EP4062188A1

EP4062188A1 - Method for determining distances between a plurality of objects

Info

Publication number: EP4062188A1
Application number: EP21805939.2A
Authority: EP
Inventors: Rönne Reimann
Original assignee: Lambda4 Entwicklungen GmbH
Current assignee: Lambda4 Entwicklungen GmbH
Priority date: 2020-11-04
Filing date: 2021-11-03
Publication date: 2022-09-28
Also published as: US20230375660A1; US20230384410A1; WO2022096515A1; WO2022096513A1; EP4078211A1

Abstract

The invention relates to a method for determining a distance between a plurality of objects. The first object can be, in particular, an authorization means, such as a key fob or a mobile telephone. The problem is solved, inter alia, by means of a method for determining the spacing between a plurality of objects (1, 2), wherein a first of the objects, for example a key, transmits at least one, in particular a plurality of first-object signals with different first-object frequencies, at least one third object (3) transmits at least one, in particular a plurality of third-object signals, and the at least one second of the objects receives the first- and third-object signals of the first object and of the at least one third object and, therefrom or on the basis thereof, the distance between the first object and the second object is determined, characterized in that the third object and/or the first object switches between at least two of the first-object and/or third-object signals such that phase coherence is maintained or such that the phase jump is known.

Description

Method for determining distances between several objects

The invention relates to a method for determining a distance between two objects using a third object.

It is known from EP 2710398 B1 to passively determine the location in an anchor network by listening in on the communication of the anchors, in that several distances are determined and the location or the distance to one or more anchors is determined therefrom.

It is known from US 2020/1 18372 A1 to use a passive sniffer in a motor vehicle to determine the distance to a key after the communication has been started by an active node in the motor vehicle. From a large number of existing antennas, the most suitable ones are determined on the basis of RSSI values. Differently polarized antennas are used and round trip times or phase shifts per frequency at which a round trip is made are measured or differences between them are determined. To do this, the change in phase over one round at a first frequency is compared with the change in phase over a second round at a second frequency, taking into account the change from the first frequency to the second frequency. A phase-coherent switching between the frequencies is not performed. Also, the phase difference when switching is not known. The object of the present invention is to determine the distance between two or more, in particular at least three, objects, with a first of the objects emitting a plurality of signals with different frequencies, in particular one after the other, in particular frequency hopping, with at least a third object also sending signals and the first and /or the second of the objects receives the signals of the first and the at least one third object and the second object sends signals, in particular frequency hopping, and the third and/or first of the objects receives the signals of the second object and from this the distance between the first and the second object is determined, in particular without requiring an indirect determination, in particular the first, second and/or third object being or being time-synchronized and the second and third objects being arranged in particular in a fixed relative spatial orientation.

In particular, the first, second and/or the at least one third object are not time-synchronized before the method is carried out, or are time-synchronized to a lesser extent than after it has been carried out.

The first object can in particular represent an authorization means such as a key fob or cell phone. The second and third objects are in particular part of an arrangement to which access is sought and/or granted using the authorization means. This arrangement can be, for example, a building, a motor vehicle or a barrier, a machine or a computer.

This is achieved, among other things, by a method for, in particular direct, distance determination between two objects, with a first of the objects sending at least one first-object signal, in particular several first-object signals, with different first-object frequencies, and with the second object sending the at least one Receives the first object signal of the first object, the second of the objects sending at least one second object signal, in particular a plurality of second object signals, with different second object frequencies, with at least a third object transmitting the at least one first object signal and/or receives a second-object signal and wherein the at least one third object transmits at least one third-object signal, in particular several third-object signals, with different third-object frequencies, and wherein the first and/or second object receives the at least one third-object signal of the third object, and wherein the first and/or the at least one third object receives the at least one second object signal of the second object, and based on the respective at least one first, second, and third object signal the distance between the first and the at least one second and/or between is determined between the first and third object, characterized in that the second object changes phase-coherently between at least two second-object frequencies and/or changes in such a way that the phase difference during the frequency change, in particular at the first, second and/or third object, is known and/ or the phase difference when changing frequency, especially the first, second and/or third object, and that the at least one third object changes phase-coherently between at least two third-object frequencies and/or changes in such a way that the phase difference when the frequency changes, in particular at the first, second and/or third object, is known and/or the phase difference during the frequency change, in particular to the first, second and/or third object, is made known.

The phase difference usually occurs when switching between two frequencies, for technical reasons, but it can also be avoided. The switching between two frequencies can be carried out with a short interruption or without interruption. At the time of the uninterrupted change, the phase jumps, or during the change with an interruption, the phase of the signals thought to continue into the interruption before and after the changeover jumps. At the time of change without interruption or at an imaginary time of change in the interruption, in particular 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, there is a defined phase shift. This is the phase difference.

Time synchronization and/or distance between the first and second object can be determined by signal exchange between the first and second object with first and second object signals, each having in particular frequency hopping, and by signal exchange between the first and third object with first and third object signals, in particular frequency hopping in each case having, time synchronization and/or distance between the first and third object can be determined. This can also be done in other combinations of objects.

