Phase difference correction methods and ultra-wideband system

Abstract

A phase difference correction method for correcting a phase drift and / or a phase offset is described, comprising: emitting a first signal by means of a first transceiver, receiving the first signal by means of a second transceiver, determining a first phase difference in the second transceiver between a first internal signal of the second transceiver and the received first signal, emitting a second signal by means of the second transceiver after a defined first delay time window has elapsed, the second signal comprising information concerning the determined first phase difference and / or information for determining the first phase difference, receiving the second signal by means of the first transceiver, determining a second phase difference in the first transceiver between a second internal signal of the first transceiver and the received second signal, and summing the first determined phase difference and the second determined phase difference, whereby a phase offset between the two transceivers is corrected. Moreover, a further phase difference correction method is described. In addition, ultra-wideband systems and a computer program code are described.

Description

[0001] Phase difference correction method and ultra-wideband system

[0002] The present invention relates to a phase difference correction method and an ultra-wideband system suitable for implementing the phase difference correction method, as well as corresponding computer program code. In particular, a method for phase difference drift and offset correction suitable for ultra-wideband (UWB) localization is disclosed.

[0003] Information about the phase of a carrier wave is often used in navigation to enhance or provide distance information. In satellite navigation, the measurement of the phase of the carrier wave is used in combination with the pseudorange. The same principle can also be used for UWB localization systems, provided 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 overcome this problem is the use of 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, using only one station requires multiple antennas in the station.

[0004] A phase measurement according to one of the prior art methods just described is only applicable to systems in which the clock signal is shared or in which a station or transceiver has several antennas available for transmitting or receiving the signal.

[0005] Fig. 1 schematically shows an ultra-wideband system 100' suitable for TOA measurement technology. A first transceiver 10' transmits a first signal 2T, which is received by a second transceiver 20'. For this purpose, the first and second transceivers 10', 20' each comprise a transmitter and a receiver. The first transceiver 10' and the second transceiver 20' can be configured to create time stamps of the received and transmitted first and second signals 2T, 2T' and to transmit and receive them, respectively. A time stamp difference dT in combination with the known propagation velocity c0 (speed of light) makes it possible to determine an unknown distance 25' via 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 the 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 returned transmission times. This method 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, the method described so far for Fig. 1 belongs to the state of the art.

[0006] With regard to the described method, which is part of the 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 use of multiple antennas or without having to share 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] With the phase difference correction method proposed herein and the further phase correction method, a position accuracy of less than 1 cm, in particular of 0.8 mm, can be determined, for example, at a frequency of 6.5 GHz. At higher frequencies, position determination becomes even more accurate because the wavelength becomes shorter. The core of the present invention is to determine correction terms to correct a phase offset and / or phase drift from the signals, in particular measured ones. In particular, the further phase correction method can include passive transceivers for executing the further phase correction method.

[0010] According to the proposal, the phase difference correction method for correcting a phase drift and / or a phase offset initially comprises transmitting a first signal by a first transceiver and receiving the first signal by a second transceiver. The proposed phase difference correction method can be implemented using time of arrival (TOA) measurement technology. After receiving the first signal, a first phase difference is determined between a first internal signal, i.e., an internal wave, of the second transceiver and the received first signal. The first phase difference is determined in the second transceiver. The phase difference is determined in the transceiver that receives a signal. Corrections can be calculated in any transceiver.The phase difference correction method in each case further comprises transmitting a second signal by the second transceiver after a defined first delay time window has elapsed, wherein the second signal comprises information about the already determined first phase difference and / or about determining 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 phase difference can be calculated by any transceiver or by a server or the like. In the phase difference correction method according to the invention, it is therefore conceivable that the first phase difference is determined in the second transceiver.In this case, the second signal, which is sent from the second transceiver to the first transceiver, can comprise information about the already determined first phase difference. In the phase difference correction method according to the invention, it is further conceivable for the first phase difference to be determined in the first transceiver. In this case, the second signal, which is sent from the second transceiver to the first transceiver, can comprise at least one piece of information that enables the first transceiver to determine the first phase difference. The second signal then preferably comprises information about the first signal and the internal signal of the second transceiver. Furthermore, it is conceivable for the first phase difference to be determined in the first transceiver and in the second transceiver. This makes it possible to reduce an error in the first phase difference.In this case, the second signal sent from the second transceiver to the first transceiver may comprise at least one piece of information enabling the first transceiver to determine the first phase difference and the information about the first phase difference already determined in the second transceiver.

