Level radar with variable quantification accuracy

Abstract

The present invention relates to a method for setting the quantization accuracy of a level radar (100) or an ultrasonic measuring device for determining the level (40, 45) of a container (20, 25). The method comprises the following steps: acquiring the amplitude value of an echo curve (200) of the level radar (100) through an analog-to-digital converter ADC (130); determining the first amplitude value of a first echo having the highest amplitude (202) or the highest local amplitude maximum (204, 208) of the echo curve (200); determining the second amplitude value of a second echo having the lowest local amplitude maximum (206) of the echo curve (200); and setting the adjusted quantization accuracy as a function of the quotient of the first amplitude value and the second amplitude value, so as to determine the level (40, 45) of the container (20, 25) using the adjusted quantization accuracy.

Description

Technical Field

[0001] The invention relates to a method for setting the quantization accuracy of a level radar or ultrasonic measuring device. The invention further relates to a field device, a program element, a computer-readable medium and a use. Background Art

[0002] The level radar device measures the distance to the filling material by means of a sensor system based on an evaluation of the transmission time of the emitted radar signal and / or ultrasonic signal. Since the level radar device is designed as a field device (e.g., a self-contained field device) at least in some cases, the energy consumption of the sensor system and / or other components of the field device may be critical. Therefore, a measure is desired to reduce the energy consumption of the field device in at least some cases. Summary of the invention

[0003] It is an object of the present invention to reduce the energy consumption of field devices in at least some circumstances.

[0004] One aspect relates to a method for setting the quantization accuracy of a level radar for determining the fill level of a container, comprising the following steps:

[0005] The amplitude value of the echo curve of the level radar is obtained through the analog-to-digital converter ADC;

[0006] determining a first amplitude value of a first echo, the first echo having the highest amplitude or the highest local amplitude maximum of the echo curve;

[0007] determining a second amplitude value for a second echo, the second echo having the lowest local amplitude maximum of the echo curve; and

[0008] The adjusted quantization accuracy is set as a function of the quotient of the first amplitude value and the second amplitude value, so as to determine the filling level of the container by using the adjusted quantization accuracy.

[0009] Here, the quantization accuracy is understood to be the "maximum resolution" and / or the "(effective) measurement accuracy" of the sensor system and / or the measuring device. The quantization accuracy can therefore, for example, relate to the sensor system, the processing path, the transmission path and / or other components of the measuring device. For example, the sensor system can be designed as a level radar using a pulse transmission time method and / or a continuous wave radar method. For example, the sensor system can be used to measure the level and / or determine the topology of the filling material. For example, the sensor system can also be designed as an ultrasonic measuring device. Even if the various aspects of the ultrasonic measuring device are no longer explicitly mentioned in the following text, the following also applies to the ultrasonic measuring device in an appropriate manner. The measuring device can be designed as a field device, in particular a self-contained field device. For example, the measuring device can be arranged in a container, for example a vessel or a metering box of any shape, or it can also be arranged on or above a channel such as a stream bed or a river bed.

[0010] The sensor system includes at least one analog-to-digital converter (i.e., ADC). The ADC may have a predefined and / or set sampling accuracy or quantization accuracy, such as 14 bits or other resolution. The sampling accuracy may be fixed or settable. The ADC may sample values ​​directly from the sensor (i.e., the echo signal), or "indirectly" from the sensor using one or more intermediate stages (e.g., an intermediate frequency generator). The frequency of the measurement may depend on the rate of change of the level, i.e., in the case of frequent changes in the level, more frequent measurements may be appropriate.

[0011] The echo signal consists of a series of amplitude values, wherein in many cases the amplitude values ​​are plotted as ordinates (e.g., in dB (decibels) or in V (volts)) over the distance from the antenna or the sampling time (with the distance d or the time t as the abscissa). Local maxima of the amplitude values ​​may be caused by reflections from the filling material, for example, by reflections from the surface of the filling material, from the mounting in the container, from the antenna (e.g., when a horn antenna is used), and / or by reflections from other objects in or on the container. Local maxima of the amplitude values ​​are usually referred to as "echoes". If the container has a greater depth, for example, of several meters, the echo at the bottom of the container may be particularly weak, i.e., have a particularly low amplitude value, and / or may require a higher transmission energy to obtain a (good) measurable echo, because a long distance has to be traversed. The amplitude value of the echo with the highest amplitude of the echo curve may be several orders of magnitude higher than the amplitude value of the echo with the lowest local amplitude maximum of the echo curve. The ADC may have a resolution or quantization accuracy capable of distinguishing the lowest local amplitude maxima from the "background noise" of the echo signal (eg, resulting from diffuse reflections from the vessel wall, the sensor system, and / or other components).

