Method for determining a filling level of a filling material in a container

Abstract

A method for determining a filling level of a filling material (104) in a container (102) by means of a filling level sensor (100) is described, wherein the filling level sensor (100) is coupled using signalling to a state sensor (120) for the filling material, having the steps of: determining an environmental condition of the filling material (104) by means of the state sensor (120); comparing the environmental condition of the filling material (104) with a first reference state (310) and a second reference state (320) in order to determine the environmental condition; determining the filling level by means of the filling level sensor (100) on the basis of a particular operating mode of the filling level sensor (100) that is assigned to the particular reference state (310, 320).

Description

[0001] Method for determining a fill level of a filling material in a container

[0002] Reference to related applications

[0003] This application claims priority from German patent application No. 102023 122 776.9, filed on August 24, 2023, which is incorporated in its entirety by reference into the present document.

[0004] State of the art

[0005] Production processes involving raw material processing, such as mixing, heating, and other batch processes, are typically monitored with industrial sensors that determine process characteristics such as pressure, flow, or fill level. Level sensors can be based on various measurement methods and are used to detect fill levels in containers, particularly for flowable media such as liquids or bulk materials.

[0006] Disclosure of the invention

[0007] Level sensors based, for example, on a guided radar measuring system, a free-space radar, or an ultrasonic system, or point level sensors for filling materials, and their signal processing results, can be influenced by processes and / or conditions in their immediate and / or wider environment. For example, an agitator installed in a container containing a filling material to be measured can influence the determination of the filling level of the filling material. If the operating state of the agitator changes, such as switching it on or off or the rotation speed of the agitator, this can influence the liquid surface of the filling material, for example through vortex formation, and consequently also influence the measurement signal of the level sensor due to the changed liquid surface.

[0008] According to aspects of the invention, a method for determining the fill level of a filling material in a container using a fill level sensor, a fill level sensor, and a use of a fill level sensor according to the features of the independent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

[0009] Throughout this description of the invention, some features are provided with numbered words to improve readability or to make the assignment clearer, but this does not imply the presence of certain features.

[0010] According to one aspect of the invention, a method for determining a fill level of a filling material in a container using a fill level sensor is proposed, wherein the fill level sensor is signal-coupled to a condition sensor for the fill material. In one step, an ambient condition of the filling material, in particular in the container, is determined using the condition sensor. In a further step, the ambient condition of the filling material is determined using a first reference state and a second reference state for determining the ambient condition. In a further step, the fill level is determined using the fill level sensor based on a respective operating mode of the fill level sensor that is assigned to the respective reference state, in particular in order to improve the reliability and / or accuracy of the fill level determination.

[0011] The ambient condition of the filling material can include a temperature of the filling material, which in particular influences the mechanical behavior of the filling material. For example, the filling material can be poured into the container in small solid pieces and, upon increasing the temperature, transform into a liquid state. By varying the topography of a surface of the filling material in the different aggregate states, the determination of the filling material can be improved using a temperature sensor and an adapted signal evaluation and / or evaluation of a measurement signal and / or a correspondingly adapted measurement signal for determining the fill level.

[0012] Alternatively or additionally, the ambient condition may include filling the container with the filling material. For example, the filling material may be transported into the container by means of an air stream, so that a pressure measurement in the container can detect the filling.

[0013] By means of an acoustic sensor and / or an acceleration sensor, an acoustic signature, which can be caused in particular by actuators acting on the filling material and / or on the container, such as an agitator, can be detected in order to determine the corresponding ambient condition.

[0014] An agitator in the product can influence the topography of a product's surface, causing a signal emitted by the product sensor to be reflected depending on the surface's topography. Alternatively or additionally, the agitator can cause periodic changes in the product's surface and / or a periodically changing distance measurement of the level sensor, thereby influencing the level measurement depending on the time at which the level is determined.