[0011] In either case, the second signal comprises a signal for determining 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, from a server, or in a cloud. The phase difference correction method comprises receiving the second signal by the first transceiver. After the second signal is received by the first transceiver, the second phase difference is determined in the first transceiver between a second internal signal of the first transceiver and the received second signal. Finally, the first determined phase difference and the second determined phase difference are summed, thereby correcting a phase offset between the two transceivers.If there were no drift, the phase difference obtained in this way would only depend on the distance between the first and the second transceiver and thus correspond to a signal phase. The first phase difference is preferably determined in the second transceiver. The measurements required for this are always carried out in the second transceiver. For example, the first signal 21 is measured in the second transceiver 20 and the second and third signals 22, 23 are measured in the first transceiver 10. Together, the measured signals 21, 22, 23 can be used to calculate the corrected phase difference, i.e., the signal phase. Where the calculation takes place is irrelevant; it can therefore be calculated in the first and / or the second transceiver. The only important thing is that the measured signals 21, 22, 23 are available for calculating the corrected phase difference when performing the calculation of the corrected phase difference.

[0012] To receive signals, a transceiver comprises at least one antenna. The phase value of a received signal is determined by obtaining a phase of the signal as a function of a complex baseband impulse response of the transmitted signal received by the antenna. When a signal is received by a transceiver, the SFD (start frame delimiter), the real part of the signal, and the imaginary part of the signal are measured. These measured values ​​can then be used to calculate the phase difference between the received signal and an internal signal. Some terms used in this application are explained below to define the terms within the scope of this application.

[0013] In the present application, a signal is to be understood as 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 case, the signals are sent and received as digital signals. Of course, an analog signal can also be transcribed into a digital signal. In the present case, the signals are transmitted between transceivers, whereby in this case 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 the person skilled in the art in the further description. As a rule, a transceiver comprises a transmitter and a receiver.

[0014] The term "internal wave" or "internal signal" can be explained as follows: A 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 via an antenna, the downconverter uses the internal signal to determine the I / Q data.

[0015] These provide information about the phase difference <P zwischen dem internen Signal und dem empfangenen Signal gemäß <P = arctan(y) .

[0016] After the I / Q data has been digitized by the analog-to-digital converter (ADC), the baseband processor can form the impulse response to map the I / Q data to the direct signal.

[0017] 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 impulse response (Channel Impulse Response). Specific to the UWB chip, this data must be further processed to determine the phase difference, for example, using the synchronization frame delimiter (SFD). When reference is made to determining the phase difference in this application, this refers to the determination of all data necessary for calculating the phase difference, in particular the SFD, the real part, and the imaginary part of the received signal, which arise when the message is received. It is irrelevant where this data is combined to form the actual phase difference. In other words, the phase difference itself can be calculated by any transceiver.

[0018] According to the technical teaching described herein, multiple phase differences between the transceivers are calculated to determine the signal phase, which depends only on the distance between two transceivers. The drift- and offset-corrected phase difference will be referred to herein as the signal phase dPc for TOA or dPcc for TDOA.

[0019] Preferably, the phase difference correction method is carried out in a sequence of the individual steps as claimed in claim 1. However, it is conceivable that the first and second phase differences are determined only after the first signal and the second signal have been exchanged between the first transceiver and the second transceiver.

[0020] A further aspect of the present invention comprises an ultra-wideband system having a first transceiver and a second transceiver, each configured to transmit and receive signals and spaced apart from one another, wherein the system is configured to carry out a phase difference correction method as described herein. By carrying out 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 obtained. The ultra-wideband (UWB) system according to the invention has transmitter, receiver, or transceiver stations, referred to herein as transceivers. The receiving stations, i.e. the transceivers, can obtain the phase difference between the carrier wave, i.e., 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 transmitted and / or received. The internal wave has a frequency with a certain accuracy and a phase drift.

[0021] With the presented correction method, the corrected phase difference, i.e., the signal phase, can be realized in the case of distributed UWB stations with clock inaccuracy. A further aspect of the present invention comprises a further phase difference correction method, in particular for passive transceivers, for correcting a phase drift and / or a phase offset. Passive transceivers comprise a receiver for receiving signals. The further phase difference correction method initially comprises transmitting a first signal by a first transceiver and receiving the first signal by a second transceiver and a third transceiver. In comparison to the previously described phase difference correction method, the first signal in the further phase difference correction method is transmitted to and received by two different transceivers, the second and the third transceiver.The first to third transceivers can be spaced apart from one another. Furthermore, it is conceivable for the second transceiver and the third transceiver to be implemented in one transceiver. The further phase difference correction method comprises, after the first signal has been received by a second transceiver and a third transceiver, determining a first phase difference in the second transceiver and determining 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 method comprises transmitting a second signal by the second transceiver after the expiration of a defined first delay time window.This step is performed analogously to the phase difference correction method already described. After the second signal is received by the third transceiver, a third phase difference is determined in the third transceiver between the second internal signal of the third transceiver and the received second signal.

