Global Navigation Satellite System (GNSS) Decoded Real-Time Clock Solution from IGS Real-Time Product Streams from NASA CDDIS

This derived product set consists of Global Navigation Satellite System satellite and receiver clock products (10-second granularity, daily files, generated daily) from the real-time IGS analysis center submissions available from NASA Crustal Dynamics Data Information System (CDDIS). GNSS provide autonomous geo-spatial positioning with global coverage. GNSS data sets from ground receivers at the CDDIS consist primarily of the data from the U.S. Global Positioning System (GPS) and the Russian GLObal NAvigation Satellite System (GLONASS). Since 2011, the CDDIS GNSS archive includes data from other GNSS (Europe’s Galileo, China’s Beidou, Japan’s Quasi-Zenith Satellite System/QZSS, the Indian Regional Navigation Satellite System/IRNSS, and worldwide Satellite Based Augmentation Systems/SBASs), which are similar to the U.S. GPS in terms of the satellite constellation, orbits, and signal structure. These clock products are generated from real-time data streams in support of the IGS Real-Time Service. The real-time observation data from a global permanent network of ground-based receivers are transmitted from the CDDIS in 1 to multi-second intervals in raw receiver or RTCM (Radio Technical Commission for Maritime Services) format. These real-time data are utilized to generate near real-time product streams. The real-time products consist of GNSS satellite orbit and clock corrections to the broadcast ephemeris. These correction streams are formatted according to the RTCM SSR standard for State Space Representation and are broadcast using the NTRIP protocol. The product streams are combination solutions generated by processing individual real time solutions from participating IGS Real-time Analysis Centers (ACs). The effect of combining the different AC solutions is a more reliable and stable performance than that of any single AC's product. This derived product solution is one of the RTS solutions generated by decoding the real-time product streams. These files use the real-time data streams that are referred to the satellite center-of-mass (CoM). These clock products have been provided in support of the IGS Real-Time Service (previously Real-Time Pilot Project) since February 2009, prior to the availability of real-time product streams. This combination is a daily solution available approximately one to three days after the end of the previous UTC day. All satellite and receiver clock solution files utilize the clock RINEX format and span 24 hours from 00:00 to 23:45 UTC.