GPS antenna installed to monitor ground motion at Yellowstone.
By Volcano Hazards Program
1905 (approx.)
Detailed Description
High-precision GPS antenna for receiving the signals from orbiting GPS satellites at Lake Junction, Yellowstone. It is connected to the earth by a specially installed 2" Invar rod. This is a special antenna that shields out extraneous microwave signals and allows the precision of measuring ground movements to millimeters.
Sources/Usage
Public Domain.