Radar-based method of measuring the level of a material in a vessel

US6054946A · kind A · utility

Assignee

• Endress+Hauser Inc. · DE

Inventors

• Robert Lalla · Bad Kötzting, DE
• Roland Muller · Weiling, DE
• Michael Sinz · Duvall, US

Key dates

• Filing date: Apr 26, 1999
• Grant date: Apr 25, 2000
• Expiry date: Apr 26, 2019

Classification

• Technology area (CPC G): Physics
• CPC primary: G01F23/284
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

For measuring the level of a material in a vessel by a radar-based method an antenna arranged above the highest level anticipated radiates electromagnetic waves to the surface of the material contained in the vessel and receives reflected echo waves. The transit time of the wanted echo waves reflected by the material surface is measured from which the level is computed. Since this transit time corresponds to the group delay, for determining the reduction factor by which the group velocity of the electromagnetic waves differs from the velocity of propagation in the free space due to the geometry of the propagation space the phase difference of the wanted echo waves relative to a reference oscillation and the group delay are measured for various levels and the reduction factor is determined on the basis of the changes in the phase difference as a function of the group delay.