Method for evaluating the measuring signals of a propagation-time based measuring device

The present invention has a propagation time<u style="single">principle</u>Based on<u style="single">Works</u>Filling level measuring device<u style="single">Using,</u>Filling level of medium in container<u style="single">Measurement</u>Regarding how to do it.

This type of filling level measuring device itself is known. The device is usually installed in a container above a medium, also called a "filler". In order to determine the filling level of the medium, a high frequency signal, an ultrasonic signal or an optical signal generated by the filling level measuring device is transmitted from the measuring device toward the medium, and the signal is reflected on the surface of the medium.<u style="single">These reflected signals are</u>Also called a useful signal<u style="single">、</u>For filling level measuring device<u style="single">Therefore record</u>Will be done. Its propagation time is determined by the distance from the reflective surface of the medium to the measuring device. If the shape of the container is known, the filling level of the medium in the container can be determined.

As a filling level measuring device of this type, for example, a microwave measuring signal or a radar measuring signal is known, in which a radar signal is freely radiated from an antenna to a medium and returned from the medium to be received. Will be done. Another filling level measuring device using a radar measurement signal is also known, in which the radar measurement signal is guided by a waveguide extending into the filling material.

The main problem of the filling level measuring device based on the above propagation time principle is that the filling level measuring device also receives not only the reflected signal from the surface of the filling material but also the unnecessary reflecting object from the so-called interference position in the container. Is. For example, the interference signal generated by the object placed in the container or the shape of the container is superimposed on the desired useful signal from the surface of the packing material, and the useful signal can no longer be distinguished from it during the evaluation of the measurement signal. It becomes ambiguous.

On the other hand, from the interference signal, the operating status of the measuring device can be checked, and additional information on the packing material (information such as permittivity, conductivity, water content, temperature, mixing ratio, bubble formation, phase separation, etc.) can also be obtained. You can get a lot of information like this. However, in this form, this has not yet been achieved.

For example, DE-A-412 33 324 describes a free radiation radar device with transmit and receive antennas. In this case, a signal from the floor of the container is used to determine the filling level of the medium in the container, although it can only be ambiguously identified. However, with the mere liquid measurement methods described therein, a very accurate permittivity must be known to determine an unknown filling level, and the magnetic permeability of the filling material may also be required. .. However, this type of information is not always available and the physical characteristics of the medium in the container can change. Under these circumstances, in this reference, the time displacement of the floor signal is used to directly measure the filling level, or when evaluating the signal of the measurement curve, the residual signal is windowed and the filling level signal in the window is used. It is designed to identify.

The EP-A-0 457 801 also uses the interference position in the stilling tube to calibrate the filling level measuring device with the guided radar signal. In that case, a polarizable signal is required, and the plane of polarization can be changed by the polarization device. Thereby, the interference reflection intensity at the interference position can be changed. Not only is the use of a polarization device expensive and extra cost, but the signal is often unpolarized, for example, when a single wire or coaxial waveguide is used in the TDR filling level measuring device. ..

WO-A-00 / 43808 describes a TDR filling level measuring device whose permittivity is determined in relation to interface measurement. Two reflective surfaces are discussed as the two "product boundary layers" of the packing material, in which case one of the interference signals is also generated at the end of the waveguide, or at the floor inside the vessel. In this cited example, the measurement of the permittivity of a medium is discussed, but the measurement includes an error.

In addition, past filling level measuring devices with guided radar measurement signals are provided with a waveguide that has already been given a reflection position, i.e., a known interference position that is determined by its shape. However, the comprehensive evaluation of the signal transmitted from there in the above direction has not yet been realized at this time.

Thus, for example, U.S. Pat. No. 3,474,337 describes a filling level measuring device with a radar signal guided through a waveguide. In a so-called "TDR system (Time Domain Reflectometry)", in this case, the geometric reflection position in the coaxial waveguide is used as a reference position. However, the features described and protected in this U.S. patent include, without exception, waveguides with at least two separate conductors, and other features are described in relatively general terms. .. With this patent, it is not possible to determine the filling level or other features solely from the reflection at the interference position. Interference signals are evaluated only in the context of reflections from fillers.

