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

US5948979A · kind A · utility

Assignee

• Endress+Hauser Inc. · DE

Inventors

• Carsten Fitsch · Bad Säckingen, DE
• Wolfgang Lubcke · Steinen, DE
• Peter Gerst · Weil am Rhein, DE
• Jurgen Lau · Hofheim, DE

Key dates

• Filing date: Jun 3, 1998
• Grant date: Sep 7, 1999
• Expiry date: Jun 3, 2018

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 container on the basis of the radar principle, microwaves are radiated downwards and reflected microwaves received by means of the antenna of a ranging device arranged above the highest level anticipated. In the normal measuring operation the received microwaves are evaluated in the distance range up to empty distance corresponding to the distance of the antenna from the bottom of the container for determining the echo waves reflected from the surface of the material, for measuring the transit time of the echo waves and for computing the distance of the material surface from the antenna of the ranging device from the measured transit time. In order to reliably detect the empty condition of a container having a curved bottom, despite the multiple reflections of the microwaves reflected from the container bottom, when no echo waves are detected in the distance range up to the empty distance, the evaluation is done in an enlarged distance range and any echo waves detected in the enlarged distance range beyond the empty distance are assigned to the empty distance.