Electronic distance meter (EDM)

To measure horizontal distance, sloping distance and vertical distance between two points.
To get the elevation of the remote object.
To set the point at a predetermined distance along grid lined.
To align the electronic plots or towers and columns of the industrial building.
EDM instruments are classified according to the type of carrier wave employed.
Instruments using light or IR waves are classified as electro-optical instruments.
Instruments based on radio waves are generally called microwave instruments.
These instruments are now obsolete within the surveying industry being replaced by total station technology.