KR20090043443A - System for mesuring distance and location - Google Patents

Abstract

The present invention relates to a distance and position measurement system, comprising: a tag; A reference transmitter for transmitting a reference signal upon receiving a measurement request signal; And an anchor measuring a distance between the tag or a position of the tag by calculating a difference between arrival times of the measurement request signal and the reference signal. According to the present invention, by transmitting a reference signal only when position measurement is required, frequency resources can be shared to increase efficiency of radio resources.

Distance, position measurement, reference signal, reference transmitter, tag, anchor

Description

Distance and position measurement system {SYSTEM FOR MESURING DISTANCE AND LOCATION}

The present invention relates to a distance and position measurement system, and more particularly, the present invention transmits a reference signal only when position measurement is required, corrects a delay time of a tag and an anchor, and minimizes a clock error between the tag and the anchor. The present invention relates to a method for measuring distance and position for improving efficiency of radio resources, sharing frequency resources, and compensating round trip time measurement errors between tags and anchors.

There are two systems for distance and position measurement, one-way distance and position measurement system and two-way distance and position measurement system.

The first system is a one-way distance measuring system that measures the distance by sending a signal from a tag and receives a signal at the anchor, or vice versa, and a signal at the anchor and a signal at the tag, and a unidirectional position using the same to measure the distance. Measurement system. In this case, a target whose position is to be measured is called a tag, and a distributed transmitter / receiver performing the measurement is called an anchor.

This one-way distance and position measurement system is very simple to configure, and the tags and anchors can be configured so that only the transmitter or receiver exists, so the configuration cost is low and suitable for low power configuration, while accurate distance and position Because measurement requires synchronization between anchors, there may be additional configuration problems.

In addition, the second system transmits a signal at an anchor, receives it at a tag, and transmits a response. The second system receives the signal at the anchor and calculates a round trip time to measure a distance, and uses the same to measure a position. Bidirectional position measuring system.

This bidirectional distance and position measurement system is a system that calculates the time taken by the tags and anchors to send and receive signals, and calculates the time required for round trip time, thereby performing distance and position measurement. This system overcomes the motivation problem.

In practice, such a bidirectional distance and position measurement system requires processing delay time for response to a transmission / reception signal that is much longer than the transmission delay time between the anchor and tag of the radio signal. However, such a processing delay time causes an error in time measurement during the processing delay time and a transmission time when there is an error in the clock between the anchor and the tag, and as a result, causes an error in the distance and position measurement. That is, although the bidirectional distance and position measurement system can fundamentally overcome the synchronization problem in the unidirectional distance and position measurement, there is a problem that an error occurs in the distance and position measurement by the clock error of the anchor and the tag. Looking at these technologies in more detail as follows.

1 is an explanatory diagram of an embodiment of a conventional unidirectional distance measuring system.

First, when the transmitting unit 101 transmits a predetermined signal, the receiving unit 102 receives the signal transmitted by the transmitting unit 101 to check the delay time for transmitting / receiving and determines the distance between the two points. Calculate Here, it is assumed that the delay time D _T of the transmitter 101 and the delay time D _R of the receiver 102 are basically recognized values, and the absolute time reference is set.

FIG. 2 is an explanatory diagram of an embodiment of a system in which the unidirectional distance measuring method of FIG. 1 is applied to position measurement, and shows three ways in which three anchors measure the position of one tag.

First, when the tag 204 transmits a predetermined signal periodically or at a point in time where position measurement is needed, each anchor 201, 202, 203 detects the corresponding signal to measure the arrival time. In this case, if the delay time D _T of the tag 204 and the delay times D _R1 , D _R2 , and D _R3 of the anchors 201, 202, and 203 are correctly recognized, the absolute distance between the tag and the anchor is measured. The exact location of the tag can be determined, but it is difficult to accurately recognize these delay values.

