METHOD FOR DETERMINING A DISTANCE BETWEEN TWO OBJECTS WITH THE INVOLVEMENT OF A THIRD OBJECT

Abstract

The invention relates to a method for determining a distance between two objects with the involvement of a third object. The first object can be, more particularly, 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 two objects, in which method a first of the objects, for example a key, transmits at least one, more particularly a plurality of first-object signals with different first-object frequencies, at least one third object transmits at least one, more particularly a plurality of third-object signals, the at least one second of the objects receives the first-object 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 and the second object is determined, the second object and the third object being clock- and / or time-synchronized, characterized in that the third object and / or the first object switches between at least two frequencies such that phase coherence is maintained or such that the phase jump is known.

Description

[0001] Method for determining a distance between two objects with the assistance of a third object

[0002] The invention relates to a method for determining a distance between two objects with the assistance of a third object.

[0003] From EP 2710398 B1 it is known to passively determine the location in an anchor network by listening to the communication of the anchors, by determining several distances and from this the location or the distance to one or more anchors is determined.

[0004] From US 2020 / 1 18372 A1 it is known to determine the distance to a key using a passive sniffer in a vehicle after communication has been initiated by an active node in the vehicle. The most suitable antennas are determined from a large number of available antennas based on RSSI values. Differently polarized antennas are used and round trip times or phase shifts for each frequency at which a round trip is made are measured or differences between them are determined. For this purpose, the change in phase over one round trip at a first frequency is compared with the change in phase during a second round trip at a second frequency, taking into account the change from the first frequency to the second frequency. Phase-coherent switching between the frequencies is not performed. Also, the phase difference during switching is not known.The object of the present invention is to determine the distance between at least two, in particular at least three, objects, wherein a first of the objects transmits a plurality of signals with different frequencies, in particular one after the other, in particular frequency hopping, wherein at least a third object also transmits signals, in particular carries out frequency hopping, and the second of the objects receives the signals of the first and the at least one third object and from this the distance between the first and the second objects is determined without requiring an indirect determination, for example via the distance between the first and the third object, wherein in particular the second and third objects are time-synchronized and / or in particular are arranged in a fixed relative spatial orientation.

[0005] The first object can, in particular, represent an authorization device, such as a key fob or mobile phone. The second and third objects are, in particular, part of an arrangement to which access is sought and / or granted using the authorization device. This arrangement can, for example, be a building, a motor vehicle, a barrier, a vending machine, or a computer.

[0006] This is achieved, inter alia, by a method for, in particular directly, determining the distance between two objects, wherein a first of the objects transmits at least one first object signal, in particular a plurality of first object signals, with different first object frequencies, and wherein the at least one second object receives the first object signals of the first object and, based thereon, the distance between the first and the at least one second object is determined, wherein the at least one second and at least one third object are clock and / or time synchronized, wherein the at least one second object does not transmit any signals other than for time synchronization and / or the at least one second object does not transmit any signals used for distance determination and / or is passive apart from time synchronization, wherein in particular the at least one second object does not transmit any radio signals, characterized in thatthat the at least one third object transmits at least one third-object signal. This third-object signal can be used and / or suitable for distance determination, for example, based on phase-based ranging (PBR) and / or time-of-flight measurements (pulse time of flight, ToF), and / or can be used solely for timing adjustment or for transmitting information for the process, for example, for its initialization. In any case, some form of radio communication takes place between the first and at least one third object.

[0007] Particularly preferably, a time synchronization between the first and second and / or between the second and at least one third and / or first and at least one third object is calculated and / or improved on the basis of the at least one first and / or third signal.

[0008] It is advantageous if the first and / or third object signals each contain at least one frequency hop. This increases the accuracy of the method.

[0009] Frequency hopping refers, in particular, to consecutive transmission on different frequencies. Bidirectional frequency hopping occurs when two objects perform frequency hopping, especially one after the other.

[0010] In particular, the frequencies, in particular those of frequency hopping, are in a range of 25 to 100 MHz, in particular they completely span such a range. In particular, the frequencies, in particular those of frequency hopping, are in the range of 2 to 6 GHz. In particular, there is a spacing in the range of 0.1 to 17 MHz, in particular in the range of 0.5 to 10 MHz, between adjacent but not necessarily consecutive frequencies, in particular those of frequency hopping.

