| With the development of Navigation technology, GNSS(Global Navigation Satellite System) has achieved rapid progress in the field of Civil Aviation, the aircraft has different requirements of the airborne equipment for each flight phase, how to accurately verify GNSS receivers, especially under the abnormal ionospheric environment, whether can meet this requirement is very important. Receiver's performance parameters including positioning accuracy, velocity measurement accuracy, timing accuracy receiver autonomous integrity monitoring, and so on. Based on GNSS receiver test platform as the research content, the research mainly focuses on the test platform for the abmormal ionospheric environment.Taking GPS as an example, firstly introduces the components of the GPS signal,including the navigation message and C/A code, and discusses the troposphere and ionosphere effect on the signal during the signal propagation process.Then, realizes the simulation of GPS signal module and error setting module, including the calculation of visible stars, signal launching time and travelling time, and based on the TEC IONEX format data provided by IGS designs the ionosphere TEC interpolation software,and analyzes several kinds of ionospheric environment anomalies, including earthquake, nuclear and electric magnetic storms, in addition, tropospheric error model is established.Then, studies the method of calculating position accuracy and protection limit, the alarm time,alarm period and integrity risk, and on this basis, this paper discusses the evaluation method and process of positioning accuracy and RAIM.Finally, based on the evaluation platform design and overall architecture, realizes the evaluation platform development. Parameter setting module and evaluation module are introduced in detail,and the effectiveness of the evaluation platform,which including signal simulation module,error setting module and evaluation module, is verified by simulation and the output of the receiver. |
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