阅读说明：本技术 利用伽马调制器的外部辐射检测 (External radiation detection using gamma modulators ) 是由 罗伯特·劳恩 于 2019-09-12 设计创作，主要内容包括：本发明涉及一种用于确定来自外部辐射源的干扰信号的脉冲强度的放射性测量装置,其中,放射性测量装置确定容器中的填充材料的填充物位或极限物位。放射性测量装置(10)包括探测器(30),该探测器被构造为接收来自伽马射线发射器(20)的利用调制频率调制的有用信号的脉冲,并且还接收来自外部辐射源(25)的干扰信号的脉冲。测量装置(10)还包括被构造为在平均值生成器输出端(59)处输出脉冲的第一计数速率(N1)的平均值生成器(50)以及包括具有可调节通带频率范围的带通滤波器(45)的带通系统(40),低通滤波器被构造为在带通系统输出端(49)处输出脉冲的第二计数速率(N2)。测量装置(10)还包括被构造为产生第一计数速率(N1)和第二计数速率(N2)之间的差分计数速率(N3)的减法器(60)。(The invention relates to a radiometric device for determining a pulse intensity of a disturbance signal from an external radiation source, wherein the radiometric device determines a filling level or a limit level of a filling material in a container. The radioactivity measuring device (10) comprises a detector (30) which is configured to receive pulses of a useful signal modulated with a modulation frequency from the gamma ray emitter (20) and also to receive pulses of an interference signal from an external radiation source (25). The measurement device (10) further comprises an average generator (50) configured to output a first count rate (N1) of pulses at an average generator output (59) and a band pass system (40) comprising a band pass filter (45) having an adjustable pass band frequency range, the low pass filter being configured to output a second count rate (N2) of pulses at a band pass system output (49). The measurement device (10) further includes a subtractor (60) configured to generate a differential count rate (N3) between the first count rate (N1) and the second count rate (N2).)

1. A radiometric measuring device (10) for determining an intensity of a pulse of an interference signal from an external radiation source (25) during a determination of a filling level or a limit level of a filling material (90) in a container (95), the measuring device (10) comprising:

a detector (30) configured to receive pulses of a useful signal modulated with a modulation frequency from a gamma ray emitter (20) and also to receive pulses of the interference signal from the external radiation source (25);

a mean generator (50) configured to output a first count rate (N1) of the pulses at a mean generator output (59), wherein the first count rate (Nl) corresponds to a mean of a first number of pulses received by the detector (30) over a predetermined time period over the predetermined time period;

a band pass system (40) comprising a band pass filter (45) having a passband frequency range, the band pass filter being configured to output a second count rate (N2) of the pulses at a band pass system output (49), wherein the passband frequency range of the band pass filter (45) corresponds to the modulation frequency of the modulated useful signal from the gamma ray emitter (20), and wherein the second count rate (N2) corresponds to a second number of pulses received by the detector (30) within the passband frequency range of the band pass filter (45) within the predetermined time period; and

a subtractor (60) configured to form a differential count rate (N3), wherein the differential count rate (N3) corresponds to a difference between the first count rate (N1) and the second count rate (N2) such that the differential count rate (N3) corresponds to a strength of the interference signal from the external radiation source (25).

2. The measuring device (10) according to claim 1,

wherein the differential count rate (N3) is compared to a threshold (N4) and an action is triggered when the threshold (N4) is exceeded.

3. The measurement device (10) according to claim 2,

wherein the action comprises suspending temperature control.

4. The measurement device (10) according to claim 2,

wherein the action comprises storing a time stamp and/or a value of the strength of the interfering signal.

5. The measurement device (10) according to claim 2,

wherein the action comprises issuing a warning.

6. The measuring device (10) according to any one of the preceding claims,

wherein the measurement device (10) further comprises a frequency determination module (42) configured to determine the modulation frequency of the modulated useful signal from the gamma ray emitter (20) and to adjust the passband frequency range of the bandpass filter (45) with an adjustable passband frequency range to the modulation frequency of the modulated useful signal.