[0011] In a first embodiment, the third object can switch between at least two third-object frequencies in a phase-coherent manner and / or switch such that the phase difference is known at the first and / or second object and / or the phase difference is made known to the first and / or second object. In a second embodiment, which can also be combined with the first embodiment, the first object can switch between at least two of the first-object frequencies of the at least one first-object signal in a phase-coherent manner and / or switch such that the phase difference is known at the second and / or third object and / or the phase difference is made known to the second and / or third object.

[0012] The phase difference or jump when changing between frequencies can be known, for example, because it is predetermined or can be derived from other known quantities, for example the duration of a, in particular immediately preceding, radiation at a frequency.

[0013] The phase difference usually occurs when switching between two frequencies for technical reasons, but 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 interruption, the phase jumps, or during the switchover with an interruption, the phase of the signals that are thought to continue into the interruption jumps before and after the switching. At the time of the switchover without an interruption or at an imaginary changeover time during 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, a defined phase jump occurs. This is the phase difference.

[0014] Preferably, the at least one third object switches between the at least two third object frequencies, in particular for receiving the first object signals, wherein 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.

[0015] Particularly advantageously, the at least one second object receives the first and third object signals of the first and at least one third object, and the distance between the first and at least one second object is determined from or based thereon. Preferably, at least one distance is determined between each of the first and each of the second objects.

[0016] In particular, signals sent by the second object are not used to determine the distance and / or the method is conducted in such a way that they play no relevant role for this and / or they do not improve the accuracy or only improve it insignificantly, in particular by less than 10% of the accuracy, in particular less than 2% of the accuracy, i.e. with an accuracy of 1 m / 100 m, for example, by less than 10 cm / 100 m, in particular by less than 2 cm / 100, i.e. not to an accuracy better than 90 cm / 100 m or not to an accuracy better than 98 cm / 100 m. In particular, signals sent by the second object are used exclusively for time synchronization. Although time synchronization or synchronicity of the clock generators is strongly preferred, this can also be achieved by means other than signals from the objects.If it is (also) caused by signals from the second object, these signals are used indirectly, by using knowledge of the times in the objects or their drift or their synchronicity to determine the distance, but preferably not the signals themselves, in particular not their travel times and not their phase positions, even if these may have been used for time synchronization.

[0017] If one imagines the process flow such that time synchronization was achieved, among other things, with a first set of signals from the second object and a second set of signals from the first and at least one third object were transmitted, the process is carried out in particular such that the accuracy of the distance determination using signals from the first set, the second set, and the synchronized clocks would not be better by more than 10%, in particular not more than 2%, of the accuracy of the distance determination based solely on the second set and the synchronized clocks than the accuracy of the distance determination based solely on the second set and the synchronized clocks. Advantageously, the at least one third-object signal has different third-object frequencies and / or alternates between them.

[0018] The signals, in particular first and third object signals, are in particular radio signals.

[0019] In particular, the distance is determined based on frequencies and phases (phase-based ranging), in particular also amplitudes, of the first and third object signals received at 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 emitted first and / or third object signals such as times of emission of certain features, for example frequency changes and / or their times of the first and / or third object signals.

[0020] 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 be used.

[0021] 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.

[0022] Signal characteristics are understood to mean, in particular, changes in the signal, such as changes in amplitude, polarization, the radiating antenna (switching between antennas), frequency, and / or phase. Such a characteristic can, for example, represent the beginning or end of the emission of a frequency. However, aggregated groups of characteristics can also be used, which in some situations increase the robustness of the method. For example, modulated packets or sync words can be used as groups of characteristics.

[0023] The object is also achieved by a system 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, wherein the first object is configured to emit first object signals of different frequencies and preferably the at least one third object is configured to emit third object signals of different frequencies and all objects are configured to receive signals, wherein the at least one second and the third object are configured to carry out a clock and / or time synchronization, and wherein the system has at least one controller which is configured to carry out the method according to the invention, characterized in that the third object is configured to switch between at least two third object frequencies in a phase-coherent manner and / or to switch so thatthat the phase difference at the first and / or second object is known and / or the phase difference is made known to the first and / or second object and / or that the first object is configured to switch between at least two of the first-object frequencies of the at least one first-object signal in a phase-coherent manner and / or to switch in such a way that the phase difference at the second and / or third object is known and / or the phase difference is made known to the second and / or third object.