[0015] A respective reference state can be assigned to the respective different ambient conditions of the filling material in order to select and / or determine a respective operating mode of the level sensor according to the respective reference state in order to improve the level measurement. For this purpose, different ambient conditions of the filling material can be carried out in practical tests in order to determine different reference states that can be detected and / or determined with the condition sensor. The level sensor can be configured with a plurality of operating modes to determine the fill level. Accordingly, the condition sensor can be configured to have a plurality of reference states in order to compare them with the respective ambient condition. The condition sensor can be configured to determine the reference state that is most similar to the ambient condition from the plurality of reference states.Furthermore, the level sensor can be configured to assign a respective operating mode of the level sensor to each of the plurality of reference states in order to determine the level using the respective operating mode of the level sensor. For this purpose, the state sensor can be signal-coupled to the level sensor and / or the state sensor can be integrated into the level sensor.

[0016] An ambient condition of the filling material to which a corresponding reference state can be assigned can, for example, be caused by an active agitator in the filling material. This can, in particular, influence the topography of a surface of the filling material. Alternatively or additionally, an active agitator can, by means of parts of the agitator that interact with a method for determining the fill level, change the ambient condition of the filling material in such a way that a further reference state can be assigned to this ambient condition. This can, in particular, relate to radar echoes if the fill level is determined using a radar signal. Alternatively or additionally, an active agitator can emit vibrations and / or direct sound that characterize the ambient condition of the filling material and can be assigned to a further reference state.The vibrations and / or the direct sound can be transmitted to the level sensor, in particular via a housing of the level sensor.

[0017] A further ambient condition of the filling material may relate to an acoustic environment of the filling material and / or a temperature of the surroundings of the filling material and / or a pressure acting on the filling material. The respective ambient condition can be detected using condition sensors coupled to the level sensor, in particular to determine a first and / or a second reference state.

[0018] Alternatively or additionally, a further ambient condition of the contents can be created by spray heads for cleaning the interior of the container, for example, which are arranged inside the container. The spray heads or sprayers can, for example, be used in the container to maintain hygiene. When cleaning is active, water droplets and / or a spray mist can change the ambient condition of the contents. If, for example, the fill level is determined using a radar signal, an electromagnetic wave of the radar signal can also be affected and / or reflected by the water droplets and / or the spray mist. If this is not taken into account in the signal processing of a fill level sensor or radar device, incorrect measurements can occur because the fill level in the container is displayed as higher than it actually is, for example.In this case, the ambient condition of the product can be characterized with a type: "Cleaning" if cleaning with the spray head is active. If cleaning with the spray head is not active, the ambient condition of the product can be characterized with a type: "Normal."

[0019] In other words, the method can be used to determine the fill level of the filling material in a container using the fill level sensor as a function of the ambient condition by adapting the operating mode of the fill level sensor to a respective ambient condition. The operating mode can comprise a measurement method used by the fill level sensor and / or an evaluation or signal processing mode of a measurement signal from the fill level sensor. The ambient condition can preferably be determined with a modified and / or adapted operating / signal processing mode of the fill level sensor as a function of the ambient condition, wherein the ambient condition is preferably determined and / or detected acoustically, for example, using a microphone.

[0020] Advantageously, the determination of the fill level by means of knowledge of the ambient condition of the filling material can be taken into account in an evaluation and / or signal processing of a measurement signal of the fill level sensor and / or adapted to the ambient condition in order to improve the reliability and / or accuracy of the fill level determination.

[0021] The method for determining the fill level can be based on acoustic signals, which can characterize an ambient condition, being transmitted via structure-borne sound from the container containing the filling material to a housing of the fill level sensor, which is mechanically coupled to the container. A sensor for acoustic signals, such as a microphone and / or an accelerometer, integrated into the housing of the fill level sensor or the electronics of the fill level sensor, can detect and / or determine an acoustic signature of the ambient condition of the fill material in the container. Using a microcontroller of the electronics of the fill level sensor, this acoustic signature can be evaluated and / or assigned to a state of the ambient condition of the fill material.