)를 이용하여, 앵커들(201, 202, 203) 간의 거리 차이가 동일한 점들의 집합인 쌍곡선의 교점을 구하는 방식으로 위치를 인식할 수 있다. 여기서는 각각의 앵커들이 동기화가 정확히 이루어져 있어야 한다는 가정이 포함되어 있다. 동기화에 존재하는 만큼의 오차는 측정하는 태그 위치의 오차로 반영된다. Meanwhile, when the delay time D _T of the tag 204 and the delay times D _R1 , D _R2 , and D _R3 of the anchors 201, 202, and 203 are not recognized, the three anchors 201, Difference in time of arrival of signals received at 202 and 203 (eg, difference in signal arrival time at first anchor 201 and second anchor 202)

), The position can be recognized in such a manner as to obtain an intersection of a hyperbolic curve in which the distance difference between the anchors 201, 202, and 203 is the same set of points. This includes the assumption that each anchor must be correctly synchronized. Any errors present in the synchronization are reflected in the error of the tag position being measured.

In addition, even if the delay time of the anchors 201, 202, 203 is not recognized or recognized correctly, the assumption that the delay times of the respective anchors 201, 202, 203 should be the same. It is difficult to accurately recognize or equalize the delay times of all anchors 201, 202, and 203 when actually configuring the system, and if the delay times of all anchors 201, 202, and 203 are set equally. Even if the change occurs over time, the change may be reflected as an error in the position measurement of the tag.

FIG. 3 is an explanatory diagram of another embodiment of a system in which a conventional unidirectional distance measuring method is applied to position measurement. FIG. The applied unidirectional position measuring method is shown.

First, the reference transmitter 301 transmits a predetermined signal always or periodically in advance. Then, each of the anchors 302, 303, 304 receives a signal transmitted from the reference transmitter 301 and sets the signal arrival time of the reference transmitter 301 as the reference time.

In addition, each of the anchors 302, 303, 304 measures a time difference between the reference time and the arrival time of the signal received from the tag when receiving a signal from the tag 305, and the reference transmitter 301 is already recognized. ) And the measured arrival time difference are corrected using the position of the anchors 302, 303, and 304.

Also, as shown in FIG. 2, the distance between the anchors 302, 303, 304 and the reference transmitter 301 at the difference in the signal arrival time of the tag 305 corrected by the respective anchors 302, 303, 304. Correct the difference (e.g., time R ₁₂ for the signal to travel the distance difference between anchor 1 302 and anchor 2 303 from the reference transmitter 301), thereby using the anchors 302, 303 The location of the tag 305 is measured in such a way that the intersection of the hyperbola, which is a set of points with the same distance difference, is obtained.

The problem of synchronization between anchors of the unidirectional distance and position measuring system of FIGS. 1 and 2 and accuracy due to the difference of each transmitting / receiving system can be properly solved using the reference transmitter as shown in FIG. 3.

However, when applying the reference transmitter as shown in FIG. 3, the reference signal should be transmitted at all times or at a predetermined period (so that the difference between the reference clocks of the anchors within the period does not significantly affect the position error). When the location information request is intermittent or when the time required for the location information of the tag occurs randomly, it is not only very inefficient to transmit the reference signal at regular intervals or at a predetermined period, but also it is difficult to share the corresponding frequency resource. There is this.

4 is an explanatory diagram of one embodiment of a conventional bidirectional distance measurement system, and illustrates a method of performing distance measurement using a round trip time so that synchronization between anchors is not required.

First, when a signal transmitted from the right transmitting / receiving unit 402 is detected by the left transmitting / receiving unit 401, the left transmitting / receiving unit 401 receives a predetermined response signal which is promised in advance after a predetermined processing time D _P. Send. The right transmitter / receiver 402 calculates a round trip time by measuring the arrival time of a signal transmitted from the left transmitter / receiver 401, and takes a signal to move a distance between two points corresponding to half of the calculated round trip time. Measure this by considering the time taken.

5 and 6 are explanatory views of one embodiment of a system in which the bidirectional distance measurement method of FIG. 4 is applied to position measurement. FIG. 5 illustrates a method for passively responding to a tag requiring location, and FIG. 6 illustrates a method for actively responding to a tag requiring location. Since the passive tag 501 of FIG. 5 needs to keep searching whether a signal arrives from the anchors 502, 503, and 504, power consumption may increase when using a battery. When the active tag 601 of FIG. 6 wants to know the location, there is a problem in that a link for informing the anchors 602, 603, and 604 of the location is additionally configured.

This bidirectional distance and position measurement system does not require absolute synchronization between anchors, thus eliminating the need for expensive oscillators and the need for additional reference transmitters, such as in unidirectional distance and position measurement systems. .

