The International GNSS Service (IGS) realtime\nservice (RTS) provides access to real-time precise\nproducts such as orbits, clocks and code biases, which can\nbe used as a substitute for ultra-rapid products in real-time\napplications. The true performance of these products can be\nassessed by the Analysis Centers daily statistics derived\nfrom the comparison with IGS rapid products. Additionally,\nindirect verification is performed by their application\nto various precise point positioning strategies. Monitoring\nresults and basic descriptions of these products are available\nat the official RTS Web page (http://rts.igs.org/). We\npresent a more detailed description of RTS products.\nInformation from various sources is collected to provide\nproducts application methodology and describe their\nimportant features. We provide extended verification of the\nproducts using 1 week of real-time correction data. Results\nare presented separately for GNSS constellations, considering\nsatellite block and type of onboard clock. Comparison\nwith ESA/European Space Operations Centre final\nproducts proves the high accuracy of RTS orbits and\nclocks, which is 5 cm for GPS orbits, 8 cm for GPS clocks,\n13 cm for GLONASS orbits and 24 cm for GLONASS\nclocks. The real-time correction performance is also\nexamined regarding availability and latency. In general, the\navailability of corrections was beyond 95 % for GPS and\nbeyond 90 % for GLONASS. Since the increasing degradation\nof product quality with latency is critical for realtime\napplications, the relation between product latency and\naccuracy is analyzed. It confirms that high-rate stream\nupdate intervals are suitable for the data provided and that\nthe obsolete data should not be used. To avoid this, we\npropose a method of short-term prediction of RTS corrections\nthat extends the application period of obsolete\ncorrection data without a significant loss in orbit quality.\nUsing polynomial fitting, it is possible to forecast the orbit\ncorrections reliably up to 8 min for GPS and 4 min for\nGLONASS.
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