Research on GNSS-R sea surface altimetry status and common methods

The Global Navigation Satellite System (GNSS) is not only used for navigation, positioning, speed measurement, and timing, etc. It can also be used for sea surface wind field and sea surface altitude retrieval since  its reflected signals can also be received. Global Navigation Satellite System-Reflection (GNSS-R) is a new research area for marine remote sensing. The GNSS-R technology has many signal sources with wide coverage and stable long-term operation. This article mainly introduces the research progress of GNSS-R marine remote sensing technology and sea surface altimetry, and it ranges from signal-to-noise ratio (SNR) data measurement method, C／A code phase measurement method, carrier phase measurement method, and carrierbased measurement method. The common methods of GNSS-R in sea level measurement are analyed and summarized .