Phase difference correction method and ultra-wideband system

Abstract

Phase difference correction methods for correcting phase drift and / or phase offset include: Emitting a first signal (21) by a first transceiver (10), Receiving the first signal (21) by a second transceiver (20), Determining a first phase difference (dP1) in the second transceiver (20) between a first internal signal (31) of the second transceiver (20) and the received first signal (21), Emitting a second signal (22) by the second transceiver (20) after a defined first delay time window, wherein the second signal (22) includes information about the determined first phase difference (dP1) and / or information for determining the first phase difference, Receiving the second signal (22) by the first transceiver (10), Determining a second phase difference (dP2) in the first transceiver (10) between a second internal signal (32) of the first transceiver (10) and the received second signal (22), Summing the first determined phase difference (dP1) and the second determined phase difference (dP2), thereby correcting a phase shift between the two transceivers, Emitting a third signal (23) by the second transceiver (20) after a defined second delay time window, in particular wherein the third signal (23) includes information about the second signal (22); Receiving the third signal (23) by the first transceiver (10); Determining a third phase difference (dP3) between the third signal (23) received by the first transceiver (10) and the second internal signal (32) in the first transceiver (10), where the third phase difference dP3 determines a phase drift of the second transceiver (20) with respect to the first transceiver (10), such that a phase difference correction term dPc is given by dPc = dP 1 + dP 2 + (dP 2 − dP 3), is given, in particular where the phase difference correction term dPc is a signal phase dPc.

Description

[0001] The present invention relates to a phase difference correction method and an ultra-wideband system suitable for performing the phase difference correction method, as well as corresponding computer program code. In particular, a method for phase difference drift and offset correction is disclosed, which is suitable for ultra-wideband (UWB) localization.

[0002] US 2021 / 0239826A1 relates to a method for determining a carrier phase shift between a first transceiver and a second transceiver, wherein the method is designed to save energy by disabling the local oscillator between transmit and receive signals.

[0003] Information about the phase of a carrier wave is frequently used in navigation to improve or provide distance information. In satellite navigation, the measurement of the carrier wave phase is used in combination with pseudo-distance. The same principle can also be used for UWB localization systems, provided that it is taken into account that the clocks used to generate the transmitted wave are inaccurate and therefore require drift and offset correction. The general approach to overcoming this problem is to use wired links between stations to distribute the clock signal. As a result, the phase drift is the same for each station. In [2], it is shown how the phase difference between two receiving stations sharing the same clock signal can be obtained. This procedure can also be reversed by using two transmitting stations [3].In both cases, it is possible to use only one station instead of two. However, when using only one station, multiple antennas must be present in the station.

[0004] Phase measurement according to one of the prior art methods described above is only applicable to systems where the clock signal is used jointly or where a station or transceiver has several antennas available for transmitting or receiving the signal.

[0005] Fig. Figure 1 schematically shows an ultra-wideband system 100' suitable for TOA measurement. A first transceiver 10' transmits a first signal 21', which is received by a second transceiver 20'. For this purpose, the first and second transceivers 10' and 20' each comprise a transmitter and a receiver. The first transceiver 10' and the second transceiver 20' can be configured to create timestamps of the received and transmitted first and second signals 21' and 22' and to transmit and receive these timestamps, respectively. A timestamp difference dT, in combination with the known propagation speed c0 (speed of light), makes it possible to determine an unknown distance 25' using d = c0 * dT. In practice, the first transceiver 10' and the second transceiver 20' are not synchronized. To solve this problem, a technique called two-way ranging can be used.To implement two-way distance measurement, the second transceiver 20' responds to the first transceiver 10' by transmitting the second signal 22'. The second signal 22' contains information about the processing time between the received and the transmitted time. This procedure is explained in more detail in [4]. In addition to the clock error, UWB measurements are also subject to other interfering factors such as signal strength dependencies [5] or warm-up errors [6]. In this respect, this has so far been part of the . Fig. 1 described process according to the state of the art.

[0006] With regard to the described method, which is state of the art, it should be noted that even with all correction methods used, it is not possible for the timestamp-based position estimation to obtain a position estimate better than several centimeters.

[0007] An object of the present invention is to provide an improved phase difference correction method and thus an improved ultra-wideband system, in particular without the need for multiple antennas or a clock signal from a quartz clock. It is an object to provide a method and an ultra-wideband system for improved ultra-wideband (UWB) localization, with which a position estimate has an accuracy of less than 5 cm.

[0008] This is achieved by the subject matter of the independent claims of the present application. Further embodiments of the invention are defined by the subject matter of the dependent claims of the present application.

[0009] Using the phase difference correction method proposed herein, and the further phase correction method, a positional accuracy of less than 1 cm, in particular 0.8 mm, can be determined at a frequency of 6.5 GHz. At higher frequencies, position determination becomes even more precise due to the shorter wavelength.

[0010] The core of the present invention is to determine correction terms to correct a phase shift and / or phase drift in the signals, particularly those measured. In particular, the further phase correction method can include passive transceivers for implementation.

[0011] The proposed phase difference correction method for correcting phase drift and / or phase offset begins with the transmission of a first signal by a first transceiver and its reception by a second transceiver. This method can be implemented using time-of-arrival (TOA) measurement techniques. After receiving the first signal, the initial phase difference between the second transceiver's internal signal (i.e., its internal wave) and the received first signal is determined. This initial phase difference is determined in the second transceiver. The phase difference is then calculated in the receiving transceiver. Correction calculations can be performed in either transceiver.The phase difference correction method in each case further comprises the transmission of a second signal by the second transceiver after a defined first delay time window has elapsed, wherein the second signal contains information about the already determined first phase difference and / or about the determination of the first phase difference. Determining the phase difference comprises measuring signals, i.e., receiving signals by a corresponding transceiver. Furthermore, determining the phase difference comprises evaluating the measured signals by calculating the phase difference. The calculation of the phase difference can be performed by any transceiver, a server, or the like. Therefore, in the phase difference correction method according to the invention, it is conceivable that the first phase difference is determined in the second transceiver.In this case, the second signal sent from the second transceiver to the first transceiver can include information about the already determined first phase difference. Furthermore, in the phase difference correction method according to the invention, it is conceivable that the first phase difference is determined in the first transceiver. In this case, the second signal sent from the second transceiver to the first transceiver can include at least one piece of information that enables the first transceiver to determine the first phase difference. Preferably, the second signal then includes information about the first signal and the internal signal of the second transceiver. It is also conceivable that the first phase difference is determined in both the first and second transceivers. This can reduce errors in the first phase difference.In this case, the second signal, which is sent from the second transceiver to the first transceiver, can include at least one piece of information that enables the first transceiver to determine the first phase difference and the information on the first phase difference already determined in the second transceiver.

