Patent Application
20230408654
The invention relates to calibrating an apparatus or a system for signal time-of-flight measurement or signal time-of-flight-measurement-based distance measurement on the basis of at least one phase measurement.
Determining a distance between two objects by means of radio signals over times-of-flight of the radio signal is known. Using phase shifts to ascertain the distance is also known.
It is desirable to provide a simple and reliable approach for calibration.
The inventor has found, surprisingly, that apparatuses for phase-based distance measurement, particularly currently commonly-used Bluetooth apparatuses and Bluetooth chips, have much less fluctuation within a series than those for signal time-of-flight-based distance measurement. This applies particularly in relation to the phase-based distance measurement, and the signal time-of-flight-based distance measurement, or the signal time-of-flight measurement, of a single apparatus or of a single chip. In particular, currently commonly-used Bluetooth apparatuses and Bluetooth chips have much less fluctuation within a series for phase-based distance measurement or phase measurement than for signal time-of-flight-based distance measurement or signal time-of-flight measurement. It is thus possible to calibrate the signal ToF-based distance measurement without much effort on the basis of a phase-based distance measurement. Thus, in relation to the phase-based distance measurement an apparatus or a pair of apparatuses of a series or model range can be calibrated exemplarily and this calibration can be used for the phase measurements of all apparatuses of the series. Thereby, all apparatuses in the series can be calibrated easily and automatically in relation to the signal time-of-flight measurement and distance measurements based thereon. This can be done for the first distance measurement of the respective apparatus or between a pair of the apparatuses. This is even possible for a pair made up of different model ranges or series, provided each one has a series-specific- and/or model-range-specific calibration with regard to the phase-based distance measurement.
In particular, accuracies of signal time-of-flight-based distance measurements in the 2.4 GHz band are typically around one meter for a measurement on the basis of an amplitude rise or an amplitude modulation with usual components, wherein without calibration, further inaccuracy in the order of 1.5 meters applies. The advantage of the present method becomes yet more apparent when a frequency modulation is used for the time-of-flight-based distance measurement, since here an elimination of an error contribution of around 20 m can be expected by the calibration. After a calibration according to the invention, an accuracy in the order of one meter can be expected.
The problem is solved by a method for calibrating at least one system for carrying out a signal time-of-flight measurement and/or signal time-of-flight difference measurement, particularly pulse signal time-of-flight measurement and/or pulse signal time-of-flight difference measurement (dToF), wherein the system is also configured for carrying out a distance measurement on the basis of a phase measurement (phase-based distance measurement, PBR), particularly in cooperation with a first object, wherein at least one first distance measurement to the first object is carried out by means of phase measurement, particularly phase shift and/or change of a phase shift with the frequency, and at least one signal time-of-flight measurement or a second distance measurement is carried out on the basis of at least one signal time-of-flight measurement to or via the first object, characterized in that the system for carrying out further signal time-of-flight measurements, and/or distance measurements, and/or position-finding, is calibrated using the at least one first phase measurement (PBR) on the basis of at least one signal time-of-flight measurement, particularly pulse signal time-of-flight measurement (ToF), and/or signal time-of-flight difference measurement, particularly pulse signal time-of-flight difference measurement (dToF).
In one embodiment, for calibrating at least one system for carrying out a plurality of signal time-of-flight difference measurements, in each case between a shared first object and a second object of a plurality of second objects, wherein the system is also configured for carrying out at least one first distance measurement, in particular between the first object and at least one reference object of the plurality of second objects, on the basis of a phase measurement, particularly in cooperation of the first object with at least one of the plurality of second objects, wherein the at least one first distance measurement to the first object is carried out by means of phase measurement, particularly phase shift and/or change of a phase shift with the frequency, and at least one plurality of signal time-of-flight difference measurements between signal times-of-flight, in each case between the shared first object and a second object from the plurality of second objects, also including the reference object, wherein that the system for carrying out further signal time-of-flight difference measurements between signal times-of-flight and/or distance measurements and/or position-findings is calibrated by means of the at least one phase measurement, based on further signal time-of-flight difference measurements between signal times-of-flight, in each case between the shared first object and a second object from the plurality of second objects, and wherein the system, in particular, is configured for carrying out a plurality of signal time-of-flight difference measurements between, in each case, the shared first object and a second object from a plurality of second objects, and to determine a distance and/or position of the first object on the basis thereof. Especially advantageously, the system is a “Time Difference of Arrival” system, particularly an Ultra Wide Band “Time Difference of Arrival” system (UWB-TDoA). The signals on which the time-of-flight measurements and/or the phase measurements are performed are then, in particular, UWB signals, particularly with a bandwidth of at least 500 MHz and/or of at least 20% of the arithmetic mean of the upper and lower frequency limits of the frequency band used.