[0022] Furthermore, the further phase difference correction method comprises transmitting a third signal by the second transceiver. In particular, after a defined second delay time window has elapsed, the third signal is transmitted by the second transceiver. Furthermore, the second signal and / or the third signal can comprise information relating to the determined first phase difference and / or for determining the first phase difference. The statements already made regarding the phase difference correction method also apply to the further phase difference correction method and will not be repeated here. In addition, the further phase difference correction method comprises receiving the third signal by the third transceiver. After the third signal has been received by the third transceiver, 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.

[0023] 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.

[0024] The corrected phase difference is ideally zero, i.e. ideally, after correcting the phase difference, there is no longer a phase difference, but the signal phase.

[0025] Some steps of the additional phase difference correction method are carried out analogously to the steps of the phase difference correction method. Consequently, the further detailed descriptions of the additional phase difference correction method are transferable to the additional phase difference correction method. Further detailed descriptions of individual features are omitted to avoid redundancies. However, it is understood that features described with reference to the phase correction method are also transferable analogously to the additional phase correction method, and vice versa, unless an analog transfer is explicitly excluded.

[0026] A further aspect of the present invention comprises an ultra-wideband system having a first transceiver and a second transceiver and a third transceiver, which are spaced apart from one another by a distance, wherein the system is configured to implement 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 has transmitter, receiver or transceiver stations, referred to herein as transceivers. The receiving stations, i.e. the transceivers, can obtain the phase difference between the carrier wave, i.e. the first signal, and / or the second signal and / or a third signal, and the internal wave, i.e. the first internal signal and / or the second internal and / or a third internal signal.With the presented correction method, the phase difference can be realized in the case of distributed UWB stations with clock inaccuracies.

[0027] Another aspect of the present invention includes computer program code that performs steps of a phase difference correction method as described herein when the computer program code is executed on a program code executable medium.

[0028] Essentially, the correction method involves correcting the phase drift and / or phase offset. This can be implemented between two active stations or active transceivers (transmit and receive signals) or any number of passive transceivers (receive only). A passive transceiver corresponds to a receiver.

[0029] The technical teaching described herein discloses how the phase difference between two or more transceivers, in particular UWB transceivers, can be corrected without having to divide the clock signal and / or without having to use special antenna arrays. By correcting the phase difference, the signal phase can be maintained, which is only a function of the distance between the transceivers.

[0030] The phase difference correction method disclosed herein and the additional phase correction method have been verified by real measurements. Based on the real measurements, it was demonstrated, 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 image caption below.

[0031] In the prior art, it was previously known that position determination in the UWB range could only be determined to within a few centimeters. However, with the invention disclosed herein, a position is determined to within 0.8 mm at a frequency of 6.5 GHz. At higher frequencies, position determination becomes even more accurate because the wavelength becomes shorter.

[0032] 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 solves this problem, but the phase difference correction method, or the further phase difference correction method, can also be used for time-of-arrival (TOA) and time-of-arrival (TDOA) measurements, respectively. Furthermore, active and / or passive transceivers can be used.

[0033] The technical teaching disclosed herein is advantageous in areas where high position accuracy plays an important role, such as augmented reality, robotics, military, etc.

[0034] Furthermore, the meaning of the abbreviations used here should be explained again at this point:

[0035] TOA: Time of Arrival measurement technology (TOA = Time of Arrival)

[0036] TDOA: Time Difference of Arrival measurement technique (TDOA = Time Difference of Arrival)

[0037] Brief description of the drawings

[0038] The drawings are not necessarily to scale; rather, emphasis is generally placed upon illustrating the principles of the invention. In the following description, various embodiments of the invention are described with reference to the following drawings. In the drawings:

[0039] Fig. 1 shows a schematic diagram of an ultra-wideband system with a TOA between two UWB transceivers;

[0040] Fig. 2 schematically shows a sequence of a phase difference correction method according to the invention in an ultra-wideband system; Fig. 3 phase difference correction for TOA;

[0041] Fig. 4 a phase difference dP1 between two transceivers without corrections;

[0042] Fig. 5 a sum of the phase difference dP1 and dP2;

[0043] Fig. 6 shows a final corrected TOA signal phase obtained according to the invention;

[0044] Fig. 7 shows a changed signal phase due to TOA distance changes;

[0045] Fig. 8 shows the calculated distance based on the signal phase;

