External radiation detection with a gamma modulator

Patent metadata

Field	Value
Publication number	US-11927468-B2
Application number	US-201917268025-A
Country	US
Kind code	B2
Filing date	Sep 12, 2019
Priority date	Sep 14, 2018
Publication date	Mar 12, 2024
Grant date	Mar 12, 2024

Abstract

A radiometric measuring device for determining an intensity of pulses of an interference signal from an external radiation source, wherein the radiometric measuring device carries out fill level or limit level determination of a filling material in a container. The radiometric measuring device has a detector which is configured to receive pulses of a useful signal modulated with a modulation frequency from a gamma emitter and additionally pulses of the interference signal from the external radiation source. Further, the measuring device comprises an averager configured to output a first count rate of the pulses at an averager output, and a bandpass system comprising a bandpass with adjustable passband frequency range configured to output a second count rate of the pulses at a bandpass system output. The measuring device further comprises a subtractor adapted to form a differential count rate between the first count rate and the second count rate.

First claim

The invention claimed is:

1. A radiometric measuring device for determining an intensity of pulses of an interference signal from an external radiation source during a filling level or limit level determination of a filling material in a container, the radiometric measuring device comprising:
detector circuitry configured to receive pulses of a useful signal modulated with a modulation frequency from a gamma emitter and additional pulses of the interference signal from the external radiation source;
averager circuitry configured to output a first count rate of the pulses at an output of the averager circuitry,

wherein the first count rate corresponds to an average of a first number of pulses within a predefined time period received from the detector circuitry over the predefined time period; and
a bandpass system including a bandpass filter having a passband frequency range configured to output a second count rate of the pulses at a bandpass system output,
wherein the passband frequency range of the bandpass filter corresponds to the modulation frequency of the modulated useful signal from the gamma emitter, and
wherein the second count rate corresponds to a second number of pulses within the predefined time period received by the detector circuitry in a bandpass frequency range of the bandpass filter over the predefined time period; and

subtractor circuitry configured to form a differential count rate, wherein the differential count rate corresponds to a difference between the first count rate and the second count rate, such that the differential count rate corresponds to an intensity of the interfering signal from the external radiation source.

2. The radiometric measuring device according to claim 1 ,
wherein the differential count rate is compared with a threshold value and, if the threshold value is exceeded, an action is triggered.

3. The radiometric measuring device according to claim 2 ,
wherein the action includes suspending a temperature control.

4. The radiometric measuring device according to claim 2 ,
wherein the action includes storing a time stamp and/or a value of an intensity of the interference signal.

5. The radiometric measuring device according to claim 2 ,
wherein the action includes issuing a warning.

6. The radiometric measuring device according to claim 1 ,
wherein the radiometric measuring device fluffier includes a frequency determination module configured to determine the modulation frequency of the modulated useful signal from the gamma emitter and to adjust the passband frequency range of the bandpass filter with adjustable passband frequency range to the modulation frequency of the modulated useful signal.

7. The radiometric measuring device according to claim 1 ,
wherein the passband frequency range of the bandpass filter has a center frequency between 0.05 and 20 Hertz, in particular of 1 Hertz.

8. The radiometric measuring device according to claim 1 ,
wherein the predefined period of the counting rates is between 0.02 and 50 seconds, for example between 0.05 and 20 seconds, and in particular 1 second.

9. The radiometric measuring device according to claim 1 ,
wherein the first counting rate is proportional to k times a mean value of the first number of pulses, in particular with k=½.

10. The radiometric measuring device according to claim 1 ,
further comprising:
a modulator driving a movable aperture around the gamma emitter and/or an electronic circuit,
wherein the modulator is configured to modulate a signal from the gamma emitter to produce the modulated signal.

11. A method of determining an intensity of an interference signal from an external radiation source during a fill level or boundary level determination, by way of a radiometric measuring device for determining an intensity of pulses of an interference signal from an external radiation source during a filling level or limit level determination of a filling material in a container, the radiometric measuring device including a detector configured to receive pulses of a useful signal modulated with a modulation frequency from a gamma emitter and additional pulses of the interference signal from the external radiation source, an averager configured to output a first count rate of the pulses at an output of averager circuitry, wherein the first count rate corresponds to an average of a first number of pulses within a predefined time period received from the detector over the predefined time period, and a bandpass system including a bandpass filter having a passband frequency range configured to output a second count rate of the pulses at a bandpass system output, wherein the passband frequency range of the bandpass filter corresponds to the modulation frequency of the modulated useful signal from the gamma emitter, and wherein the second count rate corresponds to a second number of pulses within the predefined time period received by the detector in a bandpass frequency range of the bandpass filter over the predefined time period, and a subtractor configured to form a differential count rate, wherein the differential count rate corresponds to a difference between the first count rate and the second count rate, such that the differential count rate corresponds to the intensity of the interfering signal from the external radiation source, the method comprising:
receiving, by way of the detector, pulses of a useful signal modulated with a modulation frequency from a gamma emitter and, in addition, the interfering signal from the external radiation source;
outputting a first count rate, by way of the averager;
outputting a second count rate, by way of a bandpass system;
forming a differential count rate, by way of the subtractor, which subtracts the second count rate from the first count rate; and
outputting the differential count rate.

12. The method according to claim 11 , further comprising:
comparing the differential count rate with a threshold value; and
if the threshold value is exceeded, triggering an action.

13. A non-transitory computer-readable medium having stored thereon a program that when executed by a computer causes the computer to implement a method of determining an intensity of an interference signal from an external radiation source during a fill level or boundary level determination, by way of a radiometric measuring device for determining an intensity of pulses of an interference signal from an external radiation source during a filling level or limit level determination of a filling material in a container, the radiometric measuring device including a detector configured to receive pulses of a useful signal modulated with a modulation frequency from a gamma emitter and additional pulses of the interference signal from the external radiation source, an averager configured to output a first count rate of the pulses at an output of averager circuitry, wherein the first count rate corresponds to an average of a first number of pulses within a predefined time period received from the detector over the predefined time period, and a bandpass system including a bandpass filter having a passband frequency range configured to output a second count rate of the pulses at a bandpass system output, wherein the passband frequency range of the bandpass filter corresponds to the modulation frequency of the modulated useful signal from the gamma emitter, and wherein the second count rate corresponds to a second number of pulses within the predefined time period received by the detector in a bandpass frequency range of the bandpass filter over the predefined time period, and a subtractor configured to form a differential count rat

Assignees

• Grieshaber Vega Kg

Inventors

• Laun Robert

Classifications

• G01F23/288 Primary

  X-rays; Gamma rays {or other forms of ionising radiation} · CPC title

• G01T1/17

  Circuit arrangements not adapted to a particular type of detector {(pulse-selection circuits H03K, G01R)} · CPC title

• G01T1/178

  for measuring specific activity in the presence of other radioactive substances, e.g. natural, in the air or in liquids such as rain water · CPC title