7. The measuring device (10) according to any one of the preceding claims,

wherein the adjustable passband frequency range of the band pass filter (45) has a center frequency between 0.05 and 20 hertz, in particular has a center frequency of 1 hertz.

8. The measuring device (10) according to any one of the preceding claims,

wherein the predetermined period of time of the count rate (N1, N2, N3) is between 0.02 and 50 seconds, such as between 0.05 and 20 seconds, and in particular 1 second.

9. The measuring device (10) according to any one of the preceding claims,

wherein the first count rate (N1) is proportional to k times the average of the first number of pulses, in particular k 1/2.

10. The measurement device (10) according to any one of the preceding claims, further comprising:

a modulator controlling a displaceable diaphragm around the gamma ray emitter (20) and/or electronic circuitry,

wherein the modulator is configured to modulate a signal of the gamma ray emitter (20) to produce the modulated signal.

11. A method for determining the strength of an interference signal from an external radiation source (25) during determination of a filling level or an extreme level by means of a radioactive measuring device (10) according to any of the preceding claims, the method comprising the steps of:

a) -receiving, by means of a detector (30), a useful signal modulated with a modulation frequency from a gamma ray emitter (20) and also the interference signal from the external radiation source (25);

b) outputting, by an average generator (50), a first count rate (N1);

c) outputting, by the band pass system (40), a second count rate (N2);

d) forming, by a subtractor (60), a differential count rate (N3) obtained by subtracting the second count rate (N2) from the first count rate (N1); and

e) outputting the differential count rate (N3).

12. The method of claim 11, further comprising the steps of:

f) comparing the differential count rate (N3) to a threshold (N4); and

g) if the threshold (N4) is exceeded, an action is triggered.

13. Use of the measuring device (10) according to one of claims 1 to 10 for determining a filling level or a limit level of a filling material (90), in particular a liquid and/or a bulk material.

14. A program element, which, when being executed on a processor unit (80) of a measurement apparatus (10), instructs the measurement apparatus (10) to carry out the method according to claim 11 or 12.

15. A computer readable medium having stored the program element of claim 14.

Technical Field

The invention relates to a radiometric device for determining the intensity of an interference signal from an external radiation source, wherein the radiometric device is configured to perform a filling level determination or a limit level determination of a filling material in a tank. The invention further relates to the use of such a measuring device for filling level or limit level measurement, to a method for determining the strength of a disturbance signal, to the use of the measuring device, to a program element and to a computer-readable medium having stored such a program element.

Background

For example, a radiometric device may be used for determining the filling level or limit level of the filling material. Such measuring devices are used in particular for indicating, for example, a specific level of filling material in the container, i.e. for determining whether a predetermined upper or lower limit value of the level in the container has been reached. In a radiometric device, for example, a gamma ray emitter is used as emitter, i.e. a useful signal is generated which can be received by a detector. In some cases, the signal received by the detector may be superimposed with an interference signal. The interference signal may be generated by an external radiation source, for example by a radioisotope, for example an isotope such as that used to inspect a weld in a vessel. This may therefore disturb the measurements of the measuring device itself, and also of other machines located in the area of the measuring device.

Disclosure of Invention

It is therefore an object of the present invention to provide an improved radioactivity measuring device.

This object is achieved by the subject matter of the independent claims. Advantageous embodiments are given in the dependent claims, the following description and the drawings.

One aspect of the invention relates to a radiometric device for determining the intensity of an interference signal from an external radiation source when determining a filling level or a limit level of a filling material in a container. The radioactivity measuring device comprises a detector configured to receive pulses of a useful signal modulated with a modulation frequency from a gamma ray emitter and also to receive pulses of an interference signal from an external radiation source. The number of pulses per time period corresponds to the intensity of the gamma ray source (i.e., e.g., the desired signal and/or the interfering signal). The detector for gamma-ray radiation can be a counting tube, for example a Geiger-Muller counting tube) Or a flicker counter. For example, the detector may count the number of ionized particles, e.g., each particle is detected as a pulse in the detector. The number of particles and/or pulses may be summed over a predetermined time period and/or correlated to a predetermined time period, such as "1000 particles (or pulses) per second". A gamma ray emitter may be used as a particle source to provide a useful signal. The useful signal from the gamma ray emitter may be modulated, i.e. the gamma ray emitter may be an active timing emitter (aktivgettekter Strahler) having a frequency (i.e. modulation frequency or timing frequency). The frequency of the modulated useful signal may be substantially constant. In addition to the useful signal, the detector can also receive pulses of interference signals from an external radiation source. The interfering signal may be unmodulated. For example, the interference signal can be generated by a radiometric isotope, an isotope for weld inspection or other gamma ray source whose radiation is variable, in particular in an unpredictable manner. The reception of the useful signal and the interference signal can take place during a filling level determination or a limit level determination of the filling level or the limit level of the filling material in the measuring vessel. One of the effects utilized by the inventionIt is intended that the wanted signal is modulated and the interfering signal is not modulated.