[0024] The system is also achieved by an access system comprising at least one access restriction device, wherein the access restriction device is configured 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, wherein the first object is configured to emit first object signals of different frequencies and in particular the third object is configured to emit third object signals of different frequencies and all objects are configured to receive signals, wherein the at least one second and the third object are configured to carry out clock and / or time synchronization, and wherein the third object is configured to switch between at least two third object frequencies, in particular the third object signals,and / or wherein the first object is configured to switch between at least two first object frequencies of the first object signals and wherein the system has at least one controller configured to carry out the method according to the invention by determining at least one distance between at least one second object and the first object, wherein the access restriction device is configured not to deny access and / or to grant access if the at least one determined distance between the at least one second object and the first object does not exceed a predetermined distance 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,certain 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 certain position of the first object lies outside a first and / or within a second predetermined range, characterized in that the third object is configured to switch between at least two third-object frequencies in a phase-coherent manner and / or to switch in such a way that the phase difference is known at the first and / or second object and / or the phase difference is made known to the first and / or second object and / or that the first object is configured to switch between at least two of the first-object frequencies of the at least one first-object signal in a phase-coherent manner and / or to switch in such a way,that the phase difference is known at the second and / or third object and / or the phase difference is made known to the second and / or third object.,

[0025] Phase-coherent switching or switching between two frequencies is understood in particular to mean that the phase after the switching is known relative to the phase position before the switching. This is the case if the phase change during switching is zero or amounts to a previously known value. If the switching is carried out in such a way that the phase difference is known, the difference in the phase position before and after the switching is known. The value can also be previously known because it can be derived from previously known quantities, for example, from the duration of the, particularly immediately preceding, radiation at a frequency.

[0026] This is the case, for example, if a defined phase position is always set when switching and the duration of the emissions since the last switching is measured or known.

[0027] Knowledge of the phase shift during a frequency change is particularly advantageously used to enable simple measurement or calculation, for example, to correct the measurement of the change in phase shift. With a phase shift of zero, this knowledge is also particularly useful, as the measurement of the change in phase shift is used directly to calculate a distance; it is simply corrected by zero, so to speak.

[0028] The direct determination of the distance significantly improves the accuracy and / or speed compared to the method of EP 2710398 B1.

[0029] It is known to synchronize timers in two objects, both via wired and wireless connections. For example, the NTP protocol exists. Synchronization is also provided within the framework of a Bluetooth connection, in which each object has a free-running 28-bit clock with a frequency of 3.2 kHz, and each object determines its offset to a central clock and regularly corrects it. Here, synchronization with an accuracy of approximately 125 ns is achieved. 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, for example, to save energy by having one object only receive during specific time slots known to the other object, so that it can transmit at the corresponding times. Clock synchronization is still possible, at least in the event of relatively strong one-sided interference on the radio channel, although such interference makes known distance measurements impossible, very inaccurate, or very time-consuming. However, a distinction must be made between the accuracy of time synchronization and synchronization to a clock pulse of a received signal at the signal receiver. Here, there is no synchronization of two clocks on two objects; rather, the receiving object is set so that it is synchronized with the incoming signal. The signal propagation time is not important, since it does not matter when the signal was sent and / or how long it took to transmit.

[0030] It is particularly advantageous if the at least one second and third object are or will be time and / or clock synchronized to 10 ns or better, especially in the range between 10 ns and 100 ps. This increases the accuracy of the method.

[0031] Particularly advantageously, the at least one second and the first and / or the first and the at least one third object are or will be time- and / or clock-synchronized, in particular to within 10 ns or better, in particular in the range between 10 ns and 100 ps. This increases the accuracy of the method.

[0032] The difference in drift between the timers of the first and at least one second object, or of the at least one second and at least one third object, can also be determined and used for correction. Numerous methods for this are known from the prior art.

