The Future is Now: GPS + GLONASS + SBAS = GNSS

摘要

In the future, we will enjoy the benefits of a global navigation satellite system consisting of several independent systems. But do we have to wait for the future? No. The GNSS system of systems is already here. We have the extremely successful American GPS and the partly rebuilt Russian GLONASS, as well as several active geostationary satellite-based augmentation system (SBAS) satellites in orbit. All satellites of these three GNSSs provide us with ranging signals and thus pseudorange (code-phase) and carrier-phase observations usable for positioning and many other applications. This article focuses on the combined use of all readily available GNSS signals for precise positioning applications such as real-time kinematic (RTK) surveying operations, including carrier-phase ambiguity fixing. This year, the GPS satellite constellation reached a new height: 31 active satellites in space and thus more GPS ranging signals available than ever before. But, for many applications, this still is not enough. As we all know from our own experiences, signals are often obstructed at many locations. More satellite signals can help increase GNSS availability. And more ranging signals improve positioning accuracy as well. Hence, the use of all available GNSS signals generally improves positioning performance.