Therefore, it is an object of the present invention that, using a measuring device based on the principle of propagation time, the measurement signal and information for determining the filling level of the medium in the container are more comprehensively than ever, in fact, the physical properties of the medium. A method that can be evaluated even if the information is not accurately known, and the filling level of the medium can be determined even when the signal reflected on the surface of the medium is not identified or is only vaguely identified among the measurement signals. To provide.

According to the present invention, this object is achieved by a method of measuring the filling level of a medium in a container using a filling level measuring device that operates based on the propagation time principle. The method is a reference for determining where in the container the measurement signal transmitted from the filling level measuring device to the container and returned is reflected in the following steps, that is, a). Reference signal data that serves as the container<u style="single">At the inner</u>Steps to get as a function of the propagation time of the reflected and returned measurement signal,<u style="single">b) A reference position x that is the position of a specific location in the container.</u>^{<u style="single">(0)</u>}<u style="single">Steps to find</u><u style="single">c</u>) A measurement curve consisting of an actual measurement signal transmitted from the filling level measuring device into the container and returned is shown at a certain first time point t.⁽¹⁾And a second point after that t⁽²⁾So, the steps to get each and<u style="single">d</u>) The measurement curve or the signal data selected from the measurement curve is compared with the reference signal data, and from the actual measurement signals, a useful signal which is a reflected signal from the medium surface in the container and the inside of the container. The step of finding the interference signal, which is the reflected signal from a place other than the surface of the medium,<u style="single">e</u>) The first and second time points t⁽¹⁾, T⁽²⁾At least one interference signal corresponding to each other is clearly present for each measurement curve obtained in the above-mentioned first time point t.⁽¹⁾There is clearly a useful signal in the measurement curve obtained in, and the second time point t⁽²⁾If there is no obvious useful signal in the measurement curve obtained in<u style="single">Note</u>Quasi<u style="single">Place</u>Place x⁽⁰⁾And the first time point t⁽¹⁾On the measurement curve obtained in<u style="single">Corresponds to the specific location</u>Interference signal position x⁽¹⁾And the first time point t⁽¹⁾On the measurement curve obtained in<u style="single">Be the standard</u>Position x⁽⁰⁾Filling level L corresponding to the distance from to the position of the useful signal⁽¹⁾And the second time point t⁽²⁾The identification on the measurement curve obtained in<u style="single">Corresponds to the location</u>Position x after change of interference signal⁽²⁾Using and,<maths num="2"><img file="JP4095960B2_D0001.tif" /></maths>By the second time point t⁽²⁾Unknown filling level L in⁽²⁾Includes steps to determine.

In another embodiment of the method according to the invention, reference signal data is obtained from at least one known measurement curve or is determined based on data specific to a known measuring device and / or vessel.

Yet another embodiment of the method according to the invention uses reference signal data obtained by evaluating measurements in an empty container. In yet another embodiment of the method according to the invention, the extremum of the measurement curve is used when selecting the reference signal data or the signal data of the measurement curve.

In yet another embodiment of the method according to the invention, the reference signal data exists in the form of a reference curve. In yet another embodiment of the method according to the invention, the reference curve is compared to the measurement curve by subtraction or correlation. In this case, the subtraction or correlation can be limited to only a portion of the signal data.

In yet another embodiment of the method according to the invention, interference signals and useful signals may be distinguished based on characteristic data specific to known containers or measuring devices. In this case, the measurement distance can be divided into several regions based on the known container installation or based on the in-container protrusion of the measuring device.

In yet another embodiment of the method according to the invention, the interference signal and the useful signal are distinguished by the signal information given. In this case, the signal information may be the amplitude, code, phase relationship, width and / or format of the signal data.

In yet another embodiment of the method according to the invention, the signal data selected from the measurement curve is compared to the corresponding signal data on the reference curve and the time course of the signal data is used to distinguish between useful and interfering signals.

Yet another embodiment of the method according to the invention utilizes the fact that the interference signal changes in the opposite direction to the useful signal over time to distinguish between the interference signal and the useful signal and / or to determine the fill level of the propagation time. In order to determine it as a function, the information from the detected interference or useful signal is weighted, as the case may be.

In yet another embodiment of the method according to the invention, if the filling level signal is ambiguous and indistinguishable, the desired filling level is of at least two or more interference signals of the measurement curve corresponding to a known geometric position. Determined based on time displacement.