The system preferably contains a second object and, in particular, the first object also. In particular, the distance- and/or time-of-flight measurements and/or time-of-flight difference measurements are carried out between the first object and the at least one second object.
The problem is also solved by a use of at least one phase measurement on at least one signal between a first object and at least one second object, particularly at least one phase-based distance measurement (PBR), for calibrating at least one apparatus for signal time-of-flight measurement, particularly pulse signal time-of-flight (ToF), and/or signal time-of-flight difference measurements, particularly pulse signal time-of-flight difference measurement (dToF), and/or signal time-of-flight-based, and/or signal time-of-flight difference measurement-based, distance measurement and/or position-finding of the first object and/or at least one second object.
Especially advantageously, the at least one apparatus is part of a system for signal time-of-flight difference measurement-based distance measurement and/or position-finding of the first object, and/or the system comprises a plurality of second objects, in particular, stationary relative to one another, wherein the system is configured, in particular, for carrying out a plurality of signal time-of-flight difference measurements between, in each case, the shared first object and a second object from a plurality of second objects, and to determine at least one distance and/or position of the first object on the basis thereof. Especially advantageously, the system is a “Time Difference of Arrival” system, particularly an Ultra Wide Band “Time Difference of Arrival” system (UWB-TdoA). The signals on which the time-of-flight measurements and/or the phase measurements are performed are then, in particular, UWB signals, particularly with a bandwidth of at least 500 MHz and/or of at least 20% of the arithmetic mean of the upper and lower frequency limits of the frequency band used.
The problem is also solved by an apparatus having a transmission and receiving arrangement as well as a unit for phase measurement, an oscillator, a time measurer, the apparatus being configured for carrying out a signal time-of-flight measurement, having a control for carrying out the method by means of the apparatus.
The problem is also solved by a system comprising at least two objects, in particular, at least one first object and a plurality of second objects, having in each case a transmission and/or receiving arrangement, a PLL and/or oscillator, and in particular, a time measurer, and configured together for carrying out a signal time-of-flight measurement between two of the objects and a phase-based distance measurement between two of the objects, said system having at least one control for carrying out the method by means of the at least two objects.
Particularly preferably, a plurality of second objects, particularly positionally fixed relative to one another, is used. Particularly the plurality of second objects are configured for determining time-of-flight differences of a signal of the first object to the plurality of second objects, and therefrom, in particular, at least one possible position of the first object [relative] to the second object. In particular, at least one of the second objects is a reference object and is configured for carrying out at least one phase measurement and/or measurement of the change in phase shift on the basis of a frequency change, and/or a phase-based distance measurement, on at least one signal between the first object and reference object, in particular, of the first object, and the system is configured for calibrating the determination of the possible position, and/or for resolving its ambiguity, on the basis thereof. Especially advantageously, the system is a “Time Difference of Arrival” system, particularly an Ultra Wide Band “Time Difference of Arrival” system (UWB-TDoA). The signals on which the time-of-flight measurements and/or the phase measurements are performed are then, in particular, UWB signals, particularly with a bandwidth of at least 500 MHz and/or of at least 20% of the arithmetic mean of the upper and lower frequency limits of the frequency band used.
In particular, the system is formed by the first object, or the first object and at least one second object. In particular, the first and the second object are freely movable relative to one another, in particular, they are not mechanically connected. In particular, the first or second object is a key fob, and/or the other of the objects is a motor vehicle and/or a stationary object, and/or an object fixedly connected to an object with an access prevention apparatus. In particular, the calibration and/or the calibrated system is used for detecting a relay attack and/or for deciding on a release, for example, of a door and/or a function, particularly ignition of a motor vehicle.
The signal time-of-flight measurement can be a signal round-trip time measurement, for example, from the second via the first to the second, or a measurement of the signal time-of-flight in one direction.