[0022] The activation of an agitator for the filling material in the container can be detected, for example, by an increase in the sound level and / or a detected frequency of the acoustic signature.

[0023] By switching to an appropriately adapted signal evaluation mode and / or evaluating a measurement signal from the level sensor for determining the level, the determination of the level can be adapted and / or optimized for the respective ambient conditions.

[0024] Alternatively or additionally, a measuring method of the level sensor can be selected and / or adapted by means of the acoustic signature, whereby, for example, by means of a higher or lower repetition rate of the measuring signals for determining the level, an adaptation to the ambient condition is carried out in order to improve the determination of the level.

[0025] Alternatively or additionally, a temporal position of a measuring signal for determining the fill level and / or sensor switching points can be changed following a corresponding detection of switching on of the agitator in order to adapt a measuring time of the fill level sensor to a movement of the control system and thereby prevent overflow of the container due to an incorrectly determined fill level due to "vortex formation" in the filling material.

[0026] The condition sensor can alternatively or additionally be arranged outside the fill level sensor and / or be mechanically coupled to the container for the filling material in order to determine an ambient condition of the filling material, for example, based on acoustic signals. The condition sensor can be coupled to the fill level sensor via a signal, wired and / or wireless, in order to determine the ambient condition of the filling material. In particular, the internal and / or external condition sensor of the fill level sensor can be configured to detect switching states and / or operating modes of actuators that can act on the filling material and / or the container for the filling material in order to determine the ambient condition. For this purpose, the condition sensor can be coupled to the respective actuators via a signal.

[0027] In particular, the fill level sensor can be mechanically coupled to the container for the filling material in order to determine the ambient condition of the filling material by means of the condition sensor, for example by means of acoustic signals.

[0028] The fill level sensor can be configured to measure a distance between a surface of the filling material and the fill level sensor, preferably by means of a time-of-flight measurement, in order to determine the fill level of the filling material. This time-of-flight measurement can be carried out using ultrasound and / or microwaves, i.e., for example, using a guided radar measuring system and / or a free-space radar and / or an ultrasound system. The method can alternatively or additionally be carried out using a point level sensor as the fill level sensor. A vibronic point level sensor can be mechanically coupled, e.g., to a container, in such a way that the mechanical oscillating system comes into contact with the filling material when it reaches a predetermined fill level.

[0029] According to one aspect, it is proposed that the condition sensor comprises an acoustic sensor; and / or an acceleration sensor; and / or a temperature sensor; and / or a pressure sensor; and the condition sensor is configured to determine the first reference state or the second reference state of the filling material based on signals from a plurality of the described sensors.

[0030] Using the various sensors, an ambient condition of the filling material can be determined by detecting changes and / or states in the environment, thus enabling the corresponding ambient condition to be determined. The level sensor can be configured to compare a specific ambient condition with respective reference states using the state sensor in order to determine the respective operating mode of the level sensor depending on the similarity of the ambient condition to a reference state.

[0031] The acoustic sensor and / or the acceleration sensor can be used to determine vibrations and / or sound signals caused by the ambient conditions of the filling material.

[0032] In particular, a state of the ambient condition of the product can be determined by a weighted sum of a plurality of signals from the corresponding sensors. This can then be compared with the first reference state and / or the second reference state.

[0033] According to one aspect, it is proposed that the temperature sensor is thermally coupled directly to a metallic element of the fill level sensor, which protrudes into an interior of the container.

[0034] The temperature of the contents and / or the container can be determined using a temperature sensor arranged in a housing of the level sensor. Preferably, the temperature sensor, which is arranged inside the housing of the level sensor, can be directly thermally coupled to a metallic element of the level sensor, such as a radar reflector, in order to determine the temperature inside the container and / or the temperature of the contents. Advantageously, the direct thermal coupling enables a faster response and more accurate temperature reading.