Yet another embodiment of the method according to the invention relates to where the filling level is already known. In that case, the temporal displacement of at least two interference signals on the measurement curve corresponding to the known geometric position in the vessel on the medium is used to determine the correction factor for the propagation velocity of the gas phase. .. This correction factor calibrates the determined filling level.

In yet another embodiment of the method according to the invention, the signal at a position on the measurement curve where the propagation time of the actual measurement signal coincides with the propagation time of the inherently corresponding reference signal data is information about the state or function of the measuring device. Used to obtain.

Yet another embodiment of the method according to the invention uses a different filling level measuring device based on the propagation time principle. One of the basic ideas behind the present invention is that if the signal from the stirrer or other installation in the container is actually recognizable on the measurement curve but not the filling level signal, this is a known filling. As suggested by the leveling device, it does not have to mean that the vessel is empty, but rather the reflective surface of the medium in the vessel is below the stirrer or other in-vessel installation. It means that it has to mean that it has to.

Another basic idea is that in the case of a filling level measuring device that uses a radar and a small dielectric constant of the medium in the vessel, the filling level signal cannot be recognized and a signal from a stirrer or other container installation is expected. Unrecognizable in place, these facts provide a long effective path for the signal of the measuring device from the agitator or other vessel installation and to the agitator or other vessel installation, provided by the effect of dielectric constant. It is concluded that the filling level of the medium must be above the stirrer or other installation in the container, as the stirrer appears to be far away.

Moreover, in the present invention, even the terminal weights of the tank, the hydrostatic pipe, the bypass pipe or the cable-like waveguide of the filling level measuring device using the radar signal, which is probably located there, can transmit a large amount of signal. The filling level can be inferred from their position on the propagation time curve generated and generated from the measurement signal. If the distance between the two interference signals and the actual distance of the reflection position where the interference signals are generated are known, the filling level of the filling level measuring device based on the propagation time can be estimated even if the propagation speed of the measurement signal is not known. Thus, when dealing with radar signals, the material parameters do not need to be known in advance, as the propagation velocity depends on the material parameters, eg, the permittivity.

Another basic idea is that the sought-after useful signal, the reflected wave of the measurement signal from the surface of the filler, cannot be read from the "sink" of the signal representing a feature or background feature. This sink or feature pattern changes with the fill level signal, and the unknown fill level can be determined by comparing the actual feature pattern with the known pattern. This problem often occurs near filling level measuring devices. In this case, there is a high risk that the unknown filling level reflected signal can only be vaguely distinguished due to the natural decay of the transmitted signal.

According to the method according to the present invention, the accuracy and reliability of the measurement are increased, and information on the state of the filling substance and the measuring device can be obtained as well as the unknown filling level value. In summary, according to the present invention, filling directly from the measurement signal<u style="single">level</u>Advantageous even if the signal cannot be read<u style="single">Method</u>The filling level can be determined with. Further, the region where the filling level signal on the measurement curve created from the measurement signal does not exist can be excluded from the consideration. Further, according to the present invention, the status of the measuring device and / or the filling material can be determined independently of the filling level. As a result, the filling level can be estimated and the propagation velocity can be known based on a single time-displaced interference signal. The filling level can also be determined by evaluating the time displacement of the two interference signals generated by the permittivity, even if the propagation velocity is unknown.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments and drawings. For convenience of explanation, the same devices, modules or parts, as well as fillers and media shall be assigned the same reference numbers below, unless misleading.

FIG. 1 shows an outline of a typical arrangement of a filling level measuring device 10 using a radar mounted on a container 12 and protrusions in the container as an example. The radar filling level measuring device 10 for determining the filling level 14 of the medium 16 present in the container 12 is electrically driven via the cable schematically shown in the figure and is connected to, for example, a monitor (not shown). Will be done. For this purpose, the radar filling level measuring device 10 transmits a radar signal, preferably a pulse measuring signal, in the direction of the medium 16 from the horn antenna shown in the figure. These signals are reflected on the surface 18 of the medium 16. This is indicated by the double-headed arrow 20 in FIG. The reflected measurement signal It is received by the horn antenna and compared with the transmitted measurement signal by the radar filling level measuring device 10. The time from the transmission of the measurement signal to the reception of the reflection signal is registered and used as a measure of the distance between the radar filling level measuring device 10 and the surface 18 of the medium 16. Considering the shape of the container 12, this distance is converted to the filling level required by the medium 16. If none of the received signals is clearly distinguishable from the fill level signal, i.e., the signal reflected by the surface 18 of the medium 16, the fill level of the medium 16 is determined by the method according to the invention.

