Thickness measuring device for concrete or asphalt layers uses transmission coil and relatively spaced reception coils cooperating with metal surfaces below concrete or asphalt layer

摘要

The device has a transmission coil coupled to a pulse or frequency generator and at least 2 relatively spaced reception coils, coupled to an evaluation circuit, for detection of metal surfaces of given size and shape with defined electrical and/or magnetic characteristics below the concrete or asphalt layer. The reception coils are positioned next to one another in a row with their surface normals parallel to one another. An Independent claim for a method for measuring the thickness of a concrete or asphalt layer is also included.