Patent ID: 7075479
Filing Date: 2006-07-11
Classification: G01F,G01S

Abstract:
1. A method for measuring the level of a liquid surface in an enclosed space, in which a liquid, is stored, the method comprising: a radar unit mounted on the roof of the enclosed space transmits a microwave signal downwards into the enclosed space through a waveguide that communicates with the liquid in the enclosed space, the transmitted microwave signal's polarization alters according to a predetermined time sequence in such a way that the signal is propagated alternately at least in a first and a second plane of polarization, the signal transmitted in the first plane of polarization is reflected by the liquid surface back to the radar unit, whereupon the signal's running time is measured, the signal in the second plane of polarization is reflected by at least one reference transmitter placed at a known distance from the radar unit, after which the microwave signal's velocity of propagation is measured, a calculating unit calculates the level of the liquid surface based partly on the time elapsed between the signals emitted and received by the radar unit, partly on the microwave signal's velocity of propagation.