Global Navigation Satellite System (GNSS) Ultra-Rapid Orbit/Clock/ERP Product Comparison Summary from NASA CDDIS

This derived product set consists of Global Navigation Satellite System Rapid Orbit/Reference Frame Product Summary from the 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. Analysis Centers (ACs) of the International GNSS Service (IGS) retrieve GNSS data on regular schedules to produce GNSS derived products. The IGS Analysis Center Coordinator (ACC) uses these individual AC solutions to generate the official IGS ultra-rapid combined orbit and ERP products. The ultra-rapid orbit and ERP is a sub-daily solution, released four times per day, at 03:00, 09:00, 15:00, and 21:00 UTC (prior to GPS week 1267 they were released twice daily). The solution summary file details information about the generation of the ultra-rapid products and comparison with the individual AC solutions. The reduced latency on availability of these products allows for significantly improved orbit predictions and reduced errors for user applications.

本派生产品集由美国国家航空航天局地壳动力学数据信息系统（CDDIS）提供的全球导航卫星系统快速轨道/参考框架产品概要构成。全球导航卫星系统（GNSS）具备全球覆盖的自主导航地理空间定位能力。CDDIS地面接收器收集的GNSS数据集主要包含美国全球定位系统（GPS）和俄罗斯GLObal NAvigation卫星系统（GLONASS）的数据。自2011年起，CDDIS GNSS档案中纳入了来自其他GNSS的数据（包括欧洲的伽利略卫星导航系统、中国的北斗卫星导航系统、日本的准天顶卫星系统/QZSS、印度的区域导航卫星系统/IRNSS，以及全球卫星基础增强系统/SBASs），这些系统在卫星星座、轨道和信号结构方面与美国GPS相似。国际GNSS服务（IGS）的分析中心定期检索GNSS数据，以生成GNSS派生产品。IGS分析中心协调员（ACC）利用这些独立分析中心的解决方案生成官方的IGS超快速组合轨道和ERP产品。超快速轨道和ERP产品是一种亚日解决方案，每日发布四次，分别于UTC时间的03:00、09:00、15:00和21:00发布（在GPS周1267之前，每日发布两次）。解决方案概要文件详细说明了超快速产品的生成过程以及与独立分析中心解决方案的比较。这些产品可用性的降低延迟显著提高了轨道预测的准确性，并减少了用户应用中的误差。