US 12,085,437 B2
Level meter for level limit determination and for measuring an impedance of a filling material
Bernhard Corbe, Schutterwald (DE); and Benjamin Schaetzle, Hausach (DE)
Assigned to VEGA Grieshaber KG, Wolfach (DE)
Filed by VEGA Grieshaber KG, Wolfach (DE)
Filed on Aug. 2, 2022, as Appl. No. 17/816,801.
Claims priority of application No. 10 2021 120 175.6 (DE), filed on Aug. 3, 2021.
Prior Publication US 2023/0175880 A1, Jun. 8, 2023
Int. Cl. G01F 23/26 (2022.01); G01F 23/24 (2006.01); G01F 23/263 (2022.01); G01F 25/20 (2022.01)
CPC G01F 23/241 (2013.01) [G01F 23/266 (2013.01); G01F 25/24 (2022.01)] 13 Claims
OG exemplary drawing
 
1. A level measuring device for level and/or limit determination and for measuring an impedance of a filling material in a container, comprising:
a measuring probe configured to measure the impedance of the filling material, the measuring probe comprising:
a sheath electrode; and
a measuring electrode disposed at least partially within an outer contour of the sheath electrode;
a signal generation unit configured to:
generate a first variable frequency signal, wherein the measuring probe is supplied with the first variable frequency signal and outputs a measurement signal, and
generate a second variable frequency signal, the second variable frequency signal having a constant frequency difference from the first variable frequency signal;
a measurement converter configured to convert the measurement signal into a mixed signal, the mixed signal having a phase and amplitude difference from the first variable frequency signal;
a transducer, comprising:
a reference mixing unit configured to mix the first variable frequency signal with the second variable frequency signal to produce a first reference signal; and
a receive mixer unit configured to mix the second variable frequency signal with an output of a measuring bridge to produce the mixed signal, the measuring bridge being connected to the measuring probe; and
a phase difference measuring unit configured to determine an amplitude-phase response of the material measured by the measuring probe, by means of the phase and amplitude difference between the first variable frequency signal and the mixed signal, based on the variable frequency of the first variable frequency signal.