[0012] In each case, the second signal includes a signal used to determine a second phase difference in the first transceiver. In other words, a phase difference determination signal comprises the measured signals from which the phase difference can be calculated in any transceiver, server, or cloud environment. The phase difference correction procedure involves the first transceiver receiving the second signal. After receiving the second signal, the first transceiver determines the second phase difference between a second internal signal and the received second signal. Finally, the first determined phase difference and the second determined phase difference are summed, thereby correcting any phase misalignment between the two transceivers.If there were no drift, the resulting phase difference would depend solely on the distance between the first and second transceivers and thus correspond to a signal phase. The first phase difference is preferably determined in the second transceiver. The necessary measurements are always performed in the second transceiver. For example, the first signal 21 is measured in the second transceiver 20, and the second and third signals 22 and 23 are measured in the first transceiver 10. Together, the measured signals 21, 22, and 23 can be used to calculate the corrected phase difference, i.e., the signal phase. Where the calculation takes place is irrelevant; it can be performed in the first and / or the second transceiver. The only important thing is that the measured signals 21, 22, and 23 are available for calculating the corrected phase difference.

[0013] To receive signals, a transceiver includes at least one antenna. The phase of a received signal is determined by calculating its phase as a function of the complex baseband impulse response of the transmitted signal received by the antenna. When a transceiver receives a signal, it measures the start frame delimiter (SFD), the real part of the signal, and the imaginary part. These measurements are then used to calculate the phase difference between the received signal and an internal signal.

[0014] The following explains some of the terms used in this application in order to define the terms used within the context of this application.

[0015] In the present application, a signal is understood to be an electromagnetic wave, in particular with or without modulated information. The term "signal" can be replaced by the term "wave," since "wave" and "signal" are used synonymously. In the present application, the signals are transmitted and received as digital signals. Of course, an analog signal can also be transcribed into a digital signal. In the present application, the signals are transmitted between transceivers, whereby a transceiver can comprise only one receiver, provided that the receiver is sufficient for carrying out the phase difference correction method according to the invention. When one receiver is sufficient will be explained to those skilled in the art in the following description. As a rule, a transceiver comprises a transmitter and a receiver.

[0016] The term "internal wave" or "internal signal" can be explained as follows: A quartz oscillator clock (crystal clock) drives a PLL (phase-locked loop), which generates a carrier wave. This carrier wave is used not only for transmission but also to demodulate the received signal. A downconverter mixer is used for this purpose. When a signal is received with an antenna, the downconverter uses the internal signal to determine the I / Q data.

[0017] These provide information about the phase difference Φ between the internal signal and the received signal according to Φ=arctan(QI).

[0018] After the I / Q data has been digitized by the analog-to-digital converter (ADC), the baseband processor can generate the impulse response to map the I / Q data to the direct signal.

[0019] The term phase difference refers to the difference between the phase of the received signal and the phase of the internal wave of the quartz clock. This is determined by reading the I / Q data in the channel impulse response. Specifically for the UWB chip, this data must be further processed to determine the phase difference, for example, using a synchronization frame delimiter (SFD). When this application refers to determining the phase difference, it means determining all data necessary for calculating the phase difference, in particular the SFD, real part, and imaginary part of the received signal, which are generated during message reception. It is irrelevant where this data is combined to calculate the actual phase difference. In other words, the phase difference itself can be calculated by any transceiver.

[0020] According to the technical method described herein, several phase differences are calculated between the transceivers to determine the signal phase, which depends solely on the distance between two transceivers. The drift- and offset-corrected phase difference will be referred to here as the signal phase dPc for TOA or dPcc for TDOA.

[0021] Preferably, the phase difference correction method is carried out in a sequence of individual steps as claimed in claim 1. However, it is conceivable that the determination of the first and second phase differences only takes place after the first signal and the second signal have been exchanged between the first and second transceivers.

[0022] Another aspect of the present invention comprises an ultra-wideband system with a first transceiver and a second transceiver, each configured for transmitting and receiving signals and spaced apart from one another, wherein the system is configured to perform a phase difference correction method as described herein. By performing the phase difference correction method, a phase offset between the two transceivers is corrected, whereby the phase difference is a function of the distance between the two transceivers. After correcting the phase difference, the signal phase is thus preserved. The ultra-wideband (UWB) system according to the invention includes transmitter, receiver, or transmit / receive stations, referred to herein as transceivers. The receiving stations, i.e., the transceivers, can preserve the phase difference between the carrier wave, i.e., of the first signal, and / or the second signal and / or a third signal.The internal wave or signal used to determine a phase difference is independent of the signal being sent and / or received. This internal wave has a frequency with a specific accuracy and a phase drift.

[0023] The presented correction method can be used to realize the corrected phase difference, i.e., the signal phase, in the case of distributed UWB stations with clock inaccuracies.

[0024] A further aspect of the present invention comprises another phase difference correction method, particularly for passive transceivers, for correcting phase drift and / or phase offset. Passive transceivers comprise a receiver for receiving signals. The further phase difference correction method comprises, firstly, the transmission of a first signal by a first transceiver and the reception of the first signal by a second and a third transceiver. In contrast to the previously described phase difference correction method, in the further phase difference correction method the first signal is transmitted to and received by two different transceivers, the second and the third. The first to third transceivers can be spaced apart from each other. Furthermore, it is conceivable that the second and third transceivers are implemented in a single transceiver.The further phase difference correction procedure, after the first signal has been received by a second and a third transceiver, involves determining a first phase difference in the second transceiver and a second phase difference in the third transceiver. The first phase difference is determined between a first internal signal of the second transceiver and the received first signal. The second phase difference is determined between a second internal signal of the third transceiver and the received first signal. Furthermore, the further phase difference correction procedure includes transmitting a second signal by the second transceiver after a defined initial delay time window has elapsed. This step is analogous to the phase difference correction procedure already described.After the third transceiver receives the second signal, a third phase difference is determined in the third transceiver between the second internal signal of the third transceiver and the received second signal.

