Measurement system and method for measurement

Abstract

To easily measure the distance between two arbitrary points or the change of the distance by using a sound wave.SOLUTION: A measurement system 100 includes: a first acoustic wave guide tube 101; a first sending / receiving unit 102 for sending a pulse-like first sound wave SW1 to the inside of the first acoustic wave guide tube 101 and receiving a first reflection wave RW1 formed by the first sound wave SW1 reflected by a first reflection unit 105 in the first acoustic wave guide tube 101: and a measurement device 106 for determining the distance between the first sending / receiving unit 102 and the first reflection unit 105 or the change of the distance on the basis of a first time from the transmission of the first sound wave SW1 to reception of the first reflection wave RW1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a measurement system and a measurement method. [Background technology]

[0002] Various devices have been proposed for measuring distances using sound waves. For example, Patent Document 1 discloses an acoustic pipe length measuring device for measuring the length of a tubular member from the time it takes for a speaker to send out a pulsed sound wave from one end of the tubular member until the reflected wave is collected by a microphone. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-297816 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even if the length of a tubular member can be measured by the acoustic pipe length measuring device described in Patent Document 1, it is difficult to measure the distance between any two points or the change therein.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a measurement system and a measurement method capable of measuring the distance between any two points or a change therein using sound waves. [Means for solving the problem]

[0006] In order to achieve the above object, a measurement system according to a first aspect of the present invention comprises: a first acoustic waveguide; a first transceiver that transmits a pulsed first sound wave into the first acoustic waveguide and receives a first reflected wave that is the first sound wave reflected by a first reflecting section inside the first acoustic waveguide; The device is equipped with a measuring device that determines the distance or the change therein between the first transceiver unit and the first reflector unit based on a first time from when the first sound wave is transmitted to when the first reflected wave is received.

[0007] In order to achieve the above object, a measurement method according to a second aspect of the present invention comprises: A pulsed first acoustic wave is transmitted into a first acoustic waveguide; receiving a first reflected wave that is the first sound wave reflected by a first reflecting portion inside the first acoustic waveguide; The distance between the first transceiver and the first reflector or a change therein is calculated based on a first time from when the first sound wave is transmitted to when the first reflected wave is received. Effect of the Invention

[0008] According to the present invention, it is possible to measure the distance between any two points or the change therein by using sound waves. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a measurement system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a functional configuration of a measurement device according to the first embodiment. [Diagram 3] 6 is a diagram showing an example of a waveform of a first sound wave SW1. FIG. [Figure 4] 11(a) to 11(c) are diagrams showing exemplary waveforms of a first received signal RS1 including a first reflected signal FS1, a first pulse PA1, and a second pulse PA2. [Diagram 5] 4 is a diagram illustrating an example of a functional configuration of a detection unit according to the first embodiment. FIG. [Figure 6] FIG. 4 is a diagram illustrating an example of the functional configuration of a measurement unit according to the first embodiment. [Figure 7] 5 is a flowchart showing an example of a measurement process according to the first embodiment. [Figure 8] 6 is a flowchart showing a detailed example of a detection process according to the first embodiment. [Figure 9]FIG. 4 is a diagram illustrating an example of a configuration of measurement information. [Figure 10] 2 is a diagram illustrating an example of a physical configuration of a first transceiver unit according to the first embodiment. FIG. [Figure 11] FIG. 2 is a diagram illustrating an example of the physical configuration of the measurement device according to the first embodiment. [Figure 12] 23 is a flowchart showing a detailed example of a detection process according to the 11th modification. [Figure 13] FIG. 11 is a diagram illustrating an example of the configuration of a measurement system according to a second embodiment. [Figure 14] FIG. 11 is a diagram illustrating an example of a functional configuration of a measurement device according to a second embodiment. [Figure 15] 11 is a flowchart showing an example of a sound speed measurement process according to the second embodiment. [Figure 16] FIG. 11 is a diagram showing an example of the configuration of a measurement system 300 according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0011] <Embodiment 1> A measurement system 100 according to a first embodiment of the present invention, an example of its configuration is shown in FIG. 1, and is a system for measuring a distance R or a change ΔR therein between a reference point P1 and a measurement point P2.

[0012] The reference point P1 is a point that serves as a reference for measuring the distance R or the change ΔR therein. The measurement point P2 is a target point for measuring the distance R or the change ΔR therein from the reference point P1. In this embodiment, an example will be described in which the reference point P1 and the measurement point P2 are points set on the ground.

[0013] Each of the reference point P1 and the measurement point P2 may be set arbitrarily, and may be set, for example, on a building, a structure, an apparatus, a device, an instrument, a product, or the like.

[0014] The measurement system 100 includes a first acoustic waveguide 101, a first transmitting / receiving section 102, a first fixing member 103, a second fixing member 104 including a first reflecting section 105, a measurement device 106, and an external device 107.

[0015] The first transceiver 102 and the measuring device 106 transmit and receive information to and from each other via a communication network N1 that is wired, wireless, or a combination of both. The measuring device 106 and the external device 107 transmit and receive information to and from each other via a communication network N2 that is wired, wireless, or a combination of both. The communication network N1 and the communication network N2 may be a common network or may be different networks.

[0016] The first acoustic waveguide 101 is an acoustic waveguide.

[0017] An acoustic waveguide is a hollow tube for propagating sound waves. It is desirable for sound waves to propagate through the hollow inside of an acoustic waveguide as approximately plane waves in order to minimize reflection and attenuation at the inner wall of the acoustic waveguide. The conditions for realizing such sound wave propagation can be defined by the relationship between the inner diameter of the acoustic waveguide and the wavelength (or frequency) of the sound wave.

[0018] If the inner diameter is larger than the wavelength of the sound wave, multipath occurs in the propagation path, and the sound wave is reflected in a direction different from the traveling direction. If the inner diameter is smaller than the wavelength of the sound wave, the propagation impedance increases, and the sound wave is attenuated. From this viewpoint, the wavelength of the sound wave propagating inside the acoustic waveguide is preferably, for example, about 1 / 2 to 1 / 4 of the inner diameter of the acoustic waveguide.

[0019] The first acoustic waveguide 101 has an appropriate length required for measuring the distance R between the reference point P1 and the measurement point P2, and is provided so as to extend between the reference point P1 and the measurement point P2.