However, in the practical application of cheap, low-accuracy oscillators in bidirectional distance and position measurement systems, the processing time (D _P ) required for signal transmission / reception reactions and separations, etc., must be included, compared to actual round trip transmission / reception. Due to the very large value, the difference in the oscillator value between the anchor and the tag may cause the predetermined predetermined processing time to be actually processed differently by the clock error, and finally be reflected as the measurement error of the round trip time. have.

The present invention aims to solve the problems of the prior art as described above.

Specifically, an object of the present invention is to overcome the problem of inefficient application and coexistence of radio resources due to periodic signal transmission using a reference transmitter that transmits a reference signal only when position measurement is required.

In addition, another object of the present invention is to compensate for the round trip time measurement error of the tag and the anchor by correcting the delay time of the tag and the anchor and minimizing the clock error between the tag and the anchor.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned above can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The present invention for achieving this object is a distance and position measurement system, the tag; A reference transmitter for transmitting a reference signal upon receiving a measurement request signal; And an anchor measuring a distance between the tag or a position of the tag by calculating a difference between arrival times of the measurement request signal and the reference signal.

The present invention also provides a distance and position measurement system, comprising: a tag transmitting a second signal upon receiving a first signal and transmitting a third signal after a predetermined time; And an anchor for transmitting the first signal to the tag and measuring a distance to the tag or a position of the tag by using arrival times of the second and third signals received from the tag. It is done.

The present invention also provides a distance and position measurement system, comprising: a tag that receives a first signal and transmits it as a second signal, and feeds back the second signal as a third signal; And transmitting the first signal to the tag, feeding back the first signal as a fourth signal, and using the second signal, the third signal, and the fourth signal to determine the distance to the tag or the position of the tag. Another feature is to include an anchor to measure.

In addition, in the tag used in the bidirectional distance and position measurement system, the tag detects a signal transmitted from the anchor constituting the measurement system, it is stored for a predetermined time and then transmitted to the anchor It is another feature.

In addition, the present invention is a distance and position measuring system having a signal transmitting unit and a signal receiving unit, the signal transmitting unit and at the same time receiving the signal transmitted by the signal receiving unit to receive the signal transmission and signal Another feature is to measure the time delay required for reception.

The present invention having such a configuration can overcome the problem of inefficient application and coexistence of radio resources due to periodic signal transmission by providing a distance and position measuring method using a reference transmitter that transmits a reference signal only when position measurement is required. It works. In addition, the present invention has the effect of compensating the round trip time measurement error of the tag and the anchor by providing a distance and position measurement system for correcting the delay time of the tag and the anchor and minimizes the clock error between the tag and the anchor.

The above objects, features, and advantages will become more apparent from the detailed description given hereinafter with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains may share the technical idea of the present invention. It will be easy to implement. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 7 is an explanatory diagram of an embodiment of a unidirectional distance and position measurement system using a reference transmitter according to the present invention. In addition, a receiver is added to the reference transmitter to receive a position measurement request signal of a tag, and thus the position measurement of the tag is required A unidirectional distance and position measurement method in which a reference transmitter transmits a reference signal is shown.

First, the reference transmitter 701 transmits a predetermined signal by triggering the transmitter only when the position measurement request signal is received from the tag 702 rather than always or unconditionally transmitting a signal at predetermined time intervals. . At this time, the time interval until the reference transmitter 701 transmits a predetermined signal on the basis of the time point at which the position measurement request signal from the tag 702 is received is determined according to the network configuration method. It can be configured to avoid collisions. In this case, the reference transmitter 701 may transmit the reference signal by a predetermined external trigger signal, in addition to the position measurement request signal transmitted from the tag 702.

In addition, the reference transmitter 701 adjusts a code or code offset for each reference transmitter when transmitting a predetermined signal, so that the anchors 703, 704, and 705 separate signals from the respective reference transmitters. To receive it. Alternatively, when the reference transmitter 701 transmits a predetermined signal, the tag 702 frequently transmits the position measurement request signal by not transmitting the signal within a predetermined time in consideration of the latest signal transmission time. When transmitting, the reception efficiency of the anchors 703, 704, and 705 may be increased.