FIG. 1 further shows an injection tube 22, an upper side tube 26, and a bypass tube 24 with a lower side tube 28. The upper side tube 26 also reflects the measurement signal transmitted from the radar filling level measuring device 10 in the same manner, and in the method according to the present invention, this interference signal is used to determine the unknown filling level.

Here, what is designated as an "interference signal" is one that is not reflected from the surface of the medium. In the method according to the invention, those signals do not literally "interfere", but actually serve to determine an unknown filling level. The name "interference signal" comes from the prior art, in the sense that these signals can conceal the actual fill level signal or interfere with its explicit identification. To do. Known methods for determining unknown fill levels are not very useful without a clear fill level signal, and therefore fill levels cannot be uniquely determined.

When the radar filling level measuring device 10 is installed at the diagonally shaded position 11 of the container 12, the interference signal is reflected at the top of the injection tube 22, and in the method according to the invention, this interference signal is transmitted to an unknown filling level. Used for judgment.

As a precaution, it should be added that the filling level measuring device shown in FIG. 1 may be a free radiation measuring device. For example, a filling level radar device equipped with a planar antenna or a filling level radar device provided with a rod antenna can be considered as well as an ultrasonic filling level measuring device. Even in these filling level measuring devices based on the propagation time principle, if the interference signals are generated and the filling signals are not clearly identified or are not identified at all, these interference signals are present in the context of the method according to the invention. Used to determine an unknown filling level.

Figure 2 shows another structure of the filling level measuring device when the method for determining the unknown filling level cannot be implemented. This device is called the TDR filling level measuring device 30, where microwaves or radar signals guided by the waveguide 32 are used. The measurement signal is guided to the waveguide 32 extending into the medium 16, reflected by the surface 18 of the medium 16, and guided to the TDR filling level measuring device 30 through the waveguide 32. The movement of this signal is shown by double-headed arrows 34 and 35 in FIG.

Further, in the TDR filling level measuring device 30, as described with reference to FIG. 1, the propagation time of the measurement signal going to the reflection surface 18 of the medium and returning to the TDR filling level measuring device 30 (that is, the TDR filling level measuring device 30). And the distance between the medium 16), thereby determining the unknown filling level. However, in this case, it is assumed that the received measurement signal includes a clear signal for the filling level. If not, the methods according to the invention use interfering signals and / or specially evaluate the temporal displacement of individual signals or signal patterns to determine fill levels. Interference signals in the TDR filling level measuring device are generated near the waveguide 32 wherever there is a container installation. In the example of FIG. 2, the ladder 36 and the stirrer 38 correspond to it.

When the signal from the reflective surface 18 of the medium 16 in the container 12 is ambiguous, in order to determine the filling level of the medium, the filling level measuring apparatus according to the present invention is performed according to the examples of FIGS. 1 and 2 as follows. Apply to.

First, the reference signal data can be, for example, reference signal data for at least one or more known measurement curves acquired earlier or created from known device and / or container specific data. Obtained as a function of propagation time. In the latter case, the signal relates to the above signal originating from, for example, a ladder 36, an injection tube 22, a horizontal tube 26 and 28 of a bypass tube or a stirrer 38. Further, in order to keep the waveguide in the container straight, the weight 40 attached to the end of the waveguide 32 generates a conspicuous signal generally called an EOL signal (line termination signal). Another embodiment of the waveguide 32 or another application / vessel may be used in place of the termination weight 40 shown herein to pull the waveguide 32 to the floor of the vessel. Such connections also generate EOL signals.

The simplest is to make a so-called empty measurement using a filling level measuring device in an empty container 12 to obtain signals from the interference position and the reflection position. The various signals to be the reference signals are analyzed and characterized with reference to their amplitude and signal form, and the relevant distance information is as distance information to the measuring device and / or the propagation of the signal in the vessel. Considering the speed, it is added to the signal as propagation time information. When the empty measurement signal is merged into the propagation time curve, people also refer to it as the "feature" of the vessel (and its installation).