During the signal exchange between the first and second object, the third object listens in particular. In particular, at least one or all of the currently passive object(s) hear the signal exchange of another pair. As a result, if it knows the time and phase jump (which can also be zero) of the frequency change at the transmitter, it can also determine and/or improve its distance and time synchronization with the transmitter. But even without knowing the time of the changeover, it can already determine the distance based on the phase shift, corrected for the phase jump when switching over, and the frequency change based solely on the information about the size of the phase jump when switching over (which can also be zero), for example using

Distance = dphase shift(f 1 ,f2) / 2Pi / dfrequency(f 1 ,f2) * c where c equals the speed of light dphase shift(f 1 ,f2) equals the measured change in phase shift at the receiver due to the frequency change from f1 to f2, corrected about the phase jump at the transmitter when switching from f1 to f2 and dFrequenz(f1 ,f2) equal to the difference between the frequencies f1 and f2

In this case, the change in the phase shift is caused in particular by the change in frequency, with approximately the same distance. the The phase shift is caused by the distance. The change in phase shift caused by the frequency change or is caused by the fact that, in particular when the distance is approximately the same for both measurements, a different number of wave trains fit the distance and the phase shift, which is caused by the distance, is different between the frequencies. This change in phase shift due to frequency is the change in phase caused by the change in frequency. Problems arise when measuring, because the phase measurement is always dependent on a reference and a frequently undefined phase jump can also occur when switching over to transmit the different frequencies. Thus, for sending, and in particular also for receiving, switching is preferably phase-coherent, that is to say with a phase jump of zero. However, it is also sufficient to determine or to know the phase shift. Then you can determine the phase change due to the frequency change by correcting the measured phase change by the phase jump when switching the transmitter and the phase jump when switching on the receiver to measure the measured phase change.

The information about the switching time and/or phase jump is provided in particular, for example by predetermination or transmission. In principle, it is irrelevant where the calculations are carried out, whether for example in the objects, in an object or in a central processing unit. The measurements and information required for the calculations to be carried out must be made available there.

The knowledge of the phase jump when changing the frequency is used with particular advantage in order to enable a simple measurement or calculation, for example to correct the measurement of the change in the phase shift. In particular, at zero phase shift, this knowledge is also used in that the measurement of the change in phase shift is used directly to calculate a distance, it is just corrected for zero, so to speak. With this method, a high accuracy of the time synchronization and/or distance measurement can be achieved in a simple and fast signal exchange.

Advantageously, the first, second and/or at least one third object is or will be clock-synchronized and/or time-synchronized.

Time synchronization between the first and second and/or between the second and at least one third and/or the first and at least one third object is particularly preferably calculated and/or improved on the basis of the at least one first, second and/or third signal.

The second object particularly advantageously receives the at least one third-object signal from the third object and uses it in particular for time synchronization and/or distance measurement from the third object. A distance between the second and at least one third object is preferably calculated on the basis of the first, second and/or third object signals.

First, second and/or third object signals are or contain at least one frequency hopping. This increases the accuracy of the method.

Frequency hopping is to be understood in particular as the successive transmission on different frequencies. There is frequency hopping on both sides if two objects in each case carry out frequency hopping, in particular one after the other.

In particular, the frequencies, especially frequency hopping, lie in a range of 25 to 100 MHz, in particular span such a range completely. In particular, the frequencies, especially frequency hopping, are in the range from 2 to 6 GHz. In particular, there is a distance in the range from 0.1 to 17 MHz, in particular in the range from 0.5 to 10 MHz, between adjacent but not necessarily consecutive frequencies, in particular of frequency hopping. The first object preferably sends at least one first object signal before or after the at least one second signal and before or after the at least one third signal, in particular every third object, in particular the first object with the second object and the first object with the at least one third object , in particular every third object, carries out a signal exchange, in particular bilateral frequency hopping, in which in particular each of the two objects involved in the signal exchange sends at least one signal each having different frequencies in a fixed and/or predetermined sequence and in particular the first and the at least one third object changes phase-coherently between the different frequencies and/or changes in such a way that the phase difference when the frequency changes, in particular at the first object, is known and/or the phase difference when the frequency changes, in particular at the first object, is made known.

This further increases the accuracy and speed of the method.

The at least one first object advantageously changes between at least two first-object frequencies in a phase-coherent manner and/or in such a way that the phase difference when the frequency changes, in particular at the first, second and/or third object, is known and/or the phase difference when the frequency changes, in particular the third and/or second object, is made known. This allows the accuracy to be increased and the speed of the method to be increased.

The at least one third-object changes between the at least two third-object frequencies, in particular for receiving the first-object signals, in which case these third-object frequencies are then in particular identical or at least similar to the respective first-object frequencies, and/or for transmitting at least one, in particular several, own third-object signals.

The at least one second object particularly advantageously receives the first and third object signals of the first and of the at least one third object and the distance between the first and the at least one second object is determined therefrom or based thereon.

At least one distance between the first and every second and/or third object is preferably determined.

The phase difference or phase jump when changing between frequencies can be known, for example, because it is predetermined or can be derived from other known variables, for example the duration of an, in particular immediately preceding, emission at a frequency.

The at least one third-object signal advantageously has different third-object frequencies and/or changes between them.

The signals, in particular first and third object signals, are in particular radio signals.

In particular, the distance is determined based on frequencies and phases, in particular also amplitudes, of the first and third object signals received at the at least one second object as well as the time differences between the first and third and between the third and second object and in particular also information about the radiated first and/or Third-object signals such as times of the emission of certain features, for example frequency changes and/or their times of the first and/or third-object signals are determined.

Optionally, information provided by at least one third object, in particular phase correction information, about the at least one received first-object signal and/or information provided by the first object, in particular phase correction information, about the at least one third-object signal can also be used.

In particular, the at least one first and/or the at least one third object signal has at least one feature per frequency and/or per signal.

Characteristics of the signal are to be understood in particular as changes in the signal, such as changes in the amplitude, the polarization, the radiating antenna (switching between antennas), the frequency and/or phase. However, aggregated groups of features can also be used, which increase the robustness of the method in some situations. For example, modulated packets or sync words can be used as groups of features.