Thereafter, each of the anchors 703, 704, and 705 additionally detects a signal from the reference transmitter 701 when the position measurement request signal from the tag 702 is detected and regards it as a reference time. The distance from the tag 702 may be measured by calculating a time difference of the position measurement request signal, and the position of the tag 702 may be recognized as an intersection of a hyperbola using the measured distance information.

The unidirectional distance and position measurement system using such a reference transmitter can overcome the problems of the prior art of FIG. 4. That is, the unidirectional distance and position measurement system using the reference transmitter may increase the efficiency of radio resources, share frequency resources, and reduce interference of radio signals around the network and surroundings.

FIG. 8 is an explanatory diagram of one embodiment of a bidirectional distance measuring system according to the present invention, and illustrates a dual bidirectional distance measuring method configured to compensate for a round trip time measurement error of FIG. 5. That is, the bidirectional distance measuring system according to the present invention transmits an additional signal in addition to the basic transmission signal during the transmission / reception reaction so as to compensate for the error of the reference clocks of the two transmission / reception units in calculating the round trip time in the bidirectional distance measurement. The first transmitter can compensate for the clock error.

First, the right transmitter / receiver 802 transmits a signal to the left transmitter / receiver 801. Thereafter, the left transmitting / receiving unit 801 transmits a response signal to the signal transmitted from the right transmitting / receiving unit 802, and transmits a predetermined processing time D _{P ′} of the left transmitting / receiving unit 801. The reference clock is processed to send additional signals. The right transmitter / receiver 802 then measures the arrival time of the response signal transmitted from the left transmitter / receiver 801 and the additional signal arriving after a predetermined predetermined processing time D _{P ′} .

Here, the difference between the measured arrival time of the response signal and the arrival time of the additional signal is different from the arrival time of the additional signal regardless of the delay time of the left transmitter / receiver 801 and the right transmitter / receiver 802, The measurement is performed at a value different from the predetermined additional processing time D _{P ′ that} is previously promised by the clock error D _P between the transmitter / receiver 801 and the right transmitter / receiver 802.

The right transmitting / receiving unit 802 corrects the processing time D _P from the original signal arrival time by using the difference between the measured response signal and the arrival time of the additional signal, where τ is the left round time (τ is the left side). Calculates the transmission time between the transmitter / receiver 801 and the right transmitter / receiver 802, and calculates the error due to the clock error of the left transmitter / receiver 801 and the right transmitter / receiver 802. D _P ) is removed.

9 is an explanatory diagram of an embodiment of a system in which the bidirectional distance measurement method of FIG. 8 is applied to position measurement. Here, in the bidirectional positioning system, there are two methods of starting the initial signal transmission from a tag or an anchor, but the position measuring method of configuring the tag generally simple and inexpensively due to the relatively high complexity of the initial signal transmitting unit. In the present invention, it is preferable to transmit the first signal at the anchor, and as an example, the first signal is transmitted at the anchor, but the present invention is not limited thereto.

First, anchor 902 sends a signal to tag 901. The tag 901 processes the response signal 904 to the signal 903 transmitted from the anchor 902 and an additional predetermined predetermined processing time D _{P '} as a reference clock to transmit the signal 905. do. In addition, the anchor 902 measures the arrival time of the response signal 904 transmitted from the tag 901 and the additional signal 905 transmitted after a predetermined processing time D _{P ′ which} is previously promised. As described above, the position of the tag 901 is measured by obtaining the intersection of the hyperbola by using the corrected signal (corrected distance information).

FIG. 10 is an explanatory diagram of another embodiment of a bidirectional distance measuring system according to the present invention, in which a difference between a reference clock and two transmitter / receivers contributes to an error in calculating a round trip time in a bidirectional distance measurement. A self-correcting bidirectional distance measurement method that is not affected by changes in latency.

First, the right transmitter / receiver 1002 transmits a predetermined signal (including a preamble 1003 and a selectable payload 1004) and at the same time, transmits / receives its own. Instantaneous delay of D _T1 Feedback the corresponding signal to measure + D _R1 ).

The left transmitter / receiver 1001 receives the signal transmitted from the right transmitter / receiver 1002 to detect the preamble, and captures (stores) the received signal in the internal memory by the length of the packet from the preamble detection delay time. In this case, since the time required for the preamble detection (ie, the preamble detection delay time) is considerably shorter than the preamble length, the left transmitter / receiver 1001 does not use the memory, but the memory does not lose as much as the preamble detection delay time. It is also possible to capture (store) the received signal using.

