Digital Level is an automatic instrument used to establish or check points in the same horizontal plane. It is used in surveying and building with a vertical staff to measure height differences and so transfer, measure and set heights.
Echo sounding is a type of SONAR used to determine the depth of water by transmitting sound pulses into
DGPG RTK GNSS
Differential Global Positioning System (DGPS) is an enhancement to Global Positioning System that provides improved location accuracy. DGPS uses a network of fixed, ground-based reference stations to broadcast the difference between the positions indicated by satellite systems.