The phase-based distance measurement is particularly one based on the phase shift change caused by a frequency change, particularly on signals between the second and first object.
The change in the phase shift caused by the frequency change, particularly between a first and a second frequency, is caused in that, particularly when both measurements are at approximately equal distance, a different number of wave packets fit within the distance, and consequently the phase shift, which is caused by the distance, ends up being different between the frequencies. This change in the phase shift as a result of the frequency is the phase change caused by the frequency change. In this context, problems result during measuring since in each case, the phase measurement is dependent on a reference, and a, frequently undefined, phase jump can result when switching over to transmit the various frequencies. Switching over for transmitting and, particularly also for receiving, is thus preferably done phase-coherently, i.e., with a phase jump of zero. But determining or knowing the phase jump is also sufficient. Then one can determine the phase change by the frequency change, through the measured phase change corrected by the phase jump upon switchover of the transmitter, and the phase jump upon switchover at the receiver, for measuring the measured phase change.
For example, the distance can be [determined] by means of
Distance=(phase shift between two frequencies)/2/Pi/(difference between the two frequencies)*c
where c is the speed of light
In particular, the change in phase shift is caused by the change of frequency at approximately the same distance. The phase shift is thus caused by the distance. The change in the phase shift caused by the frequency change or is caused in that, particularly when both measurements are at approximately equal distance, a different number of wave packets fit within the distance, and consequently the phase shift, which is caused by the distance, ends up being different between the frequencies. This change in the phase shift as a result of the frequency is the phase change caused by the frequency change. In this context, problems result during measuring since in each case, the phase measurement is dependent on a reference, and a frequently undefined phase jump can result when switching over to transmit the various frequencies. Switching over for transmitting and, particularly also for receiving, is thus preferably done phase-coherently, i.e., with a phase jump of zero. But determining or knowing the phase jump is also sufficient. Then one can determine the phase change by the frequency change, through the measured phase change corrected by the phase jump upon switchover of the transmitter, and the phase jump upon switchover at the receiver for measuring the measured phase change.
The information about switching time and/or phase jump is, in particular, supplied, for example by predetermination or transmission. In principle, it is irrelevant where the calculations are carried out, whether in the objects, in one object, or in a central computing unit, for example. The measurements and information required for the calculations to be carried out in each case are to be supplied there.
Thus, especially advantageously, the knowledge of the phase jump upon the change in frequency is used to enable a simple measurement or calculation, for example, for correcting the measurement of the change in phase shift. At a phase jump of zero, this knowledge is also used, in particular, in that the measurement of the change in phase shift is used directly to calculate a distance, i.e., it is corrected only by zero.
Advantageously, a time synchronization between the first and second object and/or among multiple second objects is achieved and/or exists accordingly with an accuracy greater than 2 ps, particularly in the range from 0.1 to 2 ps. The time synchronization lies particularly in the range from 0.01 to 10 ns, particularly in the range from 0.05 to 5 ns, and/or the drift of the timer is determined in the first and third object and taken into account for the time-of-flight measurement, the accuracy of the drift determination lies particularly in the range from 0.01 to 100 ppb, particularly in the range from 1 to 10 ppb. This can be achieved by phase-coherent switching and evaluation thereof at the receiver. For this purpose, the first and/or second object transmits particularly at least one signal at a first frequency and at a second frequency, and switches between them in a phase-coherent manner with a phase jump of zero, and/or such that the phase jump upon changing the frequencies is known and/or determined upon transmitting. The time synchronization, particularly between the multiple second objects, can also be done on the basis of cable.
The phase difference or phase jump when switching between two frequencies generally arises due to technical reasons, but can also be prevented. The switching between two frequencies can be carried out with a short interruption or interruption-free. At the time of the interruption-free change, the phase jumps, or during the change with interruption, the phase of the signals theoretically imagined to continue during the interruption, jumps before and after switching. A defined phase jump exists at the change time-point without interruption, or at a theoretical change time-point during the interruption, particularly in the middle of the interruption and/or at the end of the signal before the interruption or at the beginning of the signal after the interruption. This is the phase difference.
In particular, the distance measurement is also carried out by means of a phase shift change caused by a frequency change. The second object transmits at least two different frequencies, particularly a first and a second frequency, between which it switches in a phase-coherent manner, i.e., with a phase jump of zero, and/or switches such that the phase jump upon changing the frequencies is known and/or determined upon transmitting.