The object is also achieved by a system having at least one first, one second, in particular a plurality of second objects greater than one, in particular greater than two, and at least one third object, the first object being set up to emit first-object signals of different frequencies and preferably the at least one third object is set up to emit third-object signals of different frequencies and all objects are set up to receive signals, wherein the at least one second and the third object are set up to perform clock and/or time synchronization, and wherein the third object is set up to switch between at least two third-object frequencies, in particular the third-object signals, in a phase-coherent manner and/or to switch in such a way that the phase difference during the frequency change, in particular at the first, second and/or third object, is known and /or the phase difference when changing frequencies l, in particular the first, second and/or third object, is made known and/or the first object is set up to switch between at least two of the first object frequencies in a phase-coherent manner and/or to switch in such a way that the phase difference when changing the frequency, in particular at the first, second and/or third object, is known and/or the phase difference during the frequency change, in particular at the first, second and/or third object, is made known and/or the second object is set up between at least two of the second object to change frequencies in a phase-coherent manner and/or to change them in such a way that the phase difference when changing the frequency, in particular at the first, second and/or third object, is known and/or the phase difference when changing the frequency, in particular at the first, second and/or third object, is known is made. The system is also solved by an access system having at least one access restriction device, wherein the access restriction device is set up to grant and/or deny access, in particular by means of an access restriction means, further comprising at least a first, a second, in particular a plurality greater than one, in particular greater than two, second objects, and at least one third object, the first object being set up to emit first-object signals of different frequencies and in particular the third object being set up to emit third-object signals of different frequencies and all objects being set up to receive signals , wherein the at least one second and the third object are set up to carry out a clock and/or time synchronization, and wherein the third object is set up between at least two third-object frequencies, in particular the third-object signals, pha to change in a semi-coherent manner and/or to change in such a way that the phase difference during the frequency change, in particular at the first, second and/or third object, is known and/or the phase difference during the frequency change, in particular at the first, second and/or third object, is made known and/or wherein the first object is set up to switch between at least two of the first-object frequencies in a phase-coherent manner and/or to switch in such a way that the phase difference during the frequency change, in particular at the first, second and/or third object, is known and/or the phase difference when the frequency changes, in particular to the first, second and/or third object, is made known and/or the second object is set up to change between at least two of the second object frequencies in a phase-coherent manner and/or to change in such a way that the phase difference when Frequency change, particularly on the first, second and/or third object, is known and/or the phase difference chied is made known when the frequency is changed, in particular the first, second and/or third object, and the system has at least one controller which is set up to carry out the method according to the invention thereby at least a distance between at least one second object and the first object, wherein the access restriction device is set up not to deny access and/or to grant access if the at least one specific distance between the at least one second object and the first object does not exceed a predetermined distance and/or within a predetermined distance range and/or the determined position of the first object is within a first and/or outside a second predetermined range, and/or to deny access and/or not to grant access if the at least one, in particular all, determined distance (en) between the at least one second object and the first object exceeds the predetermined distance and/or is outside the predetermined distance range and/or the determined position of the first object is outside a first and/or within a second predetermined range.

Phase-coherent switching or switching between two frequencies means in particular that the phase after switching is known relative to the phase position before switching. This is the case when the change in phase on switching is zero or a previously known value. If you switch in such a way that the phase difference is known, the difference in the phase position before and after the switch is known. In this case, the value can also be previously known in that it can be derived from previously known quantities, for example from the duration of the, in particular immediately, preceding emission at a frequency.

This is the case, for example, when a defined phase position is always set when switching and the duration of the emissions since the last switching is measured or is known.

The direct determination of the distance significantly improves the accuracy and/or speed compared to the method from EP 2710398 B1.

With particular advantage, the at least one second and the first and/or the first and the at least one third object are or will be synchronized in terms of time and/or clock, in particular to 10 ns or better, in particular in the range between 10ns and 100ps, time and/or clock synchronized. This increases the accuracy of the method.

The difference in the drift between the clocks of the first and at least one second object or of the at least one second and at least one third object can be determined and used for correction. Numerous methods are known from the prior art for this purpose.

It is true that it is known to synchronize timers in two objects, both over wired and wireless connections. For example, the NTP protocol exists. Synchronization is also provided as part of a Bluetooth connection, in which each object has a free-running 28-bit clock with a clock rate of 3.2 kHz and each object determines its offset to a central clock and corrects it regularly. Here synchronization is achieved with an accuracy of about 125 ns. Improved time synchronization is also known, for example from DE1 1 2014004426T5 or "Synchronization in Wireless Sensor Networks Using Bluetooth", Casas et al., Third International Workshop on Intelligent Solutions in Embedded Systems, 2005., ISBN: 3-902463-03- 1. This can be used to save energy, for example, by keeping an object ready to receive only at certain time slots that are known to the other object in order to transmit at the appropriate times possible, with known distance measurements being impossible or very imprecise or requiring a lot of time with such interference. However, the accuracy of a time synchronization must be distinguished from the synchronization to a clock of a received signal at the receiver of the signal. Here there is no synchronization of two clocks on two Objects instead, but that is recieved ngene object set to be synchronized with the incoming signal. The signal propagation time is irrelevant, since it is irrelevant when the signal was sent and/or how long it took to transmit. With particular advantage, the at least one second and the third object are or will be time- and/or clock-synchronized to 10 ns or better, in particular in the range between 10 ns and 100 ps. This increases the accuracy of the method.

Advantageously, for each first and third object signal received at a second object, a value proportional to its amplitude and a phase value are determined and, in particular, a complex number is determined from this, which is used to determine the distance between the first or third object and the second object. In particular, a matrix, in particular an autocorrelation matrix, is formed from a plurality of the complex numbers of the first and/or third object signals and, by means of this and, for example, MUSIC, CAPON, comparison with, distance calculation to and/or projection on emission and/or reception characteristics, of distance determined. In particular, at least one matrix, in particular an autocorrelation matrix, is formed from first-object signals received at a second object and/or at least one matrix, in particular an autocorrelation matrix, from third-object signals received at a second object. The distance is advantageously calculated by means of determining the eigenvalues or eigenvectors of the at least one matrix and/or Fourier transformation of the complex values. The procedure can be analogous with signals received at the first and/or at a third object.

