Spatially resolved fill level measurement

Abstract

The invention relates to a radar-based fill level measurement device (1) that can operate with low computational power and low power consumption to determine a spatial reference fill level value (# imgabs0 #). In order to achieve this, the filling level measuring device (1) is based on a converging lens (11) which is directed towards the filling material (2) such that the radar signals (# imgabs1 #, # imgabs2 #) are a transmittable bundle and a receivable bundle after reflection towards the filling material. A plurality of radar ICs (12, 12 ') are arranged with respect to the filling material (2) behind the converging lens (11) with mutually different offsets (# imgabs3 #, # imgabs4 #) from the optical axis (a) for generating and receiving radar signals (# imgabs5 #, # imgabs6 #) on the basis of the positional resolution results. In this manner, the radar signal (# imgabs7 #, # imgabs8 #) undergoes defined different deflections towards the filling substance (2). In order to determine the corresponding spatial reference fill level value (# imgabs9 #), the control evaluation unit (14) controls the radar ICs (11, 11 ') accordingly The arrangement of the invention avoids computationally intensive signal evaluation, such as, for example, digital beamforming, while the hardware expenditure is limited because an integrated beam array is not required as the radar ICs (12, 12') Instead, a separate radiator is used.

Description

Technical Field

[0001] The invention relates to a spatially resolved fill level measuring device and a method for operating the fill level measuring device. Background Art

[0002] In process automation technology, field devices are used to register relevant process parameters. Suitable measuring principles are implemented in field devices for registering process parameters such as fill level, flow, pressure, temperature, pH value, redox potential and conductivity. The largest variety of field devices of this type is manufactured and sold by the "Endress+Hauser" group of companies.

[0003] For fill level measurement of filling substances in containers, non-contact measuring methods have proven themselves due to their robustness and low maintenance costs. In this case, the term "container" within the scope of the present invention also includes non-closed containers, such as, for example, barrels, lakes and seas as well as flowing bodies of water. An advantage of non-contact measuring methods is their ability to measure the fill level virtually continuously. In the field of continuous fill level measurement, radar-based measuring methods are mainly applied (in the context of the present invention, the term "radar" refers to signals or electromagnetic waves with a frequency between 0.03 GHz and 300 GHz).

[0004] The measuring principle established in this case is FMCW ("Frequency Modulated Continuous Wave"). The measuring principle of the distance measurement method based on FMCW radar relies on the emission of a continuous radar signal with a modulated frequency. The characteristic of FMCW is that the transmission frequency changes periodically within a defined frequency band. Taking into account regulatory specifications, higher frequency bands around a standardized center frequency are used: in addition to the 6 GHz band, the 26 GHz band and the 79 GHz band, frequencies of 100 GHz and higher are being implemented. Advantageously for high frequencies, a larger absolute bandwidth can be utilized (for example, 4 GHz in the case of the 100 GHz band). In this way, a higher resolution or a higher accuracy of the fill level measurement is then achieved.

[0005] According to the standard, the time-varying frequency within the frequency band is linear and has a sawtooth or triangular shape. In principle, a sinusoidal variation can also be achieved. The distance is determined in the FMCW method based on the instantaneous frequency difference between the currently received high-frequency signal after reflection on the measurement object and the radar signal currently emitted by the measuring device. A filling level measurement method based on FMCW is described, for example, in the publication DE 10 2013 108 490 A1.

[0006] With the FMCW method, the distance and the fill level can be measured at least spVtwise. In this case, the point at which the fill level is measured depends on the orientation of the transmitting / receiving antenna and in the direction of its beam lobe (due to the overall reciprocity properties of the antenna, the characteristics of the beam lobe or ray angle of an antenna are independent of whether it is transmitting or receiving; with regard to the terms "angle" or "ray angle", in the context of the present invention, reference is made to the angle at which the beam lobe has its maximum transmission intensity and reception sensitivity).