The measurement device also includes an average generator configured to output a first count rate of pulses. Here, the count rate may be expressed as a rate, i.e., a number of pulses per unit time and/or within a specific period of time, or may be a number of pulses normalized within the specific period of time. The first count rate corresponds to an average value of a first number of pulses received by the detector during a predetermined time period.

The measurement device also includes a band pass system configured to output a second count rate of pulses. The bandpass system has, for example, a bandpass filter with an adjustable passband frequency range. For example, a bandpass system includes a bandpass filter having an adjustable passband frequency range. The adjustable passband frequency range of the bandpass filter corresponds here to the modulation frequency of the modulated useful signal from the gamma ray emitter. Here, the "adjustable pass-band frequency range" may denote a frequency range in which the pass-band frequency range can be adjusted, for example, to the modulated useful signal before the measurement. The frequency range corresponds to a band pass with a fixed passband frequency range if the frequency of the modulated useful signal is known and constant. "adjustable passband frequency range" may also mean that the frequency of the modulated useful signal is determined at the beginning of the measurement (for example by an FFT module (FFT: fast fourier transform)) and the band pass filter is adjusted to this passband frequency range. Here, the band of the band pass filter may be selected according to the frequency of the strongest signal output by the detector, which frequency corresponds to the strongest amplitude in the FFT spectrum, for example. The FFT module may be part of a band pass system. An "adjustable pass-band frequency range" may also mean that the frequency of the modulated useful signal is also determined during the measurement and the band-pass filter is adjusted or adapted to this pass-band frequency range. For example, the frequency of the modulated useful signal may vary due to temperature fluctuations during the measurement. The second count rate corresponds to a second number of pulses within the predetermined time period, which are received by the detector within the passband frequency range of the bandpass filter within the predetermined time period.

In addition, the measurement device further includes a subtractor configured to form a differential count rate. The differential count rate corresponds to and/or is related to a difference between the first count rate and the second count rate. The first count rate and/or the second count rate may be normalized, for example by a constant, before subtracting the second count rate from the first count rate. The differential count rate may also be normalized after subtraction. Thus, the differential count rate corresponds to the strength of the interference signal from the external radiation source.

Since the useful signal is modulated but the interference signal is not modulated, the interference signal can be separated from the useful signal by the measuring device according to the invention. Thus, not only can a measured value for determining the filling level or the limit level of the filling material be obtained from the received (modulated plus unmodulated) signal by the measuring device, but also the presence of external radiation and/or the intensity of the external radiation can be determined, i.e. a quantitative value of the external signal can be determined by the measuring device. By determining a quantitative value of the interference signal, not only the external radiation can be suppressed very effectively, but the value can also be used to initiate a predefined action, such as the display and/or recording of the interference signal.

In an embodiment, the differential count rate is compared to a threshold and an action is triggered if the threshold is exceeded. The threshold may be a count rate above which it is determined that external radiation is present. The threshold value may be a count rate above which at least one partial function of the measuring device and/or at least one partial function of the other device is severely disturbed.

In one embodiment, the action includes suspending temperature control. For example, temperature control may involve temperature control of a scintillation counter and/or other devices of the measurement apparatus. This may be based, for example, on the following facts: if the external radiation exceeds a certain threshold, certain temperature controls may be disturbed such that their function is no longer relied upon, so that the suspension of these temperature controls can prevent damage.