[0033] 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 therefrom, which is used to determine the distance between the first and second objects. 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 the distance is determined using this matrix and, for example, MUSIC, CAPON, comparison with, distance calculation to, and / or projection onto radiation and / or reception characteristics. In particular, at least one complex matrix, in particular an autocorrelation matrix, of first object signals received at a second object and / or at least one matrix, in particular an autocorrelation matrix, of third object signals received at a second object is formed.Advantageously, the distance calculation is carried out by means of eigenvalue or eigenvector determination of the at least one matrix and / or Fourier transformation of the complex values.

[0034] The phase value is determined in particular alternatively by calculating a change in the phase shift normalized to a frequency spacing for a large number of pairs of signals with adjacent frequencies, i.e. approximately calculating the derivative of the phase shift at one of the frequencies of the pair and using the values ​​collected in this way to determine the phase of the complex number at the respective frequency (the value corresponding to the value proportional to the amplitude), in particular by approximate integration over the frequency. In this case, the integration does not have to start at f = 0 Hz, but can and preferably is used an offset common to all complex numbers, in particular the lowest frequency of the, in particular selected, signals. In particular, the phase value is determined from the signal propagation time or signal round trip time.

[0035] In particular, the normalized phase shift change (dPhase shift (f 1 ,f2)) is obtained using the formula: dPhase shift (f 1 ,f2) = a * RTT(f3) * dFrequency(f 1 ,f2) or dPhase shift (f 1 ,f2) = b * STT(f3) * dFrequency(f 1 ,f2) where dFrequency(f 1 ,f2) is the difference between the frequencies f1 and f2, RTT(f3) is the double 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 is equal to Pi and b is two Pi. Phase shift is a phase shift during transmission at the frequency from one object to another and back, which occurs due to distance.It can be approximately equated to twice the phase shift that occurs when transmitting frequency from one object to another due to distance.

[0036] Frequencies are considered to be similar in particular if they differ from each other by less than 17 MHz, in particular less than 10 MHz, in particular less than 2 MHz, and / or less than 5%, in particular less than 2%, of the lower frequency.

[0037] The complex value Z for a frequency is then determined in particular by:

[0038] Amount(Z(f)) = (b* Amplitude(f) + offset)

[0039] Argument(Z(f)) = Sum(dPhaseshift(f(n + 1 ),fn)) over fn from fO to f(n + 1 ) = f.

[0040] The changes in the phase shift are therefore summed up from the lowest frequency up to the frequency in question for which the complex number is to be determined. The lowest frequency is approximately the same, in particular identical, for all complex numbers. In addition, the phase shift changes are always to be summed up for successive frequency pairs where the higher frequency is approximately the same, in particular identical, to the lower frequency of the next pair, i.e. in particular dphaseshift(f1,f0) + dphaseshift(f2,f1) + dphaseshift(f3,f2) + .... + dphaseshift(f,fn) with f = f(n + 1). f0 is approximately the same, in particular the same, for all complex numbers of a vector and / or a matrix. Here, b and offset are constants, and in particular, b is equal to 1 and offset is 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, power can also be used.

[0041] In particular, a matrix, in particular an autocorrelation matrix, is formed from a plurality of complex numbers. This is done, in particular, 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. Using this matrix, the distance is determined, for example, using known methods such as MUSIC, CAPON, comparison with, distance calculation to, and / or projection onto radiation and / or reception characteristics. Advantageously, the distance calculation is performed by determining the eigenvalues ​​or eigenvectors of the at least one matrix and / or by Fourier transformation of the complex values.

[0042] Such approaches are particularly advantageous in multipath signal propagation to achieve reliable determination.

[0043] In certain embodiments, it may be advantageous to arrange the at least one second and third object in a fixed relative spatial position and orientation, for example, when the distance measurement is performed for access control purposes. This simplifies the calculation and increases reliability.

[0044] Advantageously, data is 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.

[0045] The objects are advantageously parts of a data transmission system, in particular a Bluetooth, WLAN, or mobile radio data transmission system. Preferably, the first object and / or third object signals are signals of the data transmission system and / or a data transmission standard, for example, a mobile radio standard, WLAN, or Bluetooth, which are used for data transmission in accordance with the data transmission standard.

[0046] Advantageously, the first object and / or third object signals are transmitted via a plurality of antenna paths, in particular with a plurality of antennas, in particular one after the other, at the transmitting object and / or received with a plurality of antennas at the receiving object.

