Patent ID: 8830118

Claim:
A method of monitoring operation of a radar level gauge system installed at a tank and arranged to determine a filling level of a product contained in the tank, comprising the steps of: providing a first propagation property discontinuity at a first level in the tank, said first level defining an overfill detection zone above a normal filling level range for the tank; generating and transmitting an electromagnetic signal; allowing said transmitted electromagnetic signal to propagate towards and into said product contained in the tank; receiving a reflected electromagnetic signal including a first reference echo resulting from reflection at said first propagation property discontinuity and a surface echo resulting from reflection at a surface of said product contained in the tank; determining, based on the reflected electromagnetic signal, if said first reference echo is detectable at said first level; determining, based on the reflected electromagnetic signal, if said surface echo is detectable; in response to said surface echo being detectable, providing a fill level output indicative of said filling level; and in response to said surface echo being non-detectable and said first reference being detectable at said first level, deducing that the monitoring device is functional, and continuing operation of the tank, and in response to said surface echo being non-detectable and said first reference being non-detectable at said first level, providing an overfill condition output.