In an embodiment, the action includes storing a time stamp and/or a strength value of the interfering signal. For example, the time stamp may represent the beginning and/or end of the occurrence of the interference signal. The strength value of the interference signal may comprise a strength, for example an average of the strengths over a part of the measurement period and/or an average of a plurality of strengths of the interference signal at a plurality of points in time. This may be stored in a non-volatile memory, for example, and may then be read out again for diagnostic purposes, for example, to record (e.g., external) extraneous radiation times.

In one embodiment, the action includes issuing a warning. The warning may include a warning light, a warning tone, and/or the display of specific display content.

The actions described above may be triggered individually, collectively, sequentially or in any combination.

In an embodiment, the measuring device further comprises a frequency determination module which is configured to determine the modulation frequency of the modulated useful signal from the gamma ray emitter and to adjust the passband frequency range of the bandpass filter with the adjustable passband frequency range to the modulation frequency of the modulated useful signal. This may be performed, for example, by an FFT module that determines the frequency of the strongest signal output by the detector and uses that frequency to adjust the passband frequency range of the adjustable bandpass filter. By using this arrangement, no tuning between the frequency of the modulated useful signal and the detector is required. Furthermore, a continuous adaptation to the changing frequency of the useful signal is thus possible.

In an embodiment, the adjustable passband frequency range of the bandpass filter has a center frequency between 0.05 hz and 20 hz, in particular has a center frequency of 1 hz. The frequency of the modulated useful signal (and thus the band-pass filter tuned to the useful signal) varies relatively slowly with the count rate of the particles. For example, the Q value of the band pass filter may be less than 20%, in particular less than 10%. The modulated useful signal substantially maintains its frequency and changes at most slowly, for example due to changes in the ambient temperature.

In an embodiment, the predetermined time period for measuring the first and second count rates is between 0.02 and 50 seconds, for example between 0.05 and 20 seconds, in particular 1 second. This range corresponds in particular to the characteristics of the modulated useful signal.

In an embodiment, the first count rate corresponds to an average of a first number of pulses received by the detector over a predetermined time period. Here, the first count rate may be proportional to k times the average value of the first number of pulses, in particular k 1/2. For example, the first count rate may be multiplied or normalized by a factor k 1/2. This may be based, for example, on the fact that: in the case of external radiation, this average value corresponds to approximately half the measured count rate. It should be noted that in the case of external radiation, the average value (measured at the detector) increases the value of the external radiation.

In an embodiment, the measurement device further comprises a modulator controlling the displaceable diaphragm around the gamma ray emitter and/or the electronic circuit, wherein the modulator is configured to modulate a signal of the gamma ray emitter to generate a modulated signal. The displaceable diaphragm may be realized as a rotating sieve, for example made of lead, which has openings and rotates around the gamma ray emitter, so that the gamma rays appear approximately in the form of a lighthouse with the sieve rotating around the lamp. For example, the electronic circuit may be implemented as an oscillating circuit or as a pulse or signal generator and a D/a converter (possibly with a low-pass filter). The modulated signal may be sinusoidal, up to a rectangular wave. The fundamental frequencies can advantageously be separated here by a simple low-pass filter.

Another aspect of the invention relates to a method for determining the strength of an interference signal from an external radiation source during filling level determination or limit level determination by means of a radiometric device as described above and/or below. The method comprises the following steps:

a) receiving, by a detector, pulses of a useful signal modulated with a modulation frequency from a gamma ray emitter and also interference signals from an external radiation source;

b) outputting, by an average generator, a first count rate;

c) outputting a second count rate through the band-pass system;

d) forming, by a subtractor, a differential count rate obtained by subtracting the second count rate from the first count rate; and

e) and outputting the differential counting rate.

In an embodiment, steps b) and c) are performed in parallel and/or quasi-parallel. Quasi-parallel execution may be implemented, for example, by a single processor system.

In one embodiment, the method has the following additional steps:

f) comparing the differential count rate to a threshold; and

g) if the threshold is exceeded, an action is triggered.

Another aspect of the invention relates to the use of a measuring device as described above and below for determining the filling level or limit level of a filling material, in particular of a liquid and bulk material.

