GPS-based Real-Time and High-Rate Estimation of Earth Orientation Parameters

Accurate real-time values of Earth orientation parameters (EOP) (X and Y polar motion and rates, UT1-UTC rates) are desirable for a number of real-time applications, including GNSS orbit determination, positioning and timing, and deep space navigation. We will demonstrate a new capability to estimate EOPs, namely, X and Y polar motion and rates, UT1-UTC rates from GPS data alone in real time, and at high rate. Using RTGx, a new GNSS modeling and data analysis software developed at JPL to replace GIPSY and Real Time GIPSY (RTG), we explore estimation of EOPs within a real-time GPS orbit determination operation. We first characterize the errors in the conventional 1-2 days EOP predictions available through the IERS Bulletin A, and assess the impact of these errors on GPS orbit determination accuracy and on other key performance metrics. We then evaluate a variety of EOP stochastic estimation schemes, and demonstrate the ability to recover, in real-time, accurate EOP values with very high temporal granularity.