1:45 PM - 3:15 PM
[HTT14-P01] Research on Precise Point Positioning with GPS and GLONASS Broadcast Ephemerides
★Invited Papers
Keywords:GNSS, broadcast ephemerides, PPP, Spectrum Analysis
With the advancement of Global Navigation Satellite System (GNSS) technology and the convenience of use of equipment, the maturity of GNSS applications in various fields has greatly exceeded its original development goals and ideas: military applications. GNSS provide services for many national important infrastructure that is closely related to economy and livelihood, including the unmanned autonomous driving that is actively promoting. GNSS positioning technology has advanced from relative positioning and single-point positioning, and later evolved into today’s precise point positioning (PPP), it is expected by all users that how to balance positioning speed and positioning accuracy. GNSS positioning relies on the satellite orbits and clocks, which are forecasted on the surface and delivered by satellites as part of their broadcast navigation messages. High-precision positioning depends on the quality of the using satellite orbit information. However, in many applications, in order to obtain the effect of fast positioning, low-latency orbit products (fast and ultra-fast ephemerides/clocks) or broadcast products are used instead at the cost of lower-precision satellite positioning. In addition to the old satellite system updating, it is also an important issue to determine the accuracy of the broadcast orbit with the emergence of the new global and regional GNSS.
In this study, the GPS and GLONASS constellations are taken as the main research targets. In addition to comparing the broadcast ephemeris to the precise ephemeris, the accuracy comparison of precise point positioning (PPP) by using the broadcast ephemeris are also carried out. First, about the comparison of the spectrum analysis of the broadcast ephemeris. According to our results in this research, it is pointed out that the broadcast ephemeris has obvious and strong signal cycle changes every 1.07 years, 2.05 years and 3.12 years. This cycle pattern of the broadcast ephemeris is roughly the same as that of the precision ephemeris. Next, about the PPP results for each constellation by using the broadcast ephemeris or the precise ephemeris. The 3D RMS of the difference in GPS positioning results is about 1.78 meters, in GLONASS positioning results is about 0.92 meters and in two-constellation (GPS+GLONASS) is about 2.32 meters. The difference in the two-constellation is the largest, followed by the GPS, and the GLONASS the least. Finally, take PPP results of the precise ephemeris in two-constellation be the reference values for comparison of broadcast ephemeris positioning results. The positioning results of the broadcast ephemeris in GPS constellation is the best, followed by the two-constellation and the GLONASS constellation the least, which the 3D RMS are 1.03 meters, 1.34 meters and 5.58 meters, respectively. According the above results, for the application of broadcast ephemeris to PPP, it is recommended that positioning results in GPS constellation is better than two-constellation combination.
In this study, the GPS and GLONASS constellations are taken as the main research targets. In addition to comparing the broadcast ephemeris to the precise ephemeris, the accuracy comparison of precise point positioning (PPP) by using the broadcast ephemeris are also carried out. First, about the comparison of the spectrum analysis of the broadcast ephemeris. According to our results in this research, it is pointed out that the broadcast ephemeris has obvious and strong signal cycle changes every 1.07 years, 2.05 years and 3.12 years. This cycle pattern of the broadcast ephemeris is roughly the same as that of the precision ephemeris. Next, about the PPP results for each constellation by using the broadcast ephemeris or the precise ephemeris. The 3D RMS of the difference in GPS positioning results is about 1.78 meters, in GLONASS positioning results is about 0.92 meters and in two-constellation (GPS+GLONASS) is about 2.32 meters. The difference in the two-constellation is the largest, followed by the GPS, and the GLONASS the least. Finally, take PPP results of the precise ephemeris in two-constellation be the reference values for comparison of broadcast ephemeris positioning results. The positioning results of the broadcast ephemeris in GPS constellation is the best, followed by the two-constellation and the GLONASS constellation the least, which the 3D RMS are 1.03 meters, 1.34 meters and 5.58 meters, respectively. According the above results, for the application of broadcast ephemeris to PPP, it is recommended that positioning results in GPS constellation is better than two-constellation combination.