Testing And Evaluation Of Satellite Navigation System Time

The satellite navigation system is based on time measurement, whose precisiondirectly affect the positioning and velocity performance of satellite navigation system.Precise time measurement firstly need to establish a unified time reference-thesystem time, and then make atomic clocks time synchronization system to the systemtime through the time synchronization technology, and eventually the system timebroadcast to the user via satellite. In addition, the timing is the most importantfunction of satellite navigation system, so take a satellite navigation system is thesystem time can be traced back to the international general official time-coordinateduniversal time (UTC).System time is the core element for satellite navigation system to givepositioning, velocity measurement and time service, and the performance ofestablishment, broadcasting and tracing the system time directly impacts on theperformance of satellite navigaton system, including the precision of theusers’positioning, velocity messurment and time service, so it is very important to testand evaluate the system time. In other countries, the system time monitoring andevaluation work have been widespread attention and done throughout thedevelepment and construction process, and in our country testing and evaluationtechnology in this area is relatively backward. It is necessary to carry out the researchof theory, method and technology for the system time’s testing and evaluation,establishing testing and evaluation system, developing related software, which willbring benefit to Compass’develepment and construction. The main work of this paperis:This paper studied the basic principles of system time testing and evaluation,analized the characteristics of diverse time comparation links and its precisioncalibration method was researched. A two-way portable station calibration methodwas proposed. Different testing and evaluation system were designed. In the case ofGPS and Compass, testing and evaluation test had been done for their system time’sestablishment, broadcasting and tracing, and the main research contents are asfollows:1. In case of Compass, a testing and evaluation system was designed. Thedifferent characteristic of time comparison link was analyzed, selection method oftime comparison link and sample time was researched under different performanceevaluation requirement, and the establishment performance of Compass system time was tested and evaluated. The results shows that the frequency accuracy of Compasssystem time is better than2E-13,7day frequency stability is slightly higher than1E-14, basically meet the design requirement.2. The device delay calibration method was researched, a calibration methodwith two portable stations was proposed, and delved into the variation characteristicof satellite two way time comparison device delay and small magnitude errorcorrection method.3. The broadcasting performance was tested and evaluated from the userperspective, a system was designed to test and evaluate the Compass broadcastingperformance. The results show that the Compass the performance is better than GPS,but its accuracy is the calibration should be considered for the system timebroadcasting error.4. Starting from the system level, testing and evaluation of the GNSS tracingperformance was studied. In the case of Compass and GPS, the testing and evaluationexperiment was done and the results show that the tracing deviation of BDT fluctuateswhithin±30ns, comparing with the15nsfluctuation of GPST tracing deviation. Thetracing performance form GPST to UTC is better than BDT, with GPST controllingprecision better than1.5ns, while controlling precision of BDT is20ns.