[0025] Furthermore, the additional phase difference correction method includes the transmission of a third signal by the second transceiver. Specifically, after a defined second delay time window, the third signal is transmitted by the second transceiver. The second signal and / or the third signal may contain information about the determined first phase difference and / or the determination of the first phase difference. The explanations already given regarding the phase difference correction method also apply to the additional phase difference correction method and will not be repeated here. The additional phase difference correction method also includes the reception of the third signal by the third transceiver. After receiving the third signal, a fourth phase difference is determined in the third transceiver.The fourth phase difference is determined between the second signal received by the third transceiver and the second internal signal. Finally, a corrected phase difference is determined by subtracting the first and twice the third determined phase differences from the sum of the determined second and fourth phase differences, according to: dPcc=dP2−dP3−dP1−(dP3−dP4)=dP2+dP4−2*dP3−dP1.

[0026] The second phase difference, dP2, is the phase difference between the first received signal and the second internal signal of the third transceiver. The difference between the third and fourth phase differences (dP3-dP4) indicates the drift correction, and the first phase difference, dP1, indicates the offset correction. The term dPcc can be determined using the arrival time difference measurement technique.

[0027] Ideally, the corrected phase difference is zero, meaning that after correcting the phase difference, there is no longer a phase difference, but rather the signal phase.

[0028] Some steps of the further phase difference correction procedure are analogous to those of the phase difference correction procedure. Consequently, the further detailed descriptions of the further phase difference correction procedure are transferable to the further phase difference correction procedure. Further detailed descriptions of individual features are omitted to avoid redundancy. However, it is understood that features described in relation to the phase correction procedure are also transferable to the further phase difference correction procedure in an analogous manner, and vice versa, unless such an analogous transfer is explicitly excluded.

[0029] Another aspect of the present invention comprises an ultra-wideband system with a first transceiver, a second transceiver, and a third transceiver spaced apart from one another, wherein the system is configured to perform a phase difference correction method as described. By performing the phase difference correction method, a phase offset between the two transceivers is corrected. The ultra-wideband (UWB) system according to the invention includes transmitter, receiver, or transmit / receive stations, referred to herein as transceivers. The receiving stations, i.e., the transceivers, can maintain the phase difference between the carrier wave, i.e., of the first signal, and / or the second signal, and / or a third signal, and the internal wave, i.e., of the first internal signal, and / or the second internal signal, and / or a third internal signal.The presented correction method can be used to address the phase difference in the case of distributed UWB stations with clock inaccuracies.

[0030] Another aspect of the present invention comprises computer program code which performs steps of a phase difference correction method as described herein when the computer program code is executed on a program code executable medium.

[0031] Essentially, the correction procedure involves correcting the phase drift and / or phase offset. This can be implemented between two active stations or active transceivers (transmitting and receiving signals) or any number of passive transceivers (receiving only). A passive transceiver is equivalent to a receiver.

[0032] The technical teaching described herein reveals how the phase difference between two or more transceivers, especially UWB transceivers, can be corrected without having to split the clock signal and / or without having to use special antenna arrays. By correcting the phase difference, the signal phase, which is only a function of the distance between the transceivers, can be preserved.

[0033] The phase difference correction method disclosed herein, as well as the further phase correction method, have been verified by real measurements. These measurements have shown, for example, that the corrected phase difference, i.e., the signal phase, can be used to significantly increase the precision and accuracy of UWB localization systems, as can be seen in the following image description.

[0034] Previously, it was only known that positioning in the UWB range could only be determined with an accuracy of several centimeters. However, with the invention disclosed herein, a position is determined with an accuracy of 0.8 mm at a frequency of 6.5 GHz. At higher frequencies, positioning becomes even more precise because the wavelength decreases.

[0035] This represents a technical improvement over the prior art. Phase measurement according to one of the methods described in the introduction is only applicable to systems where the clock signal is shared or where a station has multiple antennas available for transmitting or receiving the signal. The phase difference correction method according to the invention, or the further phase difference correction method, not only makes it possible to solve this problem, but the phase difference correction method, or the further phase difference correction method, can also be used for time-of-arrival (TOA) or time-of-arrival difference (TDOA). Furthermore, active and / or passive transceivers can be used.

[0036] The technical teaching revealed herein is advantageous in fields where high positional accuracy plays an important role, such as augmented reality, robotics, military, etc.

[0037] Furthermore, the meaning of the abbreviations used herein should be explained once again at this point: TOA: Time of Arrival Measurement Technology TDOA: Time Difference of Arrival measurement technique Brief description of the drawings

[0038] The drawings are not necessarily to scale; rather, the emphasis is generally placed on illustrating the principles of the invention. The following description details various embodiments of the invention with reference to the following drawings. These show: Fig. 1 schematically an ultra-wideband system with a TOA between two UWB transceivers; Fig. 2 schematically illustrates the process of a phase difference correction method according to the invention in an ultra-wideband system; Fig. 3 Phase difference correction for TOA; Fig. 4 a phase difference dP1 between two transceivers without corrections; Fig. 5 a sum of the phase difference dP1 and dP2; Fig. 6 a final corrected TOA signal phase obtained according to the invention; Fig. 7. A changed signal phase due to TOA spacing changes; Fig. 8 the calculated distance based on the signal phase; Fig. 9 a possible solution S based on four different frequencies F1-F4; Fig. 10 Results of the accuracy update due to frequency changes; Fig. 11 schematically an ultra-wideband system with a TDOA between three UWB transceivers; Fig. 12 schematically illustrates a further phase difference correction method according to the invention in an ultra-wideband system; Fig. 13 a phase difference correction for TDOA obtained according to the invention; Fig. 14 a changed phase due to TDOA position changes; and Fig. 15 a sketch to explain the term “internal signal”. Detailed description of the embodiments

[0039] Identical or equivalent elements, or elements with the same or equivalent functionality, are designated by the same or equivalent reference numbers in the following description, even if they appear in different figures. For example, the term "signal" is used synonymously with "electromagnetic wave" and vice versa. The technical teaching described herein is presented in conjunction with the Fig. Items 1 to 12 are described below.

[0040] The following description includes a large number of details to provide a comprehensive explanation of embodiments of the present invention. However, it will be obvious to a person skilled in the art that embodiments of the present invention can also be designed without these specific details. In other cases, known structures and devices are shown in block diagrams or schematic representations rather than in detail to avoid obscuring embodiments of the present teaching. Furthermore, features of the various embodiments described below can be combined with one another unless expressly stated otherwise.

[0041] As mentioned in the introduction, phase measurement has so far only been applicable to systems where the clock signal is shared or where a transceiver has multiple antennas available for sending or receiving the signal.