[0007] In the case of liquid filling materials, where the filling level is usually uniform, a measurement of any point on the surface is sufficient. In this case, the filling level measuring device is so oriented that the beam lobe of the antenna is directed, for example, vertically downwards towards the filling material and the distance to the filling material is determined in this way. However, in the case of solid-based filling materials, such as gravel or food or feed pellets, the filling level can be non-uniform, for example due to tipping and funneling that the bulk cargo may experience, so that the filling level value determined by the filling level measuring device is only conditional information. In particular in this case, it is desirable to be able to determine the distance and thus to spatially resolve the filling level in the form of a two-dimensional or three-dimensional profile. In addition to the precise volume estimation, the visual 3D representation of the imaging filling level measuring device in particular offers many benefits for automated filling processes and even mining processes. In addition, dangerous filling states can be noticed and prevented by visualization, which means that the reliability and safety of the corresponding process plant can therefore be increased.

[0008] For spatially resolved fill level measurement, the beam lobe of the radar-based fill level measuring device can be made by mechanical means to perform a scanning action so that the fill material profile can be registered over the entire container cross section or at least a portion thereof. However, due to the increased maintenance effort, this form of embodiment is only used for special applications, such as for example in mining.

[0009] Furthermore, radar-based distance measuring devices are known in the prior art in the case where the beam lobe is electronically scannable. Among other things, in the case of a measuring device with multiple antennas, the so-called "phased array" principle can be utilized, in which their radar signals are superimposed for evaluation. The antennas are arranged in rows (beam scanning along one axis) or in arrays (beam scanning on two axes). In order to radiate or receive high-frequency signals at a defined angle, the individual antennas are operated according to their position, with the phase shift of each antenna increasing. In this case, the angle of the beam lobe is given by the following formula: Depends on the phase shift

[0010] .

[0011] According to the prior art, the required hardware can be compactly integrated so that the antenna is accommodated as a patch antenna and the semiconductor components for signal generation / signal evaluation on a shared circuit board and even packaged together as a radar IC ("integrated circuit"). In addition, a distance measuring device operating according to the phased array principle is described in DE 100 36 131 A1.

[0012] In addition to the phased array principle, spatially resolving radar measuring devices can also be designed alternatively based on digital beamforming ("digital beamforming"). In this case, each antenna of the antenna array has its own signal processing and its own digitization. The received signals are digitized with respect to their amplitude and their phase difference using corresponding methods. The summation is performed digitally based on virtual phase shifts and amplitude scaling in a special computer, a so-called beamforming processor ("beamforming processor"). With digital beamforming, the radiation properties of the antenna can be formed in such a way that it has multiple independent main lobes for different directions.

[0013] High lateral resolution of the fill level measurement can be achieved both with the aid of digital beamforming and with the aid of the phased array principle. However, the signal processing is very complex in both cases and requires corresponding hardware and therefore corresponding computing power. However, due to explosion protection requirements, in the case of fill level measurement applications, in particular the power consumption is greatly restricted. Summary of the invention

[0014] It is therefore an object of the present invention to provide a spatially-resolving fill level measuring device which can be operated with a low computing power and a correspondingly low power consumption.

[0015] The invention achieves this object by a radar-based fill level measuring device for determining a spatially referenced fill level value of a fill substance in a container, comprising:

[0016] - a converging lens (11) having an optical axis, which in the fastened state is directed towards the filling material so that the radar signal is a beam which can be transmitted towards the filling material and a beam which can be received after reflection on the surface of the filling material,

[0017] - at least two radar ICs, the at least two radar ICs being designed to,

[0018] - generate a transmit radar signal, and / or

[0019] - Reflected radar signals are received after reflection on the filling material and in each case a reception signal is generated from the reflected radar signals, with the aid of which the radar signal travel time can be determined.

