Figure 1
From: Sea level measurements using multi-frequency GPS and GLONASS observations
Panoramic view of the GNSS tide gauge at the Onsala Space Observatory. The installation is directed towards the south to receive the reflected GNSS signals from the open water surface (middle). Approximate azimuth directions are indicated in the top of the picture, showing that the open sea extends from azimuth 60° to 300°. To the east (left) and west (right), the water surface is confined by bedrock.