From Network to Rover: Near Real-Time PPP Solution with Ambiguity Resolution

Abstract

While Precise Point Positioning with Ambiguity Resolution (PPP-AR) has become a major tool in multi-constellation Global Navigation Satellite System (GNSS), a critical component to enable it is the generation of satellite phase biases. Several analysis centers (AC) under International GNSS Service (IGS) have developed services to generate PPP-AR products including phase bias corrections with a typical delay reaching several days. Another significant challenge is the lack of interoperability between the various corrections streams and rover PPP engines, each one having a different error model. Current and emerging applications need not only the centimeter precision provided by the PPP-AR but also the availability merely hours after the mission is accomplished. Finally, an end-to-end solution, capable of both generating corrections and computing the user position to the centimeter level, is a key to addressing a non-expert audience. This paper aims to present an innovative solution that guarantees the end user a centimeter-level position in near real-time. The in-house solution is responsible for the entire processing chain including the estimation of satellite phase biases which are needed for integer ambiguity resolution (AR) in PPP, and the user-side PPP-AR position computation. The major advantage of our solution is the ability to provide corrections less than one hour after the mission, thus enabling new applications. Initial results of the designed estimator showed great stability of the Uncalibrated Phase Delays (UPDs). The latter when infused into our PPP solution produced a centimetric position.