The phase value is determined in particular alternatively by calculating a change in the phase shift normalized to a frequency spacing with respect to a large number of pairs of signals with adjacent frequencies, i.e. approximately the derivation of the phase shift at one of the frequencies or frequencies of the pair is calculated and the values thereby collected are used to determine the phase of the complex number at the respective frequency (corresponding to the value proportional to the amplitude), in particular by approximate integration over the frequency. The integration does not have to start at f=0 Hz, but an offset that is common to all complex numbers can and is preferably used, in particular the lowest frequency of the signals selected in particular. In particular, the phase value is determined from the signal propagation time or signal round trip time, in particular pulse propagation time (ToF).

Specifically, the normalized phase shift change (dphaseshift(f1,f2)) is obtained using the formula: dphaseshift(f1,f2) = a * RTT(f3) * dfrequency(f1,f2) or dphaseshift(f1,f2 ) = b * STT(f3) * dFrequenz(f 1 ,f2) where dFrequenz(f1 ,f2) is the difference between the frequencies f1 and f2 RTT(f3) is twice the signal propagation time or the signal round trip time (pulse propagation time, ToF) between the first and second object or STT is the simple signal propagation time (pulse propagation time, ToF) at one or more frequencies f3, similar to f1 and/or f2 and/or vice versa and where a or b is a constant, in particular a equals Pi and b is two Pi is.

Here phase shift is a phase shift in transmission in frequency from one object to another and back that occurs due to distance. It can be approximated as twice the phase shift that occurs when transmitting at the frequency from one object to another due to distance.

In particular, frequencies are considered similar if they differ by less than 17MHz, in particular 10MHz, in particular less than 2MHz, and/or less than 5%, in particular less than 2%, of the lower frequency.

The complex value Z for a frequency is then obtained in particular using:

Magnitude(Z(f)) = (b* Amplitude(f) + offset)

Argument(Z(f)) = sum(dphaseshift(f(n + 1 ),fn)) over fn from fO to f(n + 1 ) = f.

The changes in the phase shift are thus summed up, from the lowest frequency to the frequency in question, for which the complex number is to be determined. The lowest frequency is approximately the same for all complex numbers, in particular identical. In addition, the phase shift changes must always be added up, especially for consecutive frequency pairs in which the higher frequency is approximately the same, in particular identical, to the lower of the frequencies of the next pair, i.e. in particular dphase shift(f1 ,f0) + dphase shift(f2,f1 ) + dphase shift (f3,f2) + .... + dphase shift(f,fn) with f=f(n+1) f0 is approximately the same for all complex numbers of a vector and/or a matrix, in particular the same.

In this case, b and offset are constants and if b is in particular equal to 1 and offset is in particular equal to 0. Amplitude(f) is the received amplitude measured at frequency f or an average of several amplitudes measured at frequency f and/or frequencies similar to f. Alternatively, the power can also be used.

The narrower the steps of the real measurement, i.e. the available fm, the smaller the step size in the sequence f0 to f can be chosen and the more accurate the method is.

For example, is measured as follows

And if the distance between the adjacent frequencies is equidistant with the distance 2d, then F1 + 2 * d = F2, F2 + 2 * d = F3 etc. applies. Then one can calculate: dphase shift(F1 + d, F1 -d) = k1 * 2 + STT(F1 ), generally dphaseshift(Fn +d, Fn - d) = k1 * 2 + STT(Fn),

Then you form, for example

Magnitude(Z(fn + d)) = (k2* Amplitude(Fn) + offset) and

Argument(Z(fn +d)) = sum(dphase shift (fs + d,fs - d)) over fs from F1 to Fn

If the distances are not equidistant, one selects frequencies fa and fb, in particular as the lowest one, in particular slightly below the lowest measurement frequency, and then continuously frequencies, in particular in the middle, between the ascending measurement frequencies.

In particular, a matrix, in particular an autocorrelation matrix, is formed from a plurality of the complex numbers. In particular, this is done by forming a vector from the complex numbers, in which the complex numbers are written into the columns or rows of the vector and its autocorrelation matrix is formed. The distance is determined by means of this, for example by means of known methods, for example MUSIC, CAPON, comparison with, distance calculation for and/or projection on emission and/or reception characteristics. Advantageously, the distance is calculated by determining the eigenvalues or eigenvectors of the at least one matrix and/or Fourier transformation of the complex values. Such procedures are particularly advantageous in the case of multipath signal propagation in order to achieve a reliable determination.

In certain configurations it can be advantageous to arrange the at least one second and the third object in a fixed relative spatial position and orientation, for example if the distance measurement is carried out for the purpose of access control. This makes calculation easier and increases reliability.

Data is advantageously transmitted with the first-object and/or third-object signals, in particular user data, in particular data that is not required for the method according to the invention.

The objects are advantageously parts of a data transmission system, in particular a Bluetooth, WLAN or mobile radio data transmission system. The first object and/or third object signals are preferably signals of the data transmission system and/or a data transmission standard, for example mobile radio standard, WLAN or Bluetooth, which are used for data transmission in accordance with the data transmission standard.

The first-object and/or third-object signals are advantageously transmitted via a number of antenna paths, in particular with a number of antennas, in particular one after the other, sent at the transmitting object and/or received with a number of antennas at the receiving object.