[0042] The phase difference correction methods according to the invention solve these problems and can be applied both to a method in which the arrival time (TOA) is relevant and to a method in which the arrival time difference (TDOA) is relevant. This is explained below with reference to preferred embodiments. In summary, the Fig. Sections 2 to 10 and 12 to 14 explain the preferred embodiments in detail. The phase correction method according to the invention can be used in particular in connection with the time of arrival (TOA):

[0043] With regard to the prior art method described in the introduction, it should be noted again that even with all correction methods employed, it is not possible for timestamp-based position estimation to achieve a position estimate better than several centimeters. This limitation can be overcome by using the phase difference correction method according to the invention.

[0044] The phase difference correction method according to the invention for performing a phase difference correction with arrival time measurements is described in a flowchart in Fig. 2 and schematically as a realization in an ultra-wideband system 100 in Fig. 3 shown. Fig. 2 and Fig. Therefore, the three are described together.

[0045] In a first step 200 of the phase difference correction procedure for correcting a phase drift and / or a phase shift, a first signal 21 is transmitted by a first transceiver 10. The first and the second transceivers 10, 20 are separated by a distance 25. In a subsequent step 210, the first signal 21 is received by a second transceiver 20. The first and the second transceivers each comprise a transmitter 11 and a receiver 12. The first and the second transceivers each comprise a control device 13 for processing the transmitted and received signals 21, 22. As already disclosed in the general part of the description, the individual transceivers, i.e., the first and the second transceivers, are configured to measure parameters such as the SFD, the real part, and the imaginary part of the received signal 21, 22, 23 upon receiving a signal.The phase difference can then be calculated from the measured values, i.e., the measured signals 21, 22, 23, at any transceiver 10, 20, i.e., the first and / or the second transceiver 10, 20. The phase difference calculation can also be performed on a server. For this, only the measured signals 21, 22, 23 need to be provided.

[0046] After the first signal 21 is received by the second transceiver 20, a first phase difference dP1 is determined in the second transceiver 20 between a first internal signal 31 of the second transceiver 20 and the received first signal 21 in a step 220.

[0047] To explain the term "internal wave" or internal signal 31, 32, see below. Fig. 15 referenced. Fig. Figure 15 schematically shows that a 500 quartz oscillator clock drives a 510 PLL (phase-locked loop), which generates a carrier wave. This carrier wave is used not only for transmission but also to demodulate the received signal (see Figure 15). Fig. 15) A down converter mixer is used for this purpose. When a signal is received with an antenna 520, the down converter 530 determines the I / Q data. This provides information about the phase difference Φ between the internal signal and the received signal according to Φ=arctan(QI). After the I / Q data has been digitized by the Analog-to-Digital Converter (ADC) 540, the Baseband Processor 550 can form the impulse response to map the I / Q data to the direct signal.

[0048] In step 230, a second signal 22 is transmitted by the second transceiver 20 after a defined initial delay time window V1 has elapsed. This second signal 22 contains information about the determined first phase difference dP1 and / or information for determining the first phase difference. Information for determining the first phase difference includes the measured values ​​required to calculate the phase difference. The calculated phase differences dP1, dP2, dP3, and other information can be accessible to all transceivers because all active transceivers can send and receive information and therefore can also pass it on to a passive transceiver. It should be noted that steps 220 and 230 can be executed sequentially, i.e., first step 220, then step 230. Likewise, step 230 can be executed first, followed by step 220.In this case, the second signal contains information for determining the first phase difference, which would then be determined in the first transceiver 10 and not in the second transceiver 20. The first delay window V1 specifies a time interval from the reception of the first signal 21 until the transmission of the second signal 22. The first delay window V1 can span a time interval of a few milliseconds, in particular less than two milliseconds. After a defined delay time V1, the second transceiver 20 can send a response, i.e., the second signal 22, back to the first transceiver. The delay window V1 is viewed in relation to the time interval at which the first signal 21 is received.

[0049] In step 240, the first transceiver 10 receives the second signal 22. The second signal 22 can be the first internal signal 31, including any possible drift. Fig. For example, in Figure 3, the first internal signal 31 is represented as signal B, while the second signal 22 is represented as signal B1.

[0050] After the first transceiver 10 receives the second signal, a second phase difference dP2 is determined in the first transceiver 10 in step 250. The second phase difference dP2 is determined between a second internal signal 32 of the first transceiver 10 and the received second signal 22. The second internal signal 32 can, for example, correspond to the first signal 22, which is in Fig. 3 is also referred to as signal A. The second internal signal 32 can also differ from the first signal 21. Different in the sense that it is still the same second internal signal 32, but which, due to the elapsed time window, exhibits a different phase compared to the first signal 21. Furthermore, the received first signal 21 may exhibit a phase drift, which can be corrected with a third signal 23.

[0051] In a subsequent step 260, the first determined phase difference dP1 and the second determined phase difference dP2 are summed, thereby correcting any phase shift between the two transceivers. With regard to the disclosure of the Fig. 3. It should be noted that to correct a phase shift between the first and the second signal 21, 22, i.e. between the two transceivers, only a first signal 21, a second signal 22, a first internal signal 31 and a second internal signal 32 are required.

[0052] The phase difference dP1 is in Fig. 4 shown. In Fig. Figure 4 shows the determined first phase difference as a function of the number of measurements. It can be observed that the phase difference dP1 changes rapidly from one measurement to the next.

[0053] The first transceiver 10 serves as the initialization transceiver by transmitting the first signal 21. Both the first transceiver 10 and the second transceiver 20 perform the same procedural steps, namely determining a phase difference dP1, dP2 between the received signal 21, 22 and the internal signal 31, 32, cf. Fig. 3. The sum of the first phase difference dP1 and the second phase difference dP2 reduces, in particular eliminates, the phase shift between the two transceivers 10, 20 as described in Fig. 5 is shown. Fig. Figure 5 shows the sum of the first phase difference dP1 and the second phase difference dP2 as a function of the number of measurements. Both in Fig. 4 as well as in Fig. In 5, a total of 50 measurements were carried out. In contrast to Fig. 4 shows Fig. 5. A periodic signal, i.e., the sum of dP1 + dP2, behaves periodically, especially within an apparent envelope. An apparent envelope occurs when one transceiver exhibits a higher clock rate than the other. Thus, one transceiver repeatedly overtakes the other.

[0054] If the second signal is 22, in Fig. 3, also referred to as signal B1, immediately after receiving the first signal 21, in Fig. If signal 3, also referred to as signal A1, were transmitted, further drift correction, as described below, would not be necessary. "Immediately after receiving the first signal 21" means, in this case, after one millisecond or less.

[0055] Short processing times can, however, lead to phase drift. Accordingly, after a known second delay time 2, a second delay window V2, a third signal 23 is sent by the second transceiver 20. The term "short processing time" depends on the drift of the signal involved at a signal frequency. Certainly, a short processing time can refer to a processing time > 1 ns.