[0012] The first amplitude value of the first echo can have the highest amplitude of the echo curve. Here, the highest amplitude can be generated, for example, by an antenna, for example by the wall of a horn antenna, because these signals are reflected by particularly close reflecting objects and therefore (due to the short distance traveled) have only slight attenuation. The first amplitude value of the first echo can have the highest local amplitude maximum of the echo curve. The highest local amplitude maximum can be the highest "useful" amplitude maximum, for example the highest reasonably measurable level. In one embodiment, the highest local amplitude maximum can be selected as a "reference point" and therefore "overmodulation" can be accepted when measuring the highest amplitude of the echo curve. The second amplitude value of the second echo can correspond to the lowest "useful" or "effective" amplitude of the echo curve.

[0013] Thus, the adjusted quantization accuracy can be set as a function of the quotient of the first amplitude value and the second amplitude value. The following measurements and / or evaluations can be performed using this adjusted quantization accuracy. Here, the quantization accuracy can be adjusted or reduced at multiple locations, for example by changing the resolution of the ADC and / or during calculations in the processor, during transmission of the measured values ​​and / or at other locations or other components of the measuring device. The adjusted quantization accuracy can be set after each measurement, after a (e.g., predefined) number of measurements and / or according to a change in the quotient of the first amplitude value and the second amplitude value.

[0014] Thus, advantageously, the method can be particularly suitable for adapting the quantization accuracy to the measurement situation. In particular, a balance can thereby be achieved between "precise" sampling (i.e. with high resolution or high quantization accuracy) and a low processing rate (e.g. in a processor) and / or a transmission rate (e.g. in a wired and / or wireless communication unit). By means of such an adaptation or setting, the energy consumption of the field device (or of a plurality of components of the field device) can be reduced in at least some cases when determining the level of a container. For example, the operating time of the high-frequency circuit can thereby be kept as short as possible and / or the transmission time of the measured values ​​can be reduced. Since many years of evaluation have shown that fast level change rates are typical, in particular in the case of small containers, such an automatic setting of the adjusted quantization accuracy can provide a particularly good balance between the adjusted quantization accuracy (which can include a low resolution in such a measurement situation) and a high measurement rate (achieved due to lower power consumption and / or shorter quantization time).

[0015] In one embodiment, the acquisition of the amplitude value is performed using the maximum quantization accuracy of the ADC. Here, the reduction of the quantization accuracy only occurs in registers in, for example, a processor or an intermediate memory. For this embodiment, an ADC with the same quantization accuracy for each measurement can be advantageously used.

[0016] In one embodiment, the acquisition of the echo curve is performed using the adjusted quantization accuracy of the last setting of the ADC. Here, the quantization time can be reduced at least in some ADCs. It is particularly advantageous if the radar signal only covers a short distance to the surface of the filling material. Here, the memory can contain the sampling accuracy of the last measurement. If necessary, the memory can include a history of the sampling accuracy to make the measurement more robust.

[0017] In some embodiments, the processing path and / or the transmission path operate with the adjusted quantization precision. For example, the processing path may include a processor and / or a control unit of the field device. For example, the transmission path may be wired and / or wireless. Therefore, the energy consumption of the field device can be further reduced.

[0018] In some embodiments, the transmission path can be wired and / or wireless. Here, for example, protocols such as the HART protocol (HART: Highway Addressable Remote Transducer), IO-Link interface, Ethernet-based protocols (e.g., Ethernet Advanced Physical Layer (Ethernet-APL)), and / or wireless protocols such as wireless personal area networks (WPANs), wireless LANs (WLANs), and / or low power wide area networks (LPWANs) can be supported.