Actual measurement signal<u style="single">、</u>Or filling<u style="single">level</u>For the measurement distance between the measuring device and the surface of the medium<u style="single">Along</u>Of the measurement curve<u style="single">From inside</u>Choice<u style="single">Was done</u>The signal data is compared with the reference signal data to determine and mark the interference and useful signals in the measurement signal. The interference signal and the useful signal are evaluated and weighted with reference to how the filling level is determined or information about the function of the medium and the filling level measuring device is obtained, respectively. The reference signal data or the signal data of the measurement curve used in the method according to the present invention is selected, for example, as the extremum of the measurement curve.

As mentioned above, the reference signal can be arranged in the form of a reference curve and can be compared with the actual measurement curve. Also, if only selected reference signals are used, these reference signals are compared to the actual measurement signals for measurement distance or propagation time.<u style="single">Be done</u>To.<u style="single">Such a comparison</u>Of the signal<u style="single">shape</u>And the change in time relationship (propagation time), that is, the time displacement<u style="single">Find out</u>For the purpose of evaluation<u style="single">Is a thing</u>、<u style="single">Related</u>Signal data correlation<u style="single">Made by, done by subtraction,</u>Or the position of the extremum on the measurement curve and the extremum on the reference curve<u style="single">Ratio with</u>In comparison<u style="single">Therefore</u>Is desirable.

When distinguishing between interference signals and useful signals, in particular, these signals are characteristic data specific to known containers and measuring devices, such as protrusions on known container installations or containers of measuring devices, respectively. It plays a role when it can be identified based on. That is, thanks to these signals, the measurement distance or the signal representing the measurement distance can be divided into specific regions for searching for each of the interference or useful signals. The evaluation in such a case has an advantage that only the area of actual interest can be searched. This saves time and resources in evaluating signals of no interest.

Signal data amplitude, code, phase relationship, width and / or<u style="single">shape</u>Is particularly desirable to be used as signal information for evaluating the signal in the region of interest. In that case, the interference signal changes with time in the direction opposite to that of the useful signal. This is of interest. This is because, for example, when measuring an ascending filling level using a radar signal, all interference signals below the filling level signal are downward, i.e., because the propagation velocity of the medium is reduced. This is because it moves in the opposite direction to the reflected wave.

An example of determining the filling level by the method according to the present invention when the interference signal at a known reflection position can be clearly identified is described below. Therefore, the TDR filling level measuring device provided with the waveguide 32 shown in FIG. 2 is taken as an example. Figures 3a and 3b show the measurement curves 42a and 42b of the measurement signal as an example. In that case, in Figure 3a,<u style="single">Time point</u>t⁽¹⁾The measured signal amplitude in is plotted as a function of the distance x to the TDR filling level measuring device. The clearly recognizable signal 44 in the early stages of the propagation time curve 42a of FIG. 3a is generated by the coupling of the measurement signal generated by the TDR filling level measuring device 30 with the waveguide 32. This signal is a powerful reference signal and is called the "base reference signal". Another signal 46a at the end of the propagation time curve 42a is the EOL signal from the end of the waveguide 32. Figure 3a<u style="single">Time point</u>t⁽¹⁾So, the fill level signal 48 is clearly identifiable, which is reflected on the surface of the medium. This signal, referred to here for convenience as the fill level signal 48, is located between the basis reference signal 44 and the EOL signal 46a.

In the case of Figure 3b, a later point in time t⁽²⁾At time point t, if the filling level signal is not clearly recognized on the measurement curve 42⁽²⁾Unknown filling level L of medium in container in⁽²⁾Is the EOL signal 46, which is a known reflected signal from the end of the waveguide.<u style="single">b</u>(See Figure 3b). Comparing the measurement curves 42a and 42b, it seems that the initial measurement EOL signal 46a clearly shifts to the EOL signal 46b over time, even though the length of the waveguide in the vessel has not changed. .. Based on this, the filling level can be determined as follows.