The first object is preferably an authorization means, such as a keyfob or cell phone. The second and third objects are advantageously part of an arrangement to which access is sought and/or granted using the authorization means, the arrangement being in particular a building, a motor vehicle or a barrier, a machine and/or computer.

It is preferred that the third object receives the first-object signals and provides information about the received first-object signals and this is used in the calculation of the distance and/or that the first object receives the third-object signals and information about the received ones Provides third-party object signals and uses them in calculating the distance. This is particularly advantageous if the time of the transmission and/or the phase position during transmission would not otherwise be known in the system.

The at least one second object is particularly advantageously passive and/or the at least one second object itself does not send any signals or does not send any signals used to calculate the distance and/or the at least one second object itself does not send any signals or does not send any signals used to calculate the distance as part of the method . As a result, the duration of the method can be shortened and the safeguard can be hidden by determining the distance between the first and at least one second object and thus made more secure.

The method is preferably designed in such a way that at least one of the transmitting objects (first and/or at least one third object) changes between signals in a phase-coherent manner, in particular without a phase jump or with a known phase jump and/or the phase jump is measured locally and taken into account when determining the distance and/or is corrected and/or at least one of the objects determines at least one item of phase correction information from signals of one of the other objects, which is used in the distance calculation, in particular wherein the first object changes phase-coherently between at least two of the first-object frequencies of the first-object signals and/or the third Object changes phase-coherently between at least two of the third-object frequencies of the third-object signals and/or the third object determines at least one piece of phase correction information from the first-object signals and/or the first object determines at least one piece of phase correction information from the third-object signals determined and wherein the at least one piece of phase correction information is used in the distance calculation. Such a configuration, in which additional information about the phase angle at the transmitting object is available, allows the method to be configured more precisely and more robustly, and the calculation to be simpler. In particular, the first, second and/or third object also switch over in a phase-coherent manner for reception. Alternatively, they measure the phase jump of the phase when changing the frequency and this phase jump is corrected in the calculation.

Advantageously, not only does the transmitting object switch in a phase-coherent manner, but also the receiving object; in particular, a PLL is switched in a phase-coherent manner in each object.

The times and/or the schedule for the transmission of the third-object and/or the first-object signals are particularly advantageously predetermined and/or is/are this/are known to the second object and/or this/is/will be known to the second object taken into account in the distance calculation. A more accurate determination and simpler calculation can thereby be achieved.

In a preferred embodiment, the method includes the synchronization of the times and/or cycles in at least one second and third object, in particular wirelessly or with a cable. At least one time and/or clock synchronization and/or correction between the at least one second and third object is preferably carried out before, after and/or during the implementation of the method. However, the synchronization can also be provided or be brought about by other methods. In particular, the differences in times and/or cycles between at least a second and third object are known and/or synchronous. This increases the accuracy of the method. A drift of the clocks of the at least one second and/or third object or a difference in the drift of the clocks of the at least one second and third object is preferably also determined and taken into account when determining the distance. This further increases the accuracy of the method. In a preferred embodiment, the method includes the synchronization of the times and/or cycles between the first and second and/or at least one third and first and/or between the second and at least one third object, in particular wirelessly. At least one time and/or Clock synchronization and / or correction performed between the first and second and / or at least one third and first and / or between the second and at least one third object. An at least relative drift of the clocks of the first, second and/or the at least one third object is preferably also determined on the basis of the at least one first, second and/or third signal and taken into account when determining the distance. This further increases the accuracy of the method.

Time differences and/or drift can also be determined indirectly in the triangular relationship: If, for example, the time difference and/or drift between X and Y and between Y and Z is known, the time difference and/or drift between X and Z can be calculated from this.

The second and/or the at least one third object preferably determines its time and its time drift compared to the first object.

Prior to the exchange of the first, second and third signals, a rough time synchronization between the first, second and at least one third object is advantageously brought about, in particular with an accuracy of better than 2 JJS, in particular in the range from 0.1 to 2/JS. The time synchronization based on the first, second and third signals is in particular in the range from 0.01 to 10 ns, in particular in the range from 0.05 to 5 ns and/or the accuracy of the drift determination in the range from 0.1 to 100 ppb , especially in the range of 1 to 10 ppb. This can be achieved by phase-coherent switching or by making known the phase jump of the first and third signals, in particular also the first signals.

In particular, the second (A) and/or the at least one third anchor (B) each determine dTxA or dTxAB=time difference from A to the first object or B to the first object ppbA buw. ppbB = quartz difference of A or B relative to the first object Ts.localA or Ts.localB = start time of signal exchange in the local time system of object A or B

Ts. A or TS.B = start time of the signal exchange in the time system of object A or B

ToffMeas(n) = time offset of each measurement at frequency n from the start time of the signal exchange

F(n) = radiated nth frequency in the signal exchange, relative to the crystal of the transmitter

The received phases depend on the phase angles during transmission and on the distance and time offset between the measuring and the transmitting object as well as the difference in the drifts of the oscillators in the transmitter and receiver. Knowing the drift, the time aspect can be corrected by a phase error caused by the timing inaccuracy/drift.

The absolute time difference in object A at the time the first signal is measured can be given as: dT(n) = dTxA + (Ts. local + ToffMeasure(n) - Tx) * ppbA

The relative time difference is then: dRT(n) = dT(n) - (Ts. A - Ts. local)

And the phase correction to:

Phcorrection = dRT(n) * F(n)

Oscillator drift can also be corrected accordingly, further improving accuracy.