[0020] According to the invention, at least two radar ICs are arranged relative to the filling substance behind the converging lens and have defined mutually different offsets from the optical axis and are oriented towards the converging lens. In this case, it is not excluded that one of the at least two radar ICs has a zero offset from the optical axis and also includes

[0021] - A control and evaluation unit which is designed to drive the radar IC and to determine the signal travel time in such a way that at least two spatially referenced fill level values ​​are determined.

[0022] The term "unit" in the context of the present invention means in principle any individual arrangement or packaging of electronic circuits provided for a specific application, for example, for measuring signal processing or for use as an interface. Thus, depending on the application, a specific unit may include corresponding analog circuits for generating or processing analog signals. However, a unit may also include digital circuits, such as FPGAs, microcontrollers or storage media, that cooperate with corresponding programs. In this case, the program is designed to perform the required method steps, or to apply the necessary computing operations. In this context, the different electronic circuits of a unit may also, within the scope of the present invention, potentially also use a shared physical memory, or operate with the aid of the same physical digital circuits. In this case, it is unimportant whether the different electronic circuits within a unit are arranged on a shared circuit board or on multiple connected circuit boards.

[0023] Using the design of the fill level measuring device of the invention with a plurality of radar ICs suitably arranged relative to the converging lens, areas of the fill material surface can be registered with little hardware and evaluation effort without ambiguity errors or deviations due to a possibly defective calibration. The fill level measuring device of the invention is also advantageous for manufacturing, since at least two radar ICs can have a shared package.

[0024] In order to achieve a fill level measurement position with sufficient resolution, it is advantageous if:

[0025] - Number of radar ICs,

[0026] - the distance between at least two radar ICs,

[0027] - The distance between the radar IC and the focusing lens,

[0028] - the power of the converging lens, and / or

[0029] - Radar frequency of radar IC

[0030] The radar ICs are matched to each other in such a way that the resulting main radiation lobes of the radar ICs have a maximum offset of -10 dB relative to each other in the container. Furthermore, for a uniform resolution, it is advantageous if at least two radar ICs are arranged mirror-symmetrically with respect to the optical axis. On the other hand, the parameters should be selected so that the main radiation lobes have a maximum offset of -3 dB relative to each other, since the spatial unambiguity of the fill level values ​​measured in other ways is no longer ensured.

[0031] In the context of the present invention, the radar method for determining the individual travel times is not primary. The at least two radar ICs can, for example, be suitably designed to generate radar signals and receive signals using an FMCW method or a pulse travel time method. In addition, the fill level measuring device of the present invention can be further developed by implementing and arranging the at least two radar ICs in such a way that the greater the amplitude of the offset of the radar ICs from the optical axis, the narrower the radiation cone they emit the radar signals to the converging lens and receive the radar signals from the converging lens. In this way, the lateral resolution of the fill level value can be kept approximately constant over the height of the container.

[0032] In the simplest case, a monostatic operating method can be implemented in the fill level measuring device according to the invention. In this case, the radar signals are emitted and received by the same radar IC in each case in order to determine the corresponding fill level value therefrom. . Thus, in each case, the number of lateral positions at which fill level values ​​can be determined corresponds to the number of radar ICs used. In order to enable the same number of radar ICs to determine fill level values ​​at significantly more positions, it is advantageous to construct the control and evaluation unit which drives the radar ICs by means of a bistatic radar method and determines the corresponding fill level values. At least in the case of the bistatic method, it is necessary to clock all radar ICs at a high frequency by means of a shared clock source. In this way, it is ensured that the radar signals emitted by different radar ICs have the same phase difference.