First, a clear shift of the directly recognizable fill level signal 48 and EOL signal 46a on the measurement curve 42a x⁽¹⁾-x⁽⁰⁾From the constant B = (x⁽¹⁾-x⁽⁰⁾) / L⁽¹⁾Is obtained. In this case, L⁽¹⁾Is the actual position of the end of the sonde x⁽⁰⁾The filling level obtained from the filling level signal 48 on the measurement curve 42a for.<u style="single">Time point</u>t⁽²⁾If the filling level cannot be determined directly with, then Equation L⁽²⁾= (x⁽²⁾-x⁽⁰⁾) / B, the previously obtained value B and the sonde termination signal<u style="single">Obvious shift</u>x⁽²⁾-x⁽⁰⁾From filling level L⁽²⁾Is required.

If the medium in the container is a non-attenuating, non-magnetic dielectric, B =<u style="single">ε-1 (where ε represents the square root of ε)</u>Is. in this case,<u style="single">ε</u>Is the permittivity of the medium. In the known method of determining the filling level from the interference signal, the permittivity must be known. On the other hand, in the above method, this value does not have to be known. Instead, the instrument calibrates itself as the medium changes, and the user does not have to touch the new calibration. Moreover, much higher accuracy is achieved compared to known methods. If the permittivity of a fixed, preselected value is used in the calculation, for example because the water content of the particulate matter changes and it is believed that the value does not match the actual value, it is displayed as shown in FIG. It is considered that an erroneous relationship is established between the filling level to be processed and the actual filling level. Since the permittivity of the medium shifts the time coefficient of the signal after the fill level signal on the measurement curve, the graph shown in FIG. 4 shows that when determining the fill level using a permittivity that is too large or too small. There is an error in registering the estimated filling level.

The graph of FIG. 5 shows the case where the filling level L is determined by another method. This graph is an example when the filling level is measured based on the propagation time principle, preferably with a radar device. The graph plots relative fill levels for the position of the received signal on the measurement curve and, in some cases, for the propagation time. The unknown filling level is determined using the above equation and the limit line created by the EOL signal 50 on the one hand and the filling level signal 52 on the other. This is more obvious than the graph.

If the actual filling level value cannot be measured directly, or if the reflection position for determination is not clear, that is, the EOL signals 45a and 45b, or another from an installation below a filling level with a different measurement distance reflection position. When using a signal, the final valid value of L is output. In addition, it is possible that a warning or failure report will be issued by changing the value of L using the rate of change of L that was finally found. All of these reactions occur selectively and the delay time can be adjusted.

The above process can be applied to any known interference reflection. According to the method of the present invention, unlike known processes, the actual permittivity of the medium in the container need not be known. Instead, the filling level measuring device self-calibrates if there is at least one known significant interference signal, that is, a signal from a known reflection position other than the surface of the medium, along with a filling level signal received directly from the surface of the medium. ..

According to the method of the present invention, it is possible to estimate the measured values at the upper end and the lower end of the measurement distance. In this case, for example, since the interference signal reflected by the radar antenna is superimposed, direct measurement is not possible in principle. If the interference signal due to the intrinsic resonance of the nozzle installed in the container or measuring device is strong, the filling level signal has a large amplitude, and as a result, it is directly filled when it can be detected due to the superposition of the interference signal. When the level signal is always available, while the filling level signal is between the two interfering signals and does not exceed these signals, the filling level value can be interpolated by shifting the signal at the reflection position. .. In addition, this method can be applied regardless of a given measurement state. On the other hand, in the conventional method, the operator has to decide whether to measure based on the shift of the EOL signal or to measure the filling level reflected wave directly.

If at least two signals and reflection positions, preferably data in the lower region of the waveguide, are known, the method according to the invention will be described below. For convenience, the method will be described with reference to FIG. 6 using two reflection positions (see FIG. 2) at the beginning and end of the waveguide end weight 40. In principle, FIG. 6 returns to the example of the radar filling level measuring device 30 with the waveguide 32 shown in FIG. In this case, the termination positions 54 and 56 of the termination weight 40 (see FIG. 2) of the waveguide 32 are physically separated from each other by a known distance a. At the bottom of FIG. 6, a measurement curve is created from the measurement signals measured in an empty container. In addition, the base signal 44 (see FIGS. 3a and 3b) can be recognized together with the reflected signals 58 and 60 from the terminal positions 54 and 56 of the terminal weight 40. Since this is an empty measurement, there is no filling level signal. For convenience, the interference signal from the installation in the container is also omitted.