[0056] Preferably, a ratio between the second delay time window V2 and the first delay time window V1 is known; in particular, and in the simplest case, assuming the same start time, V2 = 2 * V1 (see...). Fig. 3 and Fig. 13) It is assumed that the clock drift does not change significantly during the reception of the first signal 21 until the transmission of the second signal 22. Furthermore, preferably, the first delay time window V1 corresponds to a time interval between the reception of the first signal 21 by the second transceiver 20 and the transmission of the second signal 22 by the second transceiver 20; in particular, the first delay time window V1 is less than or equal to 1 ms. Furthermore, preferably, the second delay time window V2 corresponds to a time interval between the reception of the first signal 21 by the second transceiver 20 and the transmission of the third signal 23 by the second transceiver 20, which is in particular less than or equal to 2 ms. Preferably, the following applies to the second delay time window V2: V2=2*V1.

[0057] In this case, phase drift can be corrected using a phase difference correction term, as explained below.

[0058] A phase drift of the second transceiver 20 with respect to the first transceiver 10 is caused by the phase difference between the second signal 22, in Fig. 3, also referred to as signal B1, and a third signal 23, transmitted in particular by the second transceiver after the second time delay window V2 has elapsed, in Fig. 3, also referred to as signal B2, is obtained. This leads to a final TOA phase difference correction term: dP1 = dP1 + dP2 + (dP2 - dP3) = dP1 + 2 * dP2 - dP3, where dP3 is a third phase difference. The third phase difference dP3 is the difference between the internal wave and signal B2.

[0059] Consequently, the phase difference correction method preferably comprises transmitting the third signal 23 by the second transceiver 20 after the defined second delay time window V2 has elapsed. In particular, the third signal 23 includes information about the second signal 22, such as the first phase difference dP1. Furthermore, the phase difference correction method preferably comprises receiving the third signal 23 by the first transceiver 10 and determining the third phase difference dP3 between the third signal 23 received by the first transceiver 10 and the second internal signal 32. Here, the third phase difference dP3 determines a phase drift of the second transceiver 20 with respect to the first transceiver 10, such that the phase difference correction term dPc is given by dPc=dP1+dP2+(dP2−dP3)=dP1+2*dP2−dP3, is given, which is a corrected final TOA phase difference dPc. Furthermore: Offset correction term: dP2 Drift correction term: (dP2−dP3)

[0060] In particular, the phase difference correction term dPc is a signal phase dPc.

[0061] In Fig. Figure 6 shows the corrected final TOA phase difference, i.e., the signal phase, dPc. It can be seen that the signal phase remains constant at 100 degrees ± one error, with the error decreasing as the number of measurements increases.

[0062] With changing distances 25 between the first transceiver 10 and the second transceiver 20, the corrected final phase difference, i.e., the signal phase, dPc, also changes, as shown in Fig. 7 is shown. The one in the Fig. 7 plateaus shown at 50°, 100° and 150° (a total of five plateaus are in Fig. (7 can be seen) each corresponds to a specific distance 25 between the first and second transceivers 10, 20. During the measured fluctuations between the plateaus, the first and second transceivers 10, 20 were moved.

[0063] The corrected phase difference, i.e., the signal phase, can be converted into a length measurement for signals 21, 22, 23, 31, 32 with known wavelengths. Preferably, the phase difference correction method for detecting a position change of a transceiver 10, 20 detects a changed phase difference and thus a changed signal phase when a measurement rate of received first, second, and / or third signals 21, 22, 23 is greater than a ratio of a velocity v to the wavelength of the received first, second, and / or third signal 21, 22, 23, where the velocity v is a transceiver movement speed.

[0064] With the phase difference correction method, which can in particular be a TOA pre-correction method, a phase shift of 360 degrees corresponds to only half the actual wavelength of a signal 21,22, 23. As the Fig. As can be seen in section 7, it is possible to detect whether a new period and thus a new phase difference has occurred (= fluctuations between the plateaus indicate a new phase difference) if the measurement rate is sufficiently high. The measurement rate is sufficiently high if plateaus in the corrected final phase difference, i.e., the signal phase dPc, can be measured using the phase difference correction method described herein.

[0065] The new period or phase difference dPc can be taken into account when determining the distance 25. The distance 25 can be determined by adding or subtracting half the wavelength. Each of the signals 21, 22, 23 has the same wavelength. Each measurement yields a phase difference, which, due to the known wavelength, can be converted into a distance. If the transceivers were exactly one wavelength apart, the phase difference would revert to zero. To prevent this, one wavelength is added. In TOA, for example, only half the wavelength is added. If the transceivers were closer together, the wavelengths would have to be subtracted accordingly.

[0066] Fig. Figure 8 shows the result of the distance 25 measurement using the classical timestamp-based method and the phase-based method according to the invention. The half wavelength used for the experiments corresponded to 0.0429 meters. It is clearly visible that the period changes, i.e., the phase differences dPc, can be detected and that the positional accuracy due to the phase difference according to the phase-based method is much higher than with the classical timestamp-based method. The positional accuracy with the phase-based method according to the invention is increased, and at the same time, the error in positional accuracy is reduced. The accuracy of the phase-based distance measurement with the phase-based method according to the invention is superior to the timestamp-based method.

[0067] However, if the measurement rate is low or the transmission is blocked for a certain period of time, for example by a wall or a person, it is not possible to follow the correct phase change dPc. This problem can be overcome by updating the phase-based method, i.e., the phase difference correction method, with the timestamp-based method after a certain period of time.

[0068] Additionally or alternatively, for the implementation of the phase difference correction method, the first and / or the second transceiver 10, 20 are configured to transmit the first, the second and / or the third signal at different frequencies, wherein the phase difference correction method further comprises determining a time window in which all of the different frequencies have a multiple of a period, each of the different frequencies exhibiting a different multiple of periods within the time window. As in Fig. Figure 9 shows that different transmission frequencies (F1, F2, F3, and F4) are transmitted; for example, the following frequencies were used: F1 = 3494.4 MHz, F2 = 3993.6 MHz, F3 = 4492.8 MHz, and F4 = 6489.6 MHz. In the example shown from Fig. In equation 9, only two solutions, S1 and S2, are possible for a given distance of 25. The timestamp-based method can be used to select the correct solution. Fig. Figure 9 shows that the number of possible solutions can be reduced by using a timestamp. Suppose a phase difference of 180° is measured at one frequency and also at another frequency. Then it can be calculated at which distances this exact combination occurs. For example, if it happens at one meter, at two meters, and so on. Then, using the timestamp method (which is only accurate to 10 cm), it can be determined which of the possible solutions is the most likely one.