[0047] Preferably, the first object is an authorization means, such as a key fob or mobile phone. Advantageously, the second and third objects are part of an arrangement to which access is sought and / or granted using the authorization means, wherein the arrangement is, in particular, a building, a motor vehicle, a barrier, a vending machine, and / or a computer.

[0048] It is preferred that the third object receives the first object signals and provides information about the received first object signals, which is used in calculating the distance, and / or that the first object receives the third object signals and provides information about the received third object signals, which is used in calculating the distance. This is particularly advantageous if the time of transmission and / or the phase position during transmission would otherwise be unknown in the system.

[0049] Particularly advantageously, the at least one second object is passive and / or the at least one second object itself does not transmit any signals or does not transmit any signals used for distance calculation, and / or the at least one second object itself does not transmit any signals within the scope of the method or does not transmit any signals used for distance calculation. This allows the duration of the method to be shortened, and the security by determining the distance between the first and at least one second object can be concealed and thus made more secure.

[0050] Preferably, the method is designed such that at least one of the transmitting objects (first and / or at least one third object) switches 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 and / or corrected in the distance determination, and / or at least one of the objects determines at least one phase correction information item from signals of one of the other objects, which is used in the distance calculation,In particular, the first object alternates phase-coherently between at least two of the first-object frequencies of the first-object signals, and / or the third object alternates 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, and wherein the at least one piece of phase correction information is used in the distance calculation. Such a configuration, in which further information about the phase position is available at the transmitting object, allows the method to be made more precise, more robust, and the calculation simpler.

[0051] In particular, the first, second, and / or third object also switch phase-coherently for reception. They also measure the phase shift during the frequency change, and this phase shift is corrected during the calculation.

[0052] Advantageously, not only the transmitting object switches phase-coherently but also the receiving object; in particular, a PLL is switched phase-coherently in each object.

[0053] Particularly advantageously, the timing and / or timing of the emission of the third-object and / or first-object signals is predetermined and / or is / are known to the second object and / or is / are taken into account in the distance calculation. This allows for a more precise determination and simpler calculation.

[0054] In a preferred embodiment, the method includes synchronizing the times and / or clock cycles in the at least one second and third object, in particular wirelessly or wired. Preferably, at least one time and / or clock synchronization and / or correction is carried out between the at least one second and third object before, after and / or during implementation of the method. However, the synchronization can also be provided or brought about by other methods. In particular, the differences in the times and / or clock cycles between at least one second and third object are known and / or synchronous. This increases the accuracy of the method. Preferably, 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 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 synchronizing the times and / or clock cycles between the second and first objects, in particular wirelessly. Preferably, at least one time and / or clock synchronization and / or correction is carried out between the first and third objects before, after and / or during the method. However, the synchronization can also be provided or brought about by other methods. In particular, the differences in the times and / or clock cycles between the second and third objects are known and / or synchronous; the comparison can in particular also be carried out cable-based. This increases the accuracy of the method. Preferably, a drift of the clocks of the first and / or third objects or a difference in the drift of the clocks of the second and third objects is also determined and taken into account when determining the distance. This further increases the accuracy of the method.Methods for synchronization and / or for determining time and / or clock differences and / or drift are widely known from the prior art.

[0055] Time differences and / or drift can also be determined indirectly in a triangular relationship: For example, if 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. Preferably, the second and / or at least one third object determines its time and its time drift relative to the first object.

[0056] In a preferred embodiment, the method includes synchronizing the times and / or clocks in the first and third objects, in particular wirelessly. Preferably, at least one time and / or clock synchronization and / or correction is performed between the first and third objects before, after, and / or during the method. This increases the accuracy of the method because it also allows drift to be determined and taken into account. Preferably, a drift of the clocks of the first and / or third objects or a difference in the drift of the clocks of the first and third objects is also determined and taken into account when determining the distance. This further increases the accuracy of the method.

[0057] Particularly advantageously, the distance between the at least one second object and the first object is determined without determining the distance between the first and third objects, 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 objects. This increases the speed and accuracy of the method.