[0035] According to one aspect, it is proposed that the condition sensor is configured to determine the first reference state or the second reference state of the filling material by means of pattern recognition based on the signals of the plurality of the described sensors and / or a statistical evaluation system of the signals of the plurality of the described sensors.

[0036] A pattern for pattern recognition can, for example, comprise all the respective amplitudes of the plurality of sensors, which, depending on the respective magnitude of the respective amplitude, can be characteristic of a state of the ambient condition of the product. Alternatively or additionally, pattern recognition can be performed by temporally averaging the respective amplitudes of the plurality of sensors. In particular, these amplitudes and / or temporal averages of the amplitudes can be statistically evaluated across a plurality of determinations of the ambient condition.

[0037] Alternatively or additionally, the pattern recognition may be based on a threshold value detection of an amplitude of a sensor signal, so that when a certain amplitude, such as a certain sound level, is exceeded, the operating mode of the level sensor corresponding to the first reference state is determined and / or selected and / or switched to an operating mode corresponding to the second reference state.

[0038] According to one aspect, it is proposed that the state sensor is configured to determine the first reference state or the second reference state of the filling material by means of a trained machine learning system based on the signals of the plurality of the described sensors.

[0039] According to the pattern recognition described above, the condition sensor can evaluate and / or characterize the plurality of respective signals from the plurality of sensors using a trained machine learning system. The states of the environment of the filling material, characterized accordingly by the trained machine learning system, can then be assigned to a respective reference state in order to determine the operating mode of the level sensor depending on the respective reference state.

[0040] In particular, the trained machine learning system may comprise a trained neural network and / or a trained convolutional neural network (CNN). In other words, the trained machine learning system may be configured to classify the environmental condition of the filling material.

[0041] Training can be achieved, for example, through a training phase after the sensor's installation, in which an initial reference state is learned. Deviations from this can be recognized as additional states or reference states.

[0042] Alternatively or additionally, other supervised and / or unsupervised learning methods can be used that allow the classification of environmental conditions into at least two classes. These include, for example, density-based methods such as kNN (nearest neighbor classification), Local Outlier Factor (LOF), Isolation Forests, Support Vector Machines, Neural Networks, Bayesian Networks, and / or comparable methods.

[0043] According to one aspect, it is proposed that the condition sensor is configured to determine the first reference state or the second reference state of the filling material by correlating at least one signal of the condition sensor with a measurement signal of the fill level sensor on which the determination of the fill level is based.

[0044] Such a correlation can be advantageously used when the agitator in the filling material periodically influences the topography of the filling material's surface. This periodic change in the surface of the filling material can, for example, cause a periodically variable distance measurement of the level sensor and thus influence the level measurement depending on the time of the level determination. In a level sensor based on a radar signal, a periodic change in the distance measurement can be caused if a part of the agitator protrudes into a cone of the radar signal. This effect can be detected by correlating a signal from the condition sensor with a signal from the level sensor, such as a detected level.In particular, after detecting this effect, the measurement time for the level sensor's measurement signal can be shifted within the respective period to improve the level determination. Alternatively, the repetition frequency of the level determination can be changed to avoid correlation. Alternatively, increasing the repetition frequency can be used to average the respective level determinations to improve the level determination.

[0045] According to one aspect, it is proposed that the state sensor is configured to determine the first reference state or the second reference state of the filling material based on a shift of a measurement time of the fill level sensor with respect to at least one signal of the state sensor.

[0046] According to one aspect, it is proposed that the state sensor has an energy storage device for supplying energy to the state sensor for determining the first reference state or the second reference state; and / or has an energy storage device for supplying energy to the state sensor for determining the correlation.

[0047] Advantageously, the energy storage device can be used to determine a correlation, which can be carried out over a certain period of time, by means of the correspondingly configured level sensor, without overloading a power supply of the level sensor, such as an analog current interface such as a 4 to 20 mA interface or a HART interface.