[0069] Preferably, the phase difference correction method additionally or alternatively comprises performing a known timestamp-based procedure and verifying the phase difference correction method by comparing the results of the known timestamp-based procedure with the results of the phase difference correction method. For example, a controller may be provided which is configured to execute a comparison program. The uncorrected phase difference is obtained using the same procedure as described in [2], which has already been explained in the introductory section.

[0070] Fig. Figure 10 shows the results of the accuracy correction due to frequency changes. The envelope (R) is the result of the phase difference correction method according to the invention. The columns (CR) in Fig. 10 are the solutions due to the frequency changes. Fig. Figure 10 shows seven plateaus, namely at distances of 25 from 0 m, 0.04 m and 0.1 m.

[0071] The previous section showed how phase difference drift and offset correction can be applied to correct the arrival time technique.

[0072] According to one aspect of the present invention, an ultra-wideband system 100 (see Fig. 3), comprising a first transceiver 10 and a second transceiver 20, each configured to transmit and receive signals 21, 22, 23 and spaced apart from each other, the system being configured to perform a phase difference correction procedure as described herein.

[0073] The further phase correction method according to the invention can be used in particular in connection with the time difference between arrival and arrival (TDOA): The following section shows how the developed correction method can also be used for the arrival time difference. When the phase correction method is used for the arrival time difference, the method is referred to as a further phase correction method.

[0074] In Fig. Figure 11 shows three transceivers 10', 20' and 30' of an ultra-wideband system 101', which is suitable for carrying out a method for determining a time difference arrival (TDOA) and is already known to a person skilled in the art. The signals 21' 22' are transmitted between the transceivers 10', 20', 30' with a timestamp.

[0075] The further phase correction method according to the invention is described in a flowchart in Fig. 12 and schematically embedded in an ultra-wideband system 100' in Fig. 13 shown.

[0076] In a first step 300 of the further phase difference correction procedure for correcting a phase drift and / or a phase offset, a first signal 21 is transmitted by a first transceiver 10. In a step 310, the first signal 21 is received by a second transceiver 20 and a third transceiver 30.

[0077] The first, second, and third transceivers 10, 20, 30 are each spaced 25, 26 apart, respectively. The distance 25 can differ from the distance 26. The first and second transceivers each comprise a transmitter 11 and a receiver 12. The third transceiver 30 is, as in Fig. Figure 13 shows a receiver 12 configured as a third transceiver 30, and it is conceivable to also configure the third transceiver 30 with a transmitter 11 and a receiver 12. The first, second, and third transceivers 10, 20, and 30 each include a control device 13 for processing the transmitted and received signals 21, 22, and 23. In particular, the third transceiver 30 can be a passive transceiver, i.e., a receiver. As already mentioned in connection with the phase correction method, it is possible for all phase differences to be calculated in a single transceiver. The only important thing is that the required measurements or measurement signals are taken by the receiving transceiver.

[0078] After receiving the first signal 22, step 320 involves determining a first phase difference dP1 in the second transceiver 20 between a first internal signal 31 of the second transceiver 20 and the received first signal 21. Furthermore, step 330 involves determining a second phase difference dP2 in the third transceiver 30 between a second internal signal 32 of the third transceiver 30 and the received first signal 21. Preferably, steps 320 and 330 are executed simultaneously. Steps 320 and 330 can also be executed sequentially in any order.

[0079] The first internal signal 31 can, for example, correspond to the second signal 22, which is in Fig. 13 is also referred to as signal B or B1. The first internal signal 31 can also differ from the second signal 22, in the sense that the second signal 22 corresponds to the first internal signal 31 plus a drift and / or a different phase.

[0080] In step 340, a second signal 22 is transmitted by the second transceiver 20 after a defined first delay time window V1 has elapsed. In step 350, the second signal 22 is received by the third transceiver 30. After receiving the second signal 22, a third phase difference dP3 is determined in step 360 in the third transceiver 30. The third phase difference dP3 is determined between the second internal signal 32 of the third transceiver 30 and the received second signal 22.

[0081] In step 370, a third signal 23 is transmitted by the second transceiver 20 after a defined second delay time window V2 has elapsed. In particular, the second signal 22 and / or the third signal 23 include information about the determined first phase difference dP1 or information for determining the first phase difference, as has already been described and to which reference is made here.

[0082] The first delay window V1 specifies the time span from receiving the first signal 21 until transmitting the second signal 22. The first delay window V1 can span a few milliseconds, particularly less than 1 ms, depending on the clock used and its rate of drift. After a defined delay time V1, the second transceiver 20 can send a response, i.e., the second signal 22, to the third transceiver. The delay window V1 is considered in relation to the time span at which the first signal 21 is received.

[0083] The second delay window V2 specifies the time span from receiving the first signal 21 until transmitting the third signal 23. The second delay window V2 can span a few nanoseconds, in particular less than 2 ms. The second transceiver 20 can send a response, i.e., the third signal 23, to the third transceiver after a defined delay time V2, the second delay window V2. The delay window V2 is viewed in relation to the time span at which the first signal 21 is received.

[0084] In step 380, the third signal 23 is received by the third transceiver 30. In step 390, a fourth phase difference dP4 is then determined in the third transceiver 30 between the second internal signal 32 of the third transceiver 30 and the received third signal 23.

[0085] Finally, in step 400, a corrected phase difference, i.e., the signal phase dPcc, is determined, in particular by subtracting the phase differences dP3, dP4 determined twice from the third and once from the fourth phase difference from the sum of the determined second phase difference dP2 and the determined fourth phase difference dP4 according to: dPcc=dP2−dP3−dP1−(dP3−dP4).

[0086] Here, the offset correction is given by dP1, and the drift correction is given by (dP3-dP4).

[0087] According to the further phase correction procedure, the first transceiver 10 and the second transceiver 20 transmit a signal 21, 22, 23, while the third, in particular passive, transceiver (receiver) 30 only receives the signals 21, 22, 23. The third transceiver determines the second, third, and fourth phase difference dP2, dP3, dP4 between the signals 21, 22, 23 of the first and second transceivers 10 and 20.

[0088] Preferably, the third signal 23 is sent simultaneously with the second signal 22 or after the defined second delay time window V2 has elapsed, wherein the second delay time window V2 is larger than the first delay time window.