[0033] The dual-base method is also very advantageous, and a plausibility check of the determined fill level value can be performed for the fill level measuring device according to the invention, whereby the operation of the process device is safer. The following method steps are applied for the plausibility check:

[0034] - transmitting a radar signal by means of a first radar IC,

[0035] - receiving the corresponding radar signal via the second radar IC after reflection on the surface of the filling material,

[0036] - determining a first signal travel time based on the corresponding received signal,

[0037] - determining a second signal travel time by repeating the aforementioned method steps, wherein the two radar ICs alternate between being transmitter and receiver, and

[0038] - Classifying the fill level value as not genuine when the first signal travel time and the second signal travel time do not coincide. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will now be explained in more detail based on the accompanying drawings, which are as follows:

[0040] Figure 1 The present invention is a filling level measuring device on a container,

[0041] Figure 2 The conceptual construction of the measuring device of the present invention is shown in cross section.

[0042] Figure 3 is the conceptual configuration of the measuring device of the present invention in a plan view; and

[0043] Figure 4 is a schematic block diagram of a measuring device of the present invention. DETAILED DESCRIPTION

[0044] In order to understand the present invention in principle, Figure 1 A container 3 is shown which contains a filling substance 2, the filling level L of which is to be determined. In this case, the height of the container 3 may be more than 100 m, depending on the type of filling substance 2 and on the field of application.

[0045] In order to be able to determine the fill level L, the radar-based fill level measuring device 1 is installed above the fill material 2 at a known installation height h above the base of the container 3. In this case, the fill level measuring device 1 is fastened at the corresponding opening of the container 3 in such a way that the radar signal , The fill level measuring device 1 can thus be arranged substantially outside the container 3 .

[0046] Sending / emitting radar signals After transmission on the surface of the fill material, the fill level measuring device 1 receives the reflected radar signal In this case, the corresponding radar signal is transmitted and / or received according to the following formula , The resulting signal travel time t between φ and φ is correspondingly proportional to the distance d between the fill level measuring device 1 and the filling substance 2 :

[0047] .

[0048] In this respect, the parameter "c" is the radar propagation speed which depends on the medium. In order to determine the signal travel time t, an FMCW or pulse travel time method can be implemented in the fill level measuring device 1. For example, based on a corresponding calibration, the fill level measuring device 1 can then associate the measured signal travel time t with the distance d. In this way, the fill level measuring device 1 can determine the fill level L at least point by point according to the following formula:

[0049]

[0050] When the installation height h is provided in the fill level measuring device.

[0051] As a rule, the fill level measuring device 1 is connected to a superordinated unit 4, such as, for example, a local process control system or a cloud server system, via a separate interface unit, such as, for example, "4-20mA", "PRVFIBUS", "HART" or "Ethernet". In this way, the measured fill level value L can be transmitted, for example, in order to control a possible inflow and / or outflow of the container 3. However, other information about the general operating state of the fill level measuring device 1 can also be transmitted.

[0052] like Figure 1 As shown, the surface of the filling material 2 is not planar. This can be particularly the case in which the filling material 2 is a bulk cargo, for example, when the container 3 is filled, the bulk cargo forms a cone. In addition, the discharge of the filling material 2 leads to the formation of a discharge funnel shape of the filling material surface. When the filling level measuring device 1 determines the filling level L only at one site on the surface of the filling material 2, this can lead to a defective interpretation of the filling level L. In the following way: when the filling level measuring device 1 senses an empty container 3, the emptying procedure can be erroneously stopped even if the filling material 2 is still present on the side facing the interior of the container. In another case, it can happen that in the case of a full container 3, the filling process is not paused, although the maximum filling level at the location of the filling material surface has been exceeded, because this is not detected by the filling level measuring device.

[0053] to this end, Figure 1 The fill level measuring device 1 shown determines the fill level with spatial resolution with reference to a plane x; y orthogonal to the axis a. In this case, the central component is responsible for focusing the radar signal. , The lens 11. Figure 1In the case of the embodiment shown, the converging lens 11 also seals the fill level measuring device 1 from the filling substance 2. In this case, the converging lens 11 in the fastened state of the fill level measuring device 1 on the container 3 is arranged such that its optical axis a (along which the radar signal , is focusable) is directed vertically downward toward the filling material 2, such as Figure 1 Preferably, the converging lens 11 is integrated into the fill level measuring device 1 in such a way that the components located inside the fill level measuring device 1 are encapsulated inside the container 3 in an explosion-proof manner.