Below, consider the case where the measurement curve for an empty container of the type shown in FIG. 6 is compared with an actual measurement curve that is not created from a direct signal that seems to be a filling level signal. The reflected signals 58 and 60 from the terminal position of the terminal weight 40 are temporally displaced from one measurement curve to the other. The shift of the upward reflection signal 58 from the position in the empty container assuming that the filling level is above the end position 54.<u style="single">Δ</u>x₁And the downward reflection signal<u style="single">60</u>The amount of shift from the position of the empty container at the same point of<u style="single">Δ</u>x₂On the other hand, if a is the physical distance between the two reflection positions 54 and 56, the filling level is the equation L =<u style="single">Δ</u>x₂a / (<u style="single">Δ</u>x_{2 -}<u style="single">Δ</u>x₁) Clearly required.

At the start of medium on the waveguide 32, when the permittivity is very small (see FIG. 4), it appears that a nearly full container exists, so the above equation denominator<u style="single">Δ</u>x_{2 -}<u style="single">Δ</u>x₁When is above the minimum value, it initially indicates a filling level different from zero. Only then is it guaranteed that the filling material is actually present in the container. Filling level below reflection position 54, i.e. negligible displacement<u style="single">Δ</u>x₁If it can be recognized by a / (<u style="single">Δ</u>x_{2 -}<u style="single">Δ</u>x₁) Is used to calculate the filling level. The method is suitable for measuring fillers with low dielectric constant and low water content, such as foamed plastics.

If there are two or more known reflection positions, the filling level can be determined more accurately. In that case, the uppermost reflection position and the lowermost reflection position always covered by the filler are used in the above equation, and the displacement in the middle of the reflection position is used for the check.

The last method using a plurality of reflection positions can be easily realized by intentionally using a waveguide having a plurality of reflection positions. Suitable for this are all known types of waveguides, such as Sommerfeld waveguides (single wire waveguides), Goubau waveguides (dielectric coated single wire waveguides), and Lecher. There are lines (double-track waveguides), coaxial lines, microstrip leads, or hollow leads of some cross section, such as rectangular or circular cross sections.

Suitable reflection positions are those with locally altered geometries, such as altered cross-sections of metal or dielectric structures (thickened, narrowed, or other irregularities), electric fields. The dielectric property changes at a position other than zero, the magnetic property changes at a position where the magnetic field is non-zero, or the conductivity changes at a position where the current density is non-zero.

It is desirable that the entire series of reflection positions be arranged along the waveguide, provided that only a small portion of the total energy is reflected at the individual reflection positions. Their reflection positions may or may not be equidistant. They may be similar or different.

FIG. 7 shows an example of the waveguide 32 in which a plurality of such reflection positions are arranged. The reflection position embodied in the sleeve 62 is secured on the waveguide (preferably the wire cable Somerfeld waveguide 32) in a suitable manner to withstand the mechanical load from the filler. Has been done.

Changes in amplitude and propagation time of the reflected wave at such a reflection position, that is, the signal received by the measuring device, are registered and evaluated by the method of the present invention if they occur on the surface of the packing material or at the phase boundary. ..

FIG. 8 shows an example of a propagation time signal curve of a waveguide having a plurality of intentionally arranged reflection positions. This example also relates to a wire-cable Somerfeld waveguide 32 on which seven equally spaced similar metalic thickeners (metalic). Thickenings), preferably sleeve 62, are fixed, screwed, clamped, and / or welded. The reflected signals generated at different reflection positions, excited by the pulse signal, are numbered 2-8 on the propagation time curve 64. The thickening section is designed so that the negative transmitted signal becomes the main negative reflected wave, and is, in principle, distinguished from the positive filling level signal that travels from the air to the packing material. Further, the reflection position may be made to take a special signal form amplified by cross-correlation as compared with other signals. From the propagation time curve 64, the reflected wave No. 1 is recognized as being from the transition to the Somerfeld waveguide 32, which corresponds to the known ground signals in FIGS. 3a and 3b. Reflected waves No. 2 to No. 8 are generated from the seven thickening portions 62, while reflected waves No. 9 and No. 10 are generated from the start 54 and the end 56 of the terminal weight 40, respectively. Yes (see Figure 6).

