星载GPS观测数据的模拟研究

重点分析了星载GPS观测值模拟的原理、数学模型等，并用模拟软件模拟了CHAMP卫星的星载GPS观测值情况．结果表明，根据本文提供模拟方法所模拟的CHAMP星载GPS观测值，与实测值相比，无论是在大小还是观测噪声水平上都很接近，因此能满足不同层次人员对星载GPS模拟观测值的需要．

A Simulation Study of Onboard GPS Observations of LEOs

The simulation of GPS observation on a moving low-earth-orbiter(LEO)is to simulatethe measured signals that would be received by a GPS receiver on a LEO.Since a LEO and GPSsatellites are in a three-dimensional coordinate system,the values of various errors and observationnoise level can be well calculated and known in advance,so using GPS simulation of the observationsof a onboard GPS receiver can be of great help for judging some important parameters in orbitdetermination such as ambiguity resolution method,Kalman filtering technique and so on.In thispaper,the method of simulating GPS observations of an onboard GPS receiver is systematicallystudied.The emphasis is first put on principle and mathematical model.Then,the GPS dual-frequency P codes and carrier-phase observations of potential onboard GPS receivers are simulated byemploying some elaborately selected error modes.The results show that the simulated observationsof CHAMP satellite obtained from software developed by the author are very close to the realmeasurements in-situ and such is observation noise level,therefore the simulation method used inthis paper can meet the needs of different users of GPS data.