Error compensation by measurement of the STC filter function

Patent metadata

Field	Value
Publication number	US-9719831-B2
Application number	US-201314396804-A
Country	US
Kind code	B2
Filing date	May 3, 2013
Priority date	May 3, 2012
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

Level measuring device which can compensate the distortions, caused by an STC filter, of the received signal, by measuring a reference signal which passes through the receiving branch and also through the STC filter, during the ongoing operation of the level measuring device or during manufacture. For example, after passing through the receiving branch, this reference signal can be fed to a microprocessor which can calculate the correction values of the IF signal therefrom. A switch can be provided which can switch over between the reference signal and the IF signal.

First claim

The invention claimed is:

1. A level radar for compensating an error occurring during a determination of a filling level, comprising:
a reference signal provision unit configured to provide at least one of (a) a reference signal or (b) correction values;
a receiving unit recording a measuring signal;
a receiving branch having an FMCW module which is configured to convert the measuring signal into an intermediate frequency signal; and
a processor unit configured to at least one of:
(a) calculate correction values to correct the intermediate frequency signal using the reference signal; and
(b) use the correction values provided by the reference signal provision unit to correct the intermediate frequency signal.

2. The level radar according to claim 1 , wherein the reference signal provision unit includes a reference signal generating unit generating a reference signal and wherein the level radar further comprising:
a first switching unit connected on an input side to the FMCW module and the reference signal generating unit, the first switching unit being connected on an output side to a sensitivity time control (“STC”) filter of the receiving branch, the first switching unit being configured to switch over between the intermediate frequency signal from the FMCW module and the reference signal from the reference signal provision unit so that either the intermediate frequency signal or the reference signal is fed to the STC filter.

3. The level radar according to claim 2 , wherein the reference signal generating unit is a microprocessor.

4. The level radar according to claim 1 , wherein the processor unit is configured to correct distance errors associated with a distance-dependent attenuation of the intermediate frequency signal.

5. The level radar according to claim 1 , wherein the reference signal generating unit is a voltage controlled oscillator, a phase locked loop or a direct digital synthesis device.

6. The level radar according to claim 1 , wherein the reference signal generating unit is configured to pass through the frequency of the reference signal so that the processor unit can record a reference filter curve of the receiving branch of the level radar, which reference filter curve is used to calculate the correction values.

7. The level radar according to claim 1 , wherein the processor unit is configured to calculate the correction values during operation of the level radar.

8. The level radar according to claim 1 , wherein the receiving branch includes an A/D converter and wherein the level radar further comprising:
a second switching unit directly feeding the reference signal into the A/D converter.

9. A method for error compensation in a receiving branch of a level measuring device by measuring a filter function of the receiving branch, comprising steps of:
provisioning at least one of (a) a reference signal or (b) correction values;
recording a measuring signal;
converting the measuring signal into an intermediate frequency signal; and
calculating at least one of:
(a) correction values to correct the intermediate frequency signal using the reference signal; and
(b) a correction to the intermediate frequency signal using the correction values provided by a reference signal provision unit.

10. The method according to claim 9 , further comprising the step of:
switching over, in the receiving branch, between a received signal, corresponding to the measuring signal, and the reference signal.

11. The method according to claim 9 , further comprising the step of:
passing through the frequency of the reference signal to record a reference filter curve of the receiving branch of the level measuring device, which reference filter curve is used to calculate the correction values.

12. The method according to claim 9 , further comprising the step of:
measuring the reference signal by directly feeding the reference signal into an A/D converter.

Assignees

• Grieshaber Vega Kg
• Vera Grieshaber Kg

Inventors

• Schultheiss Daniel

Classifications

• G01S13/88

  Radar or analogous systems specially adapted for specific applications (electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00) · CPC title

• G01S2007/4073

  Physics · mapped topic

• G01S7/493

  Extracting wanted echo signals · CPC title

• G01S7/4021

  of receivers · CPC title

• G01S2007/4091

  Physics · mapped topic