[0046] Fig. 9 a possible solution S based on four different frequencies

[0047] F1-F4;

[0048] Fig. 10 Results of accuracy update due to frequency changes;

[0049] Fig. 11 schematically shows an ultra-wideband system with a TDOA between three UWB transceivers;

[0050] Fig. 12 schematically shows a sequence of a further phase difference correction method according to the invention in an ultra-wideband system;

[0051] Fig. 13 shows a phase difference correction for TDOA obtained according to the invention;

[0052] Fig. 14 shows a changed phase due to TDOA position changes; and

[0053] Fig. 15 is a diagram explaining the term "internal signal." Detailed description of the embodiments

[0054] Identical or equivalent elements, or elements with identical or equivalent functionality, are designated by identical 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 described below in conjunction with Figures 1 to 12.

[0055] In the following description, numerous details are set forth to provide a thorough explanation of embodiments of the present invention. However, it will be apparent to one skilled in the art that embodiments of the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagrams or schematic representations rather than in detail to avoid obscuring embodiments of the present teachings. Furthermore, features of the various embodiments described below may be combined with one another unless expressly stated otherwise.

[0056] As already 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 to transmit or receive the signal.

[0057] The phase difference correction methods according to the invention solve these problems and can be applied both to a method in which the time of arrival (TOA) is relevant and to a method in which the time difference of arrival (TDOA) is relevant. This is explained below using preferred embodiments. The preferred embodiments are explained in detail in conjunction with Figs. 2 to 10 and 12 to 14.

[0058] The phase correction method according to the invention can be used in particular in connection with the time of arrival (TOA):

[0059] With regard to the prior art method described in the introduction, it should be noted again that even with all the correction methods used, it is not possible for the timestamp-based position estimation to obtain a position estimate better than several centimeters. This limitation can be overcome by using the phase difference correction method according to the invention.

[0060] The inventive phase difference correction method for performing a phase difference correction with arrival time measurements is shown in a flowchart in Fig. 2 and schematically as an implementation in an ultra-wideband system 100 in Fig. 3. Figures 2 and 3 are therefore described together.

[0061] In a first step 200 of the phase difference correction method for correcting a phase drift and / or a phase offset, a first signal 21 is transmitted by a first transceiver 10. The first and second transceivers 10, 20 are spaced 25 apart. In a subsequent step 210, the first signal 21 is received by a second transceiver 20. The first and second transceivers each comprise a transmitter 11 and a receiver 12. The first and 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 second transceivers, are configured to measure, upon receiving a signal, measured values ​​such as the SFD, the real part, and the imaginary part of the received signal 21, 22, 23.From the measured values, i.e., the measured signals 21, 22, 23, the phase difference can then be calculated at any transceiver 10, 20, i.e., the first and / or second transceiver 10, 20. The phase difference can also be calculated on a server. For this, only the measured signals 21, 22, 23 must be provided.

[0062] After receiving the first signal 21 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.

[0063] For an explanation of the term "internal wave" or internal signal 31, 32, reference is made to Fig. 15. Fig. 15 schematically shows that a crystal clock 500 drives a PLL 510 (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 Fig. 15). A downconverter mixer is used for this purpose. If a signal is received with an antenna 520, the downconverter 530 determines the I / Q data. This provides information about the phase difference. <P zwischen dem internen Signal und dem empfangenen Signal gemäß <P = arctan(y) . Nachdem die l / Q Daten durch den Analog-Digital-Umsetzer (ADC) 540 digitalisiert wurden, kann der Basisband-Prezessor (Baseband Processor) 550 die Impuls- Antwort bilden, um die l / Q Daten dem direkten Signal zuzuordnen.

[0064] In a step 230, a second signal 22 is transmitted by the second transceiver 20 after the expiration of a defined first delay time window V1, wherein the second signal 22 comprises information about the determined first phase difference dP1 and / or information for determining the first phase difference. Information for determining the first phase difference comprises those measured values ​​required to calculate the phase difference. The calculated phase differences dP1, dP2, dP3 and further information can be accessible to all transceivers because all active transceivers can send and receive information and can therefore also pass it on to a passive transceiver. At this point, it should be noted that steps 220 and 230 can run one after the other, i.e. first step 220 then step 230. Just as well, step 230 can run first and then step 220.In this case, the second signal comprises 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 time window V1 specifies a time period from receipt of the first signal 21 to transmission of the second signal 22. The first delay time window V1 can comprise a time period of a few milliseconds, in particular less than two milliseconds. After a defined delay time V1, the first delay time window V1, the second transceiver 20 can send a response, i.e. the second signal 22, back to the first transceiver. The delay time window V1 is viewed in relation to the time period at which the first signal 21 is received.