In addition, the left transmitter / receiver 1001 starts transmitting the captured (stored) signal at the time point of storing the captured (stored) signal in the internal memory by the packet length, and feeds back the corresponding signal by feeding back the corresponding signal ( 1005) is continuously captured (stored) for a predetermined time. Here, the left transmitter / receiver 1001 transmits the feedback signal to the preamble length and its own transmit / receive delay time (D _T2). + D _R2 ) (ie at least up to the preamble end point of the fed back signal). The left transmitter / receiver 1001 transmits the captured signal to the right transmitter / receiver 1002 until the capture (storage) is completed.

The right transmitter / receiver 1002 receives the signal 1007 transmitted from the left transmitter / receiver 1001, measures up to the preamble end point 1008 of its feedback signal 1006, and measures it up to a reference time point (that is, D). _T1 + D _R1 + preamble length), and two points 1009 and 1010 corresponding to the end of the preamble of the signal 1007 transmitted from the left transmitter / receiver 1001 are measured.

Subsequently, the right transmitter / receiver 1002 is disposed between the first preamble end point 1009 and the end point 1010 of the second preamble from the time A from the reference time point 1008 to the first preamble end point 1009. Calculate the difference of time (B), and determine the round trip time (A-B) between the two transmitters / receivers 1001 and 1002 from which the delay time of the left transmitter / receiver 1001 and the right transmitter / receiver 1002 has been eliminated. You can get it. At this time, half of the round trip time is the time required for transmission between the two transmitters / receivers 1001 and 1002, thereby enabling distance measurement irrespective of the delay time between the transmitters / receivers 1001 and 1002.

Here, A is '(D _T2 + D _R2 ) + 2τ + packet length', and B is '(D _T2 + D _R2 ) + packet length'. Therefore, the round trip time A-B is 2τ, and the transfer time τ is (A-B) / 2.

FIG. 11 is an explanatory diagram of an embodiment in which the bidirectional distance measuring method of FIG. 10 is applied to a position measuring system. Here, in the bidirectional positioning system, there are two methods in which the initial signal transmission starts from a tag or an anchor. However, since the complexity of the initial signal transmission side is relatively high, a position measurement that generally requires a simple and inexpensive configuration of a tag. In the scheme, it is preferable to transmit the first signal at the anchor, so as an example, the first signal is transmitted at the anchor, but the present invention is not limited thereto.

First, the anchor 1102 transmits a predetermined signal (including a preamble and a selectable payload) while feeding back a corresponding signal.

The tag 1101 receives the signal transmitted from the anchor 1102 to detect the preamble, and captures (stores) the received signal in the internal memory by the length of the packet from the preamble detection delay time. In addition, the tag 1101 starts transmitting the captured (stored) signal at the time when the captured (stored) signal is stored in the internal memory by the packet length, and feeds back the signal by feeding back the corresponding signal for a predetermined time. Capture (store) continuously while In addition, the tag 1101 transmits the captured (stored) signal to the anchor 1102 until the capture (store) is completed.

The anchor 1102 measures the distance independent of the delay time between the tag 1101 and the anchor 1102 using the signal transmitted from the tag 1101 and its feedback signal (see FIG. 10). In addition, the anchor 1102 measures the position of the tag 1101 using a measured distance information to find the intersection of the hyperbola.

In such a bidirectional positioning system, the tag does not need to accurately detect the arrival time of the signal from the anchor, and thus the error may be solved by measuring the arrival time of both the tag and the anchor during bidirectional distance measurement. That is, in such a bidirectional position measurement system, the accuracy of the signal may be further improved by merely performing signal detection on the side (for example, the anchor 1102) that originally transmitted the signal.

Such a bidirectional distance and position measurement system according to the present invention can additionally overcome not only the measurement error due to the clock error between the anchor and the tag, but also the error due to the delay time difference or the change according to the time between the anchor and the tag.

On the other hand, the method of the present invention as described above can be written in a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. The recording medium may include any type of computer readable recording medium.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

1 is an explanatory diagram of an embodiment of a conventional unidirectional distance measuring system.

FIG. 2 is an explanatory diagram of an embodiment of a system in which the unidirectional distance measuring method of FIG. 1 is applied to position measurement.