[0048] According to one aspect, it is proposed that the fill level sensor include the condition sensor. Advantageously, an integrated condition sensor makes it easier to parameterize the fill level sensor according to an application.

[0049] According to one aspect, it is proposed that the operating mode of the fill level sensor comprises a measuring method of the fill level sensor and / or an evaluation of a measuring signal of the fill level sensor.

[0050] The measurement method can refer to an amplitude and / or a frequency and / or a frequency sequence used to generate a measurement signal for determining the fill level. The evaluation of the measurement signal can refer to a characterization and / or determination of a distance and / or a fill level based on the measurement signal generated by the corresponding measurement method.

[0051] According to one aspect, it is proposed that the measuring method of the operating mode of the fill level sensor comprises a frequency of determining the fill level by means of the fill level sensor; and / or comprises a repetition rate of determining the fill level by means of the fill level sensor; and / or comprises a synchronization of the determination of the fill level by means of the fill level sensor with the ambient condition of the filling material; and / or comprises a profile of a signal transmitted by the fill level sensor.

[0052] According to one aspect, it is proposed that the evaluation of the measurement signal, corresponding to a respective operating mode, comprises a profile of an interference signal suppression of a runtime signal of the level sensor; and / or comprises a signal evaluation of the level sensor; and / or comprises an output of a level value from the level sensor.

[0053] For example, in the case of a level sensor based on a radar signal, the evaluation of the measurement signal can be carried out depending on the operating mode with different noise suppression curves and / or with different threshold values.

[0054] In particular, the level sensor can be configured to suppress a possible false alarm of the level sensor by means of a specific ambient condition of the filling material and a comparison with a respective reference state, for example if an incorrect determination of the level is caused by an agitator.

[0055] A fill level sensor is proposed that comprises a system for determining the fill level of a filling material in a container and a state sensor, wherein the state sensor is configured to determine a first reference state or a second reference state of the filling material. The fill level sensor can be configured to execute one of the methods described above for determining the fill level of a filling material in a container.

[0056] The system for determining a fill level can be configured according to a guided radar measuring system and / or a free-space radar and / or an ultrasonic system and / or a point level sensor. The condition sensor can be configured according to the above statements regarding the method for determining the fill level of the filling material in a container.

[0057] According to one aspect, it is proposed that the state sensor of the fill level sensor comprise an acoustic sensor and / or an acceleration sensor and / or a temperature sensor and / or a pressure sensor. The state sensor can be configured to determine the first reference state or the second reference state of the filling material based on signals from a variety of the described sensors.

[0058] The use of a level sensor for determining a level of a filling material with different ambient conditions of the filling material in a container is proposed.

[0059] Examples of implementation

[0060] Embodiments of the invention are illustrated with reference to Figs. 1 to 3 and explained in more detail below. It shows:

[0061] Fig. 1 is a schematic sketch of a level sensor configured to determine a level in a container;

[0062] Fig. 2 shows a schematic diagram of a measurement signal from a fill level sensor; and Fig. 3 shows a flowchart for a method for determining a fill level.

[0063] Fig. 1 schematically outlines a fill level sensor 100 which is configured to determine a fill level of a filling material 104 in a container 102.

