Accurate GPS LNAV Parameters and Clock Biases for ARAIM Offline Monitoring

In this article, we generate accurate global positioning system (GPS) legacy navigation (LNAV) orbital parameters to provide truth satellite positions and satellite clock biases for advanced receiver autonomous integrity monitoring offline monitoring. In our prior work, we proposed an estimator to determine satellite positions and clock biases, and here, we demonstrate the estimator performance using experimental data. We utilize the International global navigation satellite systems Service (IGS) ground network to collect dual-frequency raw GPS code and carrier phase measurements. The estimator is modified to handle practical challenges of experimental data, and detailed insight of estimated LNAV parameters and clock biases are discussed. The resulting signal-in-space ranging errors (SISREs) from the estimated LNAV parameters and clocks are predicted by covariance analysis to have a standard deviation $\sigma$ = 0.5 m. The performance of estimated LNAV parameters and clock biases is evaluated over ten days, and when compared with precise IGS orbit and clock products, the resulting SISREs are within $2\sigma$ at all times.