3 is an explanatory diagram of another embodiment of a system in which a conventional unidirectional distance measuring method is applied to position measurement.

4 is an explanatory diagram of an embodiment of a conventional bidirectional distance measurement system.

5 and 6 are explanatory views of one embodiment of a system in which the bidirectional distance measurement method of FIG. 4 is applied to position measurement.

7 is an explanatory diagram of an embodiment of a unidirectional distance and position measurement system using a reference transmitter according to the present invention.

8 is an explanatory diagram of an embodiment of a bidirectional distance measurement system according to the present invention.

9 is an explanatory diagram of an embodiment of a system in which the bidirectional distance measurement method of FIG. 8 is applied to position measurement.

10 is an explanatory diagram of another embodiment of a bidirectional distance measurement system according to the present invention.

FIG. 11 is an explanatory diagram of an embodiment in which the bidirectional distance measuring method of FIG. 10 is applied to a position measuring system.

Claims (19)

tag; A reference transmitter for transmitting a reference signal upon receiving a measurement request signal; And Anchor for measuring the distance between the tag or the position of the tag by calculating the difference between the arrival time of the measurement request signal and the reference signal; Distance and position measurement system. The method of claim 1, The anchor is provided with three or more, The position of the tag is measured using the difference in distance between the anchors to the tag Distance and position measurement system. The method according to claim 1 or 2, The reference transmitter transmits the reference signal after a predetermined time from when the measurement request signal is received. Distance and position measurement system. The method according to claim 1 or 2, The reference transmitter transmits the reference signal by adjusting a code or code offset for each reference transmitter so that the anchor can distinguish the reference signal. Distance and position measurement system. The method according to claim 1 or 2, The reference transmitter transmits the reference signal after a predetermined time from the latest transmission time of the reference signal. Distance and position measurement system. The method according to claim 1 or 2, The measurement request signal is transmitted from the tag Distance and position measurement system. The method according to claim 1 or 2, The measurement request signal is an external trigger signal Distance and position measurement system. A tag for transmitting a second signal upon receiving the first signal and transmitting a third signal after a predetermined time; And An anchor for transmitting the first signal to the tag and measuring a distance to the tag or a position of the tag by using arrival times of the second and third signals received from the tag. Distance and position measurement system. The method of claim 8, The anchor compensates for a clock error between the tag and the anchor by using a difference in arrival times of the second and third signals. Distance and position measurement system. The method according to claim 8 or 9, The anchor is provided with three or more, The position of the tag is measured using the difference in distance between the anchors to the tag Distance and position measurement system. A tag that receives a first signal and transmits it as a second signal and feeds back the second signal as a third signal; And The first signal is transmitted to the tag, the first signal is fed back as a fourth signal, and the distance to the tag or the position of the tag is measured using the second signal, the third signal, and the fourth signal. Containing anchor Distance and position measurement system. The method of claim 11, The anchor is provided with three or more, The position of the tag is measured using the difference in distance between the anchors to the tag Distance and position measurement system. The method of claim 11, The first signal is a packet signal having a preamble. Distance and position measurement system. The method of claim 13, The tag stores the received signal from the preamble detection delay time to at least an end point of the preamble of the signal fed back to the second signal after detecting the preamble from the first signal. Distance and position measurement system. The method of claim 14, The tag starts transmitting the stored signal to the anchor at the time when the received signal is stored by the length of the packet. Distance and position measurement system. The method of claim 15, The anchor may be a distance from the tag or the tag using a time difference between an end point of the preamble of the fourth signal and the second signal and a time difference between an end point of the preamble of the second signal and the third signal. To measure the position of Distance and position measurement system. For tags used in bidirectional distance and position measurement systems, When the tag detects a signal transmitted from the anchor constituting the measurement system, the tag is stored for a predetermined time and then transmitted to the anchor Distance and position measurement system. The method of claim 17, The tag receives a signal transmitted from the tag to the anchor and retransmits the signal to the anchor. Distance and position measurement system. In the distance and position measurement system having a signal transmitter and a signal receiver, Simultaneously transmitting a signal by the signal transmitter and receiving the signal transmitted by the signal receiver to measure a time delay required for signal transmission and signal reception. Distance and position measurement system.

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