic theory of developing signal simulators within the entire satellite navigation system, the realization of software receiver for GPS signal acquisition and tracking and to verify and evaluate the correctness of the generated digital intermediate frequency signal. This work also has important theoretical guiding significance for the development of China’s Bei Dou series signal simulator. So it is very necessary to establish a complete set of satellite navigation simulation system. The navigation satellite payload simulation system which based on GPS system, in the feature, will realize the replacement to the Bei Dou system.