[0020] In detail, for example, the first acoustic waveguide 101 is a circular tube having a circular cross section when viewed along the length direction. The inner diameter of the first acoustic waveguide 101 is, for example, about 5 to 30 mm. The distance R is, for example, about several cm (centimeters) to 100 m (meters). The material of the first acoustic waveguide 101 is, for example, metal, resin, or rubber. The first acoustic waveguide 101 may be a rigid tube that does not bend or flex, or may be a flexible tube. The first acoustic waveguide 101 may be a non-transparent tube, or may be a transparent or semi-transparent tube that is translucent.

[0021] The shape, dimensions, material, and composition of the first acoustic waveguide 101 may be changed as appropriate. The material of the first acoustic waveguide 101 is preferably one with a small thermal expansion coefficient.

[0022] The first transceiver 102 is a member that transmits and receives sound waves.

[0023] The first transceiver 102 receives a transmission signal from, for example, the measuring device 106 and outputs a first sound wave SW1. The first sound wave SW1 is a pulsed sound wave. When the first transceiver 102 receives a sound wave, it outputs a first reception signal RS1 corresponding to the received sound wave to the measuring device 106.

[0024] The first transceiver 102 is disposed so as to transmit a first sound wave SW1 into the first acoustic waveguide 101. The first transceiver 102 is also disposed so as to receive a first reflected wave RW1. The first reflected wave RW1 is a sound wave that is the first sound wave SW1 reflected by a first reflecting section 105 inside the first acoustic waveguide 101.

[0025] In detail, first transmitting / receiving unit 102 according to this embodiment is disposed at or near one end of first acoustic waveguide 101 with a portion for sending sound waves and a portion for receiving sound waves facing inward of first acoustic waveguide 101. Moreover, first transmitting / receiving unit 102 according to this embodiment is fixed to first acoustic waveguide 101.

[0026] Here, "vicinity" means a predetermined range from a certain position, for example, "vicinity of one end" means a predetermined range from the one end. The same applies hereinafter.

[0027] That is, the first transmitter / receiver 102 sends out a first sound wave SW1 into the inside of the first acoustic waveguide 101 and receives a first reflected wave RW1 that is generated when the first sound wave SW1 is reflected by a first reflecting section 105 inside the first acoustic waveguide 101.

[0028] When the first transceiver 102 receives the first reflected wave RW1, it outputs a first received signal RS1 including a first reflected signal FS1. The first reflected signal FS1 is a signal corresponding to the first reflected wave RW1.

[0029] The first reception signal RS1 including the first reflected signal FS1 often includes not only the first reflected signal FS1 but also a noise signal. Therefore, the first reception signal RS1 including the first reflected signal FS1 does not usually completely match the first reflected signal FS1, and becomes a signal in which a noise signal is superimposed on the first reflected signal FS1 (see FIG. 4(a)). The noise signal includes a noise signal based on noise (sound other than the first reflected wave RW1) received by the first transmission / reception unit 102, a noise signal caused by an electrical system, and the like. An example of a noise signal caused by an electrical system is a noise signal based on external noise mixed into an electronic circuit.

[0030] In Fig. 4(a), the level of the noise signal is shown large relative to the level of the first reflected signal FS1 for ease of understanding. In reality, the magnitude of the level of the noise signal relative to the level of the first reflected signal FS1 is usually smaller than that shown in Fig. 4(a).

[0031] The first fixing member 103 is a member for fixing the first transceiver 102 to a reference point P1. In the present embodiment, the base end of the first fixing member 103 is fixed to the reference point P1, and the first transceiver 102 is fixed to the tip end of the first fixing member 103. It is sufficient for the first fixing member 103 to fix or hold the first transceiver 102, and the part of the first fixing member 103 does not have to be the tip end.

[0032] That is, in this embodiment, the first transceiver 102 is fixed with respect to the reference point P1 using the first fixing member 103. As a result, the position of the first transceiver 102 is associated with the reference point P1.

[0033] Note that the first transmitting / receiving unit 102 does not need to be fixed with respect to the reference point P1 as long as the first transmitting / receiving unit 102 is associated with a positional relationship with the reference point P1.

[0034] The first fixing member 103 is, for example, a metal rod, but the material, composition, and shape thereof may be changed as appropriate.

[0035] The second fixing member 104 is a member including a first reflecting portion 105. The first reflecting portion 105 is a portion that reflects the first sound wave SW1 sent out from the first transceiver 102. The first reflecting portion 105 is disposed inside the first acoustic waveguide 101.

[0036] In detail, the second fixing member 104 includes a fixing portion 104 a and a disk portion 104 b including the first reflecting portion 105 .

[0037] The base end of the fixed portion 104a is fixed to the measurement point P2, and the disk portion 104b is fixed to the tip of the fixed portion 104a. In the example shown in Fig. 1, the fixed portion 104a is a generally L-shaped rod bent between the base end and the tip, but the shape of the fixed portion 104a may be changed as appropriate.

[0038] The disk portion 104b has a disk shape with a diameter smaller than the inner diameter of the first acoustic waveguide 101, and fits loosely into the first acoustic waveguide 101. The disk portion 104b is disposed at the other end of the first acoustic waveguide 101 or in the vicinity of the other end.

[0039] The first reflecting portion 105 is one of the two main surfaces of the disk portion 104b that is opposite to the surface to which the fixed portion 104a is fixed, i.e., the surface facing inward of the first acoustic waveguide 101. The first reflecting portion 105 faces the first transceiver portion 102 across an internal space extending in the longitudinal direction of the first acoustic waveguide 101.

[0040] The first reflecting portion 105 forms, for example, a flat surface. Note that the first reflecting portion 105 may have any shape that reflects the first sound wave SW1, and may be a curved surface or the like, without being limited to a flat surface.

[0041] That is, in this embodiment, the first reflecting unit 105 is fixed with respect to the measurement point P2 using the second fixing member 104. As a result, the position of the first reflecting unit 105 is associated with the measurement point P2.

[0042] As described above, the disk portion 104b has a smaller diameter than the inner diameter of the first acoustic waveguide 101. Therefore, the first reflecting portion 105 is movable inside the first acoustic waveguide 101.

[0043] However, the second fixing member 104 is not limited to this. For example, the second fixing member 104 may be a rod-shaped member, and in this case, an end face of the second fixing member 104 disposed inside the first acoustic waveguide 101 may be used as the first reflecting portion 105.