[0019] In some embodiments, the adjusted quantization accuracy is a logarithmic function of the quotient of the first amplitude value and the second amplitude value. The function may include a safety margin so that a clear distinction can be made between the lowest local amplitude maximum of the echo curve and the "background noise" of the echo signal.

[0020] In some embodiments, the adjusted quantization precision is a function of the spacing between the number of leading zeros of the first amplitude value and the number of leading zeros of the second amplitude value.Thus, in particular in the case of processors supporting bitwise instructions, the quotient may be determined particularly quickly.

[0021] In some embodiments, the acquisition of the echo curve is performed alternately in time by the first ADC and the second ADC (and / or further ADCs). Here, the ADC samples the measured values ​​alternately (interleaving). For example, in the case of more than two ADCs, this can be done in a circular manner. This can be particularly advantageous in the case of rapid level changes.

[0022] In some embodiments, the ADC (or multiple ADCs) acquires an intermediate frequency signal with the amplitude value of the echo curve of the level radar. This can help to process the measured values ​​more simply because the intermediate frequency signal can have a lower and / or constant fundamental frequency. Then, further processing of the digital representation can be continued by the microprocessor.

[0023] In some embodiments, the level radar uses a pulse transmission time method and / or a continuous wave radar method. Here, in the case of a level measuring device according to the pulse transmission time method, a high-frequency pulse that is short in time is generated by a transmitting oscillator, which is emitted by a transmitting antenna toward the filling material and reflected on the filling material, and the reflected signal or echo is received again by the measuring device (i.e., a receiving antenna, which can be the same as the transmitting antenna). One or more intermediate stages can be used for further evaluation of the signal, which intermediate stage can include, for example, the generation of a (low-frequency) intermediate frequency signal.

[0024] In the case of a level measuring device using the continuous wave radar method or the FMCW (FMCW: frequency modulated continuous wave radar) method, a frequency modulated high frequency signal is generated, for example, by a voltage controlled high frequency oscillator (VCO: voltage controlled oscillator), which can change the frequency by an applied voltage, and is emitted by the transmitting antenna of the measuring device towards the filling material. After the radar signal is reflected by the filling material, these echoes are received by the receiving antenna of the measuring device (which can be the same as the transmitting antenna). One or more intermediate stages can be used for further evaluation of the signal, which intermediate stage can include, for example, a high frequency mixer for mixing the echo signal with the part of the transmission signal currently generated by the VCO that is decoupled by the high frequency coupler. The low-frequency analog differential frequency signal generated here can have the following frequency components, which directly depend on the time offset between the transmission signal and the currently generated signal and therefore on the transmission time of the radar signal from the sensor to the reflector and back. In order to further process the detected analog signal, in particular using spectrum analysis, this analog signal can be converted into a digital representation by means of an ADC and input to a microprocessor for further evaluation.

[0025] One aspect relates to a field device comprising a level radar and / or an ultrasonic measuring device, which is configured to carry out a method as described above and / or below.

[0026] One aspect relates to the use of a field device as described above and / or below for measuring fill levels and / or for determining the topology of a filling material. This can be done, for example, in a container, a channel or a stockpile.

[0027] One aspect relates to a program element which, when executed on a computing unit of a field device and / or on another computing unit, instructs the computing unit to execute a method as described above and / or below.

[0028] An aspect relates to a computer-readable medium having stored thereon said program element.

[0029] It should also be noted that the various embodiments may be combined with each other.

[0030] For further explanation, the present invention will be described based on the embodiments shown in the accompanying drawings. These embodiments are only exemplary and not restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1a A measurement according to an embodiment is schematically shown when the container is almost empty.

[0032] Figure 1b A measurement according to an embodiment is schematically shown in the case where the container is almost full.

[0033] Figure 2 The internal structure of a radar level measurement device according to an embodiment is schematically shown.

[0034] Figures 3a to 3f The effect of setting different quantization precisions according to an embodiment is schematically shown.

[0035] Figure 4 The internal structure of a radar level measuring device according to another embodiment is schematically shown.

[0036] Figure 5 The internal structure of a radar level measuring device according to another embodiment is schematically shown.

[0037] Figure 6 The diagram schematically shows sampling of an echo curve by two ADCs according to an embodiment.

