Introduction to GNSS

In this chapter, GNSS history, system, signals, principle and error sources are introduced as well as its applications in positioning, navigation and timing. In addition, GNSS is an L-band microwave technique, which implies more and wider applications and potentials. The ground GNSS observations together with GNSS Radio Occultation (RO) can provide the atmospheric and ionospheric parameters. The GNSS-Refectometry (GNSS-R) from the Earth’s surface could remotely sense the land, hydrology, ocean, vegetation, snow and cryosphere.