[0058] Particularly advantageously, the method is carried out with a plurality, in particular with a common plurality greater than one, in particular greater than two, in particular greater than four, of second objects and common first and in particular common second and third objects, wherein the calculated distances, in particular between the first and the respective plurality of second objects, are preferably used to map and / or determine the position of the first object. By using a plurality of second and / or third objects, in particular those arranged spatially apart from one another, reliability and accuracy can be increased and location, for example by means of triangulation, is possible.

[0059] The method is preferably performed multiple times, whereby the at least one second and at least one third object can also swap roles, but the first object remains common and / or constant for all implementations. For example, in a plurality of objects, a changing portion of the plurality can always be second objects and another portion can be third objects.

[0060] Preferably, the plurality of second objects have a fixed position and / or orientation relative to one another, which is known in particular and / or determined by radio location. This enables, for example, simple triangulation to locate the first object.

[0061] The method is advantageously carried out using a system and / or access system according to the invention. The system or access system is advantageously configured to implement one or more advantageous embodiments of the method and, in particular, has a correspondingly configured control system for this purpose.

[0062] Advantageously, the signal bandwidth never exceeds 50 MHz, especially 25 MHz. This saves energy, avoids interference with other processes, and allows for the use of simpler components compared to broadband methods.

[0063] Advantageously, the signals are transmitted via a plurality of antenna paths, in particular with a plurality of antennas, in particular one after the other, at the transmitting object and / or received with a plurality of antennas at the receiving object.

[0064] Preferably, the first and / or third object transmits the signals on several frequencies one after the other and / or consecutively, in particular directly one after the other and / or the first and third object transmit alternately one after the other.

[0065] The distance is calculated as follows:

[0066] The phases / amplitudes measured at the second object from the first object, depending on the carrier frequency, are corrected for the expected / calculated error resulting from the known time shift between the objects and the time drift of the two system clocks. These values ​​can then be evaluated, for example, using an FFT. Vectors can also be constructed (e.g., for different antenna paths) from which an autocorrelation matrix (ACM) is generated. Distances can be searched for in this ACM using high-resolution methods such as MUSIC or CAPON.

[0067] Under the premise of phase-coherent frequency switching for the first and third object, one can work as follows, otherwise the calculation becomes somewhat more complicated:

[0068] In particular, after determining the exact time differences and time drift between the third and first object and between the second and third object, the sufficiently accurate time difference between the first and second object can be calculated at any time for a limited period of time (e.g. 100ms).

[0069] On the second object, the IQ values ​​or phases / amplitudes are determined on at least 2 (up to n) frequencies (F0 to Fn) of a signal from the first object.

[0070] At the second object, in particular the IQ values ​​or phases / amplitudes are determined on at least 2 (up to n) frequencies (F0' to Fn') of a signal of the at least one third object.

[0071] For example, if the switching times between the frequencies F0 to Fn' and / or F0 to Fn and / or their temporal relationship are known, the switching times between the frequencies F0' to Fn' can be determined for an object, for example, the first or second object, based on time synchronization with at least the third object. If the reception times of the switching are then measured, propagation times, in particular pulse propagation times (ToF), can be directly determined.

[0072] By switching with or without a known phase shift, the frequency shift caused by the frequency change can also be measured directly. This applies to both the signals from the first and the at least one third object, which are received by the second, but also partially by the first or third object. This alone allows the second object to determine the distance to both the first and the at least one third object, for example, by means of

[0073] Distance = dPhase shift (f 1 ,f2) / 2Pi / dFrequency(f 1 ,f2) * c with c equal to the speed of light and dPhase shift (f 1 ,f2) equal to the measured change in phase shift at the receiver due to the frequency change from f1 to f2, corrected for the phase jump at the transmitter when switching from f1 to f2 and dFrequency(f 1 ,f2) equal to the difference between the frequencies f1 and f2

[0074] The change in phase shift is particularly caused by the change in frequency at approximately the same distance. The phase shift is caused by the distance. The change in phase shift caused by the change in frequency is caused by the fact that, especially at approximately the same distance for both measurements, different numbers of wave trains fit the distance and therefore the phase shift, which is caused by the distance, is different between the frequencies. This change in phase shift due to the frequency is the phase change caused by the change in frequency. This causes problems when measuring because the phase measurement is always dependent on a reference and an often undefined phase jump can occur when switching to transmit the different frequencies.Thus, for transmission, and in particular also for reception, switching is preferably phase-coherent, i.e. with a phase jump of zero. However, it is also sufficient to determine or know the phase jump. The phase change caused by the frequency change can then be determined using the measured phase change corrected by the phase jump when switching the transmitter and the phase jump when switching at the receiver to measure the measured phase change. If the switching times of the first and the at least one third object have a derivable, recognizable, communicated and / or predetermined temporal relationship, which is preferred, further information can be obtained to improve the measurement.If, for example, the switching times between frequencies of the at least one third object are known to the at least second object and / or these are 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 one third object, which leads to a further improvement.