Another aspect of the invention relates to a program element, which, when being executed on a processor unit of a measuring device, instructs the measuring device to carry out the method as described above and below.

Another aspect of the invention relates to a computer readable medium having stored thereon a program element as described above and below.

All features described above and below with reference to one aspect of the invention may equally be features of one or more other aspects of the invention. In particular, all features described in relation to the measuring device can also be features and/or steps of the method and vice versa.

For further elucidation, the invention will be explained with reference to an embodiment shown in the drawings. These examples are to be construed as merely illustrative, and not as limiting.

Drawings

Fig. 1 schematically shows a measuring device according to an exemplary embodiment of the present invention.

Fig. 2 schematically shows an example of an input signal of a detector receiving a modulated wanted signal and an interfering signal.

Figure 3 schematically shows an example of the signal of figure 2 at the output of a band-pass system according to the invention.

Fig. 4 schematically shows an example of the signal of fig. 2 at the output of the average generator according to the invention.

Fig. 5 schematically shows an example of the signal of fig. 2 at the output of a measuring device in an embodiment of the invention.

Fig. 6 shows a flow chart for illustrating the steps of a method according to an exemplary embodiment of the present invention.

Detailed Description

Fig. 1 schematically shows a measuring device 10 according to an exemplary embodiment of the present invention. The measuring device 10 has a gamma ray emitter 20 which is designed to emit a modulated useful signal. The gamma ray emitter 20 may be controlled by a modulator 22 that applies a predetermined frequency to the gamma ray emitter. The gamma ray emitter 20 may transmit the modulated desired signal in multiple directions (e.g., toward the container 95). The container 95 includes a filler material 90. The filler material 90 may include a liquid and/or a loose material.

Disposed at a side of the container 95 opposite the gamma ray emitter 20 is a detector 30, the detector 30 being configured to receive pulses of radiation from the gamma ray source. One of the gamma ray sources is gamma ray source 20. The intensity of the gamma rays received by the detector 30 depends on the fill level 97 of the container 95. If the fill level 97 is high, such that the fill material 90 is located between the gamma ray emitter 20 and the detector 30, the modulated useful signal is attenuated by the fill material 90. If no filler material 90 is present between the gamma ray emitter 20 and the detector 30, the detector 30 receives a higher intensity of modulated gamma rays from the gamma ray emitter 20. This effect may be used to determine a fill level or limit level of the fill material 90 in the container 95. However, the detector 30 may not only receive gamma rays from the modulated gamma ray emitter 20, but the detector 30 may also receive pulses from other gamma ray sources, such as pulses of interference signals from the external radiation source 25. The interference signal may be unmodulated and thus have different frequency characteristics than the modulated gamma ray emitter 20.

The pulses generated by the detector 30 are passed from the detector output 39 of the detector 30 in the measurement apparatus 10 to the average generator 50 and the band pass system 40. The average generator 50 is configured to output a first count rate N1 of pulses at the average generator output 59. To this end, the average generator 50 forms an average of the first number of pulses over a predetermined period of time. The pulse may comprise the entire frequency spectrum received by the detector 30. Thus, the average value of the average generator 50 counts all pulses from the detector 30 over a predetermined period of time.

The band pass system 40 includes a band pass filter 45 having an adjustable passband frequency range. The band pass filter 45 may be adjusted to a pass band frequency range, for example, by the FFT module 42. The passband frequency range may correspond to the frequency of the modulated useful signal. For example, the passband frequency range may be adjusted at the beginning of the measurement and/or during the measurement. By means of the band-pass filter 45, substantially only pulses lying within the passband frequency range are filtered out of the pulses received from the detector 30. The bandpass system 40 counts the pulses and, if necessary, passes them to the bandpass system output 49 after normalization as a second count rate N2. Normalization may also be performed in normalization module 65 after the band pass system output 49. The second count rate N2 may be communicated to the first output 75 of the measurement device 10.