[0038] Figure 7 A flow chart of a method according to an embodiment is shown.

[0039] Figure 8 A flow chart of a method according to another embodiment is shown. DETAILED DESCRIPTION

[0040] Some of the exemplary embodiments shown illustrate various aspects of the invention using a radar measuring device operating according to the pulse transmission time method. The content also applies in a transferable manner to radar measuring devices operating according to the FMCW principle and / or ultrasonic measuring devices.

[0041] Figure 1a The measurement according to an embodiment is schematically shown in the case of an almost empty container 20. Here, in the case of an almost empty container 20, the level measuring device 100 detects an echo curve 200 by means of a high-frequency circuit, which reflects the intensity or amplitude value (y-axis) of the reflected signal as a function of the corresponding distance d (x-axis). In sensors using the pulse transit time method, the echo curve 200 can be extracted directly at the output of the high-frequency module or also after analog preprocessing (e.g. by filtering, rectifying, amplifying and / or logarithmic processing) and fed to an analog-to-digital converter (ADC). For sensors using the FMCW method, in many cases the high-frequency module provides an analog low-frequency mixing (IF signal) representing the individual reflections, which can also be filtered, amplified and fed to the ADC as an echo curve 200.

[0042] The echo curve 200 has the highest amplitude or first largest echo 202 resulting from reflection from the antenna 110 (e.g., a horn antenna) of the measuring device 100. In addition, the echo curve 200 also has the highest local amplitude maximum or echo 204 resulting from reflection of the high frequency signal on the container mount 60 and the lowest local amplitude maximum or echo 206 resulting from reflection on the surface 40 of the filling material 30. At least some echo curve evaluation algorithms may require the complete echo curve 200 in order to be able to recognize that the echo 206 is caused by the filling material surface 40 and the echo 206 can be used to determine the distance d from the surface 40 of the filling material 30. When the container 20 is almost empty, the filling material echo 206 can have a very low amplitude. At the same time, the echo 204 from the container mount 60, which is very close to the measuring device 100 and acts as a reflector, can have a very high amplitude. As a result, the conversion of the echo curve 200 into a digital representation may have to be performed with very high accuracy, so that the relatively small amplitudes of the filling material echo 206 can be reliably digitally interpreted and further processed. The measuring device 100, in particular the ADC integrated in the measuring device 100, must therefore be operated with very high quantization accuracy (i.e. fine amplitude quantization), for example with a first quantization of 14 bits. In order to be able to transmit the amount of data to the processor system via one or more serial interfaces, the radar measurement associated with this setting is slowed down; in the case of not requiring a short reaction time when the container is almost empty, this slowdown does not have a negative impact on the application shown by way of example (given a clever design).

[0043] Figure 1b Schematically, a measurement according to an embodiment is shown in the case where the container 25 is almost full. Here, for example, due to the risk of overfilling the container 25, it is desirable for the level measuring device 100 to have a very fast measuring cycle. The measuring device 100, in particular the processor integrated in the measuring device, can control the ADC for detecting the echo curve 200 so that the echo curve 200 is determined, for example, with a second (coarser) quantization accuracy of 12 bits. The data reduction associated with this setting can speed up the determination of the individual data points and their transmission to the processor system; thus, a degree of freedom for increasing the measurement repetition rate can be obtained. At the same time, through knowledge of the application, it can be ensured that no information is lost due to this reduction in bit width. Because when the container 25 is full, potential reflectors (for example, the surface 45 of the filling material 30) may be very close to the level measuring device 100; thus, echoes 208 with high local amplitude maxima are generated, which can be reliably detected even in the case of a reduced bit width during analog-to-digital conversion (A / D conversion).

