Guided wave radar level gauge system with dielectric constant compensation through multi-frequency propagation

摘要

The present invention relates to a method of determining a filling level of a product contained in a tank by propagating a first transmitted electromagnetic signal in a first frequency range and a second transmitted electromagnetic signal in a second frequency range different from the first frequency range along a transmission line probe towards a surface of the product in the tank, receiving a first reflected electromagnetic signal in the first frequency range and a second reflected electromagnetic signal in the second frequency range, and determining the filling level based on a time-of-flight of the first reflected electromagnetic signal and a difference in time-of-flight of the first reflected electromagnetic signal and the second reflected electromagnetic signal.

主权项

1. A guided wave radar level gauge system, for determination of a filling level of a product contained in a tank, said guided wave radar level gauge system comprising:
a transceiver for generating, transmitting and receiving electromagnetic signals in a first frequency range and in a second frequency range different from said first frequency range; a single conductor transmission line probe connected to said transceiver, and arranged and configured to guide transmitted electromagnetic signals from said transceiver through a surrounding medium towards said product inside the tank, and to return reflected electromagnetic signals resulting from reflection of said transmitted electromagnetic signals by a surface of said product back towards said transceiver, the transmission line probe being configured to guide electromagnetic signals in said first frequency range with a first propagation velocity exhibiting a first dependence on a dielectric constant of the surrounding medium, and guide electromagnetic signals in said second frequency range with a second propagation velocity exhibiting a second dependence, different from the first dependence, on said dielectric constant of the surrounding medium; and processing circuitry connected to the transceiver for determining the filling level based on a first reflected electromagnetic signal in said first frequency range, a second reflected electromagnetic signal in said second frequency range, and a known relation between said first dependence and said second dependence on said dielectric constant of the surrounding medium, wherein the electromagnetic signals in said first frequency range and the electromagnetic signals in said second frequency range are guided by the single conductor transmission line probe in the same propagation mode.