[0054] Therefore, inside the fill level measuring device 1, behind the converging lens 11 relative to the filling substance 2, according to the invention, a plurality of radar ICs 12, 12' are provided. In this case, each of the radar ICs 12, 12' has a full-value function with respect to the point-by-point distance measurement. This means that each of the radar ICs 12, 12' can be used to generate, transmit and receive radar signals. , Thus, depending on the implemented measurement principle, for example FMCW or the pulse travel time method, a specific radar IC 12, 12' generates its own receive signal ZF, ZF' based on which the radar signal travel time can be assigned to the receive signal ZF, ZF'. In order to be able to determine the radar signal between transmission and reception based on the receive signal ZF, ZF' , The radar signal travel time t is determined by connecting the radar IC 12, 12' using a control evaluation unit 14. In this case, the control evaluation unit 14 determines the specific signal travel time t and its fill level value based on the Fourier transformation of the received signal ZF, ZF' using the FMCW principle .

[0055] Figure 2 and Figure 3 The radar ICs 12, 12' are shown arranged on a circuit board 15 within the fill level measuring device 1. In the variant shown, all radar ICs 12, 12' are packaged together, for example by a potting compound 16. In this way, separate packaging of the individual radar ICs 12, 12' is avoided. The shared package 16 is transparent so that the radar signals carried by the radar ICs 12, 12' are not , The emission and reception of the primary radiator are not suppressed. This can also be achieved, for example, by extending the corresponding primary radiator above the package 16 and thus not being affected by it. Suitable production methods for this include, in particular, selective dispensing, suppression using 3D printing, covering the primary radiator that is not filled with a protective form or a protective film ("foil-assisted molding"), which is then removed.

[0056] The circuit board 15 is mounted inside the fill level measuring device 1 in such a way that the radiation cones λ1, λ2 within which the radar signals of the radar ICs 12, 12' are positioned approximately parallel to the axis a of the converging lens 11. , In this case, on the one hand, the radar ICs 12, 12' are arranged on the circuit board 15 at mutually different positions x, y relative to the axis a of the converging lens 11 and are in fact mirror-symmetrical to the x- and y-axes, such as can be seen in particular from Figure 3 On the other hand, the radar ICs 12 , 12 ′ are divided into two groups of four, wherein, according to the invention, these groups differ in the magnitude of the lateral offset V1 , V2 of the radar ICs 12 , 12 ′ from the optical axis a of the converging lens 11 .

[0057] like Figure 1 As shown in FIG. 1 , due to two different offsets V1 and V2, the radar IC 12 and 12 ′ emit and receive radar signals toward and from the filling material 2 in the container 3 relative to the axis a of the converging lens 11. , This enables the control and evaluation unit 14 to determine the fill level value Extends laterally over as wide an area as possible on the surface of the filling material. In single-base operating mode, the fill level value can be registered The number m is equal to the number n of radar IC12, 12', so in Figure 3 In the example of the embodiment shown, this is 8.

[0058] On the surface of the filling material and the corresponding fill level value The associated lateral position x; y results from the position of the corresponding radar IC 12, 12' on the circuit board 15 relative to the axis a of the converging lens 11 (ie the offset V1, V2), the distance value d determined and the diopter of the converging lens. The lateral registration is as uniform as possible, preferably with a tight grating, diopter and position selected so that the resulting main radiation lobe of the radar IC 12, 12' in the container 2 (see Figure 1) have an offset of -10 dB or less. In case of -3 dB or less overlap, the main radiation lobes are too directional or the viewing angles overlap too much.