[0044] Figure 2The internal structure of a radar level measuring device 100 according to an embodiment is schematically shown. A high frequency circuit 120 in the device 100 generates a high frequency signal 114, which is transmitted toward the filling material surface 40, 45 via an antenna 112 (see Figure 1a , 1b ). The signal components 116 reflected by the filling material surfaces 40, 45 and the other reflectors 60 are received by the receiving antenna 118 and are passed to the high-frequency circuit 120, in which the signal 116 detected, in particular using the pulse transmission time method or the FMCW method, is converted into a low-frequency range (intermediate frequency / IF frequency). In the exemplary embodiment shown, the high-frequency circuit 120 is controlled by a control circuit 140, which can, for example, include a difference frequency controller or a fractional integer phase controller (PLL, phase-locked loop). The high-frequency circuit 120 can be controlled by the control circuit 140, which can be set digitally by the processor 150 via a control line 145. Therefore, in particular the operating duration of the high-frequency circuit 120 with a high energy demand can be controlled, so that its energy demand is reduced. During the acquisition of the echo signal 116, the high-frequency circuit 120 provides a low-frequency representation (for example, an IF signal), which is acquired by the ADC 130 and converted into a digital representation. When acquiring the amplitude value of the simulated echo curve 200, the quantization accuracy or conversion accuracy (i.e., the width of the bit width, resolution or quantization level) can be specified by the processor 150 via the control line 136. For example, a suitable quantization accuracy can be selected by a quantization level determination device 152 integrated in the processor, for example, by hardware and / or software provided for this purpose. For example, the radar system 100 can be powered via a two-wire interface 165 or a three-wire interface 165. In addition, the communication module 160 can use the interface to transmit the material level value in analog or digital form. Alternatively or additionally, the measured value can be provided to the outside via the communication antenna 175 by the wireless communication module 170. In order to determine the appropriate quantization level, the quantization level determination device 152 can take into account the application information that can be predetermined or automatically determined according to the principle of Figure 1. Alternatively or additionally, other standards such as explained below can also be used.

[0045] Figures 3a to 3f The effect of setting different quantization accuracies according to an embodiment is schematically shown. For example, the echo curves 310 , 320 , 330 , 340 , 350 , 360 may be generated during the conversion of the low frequency echo curve 200 provided by the HF circuit 120 .

[0046] Figure 3a The digitized echo curve 310 is obtained by ADC 130 (see, for example, Figures 3a to 3f ) According to the simulated echo curve 200 (see Figure 1a) is generated with a first precision k, for example with an amplitude resolution of k=10 bits. The echo curve 200 is shown as a dashed echo curve 315, or in Figure 3b to Figure 3f 325, 335, 345, 355, 365 are shown as dashed lines in FIG. It can be clearly seen that neither echo 304 nor echo 306 is mapped into the digital echo curve 310. Therefore, operation of the measuring device with an amplitude resolution of k=10 bits can lead to erroneous measurements, such as Figure 1a In the measurement situation shown, this operation is meaningless. If a second quantization precision m is used (e.g., m=12 bits of amplitude resolution), Figure 3b If the same analog echo curve 200 shown is converted into a digital representation 320, then the echo 304 can be well resolved, while the actual level echo 306 of the echo curve 325 cannot still be detected due to its low amplitude value. Figure 3c As shown, it may be necessary to control the ADC 130 via the quantization level determination device 152 so that it acquires a digital representation 330 of the echo curve 360 ​​with a third quantization precision n (eg n=14 bits). Thus, all relevant echoes 304, 306 can be reliably detected and / or further processed.

[0047] In another measuring situation, for example when the container 25 is almost full (see Figure 1b ), the measuring device 100 may have different performances. Figure 3d As shown, the echo curve 340 digitized with a first amplitude resolution of k=10 bits can already correctly resolve the filling material echo 308. In order to increase the reliability, a higher signal-to-noise ratio can be required for the filling material echo 308, wherein the noise can be defined by quantization during the A / D conversion. At a second amplitude resolution of m=12 bits (see Figure 3e As shown in FIG. 350 , the filling material echo 308 can be measured very reliably based on the digitized echo curve 350. Figure 3f Based on the curve 360 ​​in FIG. 1 , further increasing the precision in the analog-to-digital conversion to n=14 bits does not produce any additional information. Figure 1b In the case of a measurement of , this finer resolution of the amplitude can be omitted. As a result, the energy requirement can be reduced.

[0048] By reducing the bit width and thus the A / D conversion accuracy, the amount of data transmitted to the processor 150 via the one or more interfaces 134 can be reduced. In addition, the conversion of analog voltage values ​​into digital measured values ​​can be performed faster in time, especially in the case of low-cost SAR-ADCs (SAR: Successive Approximation Register) with reduced bit width. Therefore, one embodiment of the present invention can also adjust the sampling frequency of the analog-to-digital converter in the case of a change in the quantization level.