[0044] (Example of Functional Configuration of Measuring Device 106) The measuring device 106 is a device for determining the distance R or its change ΔR based on the first time. The first time is the time from when the first sound wave SW1 is transmitted by the first transceiver 102 to when the first reflected wave RW1 is received. As described above, the distance R is the distance between the reference point P1 and the measurement point P2.

[0045] In detail, the measuring device 106 includes an acoustic wave control unit 108, a detection unit 109, a measurement unit 110, a history storage unit 111, and a communication unit 112, as shown in an example of the functional configuration in FIG.

[0046] The sonic wave control unit 108 causes the first transceiver unit 102 to transmit the pulsed first sonic wave SW1. In detail, for example, the sonic wave control unit 108 outputs a transmission signal to the first transceiver unit 102 to cause the first transceiver unit 102 to transmit the pulsed first sonic wave SW1.

[0047] Fig. 3 is a diagram showing an example of the waveform of the first sound wave SW1. The horizontal axis of Fig. 3 indicates time (unit: seconds, for example) and the vertical axis indicates the sound volume (unit: decibels, for example). The first sound wave SW1 shown in Fig. 3 has a time length (pulse width) during which the volume is A1 is PTS1, and the volume is 0 otherwise. The pulse width PTS1 is, for example, 0.5 mS (milliseconds). The first sound wave SW1 is, for example, an ultrasonic wave, and its frequency is, for example, 20 kHz to 40 kHz.

[0048] 3 is the time when the first sound wave SW1 is transmitted by the first transceiver 102. The transmission time TS1 may be any time point that represents the period during which the first sound wave SW1 is transmitted from the first transceiver 102, and may be, for example, the center of the first sound wave SW1 on the time axis.

[0049] Referring again to FIG. The detector 109 detects the reception time TR1 of the first reflected wave RW1 based on the first reception signal RS1 output from the first transmitter / receiver .

[0050] The reception time TR1 is the time when the first transceiver 102 receives the first reflected wave RW1. The reception time TR1 may be any time point that represents the period during which the first reflected wave RW1 is received by the first transceiver 102, and may be, for example, the center of the first reflected wave RW1 on the time axis. The detector 109 detects the center of the first reflected wave RW1 received by the first transceiver 102 on the time axis, based on the first received signal RS1 output from the first transceiver 102.

[0051] Fig. 4(a) is a diagram showing an example of the waveform of the first received signal RS1 including the first reflected signal FS1. The horizontal axis of Fig. 4(a) indicates time (e.g., in seconds), and the vertical axis indicates signal level (e.g., in volts). The first reflected signal FS1 shown in Fig. 4(a) is a signal corresponding to the first reflected wave RW1 received at the reception time TR1, and has a maximum signal level of AR1 and a width (time length) of PTR1.

[0052] The first reflected wave RW1 is a reflected wave of the pulsed first sound wave SW1, and is therefore generally symmetrical with respect to the center on the time axis, and therefore the first reflected signal FS1 is also generally symmetrical with respect to the reception time TR1, which is the center on the time axis of the first reflected wave RW1.

[0053] As described above, the first reception signal RS1 including the first reflected signal FS1 often includes a noise signal, but the signal level of the first reflected wave RW1 is usually greater than the signal level of the noise. Therefore, as shown in Fig. 4(a), the first reception signal RS1 including the first reflected signal FS1 is generally symmetrical with respect to the reception time TR1, which is the center of the first reflected wave RW1 on the time axis, like the first reflected signal FS1.

[0054] The detector 109 detects the center of the first reflected signal FS1 on the time axis by utilizing the fact that the first received signal RS1 including the first reflected signal FS1 is substantially symmetrical with respect to the center of the first reflected signal FS1 on the time axis. In this embodiment, the center of the first reflected signal FS1 on the time axis is the center of the first reflected wave RW1 received by the first transmitter / receiver 102 on the time axis.

[0055] Due to the time required for signal processing, etc., a time lag may occur between the time corresponding to the center on the time axis of the first received signal RS1 including the first reflected signal FS1 and the reception time TR1 at which the first transceiver 102 receives the first reflected wave RW1. In this case, the detector 109 may perform calibration based on this time lag to detect the center on the time axis of the first reflected wave RW1 received by the first transceiver 102.

[0056] 5, a detailed functional configuration of the detection unit 109 will be described. The detection unit 109 includes a first generation unit 113, a reflected wave detection unit 114, and a center identification unit 115.

[0057] The first generator 113 generates a first pulse PA1 (signal).

[0058] As shown in FIG. 4(b), the first pulse PA1 is a pulse consisting of one rectangular wave. The horizontal axis shown by the dotted line in FIG. 4(b) is the time axis. The first pulse PA1 is a signal whose level is A2 for a time length (pulse width) of PT2 and whose level is 0 otherwise. The pulse width PT2 is larger than the width PTR1 (i.e., PT2>PTR1). The pulse width PT2 is, for example, about twice the width PTR1. The level A2 may be determined as appropriate, but is, for example, 1.

[0059] Referring again to FIG. The reflected wave detection unit 114 detects that the first transceiver unit 102 has received the first reflected wave RW1, based on the first received signal RS1 and the first pulse PA1 output from the first transceiver unit 102. For example, the reflected wave detection unit 114 detects that the first transceiver unit 102 has received the first reflected wave RW1, based on a value obtained by adding together the products of the first received signal RS1 and the first pulse PA1 along the time axis.

[0060] The center identifying unit 115 identifies the center on the time axis of the first reflected wave RW1 received by the first transceiver 102. For example, the center identifying unit 115 identifies the center on the time axis of the first reflected wave RW1 received by the first transceiver 102 based on the first received signal RS1 output from the first transceiver 102.

[0061] In detail, the center identification unit 115 includes a second generation unit 116 and a pulse control unit 117.

[0062] The second generating section 116 generates a second pulse PA2 (signal).

[0063] As shown in Fig. 4(c), the second pulse PA2 is a pulse composed of a pair of square waves that are point-symmetric with respect to a reference point RP where the value is zero. The horizontal axis shown by the dotted line in Fig. 4(c) is the time axis.