[0059] exist Figure 2 and Figure 3 In the case of the exemplary embodiment of the fill level measuring device 1 according to the invention shown, the four radar ICs 12' arranged on the circuit board 15 with a greater offset V2 from the axis a have a narrower radiation cone λ2 than the radiation cone λ1 of the internal radar IC 12. In this way, the radar signal behind the converging lens 11 towards the fill material 2 , The corresponding main radiation lobe of the internal radar IC 12 is wider than the main radiation lobe of the internal radar IC 12 offset by V1, such as this Figure 1 As shown in .

[0060] in this regard, Figure 1 The schematic clearly shows that, relative to the optical axis, the radar signal , The outer main radiation lobe of only illuminates the higher fill level L and, at least in the case of a relatively narrow container 3, is not suitable for low fill levels L. In the case of higher fill levels L, the outer radar signal , The wider main radiation lobe illumination allows for surface resolution comparable to that achieved with radar signals at low fill levels L. , Due to the number of pixels and the spatially resolved fill level value Corresponding to the number of main radiation lobes and radar ICs 12, 12', a very high number of radar ICs 12 would be required to fully illuminate higher fill levels L using exclusively narrow main radiation lobes. However, due to the good imaging for the user, the surface resolution at high fill levels L does not have to be increased, wider radiation lobes are sufficient for larger deposition angles and higher fill levels L, and according to the invention only a limited number of lobes is required.

[0061] In order to set the radiation cone λ1, λ2 of the radar IC 12, 12' to be correspondingly wide or narrow, e.g. radar focusing, the main radiator 13, 13' can be mounted in front of the planar antenna of the radar IC 12 and 12'. Overall, by using the inventive design of the fill level measuring device based on a single radar IC 12, 12' associated with a converging lens 11, a fill level profile with sufficient lateral resolution over a large height range h of the container 3 can be achieved without the need for a complex and therefore power-intensive subsequent signal evaluation.

[0062] Based on the fill level values ​​determined at different positions x;y The control and evaluation unit 14 can create the contour of the filling material surface, for example by means of interpolation. In this case, the contour of the filling material surface can be displayed on a display of the filling level measuring device 1 or, for example, by the superordinate unit 4.

[0063] In addition to the monostatic operating mode, the fill level measuring device 1 according to the invention can in principle also be operated in a so-called bistatic mode. For this purpose, the operating mode can be set by the control and evaluation unit 14. Figure 4 An example of a circuit diagram of two radar ICs 12 and 12' is shown in FIG. 1 , by which radar signals can be generated and received not only by a single base but also by a dual base. , In this case, the FMCW principle is implemented in the example shown so that the radar IC 12, 12' Figure 4 The operation is based on mixers 125, 125'. These mixers are used to convert the instantaneously transmitted radar signal The radar signal currently received via the main radiator 13, 13' In this way, a received signal ZF, ZF' is generated, the frequency of which changes proportionally to the signal travel time and thus proportionally to the distance d. By reading out this frequency (for example, by means of a fast Fourier transform), the control and evaluation unit 14 can determine the corresponding signal travel time t according to the FMCW principle.

[0064] In the radar IC 12, 12', the radar signal to be transmitted is fed to the main radiators 13, 13' via the transmit / receive duplexer 123, 123', and the received radar signal is also fed to the main radiators 13, 13' via the duplexer can be forwarded to mixers 125, 125'. In this case, the radar signal , Amplification is carried out before transmission and after reception in each case by an amplifier 122, 122', 123, 123', as required, which is arranged directly before or after the transmit / receive amplifier 123, 123'. With regard to bistatic measurements, it is advantageous if at least the receive amplifier 124, 124' has sufficient reverse loss, in particular >20 dB.

[0065] In addition to signal amplification, the radar signal to be transmitted Also undergoes frequency doubling. Figure 4In the case of the embodiment shown, for this purpose, according to the radar IC 12, 12', in each case, therefore before the transmit / receive duplexer 123, 123' and before the mixer 125, 125', both in the transmit path and in the receive path, an associated frequency multiplier 121, 121', 126, 126' is provided with an equal multiplication factor N. Such separate amplification in the transmit path and in the receive path improves the LO suppression for bistatic operation in particular.