[0049] Figure 4 The internal structure of a radar level measuring device 100 according to another embodiment is schematically shown. If the quantization level determination device 152 specifies a new, adjusted quantization accuracy, this information can be passed to the sampling clock determination device 158, in which a new sampling frequency is determined taking into account the structure and performance characteristics of the ADC 130 and is passed to the ADC 130 via the clock line 403. As a result, the operating time of the ADC 130 can be significantly reduced by reducing the measurement duration, thereby saving energy. Additionally, information about the changed sampling frequency can be passed to the high-frequency parameter determination device 151. The high-frequency parameter determination device is arranged to determine new parameters that match the new sampling frequency and pass them to the control circuit 140, so as to further reduce the operating duration of the high-frequency circuit 120, thereby also further reducing the energy consumption. For example, in the case of a radar device using the pulse transmission time method, the device 151 can redetermine the difference frequency between the transmission oscillator and the internal reference oscillator and transmit it to the control circuit 140. In radar devices using the FMCW method, in particular the start frequency, the end frequency, the number of steps during the measurement and / or the steepness of the frequency sweep can be determined by the determination device 151 and transmitted to the control circuit.

[0050] In this regard it should be noted that the ADC 130 may be an intrinsic component of the processor system 150. In particular, the processor system 150 may have the analog-to-digital converter 130 fixedly embedded on its semiconductor substrate.

[0051] Figure 5The internal structure of a radar level measuring device 100 according to another embodiment is schematically shown. Here, the idea of ​​increasing the sampling frequency by adding a second ADC 135, which depends on quantization, is further extended. If the maximum sampling frequency and / or the maximum transmission rate of the first ADC 130 is not sufficient to achieve the clock rate predetermined by the sampling clock determination device, the second ADC 135 and the first ADC 130 for detecting data can be switched on alternately (in an interleaved mode), thereby increasing the sampling frequency and further reducing the operation duration of the high-frequency circuit 120. For this purpose, the processor 150 has a converter control device 156, which is arranged to control a plurality of ADCs 130, 135. For this purpose, the converter control device 156 includes a sampling clock determination device 158, which is arranged to determine a sampling clock matching the quantization based on the necessary quantization determined by the quantization level determination device 152. If a higher sampling clock than the possible sampling clock of the first ADC 130 needs to be set during this determination, the control device 156 activates the second ADC 135 and supplies sampling clocks to the second ADC 135 and the first ADC 130 so that an alternating conversion of the echo curve is performed in one of the two ADCs according to the interleaving scheme. Figure 4 Compared with the exemplary embodiment of the present invention, the generated sampling frequency can be further improved. Figure 6 The data provided by the ADCs 130, 135 are combined in a sorting unit 154 according to a scheme. The sampling values ​​X 601 of the echo curve 600 provided by the first ADC 130 are arranged alternately with the sampling values ​​O 602 provided by the second ADC 135 by rearranging in the memory of the processor. The final echo curve 600 can be composed using the sampling values ​​X 601 and O 602, and can be further processed according to known methods. It should be noted that, depending on the requirements of the measurement situation, the first ADC and / or the second ADC can be controlled by suitable control signals in terms of the required accuracy or quantization level when converting the echo curve 200 into its digital representation 330. In addition, if the predetermined sampling frequency can be achieved by the first ADC 130 independently at a predetermined amplitude resolution, the second ADC 135 can also be deactivated again.

[0052] It should also be noted that (reference but not limited to Figure 5 ), the first ADC 130 and / or the second ADC 135 may be intrinsic components of the processor system 150. In particular, it is conceivable that the processor system 150 has a plurality of ADCs 130, 135 fixedly embedded on its semiconductor substrate.

[0053] The first ADC 130 and the second ADC 135 can be controlled by means of a clock signal so that they simultaneously determine their respective sample values ​​601, 602. Thus, by numerically determining the average value of the simultaneously determined samples in the processor 150, the amplitude resolution can be computationally increased beyond the resolution technically provided by a single ADC.