[0089] Preferably, the phase difference correction method comprises determining the second and third phase differences dP2, dP3 by the third transceiver 30 in order to determine the phase difference (α) between the first signal (21) of the first transceiver (10) and the second signal (22) of the second transceiver (20) according to α = dPcc, where the phase difference α corresponds to an arrival angle θ = arcsin(αλ / 2πd), where α is the phase difference dPcc, λ is a carrier wavelength of the signals 21, 22, 23, and d is the distance 25 between the first transceiver 10 and the second transceiver 20. In particular, if the distance 25 between the first transceiver 10 and the second transceiver 20 is less than the wavelength λ, the signal phase corresponds to the arrival angle θ=arcsin(αλ / 2πd).

[0090] The signal exchange between the first transceiver 10 and the second transceiver 20 is used to correct the phase shift between the two transceivers 10 and 20. This procedure is also used in the previously described phase difference correction method. The second signal, transmitted by the second transceiver, is intended to correct the phase shift, i.e., the phase drift.

[0091] The further phase correction procedure can be summarized as follows: The first transceiver 10 initializes the process by transmitting the first signal 21. This first signal 21 is received by the second and third transceivers 20 and 30. Subsequently, both transceivers 20 and 30 determine the phase difference between the received first signal 21 and an internal signal (dP1 and dP2). The second transceiver 20 responds to the first signal 21 by transmitting the second and third signals 22 and 23, which are also referred to as signals B1 and B2. Fig. The 13 signals are designated according to the delay time window V1 and the delay time window V2. The phase difference dP1 is used to correct the phase shift between the first transceiver 10 and the second transceiver 20, while the second and third signals 22, 23 and B1 and B2, respectively, are required to correct the phase drift. The third transmitter 30 receives the first signal 21, the second and third signals 22, 23, and determines the phase differences dP2 and dP3. The phase difference dP4 corresponds to the phase difference between the third signal 23 or B2 and the second internal signal 32. The final corrected phase difference, i.e., the signal phase, for TDOA is: dPcc=dP2−dP3−dP1−(dP3−dP4).

[0092] Fig. Figure 14 shows the final corrected phase difference, i.e., the signal phase dPcc, which was obtained by applying the further phase difference correction procedure for TDOA. Fig. Figure 14 shows the corrected phase difference, i.e., the signal phase dPcc, when the position of the third transceiver 30 is changed using real measurement data, such as a distance change of approximately 30 cm. The signal phase lies in the range of -180 to 180 degrees, which corresponds, for example, to a single period of a wavelength with a frequency of 6489.6 MHz.

[0093] Another aspect of the present invention relates to ultra-wideband system 101, which comprises a first transceiver 10, a second transceiver 20, and a third transceiver 30, wherein the transceivers 10, 20, and 30 are spaced apart from each other, and wherein the ultra-wideband system 101 is configured to perform the further phase difference correction method as just described.

[0094] Another aspect of the present invention relates to a computer program code that performs steps of a phase difference correction method or a further phase difference correction method as described herein when the computer program code is executed on a program code executable medium. For example, the first to third transceivers 10, 20, and 30 are media that can execute the program code.

[0095] Individual aspects described herein regarding the described phase difference correction procedure also apply to the further described phase difference correction procedure and vice versa, without necessarily having been repeated in detail.

[0096] One difference between the described phase difference correction method and the other described phase difference correction method is that the described phase difference correction method uses two transceivers (see below). Fig. 3) includes and the further described phase difference correction procedure three transceivers (p. Fig. 13) includes.

[0097] The described phase difference correction method and the other described phase difference correction method have in common that phase differences between at least one received and one internal signal, as well as a phase difference between two received signals, are determined in order to achieve the phase difference drift and offset correction between the signals.

[0098] The following can be achieved with the phase difference correction methods described herein: • UWB phase drift correction via an additional signal. • UWB phase shift correction between two or more transceivers. • UWB phase difference correction term for TOA and TDOA. • UWB frequency change to correct the distance, which is obtained through the corrected phase difference, corresponding to the signal phase.

[0099] Even if some aspects related to a device or arrangement have been described, it is clear that these aspects also constitute a description of the corresponding process, where a block or device corresponds to a process step or a feature of a process step. Similarly, aspects described in the context of a process step also constitute a description of a corresponding block, element, or feature of a corresponding device.

[0100] The inventive methods can be stored on a digital storage medium or transmitted on a transmission medium such as a wireless transmission medium or a wired transmission medium such as the Internet.

[0101] Depending on specific implementation requirements, embodiments of the invention can be implemented in hardware or in software. The implementation can be carried out using a digital storage medium, e.g., a floppy disk, a DVD, a CD, a ROM, a PROM, an EPROM, an EEPROM, or a FLASH memory, on which electronically readable control signals are stored. These signals interact, or can interact, with a programmable computer system to execute the respective method.

[0102] Some embodiments of the invention consist of a data carrier with electronically readable control signals that can interact with a programmable computer system to perform one of the methods described herein. In particular, the electronically readable control signals are designed to capture timestamps of a signal.

[0103] In general, embodiments of the present invention can be implemented as a computer program product with program code, wherein the program code is effective for carrying out one of the methods when the computer program product runs on a computer. The program code can, for example, be stored on a machine-readable medium.

[0104] Other embodiments include a computer program stored on a machine-readable medium for carrying out one of the methods described herein.

[0105] In other words, an embodiment of the inventive method is therefore a computer program with program code for carrying out one of the methods described here, when the computer program runs on a computer.

[0106] Another embodiment of the inventive method is therefore a data carrier (or a digital storage medium or a computer-readable medium) that contains and is recorded on the computer program for carrying out one of the methods described herein.

[0107] Another embodiment of the inventive method is therefore a data stream or a sequence of signals that represents the computer program for carrying out one of the methods described herein. The data stream or signal sequence can, for example, be configured so that it can be transmitted via a data communication link, e.g., via the internet.

[0108] Another embodiment comprises a processing means, e.g. a computer or a programmable logic device, configured or adapted to perform one of the methods described herein.

[0109] Another embodiment includes a computer on which the computer program for carrying out one of the methods described here is installed.

[0110] In some embodiments, a programmable logic device (e.g., a field-programmable gate array) can be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field-programmable gate array can cooperate with a microprocessor to perform one of the methods described herein. In general, the methods are preferably executed by any hardware device.