[0064] The fill level sensor 100 is signal-coupled to a condition sensor 120 for the filling material, wherein the condition sensor 120 is arranged within the fill level sensor 100. By means of the condition sensor 120, the fill level sensor 100 is configured to determine an ambient condition of the filling material 104. By means of the condition sensor 120, the fill level sensor 100 is configured to compare the ambient condition of the filling material 104 with a first reference state and / or a second reference state in order to determine the ambient condition according to a respective reference state. The fill level sensor 100 is configured to determine the fill level based on an operating mode of the fill level sensor that is assigned to the respective reference state.The level sensor 100 is configured here, corresponding to a radar system 110, by means of an antenna 112 to determine a distance between a surface 103 of the filling material 104 and the level sensor 100 using a microwave signal 114. For example, the filling material 104 is represented here as a liquid. An agitator 108 extends into the container 102 and is coupled to a drive 106 via an axis to stir the liquid 104. The drive 106 of the agitator 108 is mechanically coupled to the container 102, so that vibrations 132 and direct sound 130 generated by the agitator 108 can be transmitted to the housing of the level sensor 100. A microphone and / or an accelerometer of the condition sensor 120 can be coupled to the housing of the level sensor 100 in order to determine an environmental condition of the filling material 104 by means of the condition sensor 120.The fill level sensor 100 can have an electronic unit configured to supply voltage and evaluate detected sensor signals and / or, in particular, detected measurement signals from the fill level sensor 100 or the radar sensor 110. The operating mode of the fill level sensor 100 can be determined by means of the state sensor 120 according to the compared reference state most similar to the respective ambient condition, based on a signature of sensor signals from the state sensor 120, in order to determine the fill level of the filling material 104 in the container 102 using the respective operating mode. The respective operating mode of the fill level sensor 100 can relate to the measuring method of the fill level sensor 100 and / or the evaluation of a measurement signal and / or a sensor signal in order to operate the fill level sensor 100 in an operating mode adapted to the respective ambient condition.

[0065] The condition sensor 120 can be configured by means of a trained neural network to determine and / or classify a state of the ambient condition of the filling material based on a plurality of sensor signals from a plurality of sensors of the condition sensor 120.

[0066] Alternatively or additionally, other methods of supervised and / or unsupervised machine learning are also conceivable here, such as nearest neighbor classification (ANN), support vector machines (SVM), decision trees, etc., and / or methods of multi-layer learning (deep learning), such as neural networks in their various forms. Fig. 2 schematically outlines a curve 210 of an amplitude S of a measurement signal of the level sensor 100, plotted against a specific distance d of the level sensor 100 from a surface of the filling material 104. The level sensor 100 uses a radar signal to perform a time-of-flight measurement, with which the distance from the surface of the filling material 104 is determined based on a time-of-flight of the radar signal. The measurement signal 210 can have a radar echo 212 from a surface of the filling material.To identify the radar echo 212, an interference signal suppression 220 can be used, which, over its course with an amplitude S depending on the distance d, can specify a threshold value above which the measurement signal must lie at the respective distance d in order to be identified as a radar echo 212. In addition, a possible partial signal 214 of the measurement signal 210 is marked in the diagram 200. This partial signal 214 is caused by a radar echo that can be caused by a reflection from an agitator. The partial signal 214 can occur periodically in time according to a rotation of the agitator. A temporally shifted synchronization of a distance determination with this partial signal 214 by means of the level sensor 100 can improve the determination of the level if the temporal shift of the level determination is carried out in such a way that the partial signal 214 does not appear in the measurement signal.

[0067] Fig. 3 outlines, with a flowchart 300, a method for determining a fill level of a filling material in a container using a fill level sensor. The fill level sensor is signal-coupled to an internal or external condition sensor for the fill material. In a step S1, an ambient condition of the fill material is determined using the condition sensor. In a step S2, the ambient condition of the fill material is compared with a first reference state 301 and / or a second reference state 302 in order to determine the ambient condition. In a step S3, the fill level is determined using the fill level sensor based on a respective operating mode of the fill level sensor that is assigned to the respective reference state. The fill level sensor can be configured to maintain the current operating mode for determining the fill level until the ambient condition changes.

Claims

Patent claims 1. A method for determining a fill level of a filling material (104) in a container (102) by means of a fill level sensor (100), wherein the fill level sensor (100) is signal-coupled to a condition sensor (120) for the filling material, comprising the steps: Determining an environmental condition of the filling material (104) in the container by means of the condition sensor (120); Comparing the ambient condition of the filling material (104) with a first reference state (310) and a second reference state (320) to determine the ambient condition; and Determining the fill level by means of the fill level sensor (100) based on a respective operating mode of the fill level sensor (100) which is assigned to the respective reference state (310, 320) in order to improve a reliability and / or an accuracy of the fill level determination.

