Extended prediction of QZSS orbit and clock

This paper presents results on the accuracy of the extended (aka autonomous) orbit and clock predictions for the first QZSS satellite in orbit. The purpose of extended prediction is the reduction of the time-to-first-fix of a stand-alone satellite navigation receiver and the improvement of the availability of positioning during weak signal conditions. We describe the models we used to predict satellite orbit and clock and present the prediction accuracies we obtained with our models. With a constant-parameter solar radiation pressure (SRP) model, we obtained orbit prediction accuracies of 8, 25, and 80m for prediction lengths of 3, 7, and 14 days, respectively. With an SRP model with seasonally varying parameters the accuracies for prediction lengths of 3, 7, and 14 days are 7, 14, and 34 m, respectively. When predicting the QZSS clock for 7 days, the 68% and 95% quantiles of the accumulated prediction errors were 9 and 24m when using parameters with age of 7 days, 13 and 33m with age of 14 days, and 22 and 62m with age of 28 days.