[0075] If, for example, the switching times between frequencies of the first object are known to the at least second object and / or these are made known to it, which is preferred, it can directly determine the time of flight (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 directly determined based solely on the frequency switching of the radiation of the signals from the first object with or without a known phase shift, for example, as explained above using: Distance = dPhase shift (f1,f2) / 2Pi / dFrequency (f1,f2) * c

[0076] To increase accuracy (except for FO, for example), the measured phase shifts (Ph) can be adjusted for time differences and / or frequency differences (including drift). It is sufficient to approximately account for the drift. Determining this is well known in the art and can be done, for example, by determining the time differences at different times, for example, before and after the signal exchange for distance measurement.

[0077] The time at which the clocks are synchronized can also be different, for example, it might not coincide with the transmission time. In this case, the calculation can be adjusted accordingly. To resolve multipathing, for example, the individual phases with their corresponding measured amplitudes can be input as complex values, for example, into a Fourier transform, or a spectral estimate can be performed in matrices using super-resolution methods such as MUSIC or CAPON.

[0078] Fig. 1 shows, purely by way of example and only schematically and not restrictively, a car with several second objects (2) and a third object (3) arranged therein, as well as a first object (1) designed as a key fob. When implementing the method, the distances between each first object and each second object are determined. If the time synchronization between the third and second objects is carried out via a cable, for example, the second objects can be designed without a transmitter and thus be passive or non-locatable.

Claims

23 Claims 1. A method for determining, in particular directly, the distance 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 at least one second object receives the first-object signals of the first object and the distance between the first and the at least one second object is determined based thereon, wherein the at least one second and at least one third object are clock- and / or time-synchronized, wherein the at least one second object does not transmit any signals except for time synchronization and / or the at least one second object does not transmit any signals used for distance determination and / or is passive apart from time synchronization, wherein in particular the at least one second object does not transmit any radio signals, characterized in thatthat the at least one third object transmits at least one third-object signal and the third object switches in phase coherence between at least two third-object frequencies and / or switches in such a way that the phase difference is known at the first and / or second object and / or the phase difference is made known to the first and / or second object and / or that the first object switches in phase coherence between at least two of the first-object frequencies of the at least one first-object signal and / or switches in such a way that the phase difference is known at the second and / or third object and / or the phase difference is made known to the second and / or third object.