[0054] In another embodiment, a third ADC (or other ADC) for detection in the interleaved mode may be permanently and / or according to circumstances, so that the sampling frequency can be further increased and the operation duration of the high-frequency circuit 120 can be further reduced. In this case, the ADC may be an external ADC or an ADC fixedly embedded on a semiconductor substrate of the processor system 150.

[0055] As already explained, the quantization level determination device 152 can use application information that can be predetermined or automatically determined to determine a suitable quantization level. Alternatively or additionally, the characteristics of the components used in the radar measuring device 100, in particular the characteristics of the ADC 130, can also be taken into account. For at least some ADCs, their accuracy may depend on the desired sampling frequency and / or the ambient temperature prevailing during sampling. For example, if temperature measurements performed in the device show that the required accuracy can no longer be achieved with the first ADC 130 at the prevailing ambient temperature due to temperature-related component tolerances, then by adding a second ADC 135 and by clock synchronization control and subsequent averaging, the required quantization accuracy or amplitude resolution of the A / D conversion can be ensured even at high temperatures. Alternatively, with reference to Figure 5 In an exemplary embodiment, it is also possible to approximately or exactly halve the sampling rate set in a single ADC by adding another ADC, thereby improving the accuracy of the conversion. When setting the quantization, sampling frequency and / or the number of analog-to-digital converters to be used, the aging effects of the built-in components can also be taken into account. In addition, the ADCs can be operated with different quantization accuracies within predeterminable time intervals in order to periodically verify their reliability in the context of safety-critical applications. These aspects can also be further expanded by adding a third ADC (or even more ADCs).

[0056] Figure 7A flow chart 700 of a method according to an embodiment is shown. In particular, the flow chart 700 shows a sequence during a first operating phase and a second operating phase of a radar measuring device, wherein the sequence shown is rerun with each new measuring cycle. The method starts in a start state 701. In step 702, the current operating state of the level measuring device is evaluated. In this case, in particular, information such as the last determined measurement value, the last existing amplitude ratio of the echo of the echo curve, the currently available energy, the ambient temperature and / or the aging of the level measuring device can be determined. In step 703, information about the application is determined and evaluated. In this case, in particular, user specifications for application conditions such as the measuring range or the reflectivity of the medium or the installation conditions of the sensor can be determined. In step 704, the quantization level determination device 152 uses the information compiled in steps 702 and 703 to determine the currently adjusted quantization accuracy in the A / D conversion of the echo curve. In step 705, it is checked whether the ADC 130 has been appropriately set for the measurement with the adjusted quantization accuracy. If this is not the case, in step 711 it is first checked whether the desired accuracy requires the use of the second ADC 135. If necessary, the second ADC 135 is activated in step 712. Otherwise, it is deactivated in step 713. In the subsequent method step 714, the ADCs 130, 135 are set to the desired accuracy by providing correspondingly executed control signals. In step 706, the high-frequency circuit 120 is activated to trigger the measurement and convert the provided analog echo signal or echo curve 200 into their digital representation. After the measurement has been completed, it is checked in step 707 whether the measurement data are provided by a single ADC 130. If this is not the case, in step 708, the measured values ​​601 of the first ADC 130 and the measured values ​​602 of the second ADC 135 are merged in a memory (for example of a processor of the field device). Then, in step 709 , a fill level measurement value is determined based on the digital representation of the echo curve 200 , and in step 710 the determined fill level measurement value is provided externally in an analog and / or digital manner via the wired communication interface 165 or the wireless interface 175 . The method ends in state 715 .

[0057] Figure 8 FIG. 8 is a flow chart 800 of a method according to another embodiment. In step 802, the amplitude value of the echo curve 200 of the level radar is obtained by an analog-to-digital converter ADC (for example, see Figure 1a , 1b). In step 804, a first amplitude value of a first echo having the highest amplitude or the highest local amplitude maximum of the echo curve is determined. In step 806, which is performed before, after or in parallel with step 804, a second amplitude value of a second echo having the lowest local amplitude maximum of the echo curve is determined. In step 808, the adjusted quantization accuracy is set as a function of the quotient of the first amplitude value and the second amplitude value.