[0064] The second pulse PA2 is composed of, for example, a first square wave FPA2 with a level of -A3 and a second square wave RPA2 with a level of A3, and the time length (pulse width) of the whole is PT3, and the other levels are 0. The pulse width PT3 is approximately the same as the pulse width PT2 or is larger than the pulse width PT1 (i.e., PT3 ≥ PT2). The magnitude of the level A3 may be appropriately determined, but is, for example, 1.

[0065] In detail, for example, the first square wave FPA2 is a square wave before the reference point RP where the value becomes zero. The first square wave FPA2 has a time length of -A3 for a level of PT3 / 2. The second square wave RPA2 is a square wave after the reference point RP. The second square wave RPA2 has a time length of A3 for a level of PT3 / 2.

[0066] The first square wave FPA2 and the second square wave RPA2 have the same level A3 and the same time length (PT3 / 2). Therefore, the first square wave FPA2 and the second square wave RPA2 are point-symmetrical with respect to the reference point RP, whose value is zero. The level of the first square wave FPA2 may be A3, and the level of the second square wave RPA2 may be -A3.

[0067] Referring again to FIG. The pulse control unit 117 identifies the center on the time axis of the first reflected wave RW1 received by the first transceiver unit 102 based on the first received signal RS1 including the first reflected signal FS1 detected by the reflected wave detection unit 114 and the second pulse PA2.

[0068] In detail, for example, the pulse control unit 117 adjusts the timing (generation timing) at which the second generation unit 116 generates the second pulse PA2 so that the reference point RP is the center of the time axis of the first reflected signal FS1. More specifically, the pulse control unit 117 adjusts the timing at which the second generation unit 116 generates the second pulse PA2 so that a second sum value obtained by adding up the products of the first received signal RS1 and the second pulse PA2 along the time axis becomes small (preferably, zero). When the second pulse PA2 has a waveform shown in FIG. 4(c), the pulse control unit 117 adjusts the generation timing to be earlier if the second sum value is "positive" and to be later if the second sum value is "negative".

[0069] Then, the pulse control unit 117 detects the center of the first reflected signal FS1 on the time axis based on the adjusted second pulse PA2. Upon detecting the center of the first reflected signal FS1 on the time axis, the pulse control unit 117 identifies the center of the first reflected signal FS1 on the time axis based on the reference point RP of the second pulse PA2 whose generation timing has been adjusted.

[0070] Since the first reflected signal FS1 and the first reflected wave RW1 correspond on the time axis, their centers on the time axis also correspond. Therefore, by identifying the center of the first reflected signal FS1 on the time axis, the pulse control unit 117 can identify the center of the first reflected wave RW1 received by the first transmitting / receiving unit 102 on the time axis.

[0071] The pulse control unit 117 may detect the center on the time axis of the first reflected wave RW1 received by the first transmitting / receiving unit 102 by directly using the first received signal RS1 without using the first reflected signal FS1 detected by the reflected wave detection unit 114. In this case, the measurement device 106 does not need to include the first generation unit 113 and the reflected wave detection unit 114.

[0072] Referring again to FIG. The measurement unit 110 obtains the propagation distance DT, the change ΔDT in the propagation distance DT, the distance R, and the change ΔR in the distance R, based on the first time. Here, the propagation distance DT is the distance between the first transmitting / receiving unit 102 (for example, a part that transmits and receives sound waves) and the first reflecting unit 105.

[0073] In detail, the measurement unit 110 functionally includes a time acquisition unit 118 and a distance acquisition unit 119 as shown in FIG.

[0074] The time acquisition unit 118 acquires a first time based on the sending time TS1 and the receiving time TR1.

[0075] The distance acquisition unit 119 acquires the propagation distance DT, the change ΔDT in the propagation distance DT, the distance R, the change ΔR in the distance R, and the like, based on the first time acquired by the time acquisition unit 118.

[0076] More specifically, for example, the distance acquiring unit 119 calculates the propagation distance DT based on the first time and the sound speed calculated by the time acquiring unit 118. The distance acquiring unit 119 holds in advance the positional relationship between the reference point P1 and the first transmitting / receiving unit 102 and the positional relationship between the first reflecting unit 105 and the measurement point P2, and calculates the distance R based on these positional relationships and the propagation distance DT.

[0077] Further, for example, the distance acquisition unit 119 calculates a change ΔDT in the propagation distance DT based on the previously calculated propagation distance DT and the current propagation distance DT by performing a calculation to subtract the previously calculated propagation distance DT from the current propagation distance DT. The distance acquisition unit 119 calculates a change ΔR in the distance R (=current distance R−previously calculated distance R) based on the previously calculated distance R and the current distance R by performing a calculation to subtract the previously calculated distance R from the current distance R.

[0078] The distance acquisition unit 119 generates measurement information including the results of the measurement, and stores the measurement information in the history storage unit 111. The measurement information includes the propagation distance DT, its change ΔDT, the distance R, and its change ΔR. The history storage unit 111 is a storage unit for storing the history of the measurement information.

[0079] The communication unit 112 communicates with the external device 107 (see FIG. 1) via the communication network N. The communication unit 112 transmits, for example, measurement information to the external device 107. The external device 107 is a device other than the measurement device 106. For example, the external device 107 is a device for managing the measurement information.

[0080] Up to this point, the functional configuration of the measurement system 100 according to the first embodiment of the present invention has been mainly described. From now on, the operation of the measurement system 100 according to this embodiment will be described.

[0081] (Operation of Measurement System 100) The measurement system 100 executes a measurement process, an example of which is shown in a flowchart in Fig. 7. The measurement process is a process for measuring a distance R or a change ΔR therein between an arbitrarily set reference point P1 and a measurement point P2.

[0082] Before starting the measurement process, the first acoustic waveguide 101 is placed between the reference point P1 and the measurement point P2.

[0083] For example, when the measurement system 100 is used to measure the movement of the ground surface, such as a landslide or a slope, the reference point P1 is set on the ground surface that serves as a reference. Specifically, for example, the first fixing member 103 may be fixed in association with the reference point P1 by an appropriate method, such as fixing a part of the first fixing member 103 to the ground. The measurement point P2 is set on the ground surface that is the target of the measurement of the movement relative to the reference point P1. Specifically, for example, the second fixing member 104 may be fixed in association with the measurement point P2 by an appropriate method, such as fixing a part of the second fixing member 104 to the ground. In this case, for example, the first acoustic waveguide 101 may be placed on the ground surface between the outdoor reference point P1 and the measurement point P2.