[0065] In a step 240, the second signal 22 is received by the first transceiver 10. The second signal 22 can be the first internal signal 31 including any possible drift. In Fig. 3, for example, the first internal signal 31 is shown as signal B, while the second signal 22 is shown as signal B1. After the second signal has been received by the first transceiver 10, 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 also referred to as signal A in Fig. 3. However, the second internal signal 32 can also be different from the first signal 21.Different in the sense that it is still the same second internal signal 32, but due to the past time window, it has a different phase in the first signal 21. Furthermore, the received first signal 21 may exhibit a phase drift, which can be corrected with a third signal 23.

[0066] In a subsequent step 260, the first determined phase difference dP1 and the second determined phase difference dP2 are summed, thereby correcting a phase offset between the two transceivers. With regard to the disclosure of Fig. 3, it should be noted that to correct a phase offset between the first and second signals 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.

[0067] The phase difference dP1 is shown in Fig. 4. Fig. 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.

[0068] The first transceiver 10 serves as an initialization transceiver by transmitting the first signal 21. Both the first transceiver 10 and the second transceiver 20 comprise the same method steps, namely determining a phase difference dP1, dP2 between the received signal 21, 22 and the internal signal 31, 32, see Fig. 3. The sum of the first phase difference dP1 and the second phase difference dP2 reduces, in particular eliminates, the phase offset between the two transceivers 10, 20, as shown in Fig. 5. Fig. 5 shows the sum of the first phase difference dP1 and the second phase difference dP2 as a function of the number of measurements. In both Fig. 4 and Fig. 5, a total of 50 measurements were performed. In contrast to Fig. 4, Fig. 5 shows a periodic signal, ie the sum of dP1 + dP2 is periodic, especially within an apparent envelope.The apparent envelope occurs when one transceiver has a higher clock rate than the other. This causes one transceiver to repeatedly overtake the other.

[0069] If the second signal 22, also referred to as signal B1 in Fig. 3, were transmitted immediately after receiving the first signal 21, also referred to as signal A1 in Fig. 3, further drift correction, as described below, would not be necessary. In this case, "immediately after receiving the first signal 21" means after one millisecond or less has elapsed.

[0070] However, short processing times can lead to phase drift. Accordingly, after a known second delay time 2, a second delay window V2, a third signal 23 is transmitted by the second transceiver 20. The term "short processing time" depends on the drift of the signal involved at a signal frequency. A short processing time can certainly mean a processing time > 1 ns.

[0071] 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 starting time, V2=2*V1 (see Figs. 3 and 13) applies. 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, the first delay time window V1 preferably corresponds to a time period 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, the second delay time window V2 preferably corresponds to a time period 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. The following preferably applies to the second delay time window V2:

[0072] V2=2*V1.

[0073] In this case, phase drift can be corrected using a phase difference correction term, as explained below.

[0074] A phase drift of the second transceiver 20 with respect to the first transceiver 10 is obtained by the phase difference between the second signal 22, also referred to as signal B1 in Fig. 3, and a third signal 23, also referred to as signal B2 in Fig. 3, transmitted in particular by the second transceiver after the expiration of the second time delay window V2. This results in a final TOA phase difference correction term: dPc=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 with respect to the signal B2.

[0075] 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 comprises 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, which is a corrected final TOA phase difference dPc. Furthermore, the following applies:

[0076] Offset correction term: dP2 Drift correction term: (dP2-dP3)

[0077] In particular, the phase difference correction term dPc is a signal phase dPc.

[0078] Fig. 6 shows the corrected final TOA phase difference, i.e., the signal phase, dPc. It can be seen that the signal phase is constant at 100 degrees ± one error, with the error decreasing with increasing number of measurements.

[0079] 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. The plateaus shown in Fig. 7 at 50°, 100°, and 150° (a total of five plateaus are visible in Fig. 7) each correspond 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.

[0080] The corrected phase difference, i.e., the signal phase, can be converted into a length measurement at known wavelengths of the signals 21, 22, 23, 31, 32. 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 speed v to the wavelength of the received first, second, and / or third signals 21, 22, 23, wherein the speed v is a transceiver movement speed.

[0081] 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 can be seen from Fig. 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, with the phase difference correction method described herein, plateaus can be measured in the corrected final phase difference, i.e., the signal phase dPc.