A differential count rate N3 is formed in subtractor 60. The differential count rate N3 corresponds to and/or is related to the difference between the first count rate N1 and the second count rate N2. The differential count rate N3 may be communicated to the second output 70 of the measurement device 10. Thus, a useful signal measurement is present at the output of the measurement device 10 (i.e., at the first output 75), and a jammer signal measurement is present at the second output 70. Both of these measurements may be used by downstream modules (not shown). The measurement device 10 may at least partially include one or more processor units 80. Here, the processor unit 80 may comprise at least the mean value generator 50, the band pass system 40 and/or the normalization module 65.

Fig. 2 schematically shows an example of an output signal 39 of a detector 30 (see fig. 1) receiving a modulated wanted signal and an interfering signal. The x-axis shows the time axis on which the measured values are plotted over a time range of 80s to 150 s. The y-axis shows the count rate N as may be measured at the output signal 39 of the detector 30. The sine wave of the modulated useful signal from the gamma ray emitter 20 can be clearly seen. The sine wave is superimposed with the unmodulated interference signal over a time range of 90s to about 115s and starting from 140 s. In the undisturbed range of 80s to 90s and 115s to 140s, the count rate is about 0.1 x 10 per second⁴And 1.1X 10⁴The pulses fluctuate between pulses and in the disturbed area the count rate is about 1.6 x 10 per second⁴And 2.6X 10⁴Fluctuating between pulses. In this example, the amplitude of the interference signal is therefore higher than the amplitude of the modulated useful signal. All numerical values are purely exemplary.

Fig. 3 schematically shows an example of the useful signal of fig. 2 at the bandpass system output 49 of the bandpass system 40 (see fig. 1) after bandpass filtering. The x-axis and y-axis show the same time range and count rate, respectively, as in fig. 2. The illustrated curve represents a useful signal as may be measured at the output 75 of the measuring device 10. It is evident that the counting rate is substantially at 1.0 x 10 per second⁴The value of each pulse oscillates around. The filling level 97 in the container 95 therefore does not change or changes only slightly in the time range shown.

Fig. 4 schematically shows an example of the signal of fig. 2 at the average generator output 59 of the average generator 50 (see fig. 1). The x-axis and y-axis show the same time range or count rate as in fig. 2. This represents the average of the sum of the useful signal plus the interfering signal.

Fig. 5 schematically shows an example of the signal of fig. 2 at the output 70 of the measuring device 10 (see fig. 1). The x-axis and y-axis show the same time range or count rate as in fig. 2. This represents a pure interferer, i.e., a differential count rate N3. For example, the signal may be further processed in the following manner: the differential count rate N3 is compared to a threshold N4 (dashed line) and an action is triggered when the threshold N4 is exceeded. For example, the action may be to notify "there is a jamming signal" on a connected display.

Fig. 6 shows a flow chart 100 for illustrating the steps of a method according to an exemplary embodiment of the invention. In step 101, pulses of the useful signal modulated with the modulation frequency are received from the gamma ray emitter 20 by the detector 30 (see fig. 1) and additionally interference signals are received from the external radiation source 25. In step 102, a first count rate N1 is output by the average generator 50. In step 103, a second count rate N2 is output by bandpass system 40. Step 102 may be performed in parallel, quasi-parallel, or sequentially (102 after 103 or 103 after 102). In step 104, a differential count rate N3 is formed by the subtractor 60, wherein the differential count rate N3 is obtained by subtracting the second count rate N2 from the first count rate N1. In step 104, the differential count rate N3 is output.

In addition, it should be noted that "comprising" and "having" do not exclude any other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. It should also be noted that features or steps which have been described with reference to one of the above exemplary embodiments may also be used in combination with other features or steps of other exemplary embodiments described above. Reference signs in the claims shall not be construed as limiting.

List of reference numerals

10 radioactivity measuring device

20 gamma ray emitter

22 modulator

25 external radiation source

30 Detector

39 detector output

40 bandpass system

42 frequency determination module and FFT module

45 band-pass filter

49 output terminal of band-pass system

50 average value generator

59 average value generator output

60 subtracter

65 normalization module

75. 70 first and second outputs of the measuring device

80 processor unit

90 filler material

95 container

97 level of filling

100 flow chart

101 to 105 method steps