[0084] Furthermore, for example, when measuring the distance between structures (e.g., between bridge piers or buildings) using the measurement system 100, the reference point P1 is set at a specific portion of the structure that serves as a reference, such as the ground, and the measurement point P2 is set at a specific portion of the structure that is the target of measuring the movement relative to the reference point P1. In this case, for example, the first acoustic waveguide 101 may be disposed in the air between the reference point P1 and the measurement point P2, or a part of or almost the entirety of the first acoustic waveguide 101 may be placed on the ground.

[0085] Note that the reference point P1 and the measurement point P2 are not limited to these. The first acoustic waveguide 101 may be placed indoors, or may be placed both outdoors and indoors. A part or the whole of the first acoustic waveguide 101 may be buried in the ground or the like.

[0086] The first transmitting / receiving unit 102 is attached, for example, to a first fixing member 103 fixed to a reference point P1, and is attached to the first acoustic waveguide 101 (for example, one end thereof) so as to be able to send a first sound wave SW1 into the inside of the first acoustic waveguide 101. In this way, the first transmitting / receiving unit 102 is provided in association with the reference point P1.

[0087] The first reflecting portion 105 is attached to, for example, a second fixing member 104 fixed to the measurement point P2, and is disposed inside the first acoustic waveguide 101 to reflect the first sound wave SW1. Thus, the first reflecting portion 105 is provided in association with the measurement point P2.

[0088] After such preparation, the measurement device 106 starts the measurement process, for example, in response to an instruction from a user.

[0089] Please refer to Figure 7. The sonic wave control unit 108 causes the first transmission / reception unit 102 to emit the first sonic wave SW1. For example, the sonic wave control unit 108 outputs a transmission signal for causing the first transmission / reception unit 102 to emit the first sonic wave SW1. In response to this, the first transmission / reception unit 102 emits the first sonic wave SW1 (step S101).

[0090] In step S101, the first transceiver 102 may transmit a first pulsed sound wave SW1. After performing step S101, the first transceiver 102 receives the sound wave inside the first acoustic waveguide 101 and outputs a first reception signal RS1 corresponding to the received sound wave.

[0091] The detector 109 detects, based on the first received signal RS1, that the first transmitter / receiver 102 has received the first reflected wave RW1 (step S102).

[0092] FIG. 8 is a flowchart showing a detailed example of the detection process (step S102) according to the present embodiment.

[0093] The reflected wave detector 114 acquires the first received signal RS1 from the first transmitter / receiver 102 (step S111).

[0094] For example, when the first transmitting / receiving unit 102 receives a sound wave, the first transmitting / receiving unit 102 outputs a first receiving signal RS1 corresponding to the sound wave in approximately real time. After step S101 is executed, the reflected wave detection unit 114 continuously acquires the first receiving signal RS1 output in real time from the first transmitting / receiving unit 102. The reflected wave detection unit 114 may hold the acquired first receiving signal RS1.

[0095] The first generator 113 and the second generator 116 generate a first pulse PA1 and a second pulse PA2, respectively (step S112).

[0096] At this time, the first generating unit 113 and the second generating unit 116 may generate a first pulse PA1 and a second pulse PA2 that are synchronized (i.e., have the same center position on the time axis). The first generating unit 113 and the second generating unit 116 may also generate a first pulse PA1 and a second pulse PA2 that have the same pulse widths PT2, PT3. This causes the generation times (times that are not 0 except for the reference point RP) of the first pulse PA1 and the second pulse PA2 to roughly coincide.

[0097] The reflected wave detection unit 114 determines whether or not the first reflected wave RW1 has been detected, based on the first received signal RS1 and the first pulse PA1 acquired in step S111 (step S113).

[0098] In detail, for example, the reflected wave detection unit 114 adds up the value obtained by multiplying the first received signal RS1 output from the first transmitting / receiving unit 102 by the first pulse PA1 along the time axis over the entire pulse width PT2 of the first pulse PA1. When multiplying the first received signal RS1 by the first pulse PA1 along the time axis, the level A2 of the first pulse PA1 may be appropriately corrected, for example, to be equal to the level AR1 of the first received signal RS1.

[0099] The reflected wave detection unit 114 compares a first sum obtained by adding the two values ​​with a first threshold. The reflected wave detection unit 114 detects a first reflected signal FS1 included in the first received signal RS1 based on a result of comparing the first sum with the first threshold. The first threshold is a predetermined value.

[0100] The pulse width PT2 is larger than the pulse width PT1, and is therefore usually larger than the pulse width of the first reflected wave RW1. Furthermore, the noise contained in the first received signal RS1 is usually smaller than the first reflected wave RW1. Furthermore, in the case of a noise signal that has a higher frequency than the first reflected wave RW1 and whose level occurs approximately uniformly in positive and negative directions along the time axis, such as a noise signal based on external noise, the noise is canceled out along the time axis (passed through a low-pass filter in an electric circuit) and becomes small enough to be considered as approximately zero. Therefore, the first sum value is a value that accurately represents the degree of overlap between the first reflected signal FS1 and the first pulse PA1 along the time axis.

[0101] The larger the first sum is, the more likely it is that the portion of the first received signal RS1 multiplied by the first pulse PA1 contains the first reflected signal FS1. Therefore, for example, when the first sum is greater than a first threshold, the reflected wave detection unit 114 determines that the first reflected wave RW1 has been detected. Also, for example, when the first sum is equal to or less than the first threshold, the reflected wave detection unit 114 determines that the first reflected wave RW1 has not been detected.

[0102] As described above, the first reception signal RS1 is a signal output in response to the sound wave received by the first transmission / reception unit 102. Therefore, as described above, the first reception signal RS1 may include not only the first reflected wave RW1 but also a signal corresponding to noise. In addition, generally, the amplitude fluctuation of the first reflected wave RW1 may become large in an acoustic waveguide. By detecting the first reflection signal FS1 based on the degree of overlap between the first reflection signal FS1 and the first pulse PA1, the effect of noise and amplitude fluctuation on the detection accuracy can be reduced, and therefore the first reflection signal FS1 can be accurately detected from the first reception signal RS1. Therefore, it is possible to accurately detect that the first reflection wave RW1 has been received.