[0082] The new period or the new phase difference dPc can be taken into account when the distance 25 is determined. The distance 25 can be determined by adding or subtracting half the wavelength. Each of the signals 21, 22, 23 has the same wavelength. With each measurement, a phase difference is obtained which, based on knowledge of the wavelength, can be converted into a distance. If, for example, the transceivers were exactly one wavelength apart, the phase difference would return to zero. To avoid this, however, a wavelength is added. With TOA, for example, only half the wavelength is added. If the transceivers were to come closer together, the wavelengths would have to be subtracted accordingly. Fig.Figure 8 shows the result of measuring distance 25 using the classic timestamp method (timestamp-based) and the phase difference correction method according to the invention (phase-based). 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 positioning accuracy due to the phase difference according to the inventive phase difference correction method is much higher than with the classic timestamp-based method. The positioning accuracy with the inventive phase difference correction method is increased, and at the same time, the error in the positioning accuracy is reduced. The accuracy of the phase-based distance measurement using the inventive phase difference correction method is superior to the timestamp method.

[0083] However, if the measurement rate is low or the transmission is blocked for a certain period of time, for example, due to shielding from a wall or a person, it is not possible to track 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.

[0084] Additionally or alternatively, to implement the phase difference correction method, the first and / or second transceivers 10, 20 are configured to transmit the first, second, and / or third signals 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, each of the different frequencies having a different multiple of period in the time window. As shown in Fig. 9, 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 in Fig. 9, only two solutions S1 and S2 are possible for a specific distance 25. The timestamp-based method can be used to select the correct solution. In Fig.Figure 9 shows that the time stamp can reduce the number of possible solutions. Suppose a phase difference of 180° is measured at one frequency, and 180° is also measured at another frequency. Then, it is possible to calculate at which distances this exact constellation occurs. Suppose it occurs at one meter, two meters, and so on. Then, using the time stamp method (which is only accurate to within 10 cm), it is possible to decide which of the possible solutions is appropriate.

[0085] Preferably, the phase difference correction method additionally or alternatively comprises performing a known timestamp-based method, 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. For example, a controller configured to execute a comparison program may be provided. The uncorrected phase difference is obtained using the same method as described in [2], which has already been explained in the introductory part.

[0086] Fig. 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. 10 shows seven plateaus, namely at distances 25 from 0 m, 0.04 m, and 0.1 m.

[0087] The previous section showed how phase difference drift and offset correction can be applied to correct the arrival time technique.

[0088] 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, is provided, wherein the system is configured to perform a phase difference correction method as described herein.

[0089] The further phase correction method according to the invention can be used in particular in connection with the time difference of arrival (TDOA):

[0090] The following section shows how the developed correction method can also be used for the arrival time difference. When using the phase correction method for the arrival time difference, the method is referred to as an additional phase correction method.

[0091] Figure 11 shows three transceivers 10', 20', and 30' of an ultra-wideband system 10T, which is suitable for implementing a method for determining a time difference of arrival (TDOA) and is already known to a person skilled in the art. The signals 2T, 22' are transmitted between the transceivers 10', 20', and 30' with a time stamp.

[0092] The further phase correction method according to the invention is shown in a flow chart in Fig. 12 and schematically embedded in an ultra-wideband system 100' in Fig. 13.

[0093] In a first step 300 of the further phase difference correction method 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.

[0094] The first, second, and third transceivers 10, 20, 30 are each spaced apart by a distance 25, 26. The distance 25 may be different from the distance 26. The first and second transceivers each comprise a transmitter 11 and a receiver 12. The third transceiver 30 is, as shown in Fig. 13, designed as a receiver 12, although it is conceivable to also design the third transceiver 30 with a transmitter 11 and a receiver 12. The first, second, and third transceivers 10, 20, 30 each comprise a control device 13 for processing the transmitted and received signals 21, 22, 23. In particular, the third transceiver 30 may 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 just a single transceiver.It is only important that the required measured values ​​or measurement signals are measured by the receiving transceiver.

[0095] After receiving the first signal 22, 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 step 320. Furthermore, a second phase difference dP2 is determined in the third transceiver 30 between a second internal signal 32 of the third transceiver 30 and the received first signal 21 in step 330. Steps 320 and 330 preferably run concurrently. Steps 320 and 330 can also run consecutively in any order. The first internal signal 31 can, for example, correspond to the second signal 22, which is also referred to as signal B or B1 in Fig. 13. However, the first internal signal 31 may also be different 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.

[0096] In step 340, a second signal 22 is transmitted by the second transceiver 20 after expiration of a defined first delay time window V1.

[0097] 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 the third transceiver 30 in step 360. The third phase difference dP3 is determined between the second internal signal 32 of the third transceiver 30 and the received second signal 22.