The corrected phase measurements can then be used directly for one-sided distance measurement. A correction is not absolutely necessary, but improves the accuracy. Even if the initial phase of the first frequency should not be known at the transmitter, can be through the known change in phase when switching at the transmitter determine a distance through the phase shift, for example by means

Distance = (phase shift between two frequencies) / 2Pi / (difference between the two frequencies) * c

It should be noted that there is an ambiguity here

Distance = c/(difference between the two frequencies) where c equals the speed of light

The second object particularly advantageously uses the signals of the signal exchange between the first and at least one third object to determine its time, time drift and/or distance to the first and/or at least one third object by passively monitoring the signal exchange between the first and at least one third object . The at least one third object particularly advantageously uses the signals of the signal exchange between the first and second object to determine its time, time drift and/or distance to the first and/or second object by passively listening in on the signal exchange between the first and second object.

With particular advantage, the distance between the at least one second and the first object is determined without determining the distance between the first and third object and/or the distance between the first and the at least one second object is determined independently of the distance between the first and third object determined. This increases the speed and accuracy of the process.

The method is particularly advantageously carried out with a plurality, in particular with a common plurality greater than one, in particular greater than two, in particular greater than four, second objects and common first and in particular common second and third objects, preferably the calculated distances , In particular between the first and each of the plurality of second objects, used to map and / or Carry out position determination of the first object. By using a plurality of second and/or third objects, in particular ones that are spatially remote from one another, the reliability and accuracy can be increased and locating, for example by means of triangulation, is possible.

The method is preferably carried out multiple times, with the at least one second and at least one third object also being able to swap roles, but the first object being common and/or constant to all executions. For example, from a plurality of objects, a changing part of the plurality can always be second objects and another part third objects.

The plurality of second objects preferably have a fixed position and/or orientation relative to one another, which is known in particular and/or is determined by radio location. As a result, a simple triangulation for locating the first object is possible, for example.

The method is advantageously carried out using a system and/or access system according to the invention. The system or access system is advantageously set up to implement one or more advantageous configuration(s) of the method and, in particular, has a correspondingly set up controller for this purpose.

Advantageously, the bandwidth of the signals never exceeds 50 MHz, in particular 25 MHz. As a result, energy can be saved, disruptions to other processes can be avoided and simple components can be used compared to broadband methods.

The signals are advantageously transmitted via a number of antenna paths, in particular with a number of antennas, in particular one after the other, sent at the transmitting object and/or received with a number of antennas at the receiving object.

The first and/or third object preferably transmits the signals on a plurality of frequencies one after the other and/or consecutively, in particular immediately consecutively and/or send first and third objects alternately consecutively.

For example, the distance is calculated as follows:

The phases/amplitudes of the first object measured on the second object as a function of the carrier frequency are corrected by the expected/calculated error from the known time shift between the objects and the time drift of the two system clocks of the objects. Then these values can be evaluated e.g. via an FFT. Vectors can also be set up (e.g. for different antenna paths) from which an autocorrelation matrix (AKM) is generated and the distances searched for in this AKM using high-resolution methods such as MUSIC or CAPON.

On the premise of phase-coherent frequency switching for the first and third objects, one can work as follows, otherwise the calculation becomes somewhat complicated:

In particular after determining the precise time differences and time drift between the third and first object and between the second and third object, the sufficiently precise time difference between the first and second object can be calculated at any time for a limited period of time (e.g. 100 ms).

The IQ values or phases/amplitudes of at least 2 (up to n) frequencies (F0 to Fn) of a signal from the first object are determined on the second object.

In particular, the IQ values or phases/amplitudes at at least 2 (up to n) frequencies (F0′ to Fn′) of a signal of the at least one third object are determined on the second object.

If, for example, the switching times between the frequencies F0 to Fn' and/or F0 to Fn and/or their chronological relationship are known, the second object can record the switching times between the frequencies in F0' to Fn' at least with the third object due to the time synchronization definitely will. If the times of reception of the switchover are then measured, transit times, in particular pulse transit times (ToF), can be determined directly from this.

However, by switching with a known or without a phase jump, the frequency shift due to the frequency change can also be measured directly. This applies both to the signals from the first object and from the at least one third object, which are received at the second object. This alone allows the second object to determine both the distance on a phase-based basis (phase based ranging, PBR) to the first and to the at least one third object, for example by means of

Distance = dphase shift(f 1 ,f2) / 2Pi / dfrequency(f 1 ,f2) * c where c equals the speed of light and dphase shift(f 1 ,f2) equals the measured phase change at the receiver due to the frequency change from f1 to f2 corrected by the phase jump at the transmitter when switching from f1 to f2 and dFrequenz(f1 ,f2) equal to the difference between the frequencies f1 and f2

If the switching times of the first and the at least one third object have a derivable, recognizable, communicated and/or predetermined time relationship, which is preferred, further information for improving the measurement can be obtained as a result. If the at least second object knows, for example, the switching times between frequencies of the at least one third object and/or if this is made known to it, which is preferred, it can determine the switching times of the frequencies of the first object from the relation of the switching times, at least as a function of the distance between the first and at least a third object, which leads to a further improvement.

For example, if the at least second object is aware of the switchover times between frequencies of the first object and/or if they become aware of them made known, which is preferred, it can directly determine the transit time, in particular pulse transit time (ToF) of the signal from the first to the second object and thus the distance. However, the distance through the second object can also be determined directly simply because of the frequency switching of the emission of the signals from the first object with or without a known phase jump, for example, as explained above, using:

distance = dphase shift(f 1 ,f2) / 2Pi / dfrequency(f 1 ,f2) * c

The measured phase shifts can be adjusted to the time differences and frequency differences (incl. drift) to increase the accuracy. It is sufficient to consider the drift approximately. Determining this is known from the prior art and can be done, for example, by determining the time differences at different times, for example before and after the signal exchange for the distance measurement.

In general, however, the time synchronization and the distance calculation can be carried out together using a system of equations. This is made possible by switching in a phase-coherent manner or with knowledge of the phase jump.