[0103] If it is determined that the first reflected wave RW1 has not been detected (step S113; No), the first generating unit 113 and the second generating unit 116 execute step S112 again.

[0104] If it is determined that the first reflected wave RW1 has been detected (step S113; No), the pulse control unit 117 determines whether or not the center of the first reflected wave RW1 on the time axis has been detected based on the first received signal RS1 and the second pulse PA1 for which it was determined in step S113 that the first reflected wave RW1 has been detected (step S114).

[0105] In detail, for example, the pulse control unit 117 obtains the second sum value by multiplying the first reception signal RS1 including the first reflected signal FS1 by the second pulse PA2 along the time axis and adding the resultant value over the entire pulse width PT3 of the second pulse PA2. Note that when multiplying the first reception signal RS1 by the second pulse PA2 along the time axis, the level A3 of the second pulse PA2 may be appropriately corrected, for example, to be equal to the level AR1 of the first reception signal RS1.

[0106] The pulse control unit 117 compares the second sum with a second threshold value. The pulse control unit 117 detects the center on the time axis of the first reflected signal FS1 included in the first received signal RS1 based on the result of comparing the second sum with the second threshold value.

[0107] Since the pulse width PT3 is larger than the pulse width PT1, it is usually larger than the pulse width of the first reflected wave RW1. In addition, for example, in the case of a noise signal based on external noise, which has a higher frequency than the first reflected wave RW1 and whose level occurs approximately uniformly in positive and negative directions along the time axis with zero as the center, the noises are canceled out by each other by adding them along the time axis (by passing them through a low-pass filter of an electric circuit), and become small enough to be considered as approximately zero. Therefore, the second sum value is a value that accurately represents the degree of coincidence of the centers of the first reflected signal FS1 and the second pulse PA2 along the time axis.

[0108] More specifically, the closer the second sum is to 0, the closer the reference point RP of the second pulse PA2 is to the center of the first reflected signal FS1 along the time axis. Therefore, for example, when the second sum is smaller than the second threshold, the pulse control unit 117 determines that the center of the first reflected wave RW1 has been detected. Also, for example, when the second sum is equal to or larger than the second threshold, the pulse control unit 117 determines that the center of the first reflected wave RW1 has not been detected.

[0109] The second threshold may be a predetermined appropriate value, for example, 1 / 1000 of the first sum. In general, since the voltage level of the first reception signal RS1 varies depending on the distance R, if the second threshold is about 1 / 1000 of the first sum, the second sum can be regarded as 0.

[0110] When it is determined that the center of the reflected wave RW1 on the time axis has not been detected (step S114; No), the pulse control unit 117 adjusts the timing at which the second pulse PA2 is generated (generation timing) (step S115).

[0111] In detail, for example, the pulse control section 117 adjusts the timing (generation timing) at which the second generating section 116 generates the second pulse PA2 so that the second sum becomes smaller than the second threshold value.

[0112] The method of adjusting the generation timing will be described using the second pulse PA2 shown in Fig. 4(c) as an example. In the second pulse PA2 shown in Fig. 4(c), the level of the first square wave FPA2 before the reference point RP is positive, and the level of the second square wave RPA2 after the reference point RP is negative.

[0113] In this case, when the second sum is a positive value, the reference point RP lags behind the center of the first reflected wave RW1 along the time axis, so that the pulse control unit 117 controls the second generation unit 116 to generate the second pulse PA2 a predetermined time earlier than the current setting.

[0114] When the second sum is a negative value, the reference point RP is earlier than the center of the first reflected wave RW1 along the time axis, so that the pulse control unit 117 controls the second generation unit 116 to generate the second pulse PA2 a predetermined time later than the current setting.

[0115] In this embodiment, since the first pulse PA1 and the second pulse PA2 are synchronized, the generation timing of the first pulse PA1 is also adjusted in the same manner as the generation timing of the second pulse PA2.

[0116] Subsequently, the processes from step S111 onwards are executed again. In the next step S112, the first pulse PA1 and the second pulse PA2 are generated at the generation timings adjusted in step S115.

[0117] If it is determined that the center of the first reflected wave RW1 on the time axis has been detected (step S114; Yes), the pulse control unit 117 identifies the center of the first reflected wave RW1 on the time axis (step S116) and returns to the measurement process (see FIG. 7).

[0118] In detail, for example, the center of the detected first reflected wave RW1 on the time axis corresponds to the reference point RP of the adjusted second pulse PA2 on the time axis. Therefore, the pulse control unit 117 specifies the center of the first reflected wave RW1 on the time axis as the center of the first reflected wave RW1 received by the first transmitting / receiving unit 102 on the time axis.

[0119] Here, if it is determined that the center of the first reflected wave RW1 on the time axis has been detected (step S114; Yes), the pulse control unit 117 does not adjust the generation timing as in step S115. Therefore, the first pulse PA1 and the second pulse PA2 can maintain good generation timing. Therefore, it becomes possible to accurately track the time when the first reflected wave RW1 was received.

[0120] Referring again to FIG. The time acquisition unit 118 obtains the first time based on the sending time TS1 and the receiving time TR1 (step S103).

[0121] In detail, for example, the time acquisition unit 118 identifies the transmission time TS1 of the first sound wave SW1 based on the time when step S101 was executed.

[0122] Furthermore, for example, the time acquiring unit 118 identifies a reception time TR1 of the first reflected wave RW1 based on the detection result of the first reflected wave RW1 in step S102. In this embodiment, the time acquiring unit 118 acquires the time corresponding to the center on the time axis of the first reflected wave RW1 identified in step S116 as the reception time TR1 of the first reflected wave RW1.

[0123] As described above, the first reception signal RS1 is a signal output in response to the sound received by the first transmission / reception unit 102. Therefore, the first reception signal RS1 may include not only the first reflected wave RW1 but also a signal corresponding to noise. In addition, the amplitude fluctuation of the first reflected wave RW1 is generally large in an acoustic waveguide. Even in such a case, the center of the first reflected wave RW1 on the time axis can be accurately detected by using the median of the total area of ​​the first reflected wave RW1 as in step S114. Therefore, the center of the first reflected wave RW1 on the time axis can be accurately identified, and the first time can be accurately obtained.

[0124] Then, the time acquiring unit 118 acquires the first time based on the difference between the sending time TS1 and the receiving time TR1. Note that the method of acquiring the first time is not limited to this, and the time acquiring unit 118 may acquire the first time by measuring the time from the sending time TS1 of the first sound wave SW1 to the receiving time TR1 of the first reflected wave RW1.