Thus, especially advantageously, the knowledge of the frequency jump upon the change in frequency is used to enable a simple measurement or calculation, for example, for correcting the measurement of the change in phase shift. At a phase jump of zero, this knowledge is also used, in particular, in that the measurement of the change in phase shift is used directly to calculate a distance, i.e., it is corrected only by zero.
Preferably, the calibration is a calibration of the signal time-of-flight measurement, particularly pulse time-of-flight measurement, and/or signal time-of-flight-based distance measurement, particularly pulse time-of-flight-based (ToF), between the first and second object. This makes sense, in particular, since a more accurate calibration that relates to this pair can be achieved thereby. In particular, the method is carried out pair-wise, in each case for an object with a plurality of other objects, and a calibration is undertaken for each pair, said calibration being used for measurements between this pair for further signal time-of-flight measurements and/or signal time-of-flight-based distance measurements.
Advantageously, the calibration is used for carrying out at least one, particularly a plurality of, signal time-of-flight measurement(s) and/or signal time-of-flight-based distance measurement(s) of the system, particularly of the first object, in particular between the first and second object, particularly such that the calibration ascertains an offset, particularly one that is dependent on frequency and/or temperature, said offset being used as a correction in the at least one signal time-of-flight measurement and/or signal time-of-flight-based distance measurement. A frequency- and/or temperature-dependent offset, and/or a frequency- or temperature-dependent calibration, increases the accuracy. The offset can be composed, for example, of a plurality of offsets for, in each case, a frequency range, and/or temperature range, or through a function dependent on temperature and/or frequency.
Especially advantageously, the phase measurement and/or phase-based distance measurement is not and/or will not be calibrated in an apparatus-specific/system-specific, and/or merely model range-specific and/or series-specific, manner. This is particularly efficient.
Preferably, multiple phase measurements and/or phase-based distance measurements at different frequencies, and/or multiple measurements of the changes in the phase shifts with the frequency at different frequency spacings, are performed and/or used for the calibration, for reducing and/or excluding ambiguities, particularly with regard to the inaccuracy of the signal time-of-flight measurement and/or signal time-of-flight-based distance measurement before the calibration. This makes it possible to also achieve a calibration with a large possible offset or a large fluctuation across model ranges and/or series.
Advantageously, the calibration is performed such that a difference, particularly a frequency- and/or temperature-dependent difference, between distance determined in a phase-based manner and signal time-of-flight-based distance measurement is ascertained as a correction term, particularly frequency- and/or temperature-dependent, by means of which one additional signal time-of-flight measurement and/or additional distance measurements are corrected on the basis of at least one additional signal time-of-flight measurement of the system, particularly of the first object, particularly between the first and second object. This is a simple alternative and is usually sufficient to achieve an accuracy of the calibration that makes sense in relation to the fluctuation of the time-of-flight measurement, particularly on the basis of time measurement inaccuracies.
Especially advantageously, the signal of the signal time-of-flight measurement and/or the signal on which the phase measurement is performed, is a radio signal, in particular, a shared radio signal is used for signal time-of-flight measurement and at least one phase measurement. In this manner, for example, a signal at a first frequency can be used for a phase measurement and signal time-of-flight measurement, and a second signal with a second frequency is used for an additional phase measurement to measure the change in phase shift. The second signal can also be used for an additional signal time-of-flight measurement, however. The signal time-of-flight measurements can then be averaged, for example, and can be used with the phase-shift-change-based measurement to determine the calibration or the offset or the correction term. This can be repeated at a plurality of first and second frequencies to improve the accuracy. However, it is also possible to use different signals and/or frequencies for phase-based and time-of-flight-based measurements. The frequencies, particularly those of measurements that are compared to one another, are similar to one another, in particular.
Especially advantageously, the signal time-of-flight is the signal time-of-flight for a path between the second and first object, or the signal round-trip time between the second and first object and back.
Preferably, the time spacing between the transmission of a signal for the signal time-of-flight measurement and a signal for the phase measurement, particularly those to be compared to one another, is less than 500 ms. This increases the accuracy, particularly for changeable distances and/or environments.