In order to resolve multipathing, for example, the individual phases with the associated measured amplitudes can be entered as complex values in a Fourier transformation, for example, or a spectral estimation can be carried out in matrices using super-resolution methods such as MUSIC or CAPON.

1 shows, purely by way of example and only schematically and without limitation, a car with a number of second objects (2) and a third object (3) arranged therein, as well as a first object (1) designed as a keyfob. When the method is carried out, the distances between the first and every second object are determined. If the time synchronization between the third and the second object takes place, for example, by cable, the second objects can be designed without a transmitter and can therefore be passive or not locatable. An example with at least two anchors (A1 An) and a key (Key) can look like this. Two of the anchors from A1 to An are second and third objects

At least one pair of anchors from A1 to An, including second and third objects, in particular the first object/second object and first object/third object pairs, exchange first, second and/or third object signals, at different frequencies (e.g. 20 to 50 Frequencies) and switch between the frequencies at least in pairs in phase synchronism or in such a way that the phase jump is known. This can be done, for example, by transmitting it to the partner.

In addition, one of the objects in each pair preferably sends the measured phases to at least the other of the pair or to a central location, for example the third object sends its phase measurements to the first object, this can be done by radio and/or cable-based.

Key, i.e. first object, and second object exchange first and second object signals at several different frequencies (e.g. in the range of 20 to 100 frequencies) and switch between the frequencies at least in pairs in phase synchronization or in such a way that the phase jump is known. This can be done, for example, by transmitting it to the partner.

Key sends its phase measurements to FirstObject. Now the firstobject can calculate the time synchronization between firstobject and key and the distance between firstobject and key. If the first object also passes on its measurements and/or those of the key to the third object, the third object can also carry out time synchronization and a distance calculation of its distance from the key.

This can be done with any number of third-party objects. In particular, the second object and the at least one third object have a fixed spatial arrangement in relation to one another, while the key for this is mobile. This can the time synchronization and the determination of the distance between the second and third object(s) are constantly being improved.

Mathematically, it doesn't matter when the individual signals are sent. In particular, the signals that A1 exchanges with Key can also be used by A2 for time synchronization.

It is even sufficient if the objects/anchors (first, second and third object(s)) carry out a normal tone exchange and/or hopping for ranging in pairs one after the other, in particular with the key (first object), and in doing so in a phase-coherent manner or with known phase jump change the frequency. In total, enough tones are sent and heard to calculate a time synchronization between ALL partners (between the key and each of the anchors) in addition to determining the distance.

Due to the fact that when a signal is exchanged in a pair of objects, the other objects can listen in and measure the phase changes when the frequency of the transmitter changes, they can also determine their time synchronization and/or distance determination to the objects of the currently Improve signal exchange performing objects.

Claims

29 claims

1 . Method for, in particular direct, distance determination between two objects (1, 2), wherein a first of the objects (1) transmits at least one first-object signal, in particular several first-object signals, with different first-object frequencies, and wherein the second object transmits the at least receives a first-object signal of the first object, with the second of the objects (2) sending at least one second-object signal, in particular several second-object signals, with different second-object frequencies, with at least a third object (3) sending the at least one first-object signal and/or second-object signal receives and wherein the at least one third object transmits at least one third-object signal, in particular several third-object signals, with different third-object frequencies, and wherein the first and/or second object receives the at least one third-object signal of the third object, and wherein the first object which receives at least one second object signal of the second object, the distance between the first and the at least one second and/or between the first and third object being determined based on the at least one first, second and third object signal, , characterized in that the second object is in the second object signal changes phase-coherently between at least two second-object frequencies and/or changes in such a way that the phase difference during the frequency change, in particular at the first, second and/or third object, is known and/or the phase difference during the frequency change, in particular the first, second and/or third object, is made known and that the at least one third object in the third-object signal changes phase-coherently between at least two third-object frequencies and/or changes in such a way that the phase difference during the frequency change, in particular at the first, second and/or third object, is known and /or the phase difference when changing frequencies, in particular the first, second and/or third object, is made known. 30 The method of claim 1, wherein the first, second and / or at least and at least one third object are clock and / or synchronized in time and / or based on the respective at least one first, second and / or third signal, a time synchronization between the first and second and/or between second and at least one third and/or first and at least one third object is calculated and/or improved. Method according to one of the preceding claims, wherein the second object receives the at least one third-object signal of the third object and/or wherein a distance between the second and at least one third object is calculated on the basis of first, second and/or third signals. Method according to one of the preceding claims, in which the first object transmits at least one first-object signal before or after the at least one second object and before or after the at least one third-object signal, in particular every third object, with the first object in particular communicating with the second object and the first object carries out a signal exchange, in particular bilateral frequency hopping, with the at least one third object, in particular every third object, in which in particular each of the two objects involved in the signal exchange has at least one signal in a fixed and/or predetermined sequence, each having at least one signal transmits different frequencies, in particular frequency hopping, and in particular the first object in the at least one first-object signal and/or the at least one third object in the at least one third-object signal changes phase-coherently between the different frequencies and/or changes in this way/ n that the phase difference at the frequency change, in particular at the first object, is known and/or the phase difference at the frequency change, in particular at the first object, is made known. Method according to one of the preceding claims, wherein the at least one first object in the first-object signal changes phase-coherently between at least two first-object frequencies and/or changes in such a way that the phase difference when the frequency changes, in particular at the first, second and/or third object, is known and/or the phase difference during the frequency change is made known, in particular to the third and/or second object. Method according to one of the preceding claims, wherein for at least one, in particular all received (s) first, second, - and / or third object signal (s) per, in particular per received frequency and / or first, second and / or Third-object frequency and/or each frequency of frequency hopping, a value proportional to its amplitude and a phase value are determined and, in particular, a complex number is determined therefrom, which is used to determine the distance between the first and second object, in particular by creating a vector from the complex numbers and/or an autocorrelation matrix, in particular for each received first, second and/or third object signal. Method according to one of the preceding claims, wherein the second and the at least one third object are arranged in a fixed relative spatial position and/or orientation and/or wherein the first object is an authorization means, such as a keyfob or mobile phone, and wherein in particular the second and third Object are part of an arrangement to which access is sought and/or granted by means of the authorization means, the arrangement being in particular a building, a motor vehicle or a barrier, a machine and/or a computer. Method according to one of the preceding claims, wherein the third object receives the at least one second and/or first object signal and provides information about the at least one received second and/or first object signal and this is used in calculating the distance and/or or wherein the first object is the at least one Receives second and/or third object signal and provides information about the at least one received second and/or third object signal and this is used in calculating the distance and/or wherein the second object is the at least one first and/or third object -Receives signal and provides information about the at least one received first and / or third object signal and this is used in calculating the distance. Method according to one of the preceding claims, wherein at least one of the transmitting objects, first object and/or third object, changes between frequencies in a phase-coherent manner and/or at least one of the objects determines at least one piece of phase correction information from signals from one of the other objects, which is used in the distance calculation , in particular wherein the first object changes phase-coherently between at least two of the first-object frequencies and/or the third object changes phase-coherently between at least two of the third-object frequencies and/or the third object determines at least one piece of phase correction information from the first-object signals and/or the first Object determines at least one piece of phase correction information from the third-object signals and wherein the at least one piece of phase correction information is used in the distance calculation. Method according to one of the preceding claims, wherein the times and/or the schedule of the transmissions of the at least one second, third and/or first object signal and/or their characteristics is/are predetermined and/or the first, second and/or third object is/are known and/or made known and/or is/are taken into account when calculating the distance and/or the method involves synchronizing the times and/or clocks in between the first and second, second and third and/or first and third object includes, wireless or wired. 33 1 . Method according to one of the preceding claims, wherein the distance between the first and the second object is determined without determining the distance between the first and third object and / or wherein the distance between the first and the second object is independent of the distance between the first and third object is determined.