[0125] The distance acquisition unit 119 obtains a propagation distance DT, which is the distance between the first transmitting / receiving unit 102 and the first reflecting unit 105, based on the first time obtained in step S103 (step S104).

[0126] The first time is the time it takes for the first sound wave SW1 to travel back and forth between the first transmitting / receiving unit 102 and the first reflecting unit 105. Therefore, the propagation distance DT can be calculated by DT=v×the first time / 2, where v is the speed of sound.

[0127] The speed of sound v (m / s) is calculated, for example, by v=331.5+0.6071×T, where T is temperature (°C). The temperature used to determine the speed of sound may be, for example, the air temperature measured in the vicinity of the first acoustic waveguide 101. When the first acoustic waveguide 101 is placed outdoors, the temperature T (°C) is generally a few degrees below zero to about 50°C.

[0128] Also, for example, temperatures may be measured at a plurality of measurement points near the first acoustic waveguide 101, and the average value may be used as the temperature for determining the sound speed. The distance acquisition unit 119 may acquire the sound speed v, for example, through a user's input. Also, the distance acquisition unit 119 may acquire the temperature T, for example, through a user's input, and acquire the sound speed v based on the acquired temperature and the above-mentioned formula.

[0129] In this embodiment, as described above, the first transmitting / receiving unit 102 and the first reflecting unit 105 are fixed with respect to the reference point P1 and the measurement point P2, respectively. The distance acquiring unit 119 may hold in advance the distance between the first transmitting / receiving unit 102 and the reference point P1 as the positional relationship between the first transmitting / receiving unit 102 and the reference point P1. The distance acquiring unit 119 may hold in advance the distance between the first reflecting unit 105 and the measurement point P2 as the positional relationship between the first reflecting unit 105 and the measurement point P2. The distance acquiring unit 119 calculates the distance R between the reference point P1 and the measurement point P2, for example, based on these distances held in advance and the propagation distance DT.

[0130] The distance acquisition unit 119 refers to the measurement information stored in the history storage unit 111 and acquires the previously calculated propagation distance DT and distance R. The distance acquisition unit 119 acquires a change ΔDT in the propagation distance DT based on the difference between the current propagation distance DT calculated in step S104 and the previously calculated propagation distance DT. Similarly, the distance acquisition unit 119 acquires a change ΔR in the distance R based on the difference between the current distance R calculated in step S104 and the previously calculated distance R.

[0131] The distance acquisition unit 119 generates measurement information 111a including the propagation distance DT calculated in step S104 (step S105). The distance acquisition unit 119 stores the generated measurement information in the history storage unit 111.

[0132] 9 is a diagram showing an example of the configuration of the measurement information 111a. The measurement information shown in the figure associates a measurement time, a propagation distance DT, a change ΔDT in the propagation distance DT, a distance R, and a change ΔR in the distance R. The measurement time is information related to the time when the measurement was made, and includes the date and time of the measurement. The propagation distance DT, the distance R, the change ΔDT, and the change ΔR are all the distance or its change calculated in step S104.

[0133] In this embodiment, as described above, the first transmitting / receiving unit 102 and the first reflecting unit 105 are fixed with respect to the reference point P1 and the measurement point P2, respectively. Therefore, the change ΔDT and the change ΔR are approximately equal. Therefore, when the change ΔR is managed without managing the distance R itself, the positional relationship between the first transmitting / receiving unit 102 and the reference point P1 and the positional relationship between the first reflecting unit 105 and the measurement point P2 do not need to be held in advance in the distance acquiring unit 119.

[0134] Also, the first transmitting / receiving unit 102 and the first reflecting unit 105 only need to be associated with the reference point P1 and the measurement point P2, respectively, and for example, the first transmitting / receiving unit 102 (for example, a portion where the first transmitting / receiving unit 102 transmits the first sound wave SW1 and receives the first reflected wave RW1) may be the reference point P1. Also, for example, the first reflecting unit 105 may be the measurement point P2.

[0135] The distance acquisition unit 119 may obtain at least one of the propagation distance DT, its change ΔDT, the distance R, and its change ΔR. The measurement information may include at least one of the propagation distance DT, its change ΔDT, the distance R, and its change ΔR obtained by the distance acquisition unit 119.

[0136] The communication unit 112 transmits the measurement information generated in step S105 to the external device 107 via the communication network N (step S106), and ends the measurement process.

[0137] By performing such a measurement process, it is possible to measure the propagation distance DT or the change ΔDT therein between the first transceiver 102 and the first reflector 105. Even when measuring the distance R or the change ΔR therein between two points other than the first transceiver 102 and the first reflector 105, it is possible to measure the distance R or the change ΔR therein by setting the first transceiver 102 and the first reflector 105 in association with each of any two points (reference point P1, measurement point P2).

[0138] Such a measurement process may be performed at a predetermined time such as one day, one week, or one month, or at a predetermined time interval. This allows the history of the measurement information 111a to be collected and managed, and for example, the movement of the ground surface can be monitored. At this time, the first fixing member 103, the second fixing member 104, and the first acoustic waveguide 101 fixed or installed in the first measurement process may be left in the same fixed or installed state and used in the second and subsequent measurement processes. This allows the same reference point P1, measurement point P2, and first acoustic waveguide 101 to be used in each measurement process that is repeatedly executed, and therefore the change ΔR in the distance R can be accurately measured.

[0139] The measurement process may be repeatedly executed at a predetermined time interval longer than the first time, for example, a predetermined number of times or until an end instruction is received from the user. The average values ​​of the distance R and its change ΔR obtained in each measurement process may be used as the distance R and its change ΔR.

[0140] So far, the operation of the measurement system 100 according to the first embodiment of the present invention has been described. From here, an example of the physical configuration of the measurement system 100 according to this embodiment will be described.

[0141] (Example of a physical configuration of the measurement system 100) 10 is a diagram showing an example of the physical configuration of the first transceiver 102. The first transceiver 102 includes, for example, an acoustic wave element 910, an acoustic wave generator 912, a receiving circuit 914, and an A / D (Analog / Digital) converter 916.