[0111] The embodiments described above serve only to illustrate the principles of the present technical teaching. It is self-evident that modifications and variations of the arrangements and the details described herein will be obvious to other skilled persons. It is therefore intended that the scope of the patent claims be limited only by the scope of the foregoing patent claims and not by the specific details presented in the description and explanation of the embodiments described herein. Bibliography [1] https: / / patents.justia.com / patent / 20200045661 [2] https: / / patents.justia.com / patent / 10509116 [3] https: / / patents.justia.com / patent / 10992340 [4] J. Sidorenko, V. Schatz, N. Scherer-Negenborn, M. Arens and U. Hugentobler, „Error Corrections for Ultrawideband Ranging,“ in IEEE Transactions on Instrumentation and Measurement, vol. 69, no. 11, pp. 9037-9047, Nov. 2020, doi: 10.1109 / TIM.2020.2996706. [5] https: / / patentscope.wipo.int / search / en / detail.jsf?docld=WO2020165429 [6] J. Sidorenko, V. Schatz, N. Scherer-Negenborn, M. Arens and U. Hugentobler, „DecaWave Ultra-Wideband Warm-Up Error Correction,“ in IEEE Transactions on Aerospace and Electronic Systems, Bd. 57, Nr. 1, S. 751-760, Feb. 2021, doi: 10.1109 / TAES.2020.3015323.

Claims

[1] Phase difference correction methods for correcting phase drift and / or phase offset comprising: Emitting a first signal (21) by a first transceiver (10), Receiving the first signal (21) by a second transceiver (20), Determining a first phase difference (dP1) in the second transceiver (20) between a first internal signal (31) of the second transceiver (20) and the received first signal (21), Emitting a second signal (22) by the second transceiver (20) after a defined first delay time window, wherein the second signal (22) includes information about the determined first phase difference (dP1) and / or information for determining the first phase difference, Receiving the second signal (22) by the first transceiver (10), Determining a second phase difference (dP2) in the first transceiver (10) between a second internal signal (32) of the first transceiver (10) and the received second signal (22), Summing the first determined phase difference (dP1) and the second determined phase difference (dP2), thereby correcting a phase shift between the two transceivers, Emitting a third signal (23) by the second transceiver (20) after a defined second delay time window, in particular wherein the third signal (23) includes information about the second signal (22); Receiving the third signal (23) by the first transceiver (10); Determining a third phase difference (dP3) between the third signal (23) received by the first transceiver (10) and the second internal signal (32) in the first transceiver (10), where the third phase difference dP3 determines a phase drift of the second transceiver (20) with respect to the first transceiver (10), such that a phase difference correction term dPc is given by dPc=dP1+dP2+(dP2−dP3), is given, in particular where the phase difference correction term dPc is a signal phase dPc. [2] Phase difference correction method according to the previous claim, wherein the first delay time window corresponds to a time interval between the reception of the first signal (21) by the second transceiver (20) and the transmission of the second signal (22) by the second transceiver (20). [3] Phase difference correction method according to one of the preceding claims, wherein the second delay time window corresponds to a time interval between the reception of the first signal (21) by the second transceiver (20) and the transmission of the third signal (23) by the second transceiver (20). [4] Phase difference correction method according to one of the preceding claims, wherein for the second delay time window V2 V2=2*V1. [5] Phase difference correction method according to one of the preceding claims, wherein to detect a change in position of a transceiver (10, 20) a changed phase difference is detected when a measurement rate of received first, second and / or third signals (21, 22, 23) is greater than a ratio of a velocity (v) to the wavelength of the received first, second and / or third signal (21, 22, 23), wherein the velocity (v) is a transceiver movement velocity. [6] Phase difference correction method according to one of the preceding claims, wherein the first and / or the second transceiver (10, 20) is / are configured to transmit the first, the second and / or the third signal at different frequencies, the phase difference correction method further comprising: Determining a time window in which all of the different frequencies have a multiple of a period, where each of the different frequencies exhibits a different multiple of periods in the time window. [7] Phase difference correction method according to claim 6, which additionally comprises or according to any of the preceding claims alternatively comprises: Performing a known timestamp-based procedure, and Verifying the phase difference correction method by comparing the results of the known timestamp-based method with the results of the phase difference correction method. [8] Ultra-wideband system (100), which includes: a first transceiver (10) and a second transceiver (20), each configured for transmitting and receiving signals (21, 22, 23) and spaced apart from each other, wherein the system is configured to perform a phase difference correction method according to one of claims 1 to 7. [9] Phase difference correction methods for correcting phase drift and / or phase offset including: Emitting a first signal (21) by a first transceiver (10), Receiving the first signal (21) by a second transceiver (20) and a third transceiver (30), Determining a first phase difference (dP1) in the second transceiver (20) between a first internal signal (31) of the second transceiver (20) and the received first signal (21), Determining a second phase difference (dP2) in the third transceiver (30) between a second internal signal (32) of the third transceiver (30) and the received first signal (21), Emitting a second signal (22) by the second transceiver (20) after a defined first delay time window has elapsed, Receiving the second signal (22) by the third transceiver (30), Determining a third phase difference (dP3) in the third transceiver (30) between the second internal signal (32) of the third transceiver (30) and the received second signal (22), Emitting a third signal (23) by the second transceiver (20) after the expiry of a defined second delay time window by the second transceiver, in particular wherein the second signal (22) and / or the third signal (23) includes information on the determined first phase difference (dP1) and / or information on determining the first phase difference (dP1); Receiving the third signal (23) by the third transceiver (30); Determining a fourth phase difference (dP4) in the third transceiver (30) between the second internal signal (32) of the third transceiver (30) and the received third signal (23), and finally Determining a corrected phase difference (dPcc) according to: dPcc=dP2−dP3−dP1−(dP3−dP4). [10] Phase difference correction method according to claim 9, wherein the third signal (23) is sent simultaneously with the second signal (22) or after the defined second delay time window (V2) has elapsed, wherein the second delay time window (V2) is larger than the first delay time window (V1). [11] Phase difference correction method according to claim 9 or 10, further comprising: Determining the second and third phase differences (dP2, dP3) by the third transceiver (30) in order to determine the phase difference (α) between the first signal (21) of the first transceiver (10) and the second signal (22) of the second transceiver (20) according to α = dPcc, where the phase difference α corresponds to an arrival angle θ = arcsin(αλ / 2πd), where α is the phase difference, λ is the carrier wavelength, and d is the distance between the first transceiver (10) and the second transceiver (20). [12] Ultra-wideband system (101) which includes: a first transceiver (10) and a second transceiver (20) and a third transceiver (30) which are spaced apart from each other, wherein the system is configured to perform a phase difference correction method according to one of claims 9 to 11. [13] Computer program code which performs steps of a phase difference correction method according to one of claims 1 to 7 or 9 to 11 when the computer program code is executed on a program code executable medium.

Images