[0058] CROSS-REFERENCE TO RELATED APPLICATIONS

[0059] This application claims priority from European patent application No. 21 178 038.2 filed on June 7, 2021, the entire contents of which are incorporated herein by reference.

[0060] Reference numerals list

[0061] 20 Almost Empty Containers

[0062] 25 Almost full container

[0063] 30 Filling material

[0064] 40 Filling material surface of almost empty container

[0065] 45 Filling material surface of almost full container

[0066] 60 container mounting parts, reflectors

[0067] 100Level measurement equipment, level radar

[0068] 110 Antenna

[0069] 112 Transmitting Antenna

[0070] 114 High frequency signal

[0071] 116 echo signal

[0072] 118 receiving antenna

[0073] 120 high frequency circuit

[0074] 130ADC (Analog-to-Digital Converter)

[0075] 134 interfaces

[0076] 135 Other ADC (Analog-to-Digital Converter)

[0077] 136 control line

[0078] 140 control circuit

[0079] 145 control line

[0080] 150 processors, processor systems

[0081] 151 High frequency parameter determination device

[0082] 152Quantization level determination device

[0083] 154 sorting units

[0084] 156 Converter control device

[0085] 158 Sampling clock determination device

[0086] 160 communication module

[0087] 165 Communication interface, for example, two-wire interface

[0088] 170 wireless communication module

[0089] 175 communication antenna

[0090] 200 echo curve

[0091] Echoes 202, 204, 206, 208

[0092] Echo 302, 304, 306, 308

[0093] 310-360 echo curve

[0094] 315-365 echo curve

[0095] 403 clock line

[0096] 600 echo curve

[0097] 601 sampling value X

[0098] 602 sampling value O

[0099] 700 Flowchart

[0100] Steps 701-715

[0101] 800 Flowchart

[0102] Steps 802-808

Claims

1. A method for setting the amplitude quantization accuracy of a level radar (100), wherein the level radar is used to determine the level (40, 45) of a container (20, 25), the method comprising the following steps: Acquiring an amplitude value of an echo curve (200) of the object level radar (100) through an analog-to-digital converter, namely, an ADC (130); determining a first amplitude value of a first echo, the first echo having a highest amplitude (202) or a highest local amplitude maximum (204, 208) of the echo curve (200); determining a second amplitude value of a second echo, the second echo having the lowest local amplitude maximum (206) of the echo curve (200); and The adjusted amplitude quantization accuracy is set as a function of the quotient of the first amplitude value and the second amplitude value, so as to determine the filling level (40, 45) of the container (20, 25) by using the adjusted amplitude quantization accuracy.

2. The method according to claim 1, in, The acquiring of the amplitude value is performed using a maximum amplitude quantization accuracy of the ADC.

3. The method according to claim 1, in, The acquisition of the echo curve (200) is performed using the adjusted amplitude quantization accuracy of the ADC that was last set.

4. The method according to any one of claims 1 to 3, in, The processing path and / or the transmission path operates with the adjusted amplitude quantization accuracy.

5. The method according to claim 4, in, The transmission path is wired and / or wireless.

6. The method according to any one of claims 1 to 3, in, The adjusted amplitude quantization accuracy is a logarithmic function of the quotient.

7. The method according to any one of claims 1 to 3, in, The adjusted amplitude quantization accuracy is a function of a spacing between a number of leading zeros of the first amplitude value and a number of leading zeros of the second amplitude value.

8. The method according to any one of claims 1 to 3, in, The acquisition of the echo curve (200) is performed alternately in time by means of a first ADC and a second ADC.

9. The method according to any one of claims 1 to 3, in, The ADC acquires an intermediate frequency signal having an amplitude value of the echo curve (200) of the object level radar (100).

10. The method according to any one of claims 1 to 3, in, The level radar (100) utilizes a pulse transmission time method and / or a continuous wave radar method.

11. A field device comprising a level radar (100) and / or an ultrasonic measuring device configured to perform the method according to any one of claims 1 to 10. 12 . Use of the field device according to claim 11 for measuring a fill level and / or for determining a topology of a filling material. 13 . A program product which, when executed on a computing unit of a field device and / or on another computing unit, instructs the computing unit to execute the method according to claim 1 .

14. A computer readable medium storing the program product according to claim 13.

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