Especially advantageously, the calibration according to the invention is performed individually in each case for a plurality of apparatuses and/or pairs of same-model apparatuses and/or apparatuses from a model series or series, wherein only a uniform calibration that is identical for all is used for the phase measurement and/or phase-based distance measurement for all apparatuses and/or pairs of the plurality. This increases the accuracy with little effort, since the calibrations can be performed rapidly and automatically, particularly at least when the objects exchange signals among one another for the first time.
The problem is also solved by an apparatus having a transmission and receiving arrangement as well as a unit for phase measurement, an oscillator, a time measurer, configured for carrying out a signal time-of-flight measurement, having a control for carrying out the method by means of the apparatus.
The problem is also solved by a system comprising two objects, having in each case a transmission and/or receiving arrangement, and a unit for phase measurement, a PLL and/or oscillator, and in particular, a time measurer, and configured together for carrying out a signal time-of-flight measurement between the two objects and a phase-based distance measurement between the two objects, said system having at least one control for carrying out the method by means of the two objects.
Especially advantageously, the method is performed such that the phase measurements and/or signal time-of-flight measurements are performed with signals in only one direction, particularly from the second to the first object. In particular, however, the method is also performed with reversed roles in the opposite direction.
Especially advantageously, the first and second object change between first and second frequencies phase-coherently and/or such that the phase jump is known and/or determined upon change of the frequencies during transmitting and/or upon receiving, and particularly the phases measured upon reception are corrected by this phase jump or these phase jumps. This facilitates the calculation and enables particularly rapid execution.
Especially advantageously, the method is carried out repeatedly with a plurality of pairs of first and second frequency. The accuracy can be increased in this way, for example by averaging and/or reducing the ambiguity.
In particular, the first and/or second object transmit a frequency hopping by transmitting, in particular, approximately identical frequencies, wherein the sequence of these frequencies in the frequency hopping of the first and second object is not decisive.
The frequencies are approximately identical or similar within the meaning of these statements particularly when they differ by less than 5%, particularly less than 1% of the lower frequency, and/or less than 17 MHz, particularly less than 10 MHz, particularly less than 9 MHz, particularly less than 2 MHz. For example, Object A can thus use the frequencies FA1, FA2 to FAn, and Object B can use the frequencies FB1, FB2 to FBn, wherein 95% FAx<=FBx<=105% FAx, with x from 1 to n.
Frequency hopping particularly refers to consecutively transmitting on different frequencies, of which pairs particularly always constitute a first and a second frequency.
In particular, the frequencies, particularly of the frequency hopping(s), lie in a spectrum from 25 to 100 MHz, in particular they completely span such a spectrum. Particularly the frequencies, particularly of the frequency hopping, lie in the range from 2 to 6 GHz. A spacing in the range from 0.1 to 17 MHz, particularly in the range from 0.5 to 10 MHz lies particularly between adjacent but not necessarily consecutive frequencies, particularly of the frequency hopping, and/or between the first and second frequency.
Phase-coherent switching or changing between two frequencies is understood to mean, particularly, that the phase after the switching is known relative to the phase situation before the switching. This is the case when the change of phase when switching is zero, or is a previously known or ascertainable value. In this manner, further measurements of the phase at the transmitter can be avoided, and the calculation can be simplified, particularly when frequencies are switched between without phase change. It is advantageous not only for the transmitting object to switch in a phase-coherent manner, but also for the receiving object to do so, in particular a PLL is switched in a phase-coherent manner in each object.
Alternatively, switching can be preferably phase-coherent, but also not, and the change in phase can be determined locally, i.e., particularly at the transmitter before the transmission and/or at the receiver relative to the PLL of the receiver, and this change can be corrected in the calculation.
For example, when the point in time of the phase-coherent change or of the change with measured phase jump at the transmitting object is known, and when the change in the received signal is determined at the received object, the time between transmitting and receiving the change is determined, which time represents the signal time-of-flight (ToF), and the phase shift is also determined, which results solely from the signal flight. The distance can be directly determined from the signal time-of-flight by means of the speed of light. This is also possible via the phase shift, however with an ambiguity, which is generally more accurate. The ambiguity accompanying the phase-based measurement can be reduced by using multiple frequencies. A particularly accurate and robust distance measurement can be realized by combining the signal time-of-flight measurements and phase-based measurements.