2. The method according to any one of the preceding claims, wherein the method is carried out according to one of the above methods with a plurality of third objects and common first and in particular common second object, and wherein the calculated distances, in particular between the first and the plurality of second objects, are used in order to carry out a mapping and/or position determination of the first object and/or wherein in particular the second and the at least one third object have a fixed position and/or orientation to one another.

3. System comprising at least a first, a second, in particular a plurality of greater than one, in particular greater than two, second objects (1, 2) and at least one third object (3), the first object (1) for emitting at least one first object -Signals with different frequencies are set up and wherein all objects are set up to receive signals, wherein the at least one second and the third object are set up to carry out clock and/or time synchronization, and the third object is set up between at least to change two of the third-object frequencies in a phase-coherent manner and/or to change them in such a way that the phase difference when changing the frequency, in particular at the first, second and/or third object, is known and/or the phase difference when changing the frequency, in particular the first, second and/or third object, is made known and/or wherein the first object is established between at least two of the first to change object frequencies in a phase-coherent manner and/or so to 34 change that the phase difference when changing the frequency, in particular at the first, second and/or third object, is known and/or the phase difference when changing the frequency, in particular at the first, second and/or third object, is made known and/or wherein the second object is set up to switch between at least two of the second-object frequencies in a phase-coherent manner and/or to switch in such a way that the phase difference when the frequency changes, in particular at the first, second and/or third object, is known and/or the phase difference when the frequency changes, in particular at the first, second and/or third object, and wherein the system has at least one controller which is set up to carry out the method according to the invention and thereby to determine at least one distance between at least one second object and the first object. Access system having at least one access restriction device, wherein the access restriction device is set up to grant and/or deny access, in particular by means of an access restriction means, further comprising at least a first, a second, in particular a plurality of greater than one, in particular greater than two, second objects (1st ,2), and at least one third object (3), wherein the first object is set up to emit at least one first-object signal with different frequencies and all objects are set up to receive signals, wherein in particular the at least one second and the third and /or the first object is set up to carry out clock and/or time synchronization, and the third object is set up to switch between at least two of the third-object frequencies in a phase-coherent manner and/or to switch in such a way that the phase difference when changing frequencies, in particular at first , second and/or third object, is known and/or the phase difference during frequency change, in particular the first, second and/or third object, is made known and/or wherein the first 35

object is set up to switch between at least two of the first-object frequencies of the first-object signals in a phase-coherent manner and/or to switch in such a way that the phase difference during the frequency change, in particular at the first, second and/or third object, is known and/or the phase difference at Frequency change, in particular the first, second and/or third object, is made known and/or the second object is set up to change between at least two of the second-object frequencies of the second-object signals in a phase-coherent manner and/or to change in such a way that the phase difference is known during the frequency change, in particular at the first, second and/or third object, and/or the phase difference is made known during the frequency change, in particular at the first, second and/or third object, and the system has at least one controller that is set up That carry out the method according to the invention and thereby at least a distance between en at least one second object and the first object to be determined, wherein the access restriction device is configured not to deny access and/or to grant access if the at least one specific distance between the at least one second object and the first object is a predetermined distance does not exceed and/or is within a predetermined distance range and/or the determined position of the first object is within a first and/or outside a second predetermined range, and/or to deny access and/or not to grant access if the at least one, in particular all, specific distance(s) between the at least one second object and the first object exceeds the predetermined distance and/or lies outside the predetermined distance range and/or the specific position of the first object is outside the first and/or inside the second predetermined range.