[0066] The frequency multiplication factor N of the frequency multipliers 121, 121', 126, 126' is equal to the radar signal , The desired frequency of the radar signal is divided by the frequency of the clock source 17 driving the radar IC 12, 12'. The clock source 17 can be implemented as an adjustable, phase-controlled control loop (better known as a "phase-locked loop, PLL") for example for a VCO ("voltage controlled regulator"). In this way, the radar signal The frequency can accordingly have a ramp-shaped modulation time according to the FMCW principle.

[0067] exist Figure 4 In the case of the embodiment shown, all radar ICs 12, 12' are driven by the same clock source 17. This can be achieved, for example, by having the VCO of one of the radar ICs 12, 12' supplementarily used as the clock source 17 for all additional radar ICs 12, 12', while their VCOs are deactivated. In this way, the radar signals emitted from the different radar ICs 12, 12' are The phase equality of is ensured, which is necessary for the bistatic operation of the radar IC 12, 12'. In contrast to the monostatic operation, the position-dependent fill level value In the case where the number of radar ICs 12, 12' is limited, bistatic operation enables filling level values ​​at more positions x; y in the container 3 than the current number of radar ICs 12, 12'. of the registration.

[0068] In addition to the fill level value in single base operation mode In addition (in each case, the radar signal in monostatic operation , Transmitted and received by the same radar IC 12, 12' in order to determine the corresponding fill level value therefrom ), radar signal in bistatic operation is transmitted by the first radar IC 12 and, after reflection, is received by the second radar IC 12'. To this end, for bistatic operation, Figure 4The components 124, 126, 121', 122' of the radar IC 12, 12' in the cross-hatching in are deactivated. In this case, the (de)activation and coordination of the bistatic measurement of these components 124, 126, 121', 122' can be done by the control and evaluation unit 14. Figure 4 In contrast to the display of FIG. 1 , the bistatic principle for spatially resolved fill level measurement can also be transferred to any number n of radar ICs 12 within the scope of the invention. In general, the fill level value is given by the Gaussian empirical formula is the theoretical maximum number of positions that can be registered and m is the number in bistatic operation:

[0069] .

[0070] Another advantage of the dual-base method, especially compared to industrial fill level measurement, is that the fill level value For the authenticity is testable. In the context of the present invention, this is possible because for those measurements, the fill level value In the case of non-monostatic registration, the paired functions of the radar IC 12, 12' as transmitter and receiver are reversed. In this case, in both constellations, the signal travel time and the corresponding fill level value Logically, the results should be identical. If this is not the case, for example due to a fault in the fill level measuring device 1 , an untrue fill level value is assumed. For such scenarios, the control and evaluation unit 14 can, for example, be designed to generate a corresponding disturbance message. This causes the fill level measuring device 1 to perform a corresponding self-diagnosis in order to be able to report a possible malfunction to the superordinate unit 4. In this way, the risk of uncontrolled process states in the container 3 can be further reduced.

[0071] Reference numerals list

[0072] 1 Fill level measuring device

[0073] 2 Filling material

[0074] 3 Container

[0075] 4 Parent unit

[0076] 11 Converging lens

[0077] 12 Radar IC

[0078] 13 13' Main Radiator

[0079] 14 Control and evaluation unit

[0080] 15 Circuit Board

[0081] 16 Packaging

[0082] 17 Clock Source

[0083] 121, 121' Frequency doubler in the transmission path

[0084] 122, 122' Transmitter Amplifier

[0085] 123, 123' transmit / receive splitter, directional coupler

[0086] 124, 124' receiving amplifier

[0087] 125, 125' mixer

[0088] 126, 126' Frequency multiplier in the receive path

[0089] λ1, λ2 Radiation cone width

[0090] a Optical axis of the converging lens

[0091] d Distance

[0092] h Installation height

[0093] Fill level value

[0094] m Number of positions x;y at which the fill level value is registered.