2. The method according to claim 1, wherein the at least one third object (3) sends at least one third-object signal, in particular several third-object signals, and the at least one second object receives the third-object signals of the at least one third object, and this occurs during the Determination of the distance between the first and the at least one second object, taking into account the distance, and wherein the at least one third-object signal has different third-object frequencies. Method according to one of the preceding claims, wherein the first object transmits at least one first-object signal before or after the at least one third-object signal, in particular each third object, wherein in particular the first object performs a signal exchange, in particular two-way frequency hopping, with the at least one, in particular each, third object, in which in particular each of the two objects involved in the signal exchange transmits at least one signal, each having different frequencies, in particular frequency hopping, in a defined and / or predetermined sequence.transmits and wherein, 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 switches in phase coherently between the different frequencies and / or switches in such a way that the phase difference during the frequency change, in particular at the second, first and / or at least one third object, is known and / or the phase difference during the frequency change, in particular at the second, first and / or third object, is made known. Method according to one of the preceding claims, wherein, for first- and / or third-object signals received at the at least one second object, a value proportional to its amplitude and a phase value are determined for each, in particular for each received frequency and / or first- and / or third-object frequency and / or each frequency of the frequency hopping, and in particular a complex number is determined therefrom in each case.which is used for determining the distance between the first and the second object, in particular by creating a vector from the complex numbers and / or an autocorrelation matrix, especially for each received first, second, and / or third object signal. A method according to any one of the preceding claims, wherein the second and at least one third object are arranged in a fixed relative spatial position and / or orientation. A method according to any one of the preceding claims, wherein the first object is an authorization means, such as a key fob or mobile phone, and wherein, in particular, the second and third objects are part of an arrangement to which access is sought and / or granted by means of the authorization means, wherein the arrangement is, in particular, a building, a motor vehicle or barrier, a vending machine, and / or a computer.Method according to one of the preceding claims, wherein the third object receives the at least one first object signal and / or provides information about the at least one received first object signal and uses this information in calculating the distance and / or wherein the first object receives the third object signals and provides information about the received third object signals and / or uses this information in calculating the distance.A method according to any one of the preceding claims, wherein at least one of the objects determines at least one phase correction piece of information from a received first- or third-object signal, which is used in the distance calculation, in particular the third object determines at least one phase correction piece of information from the first-object signals and / or the first object determines at least one phase correction piece of information from the third-object signals and / or the second object determines at least one phase correction piece of information from the first- and / or third-object signals, and wherein the at least one phase correction piece of information is used in the distance calculation. A method according to any one of the preceding claims, wherein the times and / or the schedule of the emission of the at least one third-object and / or the first-object signal and / or their characteristics are predetermined. 26 is / are and / or is / are known to the second object and / or is / are taken into account in the distance calculation. . Method according to one of the preceding claims, wherein the method includes the synchronization of the times and / or clock cycles in the second and third object, wirelessly or via cable.

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 determined independently of the distance between the first and third object. 2.A method according to any one of the preceding claims, wherein the method according to any one of the preceding claims is carried out with a plurality of second objects and with exactly one common first object and, in particular, at least one common third object, and wherein the calculated distances, in particular between the first and the plurality of second objects, are used to perform a mapping and / or position determination of the first object; 3. A method according to claim 12, wherein, in particular, the plurality of second and / or third objects have a fixed position and / or orientation relative to each other.System comprising at least one first, one second, in particular a plurality greater than one, in particular greater than two, second objects (1, 2), and at least one third object (3), wherein the first object (1) is configured to emit at least one first-object signal with different frequencies and wherein all objects are configured to receive signals, wherein the at least one second and the third object are configured to perform clock and / or time synchronization and wherein the system comprises at least one controller which. 27 is configured to carry out the methods according to the invention and thereby determine at least one distance between at least one second object and the first object, characterized in that the third object is configured to switch between at least two third-object frequencies in phase coherence and / or to switch in such a way that the phase difference is known at the first and / or second object and / or the phase difference is communicated to the first and / or second object and / or that the first object is configured to switch between at least two of the first-object frequencies of the at least one first-object signal in phase coherence and / or to switch in such a way that the phase difference is known at the second and / or third object and / or the phase difference is communicated to the second and / or third object. Access system comprising at least one access restriction device, wherein the access restriction device is configuredto grant and / or deny access, in particular by means of an access restriction device, further comprising at least one first, one second, in particular a plurality greater than one, in particular greater than two, second objects (1, 2), and at least one third object (3), wherein the first object is configured to emit at least one first-object signal with different frequencies, and wherein all objects are configured to receive signals, wherein the at least one second and the third object are configured to perform clock and / or time synchronization, and wherein the third object is configured to switch between at least two of the third-object frequencies, and / or wherein the first object is configured to switch between at least two of the first-object frequencies of the first-object signals, and wherein the system comprises at least one control unit configured tothat the inventive method is carried out and thereby at least one distance between at least one second object and the first object is determined, wherein the, 28 The access restriction device is configured to not 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 lies within a predetermined distance range and / or the specific position of the first object is within a first and / or outside a second predetermined range, and / or to deny access and / or not 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 lies outside the first and / or within the second predetermined range, characterized in that the third object is configuredto switch in phase coherence between the at least two third-object frequencies and / or to switch in such a way that the phase difference at the first and / or second object is known and / or the phase difference is made known to the first and / or second object and / or that the first object is configured to switch in phase coherence between the at least two first-object frequencies of the at least one first-object signal and / or to switch in such a way that the phase difference at the second and / or third object is known and / or the phase difference is made known to the second and / or third object.