Phase-coherent switching between two frequencies is understood to mean, particularly, that the time-point of the switching is precisely determined and/or measured, and the phase after the switching, relative to the phase position before the switching, is known. This is the case when the change of phase when switching is zero, or is equivalent to a previously known value, or is measured at the transmitter.
Moreover, surprisingly, it was established that the distances obtained from the one-sided distance measurement or the distance measurement according to the invention described here, are dependent upon the frequency used for the distance determination when standard commercial transceivers are used, such as the somewhat older cc2500 or the current cc26xx by Texas Instruments or the Kw35/36/37/38 by NXP or the DA1469x by Dialog. In this context, inaccuracies in the transceivers also seem to result in calculated distances that are less than the actual distance, but only with those frequencies whose transmission channel is highly attenuated, such that these can be eliminated from the calculation without issue.
Therefore, it is advantageous for the distance determination not to use signal components of the object whose signals are used for the distance determination, for the distance determination in certain cases, and specifically to not use such components that lie above an upper power limit and/or to not use such components that lie below a lower power limit. These limits can be predetermined, or can be determined based on the received signals, and particularly can be above or below the mean received power, and can be particularly at least 20% above the mean received power (upper power limit) and/or at least 20% above the mean received power (lower power limit).
Preferably, not taken into account are signal components at frequencies received with less than 40%, or at least signals received with less than 20%, particularly less than 40%, of the mean energy of the signals, and/or signals received with greater than 140%, particularly with greater than 120% of the mean energy.
Advantageously, the lower power limit lies in the range from 5 to 50% of the mean power of the received signals, and/or the upper lower limit lies in the range from 120 to 200% of the mean power of the received signals.
In another embodiment, of the signals, particularly those selected in the decision, the x % of the signals with the smallest received amplitude are sorted out and not used, and/or the y % of the signals with the greatest received amplitude are sorted out and not used. It has been shown to be particularly advantageous when the sum of x and y is not less than 10 and/or does not exceed 75, and/or x lies in the range from 10 to 75, and/or y lies in the range from 20 to 50. In most situations, high accuracy and reliable distance determination can be obtained with these values.
Preferably the first and/or second, or each of the two objects, sends the signals on multiple frequencies successively and/or consecutively, in particular directly consecutively. In particular, when sending is taking place by the first and second object, all signals of the first or of the second object are sent first, then those of the other. If one is working with multiple objects, in particular they all send a frequency hopping successively, particularly one frequency hopping each. Influences of environmental or distance changes, and of movements of one or both objects, can be thus reduced.
Advantageously, at no time does the bandwidth of the signals exceed 50 MHz, particularly 25 MHz. Consequently energy can be saved, interference with other processes can be prevented, and simple components can be used compared to broadband methods.
Preferably, a time- and/or clock-cycle synchronization and/or correction is carried out between the two objects before, after and/or while the method is carried out. This augments the accuracy of the method. Preferably, a drift of the clock of the first and/or second object, or a difference in the drift of the clock of the first and of the second object, is also determined and considered in the distance determination or time-of-flight measurement. This augments the accuracy of the method.
The drift of the oscillators can be corrected for the phase measurement as known in the prior art and further improves the accuracy.
Advantageously, the method is carried out such that the frequency spacing between two consecutive frequencies of the multiple frequencies is at least 0.1 MHz and/or a maximum of 17 MHz, in particular is 10 MHz, and/or the multiple frequencies are at least five frequencies and/or a maximum of 200 frequencies, and/or wherein the multiple frequencies span a frequency band of at least two MHz and/or a maximum of 100 MHz. Thus can a balanced measure be found between bandwidth requirement, which imposes requirements for available frequencies and hardware, and accuracy.
Advantageously, the objects are parts of a data transmission system, particularly a Bluetooth, WLAN, or radio data transmission system. Preferably, the signals are signals of the data transmission system, particularly of a data transmission standard, for example a radio standard, WLAN or Bluetooth, which signals are used for data transmission according to the data transmission standard.
Advantageously, the signals are transmitted over multiple antenna paths, particularly at least three, particularly with multiple antennas, particularly successively, sent at the sending object and/or received at the receiving object with multiple antennas.
At the top,
At the bottom,
Purely schematically,
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/081015 | Nov 2020 | WO | international |
| PCT/EP2020/081016 | Nov 2020 | WO | international |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/080521 | 11/3/2021 | WO |