[0095] N-multiplication factor

[0096] n Number of radar ICs

[0097] , Radar signals (reflected and transmitted)

[0098] V1, V2 offset

[0099] x;y position coordinates

Claims

1. A method for determining a spatially referenced filling level value ( 2 ) of a filling substance ( 3 ) in a container ( 3 ) ) is a radar-based fill level measuring device comprising: - a converging lens (11) having an optical axis (a), which, in the fastened state, is directed towards the filling substance (2) so that the radar signal ( , ) is the transmittable beam towards the filling material (2) and the receivable beam after reflection on the surface of the filling material, - at least two radar ICs (12, 12'), the at least two radar ICs (12, 12') being designed to: ° Generate transmit radar signal ( ), and / or ° Receive the reflected radar signal ( ), and in each case from the reflected radar signal ( ) generating a received signal, with the aid of which the radar signal travel time can be determined, The at least two radar ICs (12, 12') are arranged relative to the filling material (2) behind the converging lens (11) and have defined mutually different offsets from the optical axis (a) ( , ), and is oriented toward the converging lens (11), and - a control and evaluation unit (14) designed to drive the radar IC (11, 11') and to fill the fill level value with at least two spatial references ( ) is determined in such a way as to determine the signal travel time.

2. The filling level measuring device according to claim 1, wherein: The at least two radar ICs (12, 12') are designed to generate radar signals using a FMCW method ( ) and the received signal.

3. The filling level measuring device according to claim 1 or 2, wherein: One of the at least two radar ICs (12, 12') is not offset from the optical axis (a) ( , ).

4. Fill level measuring device according to one of the preceding claims, wherein: The at least two radar ICs (12, 12') have a shared package (16).

5. Fill level measuring device according to one of the preceding claims, wherein In the case where the fill level measuring device (1) comprises more than two radar ICs (12, 12'), the radar ICs (12, 12') are arranged mirror-symmetrically with respect to the optical axis (a).

6. Fill level measuring device according to at least one of the preceding claims, wherein: The at least two radar ICs (12, 12') are implemented and arranged such that the offset ( , ) is larger, the radar IC (12, 12') transmits the radar signal ( , ) is transmitted to the converging lens (11), and the radar signal is received from the converging lens (11) ( , ).

7. Fill level measuring device according to at least one of the preceding claims, wherein: - Number of radar ICs (12, 12'), - the distance between the at least two radar ICs (12, 12'), - the distance between the at least two radar ICs (12, 12') and the converging lens (11), - the diopter of the converging lens (11), and / or - Radar frequency of the radar IC (12, 12') The radar ICs (12, 12') are matched to each other in such a way that the resulting main radiation lobes of the radar ICs (12, 12') have a minimum -3 dB and / or maximum -10 dB shift relative to each other in the container (2).

8. Fill level measuring device according to at least one of the preceding claims, wherein: The control and evaluation unit (14) is designed to drive the radar IC (12, 12') by means of a bistatic radar method and to determine a corresponding fill level value ( ).

9. The filling level measuring device according to claim 8, wherein: The at least two radar ICs (12, 12') are clocked at a high frequency by means of a shared clock source (17).

10. A method for measuring a spatially resolved fill level value ( ) authenticity method, where The method comprises the following method steps: - Transmitting a radar signal ( ), - receiving a corresponding radar signal via a second radar IC (12') after reflection on the surface of the filling material ( ), - determining a first signal travel time based on the corresponding received signal, - determining a second signal travel time by repeating the aforementioned method steps, wherein the two radar ICs (12, 12') alternate between being transmitter and receiver, and - When the first signal travel time and the second signal travel time are inconsistent, the filling level value ( ) is classified as untrue.

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