[0098] In step 370, a third signal 23 is transmitted by the second transceiver 20 after a defined second delay time window V2 has elapsed by the second transceiver. In particular, the second signal 22 and / or the third signal 23 comprise / comprise information regarding the determined first phase difference dP1 or information for determining the first phase difference, as already described and to which reference is hereby made.

[0099] The first delay time window V1 specifies a time period from the reception of the first signal 21 to the transmission of the second signal 22. The first delay time window V1 can comprise a time period of a few milliseconds, in particular less than 1 ms, whereby this depends on the clock used and the extent to which the clock drifts. After a defined delay time V1, the first delay time window V1, the second transceiver 20 can send a response, i.e., the second signal 22, to the third transceiver. The delay time window V1 is viewed in relation to the time period at which the first signal 21 is received.

[0100] The second delay time window V2 specifies a time period from the reception of the first signal 21 to the transmission of the third signal 23. The second delay time window V2 can comprise a time period of a few nanoseconds, in particular less than 2 ms. After a defined delay time V2, the second delay time window V2, the second transceiver 20 can send a response, i.e., the third signal 23, to the third transceiver. The delay time window V2 is viewed in relation to the time period at which the first signal 21 is received.

[0101] 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.

[0102] Finally, in step 400, a corrected phase difference, ie 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 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).

[0103] Here, the offset correction is given by dP1 , and the drift correction is given by (dP3-dP4).

[0104] According to the further phase correction method, the first transceiver 10 and the second transceiver 20 transmit a signal 21, 22, 23, while the third, in particular passive, transceiver (receiver) 30 receives only the signals 21, 22, 23. The third transceiver determines the second, third, and fourth phase differences dP2, dP3, dP4 between the signals 21, 22, 23 of the first and second transceivers 10, 20.

[0105] Preferably, the third signal 23 is transmitted simultaneously with the second signal 22 or after expiration of the defined second delay time window V2, wherein the second delay time window V2 is greater than the first delay time window.

[0106] 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 therefrom the phase difference (a) between the first signal (21) of the first transceiver (10) and the second signal (22) of the second transceiver (20) according to a = dPcc, wherein the phase difference a corresponds to an arrival angle θ = arcsin(αA / 2TTd), where a is the phase difference dPcc, A 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 A, the signal phase corresponds to the arrival angle θ = arcsin(αA / 2TTd).

[0107] 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, 20. This procedure is also used in the phase difference correction method described above. The second signal transmitted by the second transceiver is intended to correct the phase shift, i.e., the phase drift.

[0108] The further phase correction method 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, 30. Both transceivers 20, 30 then 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, 23, also referred to as signals B1 and B2 in Fig. 13, after the delay time window V1 and the delay time window V2. The phase difference dP1 is used to correct the phase offset between the first transceiver 10 and the second transceiver 20, while the second and third signals 22, 23, or signal B1 and signal B2, 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 signal B2 and the second internal signal 32. The final corrected phase difference, i.e., the signal phase, for TDOA is equal to: dPcc = dP2 - dP3 - dP1 - (dP3 - dP4).

[0109] Fig. 14 shows the final corrected phase difference, i.e. the signal phase dPcc, which was obtained by applying the further phase difference correction method for TDOA. Fig. 14 shows the corrected phase difference, i.e. the signal phase dPcc, when the position of the third transceiver 30 is changed with real measurement data, such as a distance change of 30 cm. The signal phase is 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. Another aspect of the present invention relates to an ultra-wideband system 101 which comprises a first transceiver 10 and a second transceiver 20 and a third transceiver 30, wherein the transceivers 10, 20, 30 are each spaced apart from one another, the ultra-wideband system 101 being configured to carry out the further phase difference correction method as just described.

[0110] Another aspect of the present invention relates to computer program code that executes steps of a phase difference correction method or another 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, 30 are media that can execute the program code.

[0111] Individual aspects of the described phase difference correction method described herein also apply to the further described phase difference correction method and vice versa, without necessarily having to be repeated in detail.

[0112] A difference between the described phase difference correction method and the further described phase difference correction method is that the described phase difference correction method comprises two transceivers (see Fig. 3) and the further described phase difference correction method comprises three transceivers (see Fig. 13).

[0113] What the described phase difference correction method and the further described phase difference correction method have in common is 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.

[0114] The phase difference correction methods described here can achieve the following:

[0115] UWB phase drift correction using an additional signal.

[0116] UWB phase shift correction between two or more transceivers.

[0117] UWB phase difference correction term for TOA and TDOA. UWB frequency change to correct the distance obtained by the corrected phase difference, which corresponds to the signal phase.