2. The method according to claim 1, wherein the state sensor (120) comprises an acoustic sensor; and / or an acceleration sensor; and / or a temperature sensor; and / or a pressure sensor; and the state sensor (120) is configured to determine the first reference state (310) or the second reference state (320) of the filling material (104) based on signals from a plurality of the described sensors.

3. The method according to claim 2, wherein the temperature sensor is thermally coupled directly to a metallic element (112) of the fill level sensor (100) which projects into an interior of the container (102).

4. The method according to claim 2 or 3, wherein the state sensor (120) is configured to determine the first reference state (310) or the second reference state (320) of the filling material (104) by means of pattern recognition based on the signals from the plurality of the described sensors; and / or a statistical evaluation system of the signals from the plurality of the described sensors.

5. The method according to any one of claims 2 to 4, wherein the state sensor (120) is configured by means of a trained machine learning system based on the signals of the variety the described sensors, is configured to determine the first reference state (310) or the second reference state (320) of the filling material (104).

6. The method according to one of the preceding claims, wherein the state sensor (120) is configured to determine the first reference state (310) or the second reference state (320) of the filling material (104) by correlating at least one signal of the state sensor (120) with a measurement signal of the fill level sensor (100) on which the determination of the fill level is based.

7. The method according to one of the preceding claims, wherein the state sensor (120) is configured to determine the first reference state (310) or the second reference state (320) of the filling material (104) based on a shift of a measurement time of the fill level sensor with respect to at least one signal of the state sensor (120).

8. The method according to one of the preceding claims, wherein the state sensor (120) comprises an energy storage device for supplying energy to the state sensor (120) for determining the first reference state (310) or the second reference state (320); and / or an energy storage device for supplying energy to the state sensor (120) for determining the correlation.

9. Method according to one of the preceding claims, wherein the level sensor (100) comprises the condition sensor (120).

10. The method according to one of the preceding claims, wherein the operating mode (310, 320) of the fill level sensor (100) comprises a measuring method of the fill level sensor (100) and / or an evaluation of a measuring signal of the fill level sensor (100).

11. The method according to one of the preceding claims, wherein the measuring method of the operating mode of the fill level sensor (100) comprises a frequency of determining the fill level by means of the fill level sensor (100); and / or a repetition rate of determining the fill level (100) by means of the fill level sensor (100); and / or a synchronization of determining the fill level by means of the fill level sensor (100) with the ambient condition of the filling material (104); and / or a profile of a signal transmitted by the fill level sensor (100) for determining the fill level.

12. The method according to one of the preceding claims, wherein the evaluation of the measurement signal comprises a profile of an interference signal suppression (220) of a propagation time signal (210) of the level sensor (100); and / or comprises a signal evaluation of the level sensor (100); and / or comprises an output of a level value from the level sensor (100).

13. A fill level sensor (100), comprising: a system for determining a fill level (110) of a filling material (104) in a container (102); a state sensor (120) configured to determine a first reference state (310) or a second reference state (320) of the filling material (104); and wherein the fill level sensor (100) is configured to carry out a method according to one of claims 1 to 12.

14. The fill level sensor (100) according to claim 13, wherein the state sensor (120) comprises an acoustic sensor; and / or an acceleration sensor; and / or a temperature sensor; and / or a pressure sensor; and the state sensor (120) is configured to determine the first reference state (310) or the second reference state (320) of the fill material (104) based on signals from a plurality of the described sensors.

15. Use of a fill level sensor (100) according to claim 13 or 14 for determining a fill level of a filling material (104) with different ambient conditions of the filling material (104) in a container (102).

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