When the filling level is determined by multiple reflection positions, the locally dependent complex permittivity<u style="single">ε</u>=<u style="single">ε</u>₁+ i<u style="single">ε</u>₂Is also partially determined. This is shown in FIG. In this process, the position of the interference signal on the clan time curve 66 of the empty container xi⁽⁰⁾And amplitude Ai⁽⁰⁾And the position of the interference signal on the actual propagation time curve 68 xi⁽¹⁾And amplitude Ai⁽¹⁾To compare. There is no obvious filler at positions where these values do not change. The change in position partially determines the propagation time (determined by the index of refraction n), which in turn is the real part of the permittivity.<u style="single">ε</u>₁Is decided. Moisture content due to changes in amplitude<u style="single">α</u>Is decided, and this time, depending on the water content, the imaginary part of the permittivity<u style="single">ε</u>₂Is decided. Those skilled in the art are well aware of the formal relationship of this calculation, for example, the book "Solid Electrodynamics" by M. Dressel and G. Grune, Cambridge University Press, Cambridge ( It is written in 2002).

dielectric<u style="single">function</u>The (dielectric function) contains information about propagation velocity and water content. For example, the correction factor for filling level measurements comes from the propagation velocity above the medium. This allows, for example, the effect of different gases above the filler on the speed of light to obtain more accurate measurements of the'signature'of hydrostatic pipes (many small geometries such as weld seams or holes). Compensated by high-precision radar tank level measurements using accidental reflection superposition on target interferers). There is no need for expensive equipment to change the polarization that was previously required. In addition, the propagation rate and / or water content of the medium is used to draw conclusions about the properties of the medium, namely properties such as conductivity, water content, temperature, mixing ratio, separation, layering, foam formation, etc. be able to. If the signal attenuation above the surface of the packing material is large, it can be asserted that the measurement reliability is reduced due to the signal attenuation.

As shown above, various embodiments of the method according to the invention allow for: Signals that are not generated by the filling level can be used to determine the range on the measurement curve where the filling level cannot exist, i.e. the range of the measurement distance. Signals that are not generated by the filling level can be used to determine the condition or measurement capability of the device. Signals that are not generated by the filling level can be used to determine the properties of the packing material, such as complex permittivity, conductivity, water content, temperature, mixed state, foam formation, etc. For that purpose, the present invention does not occur depending on the filling level, eg, instead of adding to the container or tank itself, bypass pipes, hydrostatic pipes and other waveguides as part of the measurement system or tank, or to said objects. The interference signal from the marking is used. However, reflection signals that are not generated by these filling levels can also be obtained from the coupling of the filling level measuring device.

Further, in the present invention, the signal referred to here may be a superposition of several or many signals. Also, it is particularly important that when the measurement signal by the method of the present invention is evaluated, if no change region is found on the measurement curve even when the actual measurement value is compared with the measurement value at the initial time point, the container is used. Indicates that it is already overflowing.

<figref num="1">FIG. 1 is a schematic diagram of a free radiation radar measuring device for determining the filling level of a medium in a container.</figref><figref num="2">FIG. 2 is a schematic view of a filling level measuring device on a container using a radar signal guided by a waveguide.</figref><figref num="3">3a and 3b are schematic diagrams of two measurement curves of the filling level measuring device using known interference signals at different time points.</figref><figref num="4">FIG. 4 is a graph schematically showing the effect of permittivity selection on the displayed filling level compared to the actual filling level.</figref><figref num="5">FIG. 5 is a graph for determining the filling level according to the present invention.</figref><figref num="6">FIG. 6 is a schematic diagram showing a filling level measuring device having two reflection positions on a waveguide and its termination weight, along with a corresponding propagation time curve.</figref><figref num="7">FIG. 7 is a schematic diagram of a fill level measuring device with a waveguide and another reflection position on the waveguide.</figref><figref num="8">FIG. 8 is a schematic diagram of a propagation time curve of a filling level measuring device including a waveguide and a plurality of reflection positions on the waveguide.</figref><figref num="9">FIG. 9 shows an outline of the propagation time curves corresponding to FIG. 8 for two different filling levels and a graph for determining the complex permittivity according to the present invention.</figref>