[0118] Although some aspects have been described in the context of a device or arrangement, it is clear that these aspects also represent a description of the corresponding method, with a block or device corresponding to a method step or a feature of a method step. Similarly, aspects described in the context of a method step also represent a description of a corresponding block, element, or feature of a corresponding device.

[0119] 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.

[0120] Depending on specific implementation requirements, embodiments of the invention may be implemented in hardware or software. The implementation may 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 that interact or can interact with a programmable computer system to perform the respective method.

[0121] Some embodiments of the invention consist of a data carrier with electronically readable control signals that interact with a programmable computer system in such a way that one of the methods described here is carried out. In particular, the electronically readable control signals are designed to capture time stamps of a signal.

[0122] 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 performing one of the methods when the computer program product is run on a computer. The program code can be stored, for example, on a machine-readable medium. Other embodiments include the computer program stored on a machine-readable medium for performing one of the methods described herein.

[0123] In other words, an embodiment of the inventive method is therefore a computer program having program code for carrying out one of the methods described herein when the computer program is run on a computer.

[0124] A further embodiment of the inventive method is therefore a data carrier (or a digital storage medium or a computer-readable medium) containing and recorded thereon the computer program for carrying out one of the methods described herein.

[0125] A further embodiment of the inventive method is therefore a data stream or a sequence of signals representing the computer program for carrying out one of the methods described here. The data stream or signal sequence can, for example, be configured so that it can be transmitted via a data communication connection, e.g., via the Internet.

[0126] Another embodiment comprises a processing means, e.g., a computer or a programmable logic device, configured or adapted to perform any of the methods described herein.

[0127] A further embodiment comprises a computer on which the computer program for carrying out one of the methods described here is installed.

[0128] In some embodiments, a programmable logic device (e.g., a field-programmable gate array) may be used to perform some or all of the functionality of the methods described herein. In some embodiments, a field-programmable gate array may cooperate with a microprocessor to perform any of the methods described herein. In general, the methods are preferably performed by any hardware device.

[0129] The embodiments described above are merely illustrative of the principles of the present technical teachings. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended to be limited only by the scope of the appended claims and not by the specific details presented by the description and explanation of the embodiments described herein.

[0130] Bibliography

[0131] [1] https: / / patents.justia.com / patent / 20200045661

[0132] [2] https: / / patents.justia.com / patent / 10509116

[0133] [3] https: / / patents.justia.eom / patent / 10992340

[0134] [4] J. Sidorenko, V. Schatz, N. Scherer-Negenborn, M. Arens and II. 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.

[0135] [5] https: / / patentscope.wipo. int / search / en / detail.jsf?docld=WO2020165429

[0136] [6] J. Sidorenko, V. Schatz, N. Scherer-Negenborn, M. Arens and II. 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

Patent claims:

1. 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), 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), and Summing the first determined phase difference (dP1) and the second determined phase difference (dP2), thereby correcting a phase shift between the two transceivers.

2. Phase difference correction method according to claim 1, which further comprises: 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), wherein 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), in particular wherein the phase difference correction term dPc is a signal phase dPc. Phase difference correction method according to any of the preceding claims, 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).Phase difference correction method according to any 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). Phase difference correction method according to any one of the preceding claims 2 to 4, wherein for the second delay time window V2, V2 = 2 * V1. Phase difference correction method according to any one of the preceding claims, wherein, to detect a change in the 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.

7. 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, 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, where each of the different frequencies exhibits a different multiple of periods in the time window.

8. Phase difference correction method according to claim 7, which additionally comprises, or alternatively comprises according to any of the preceding claims: 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.

9. Ultra-wideband system (100) comprising: 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 any one of claims 1 to 8.

10. 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).

11. Phase difference correction method according to claim 10, 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).

12. Phase difference correction method according to claim 10 or 11, further comprising: Determining the second and third phase differences (dP2, dP3) by the third transceiver (30) in order to determine the phase difference (a) between the first signal (21) of the first transceiver (10) and the second signal (22) of the second transceiver (20) according to a = dPcc, where the phase difference a corresponds to an arrival angle 0 = arcsin(aA / 2TTd), where a is the phase difference, A is the carrier wavelength, and d is the distance between the first transceiver (10) and the second transceiver (20).

13. Ultra-wideband system (101) comprising: a first transceiver (10) and a second transceiver (20) and a third transceiver (30) spaced apart from each other, wherein the system is configured to perform a phase difference correction method according to any one of claims 10 to 12.

14. Computer program code which performs steps of a phase difference correction method according to one of claims 1 to 8 or 10 to 12 when the computer program code is executed on a program code executable medium.

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