[0142] The acoustic wave element 910 is an element that generates a pulsed acoustic wave and receives an acoustic wave (reflected wave). The acoustic wave element 910 is, for example, a piezoelectric element.

[0143] The acoustic wave generator 912 is a circuit that causes the acoustic wave element 910 to generate pulsed acoustic waves.

[0144] The receiving circuit 914 is a circuit that receives the analog signal output from the acoustic wave element 910. The receiving circuit 914 is composed of, for example, an amplifier circuit, a rectifier circuit, a filter circuit, a buffer circuit, and the like.

[0145] The A / D converter 916 is a circuit that converts an analog signal into a digital signal.

[0146] The A / D converter 916 and the sound generator 912 are connected to the measurement device 106 to transmit and receive data. This connection may be wired or wireless.

[0147] The first transceiver 102 is configured as, for example, one unit and is housed in a case 918. By including the case 918, the acoustic wave generating element can be protected and the first acoustic waveguide 101 can be acoustically matched.

[0148] The first transceiver 102 may be composed of a plurality of units connected by wiring, etc. The first transceiver 102 may include an element that generates sound waves and an element that receives sound waves separately.

[0149] 11 is a diagram showing an example of the physical configuration of measurement device 106. The measurement device physically includes, for example, a bus 1010, a processor 1020, a memory 1030, a storage device 1040, a network interface 1050, a user interface 1060, and an input / output interface 1070.

[0150] The bus 1010 is a data transmission path for transmitting and receiving data among the processor 1020, memory 1030, storage device 1040, network interface 1050, user interface 1060, and input / output interface 1070. However, the method of connecting the processor 1020 and other components to each other is not limited to bus connection.

[0151] The processor 1020 is a processor realized by a central processing unit (CPU), a graphics processing unit (GPU), etc. The memory 1030 is a main storage device realized by a random access memory (RAM), etc.

[0152] The storage device 1040 is an auxiliary storage device realized by a hard disk drive (HDD), a solid state drive (SSD), a memory card, a read only memory (ROM), or the like. The storage device 1040 stores program modules for realizing the functions of the measurement device 106. The processor 1020 loads each of these program modules into the memory 1030 and executes them to realize the function corresponding to the program module.

[0153] The network interface 1050 is an interface for connecting the measurement device 106 to the communication network N.

[0154] The user interface 1060 includes a touch panel, a keyboard, a mouse, and the like as interfaces for the user to input information, and a liquid crystal panel and the like as an interface for presenting information to the user.

[0155] The input / output interface 1070 is an interface for transmitting and receiving signals to and from the first transmitting / receiving unit 102 .

[0156] The first embodiment of the present invention has been described above.

[0157] (Action and effect) According to this embodiment, the measurement system 100 includes a first acoustic waveguide 101, a first transmitting / receiving unit 102, and a measuring device 106. The first acoustic waveguide 101 is a member for propagating a pulsed first sound wave SW1. The first transmitting / receiving unit 102 transmits the first sound wave SW1 into the inside of the first acoustic waveguide 101, and receives a reflected wave (first reflected wave RW1) of the first sound wave SW1 reflected by a first reflecting unit 105 inside the first acoustic waveguide 101. The measuring device 106 obtains a distance DT between the first transmitting / receiving unit 102 and the first reflecting unit 105 or a change therein ΔDT based on a first time from when the first sound wave RW1 is transmitted to when the reflected wave (first reflected wave RW1) is received.

[0158] According to this embodiment, the measurement device 106 includes a sound wave control unit 108, a detection unit 109, and a measurement unit 110. The sound wave control unit 108 causes the first transmission / reception unit 102 to transmit a pulsed first sound wave SW1. The detection unit 109 detects reception of a reflected wave (first reflected wave RW1) of the first sound wave SW1 reflected by the first reflection unit 105 inside the first acoustic waveguide 101. The measurement unit 110 calculates the distance DT between the first transmission / reception unit 102 and the first reflection unit 105 or the change therein ΔDT based on a first time from when the first sound wave SW1 is transmitted to when the reflected wave (first reflected wave RW1) is received.

[0159] As a result, by setting the first transmitting / receiving unit 102 and the first reflecting unit 105 in association with any two points (reference point P1, measurement point P2), it is possible to measure the distance R between any two points or the change ΔR therein. Therefore, it becomes possible to measure the distance R between any two points or the change ΔR therein using sound waves.

[0160] Moreover, the first sound wave SW1 and the first reflected wave RW1 propagate inside the first acoustic waveguide 101. Therefore, the propagation area of ​​the first sound wave SW1 and the first reflected wave RW1 can be limited, and the propagation of these waves can be made less susceptible to external influences. Therefore, the first sound wave SW1 and the first reflected wave RW1 can be propagated stably. Therefore, it becomes possible to stably and easily measure the distance R between any two points or the change ΔR therein by using sound waves.

[0161] Moreover, since the measurement system 100 contains almost no mechanical moving parts, it is possible to provide a robust and compact measurement system 100. Furthermore, the acoustic wave element 910 is generally relatively inexpensive. Therefore, it is possible to provide a measurement system 100 that is more economical than a system that uses radio waves, light, or the like to measure distance.

[0162] Generally, light, radio waves, and sound waves are used to measure distance. However, when light, radio waves, and sound waves are used, a linear space is required between the reference point P1 and the measurement point P2 for them to propagate, and if there is an obstacle between them, it may be difficult to measure the distance. In particular, when one or both of the reference point P1 and the measurement point P2 are set outdoors, it may be difficult to measure the distance using general light, radio waves, and sound waves due to the influence of the measurement environment such as rain, snow, fog, vegetation, unevenness of the ground surface, and stones. Furthermore, the influence of the measurement environment may cause multi-passes due to unexpected reflections, which may increase the error of the measurement result.

[0163] In the measurement system 100 according to the present embodiment, the first acoustic waveguide 101 may be installed between the reference point P1 and the measurement point P2. For example, even if it is difficult to secure a linear space between the reference point P1 and the measurement point P2, it is often easy to install the first acoustic waveguide 101. As described above, the propagation area of ​​the first sound wave SW1 and the first reflected wave RW1 can be limited and the propagation of these waves can be made less susceptible to external influences, so that the measurement environment is less susceptible. Therefore, even if it is generally difficult to measure the distance or the measurement result has a large error, it becomes possible to stably and easily measure the distance R or the change ΔR between any two points using sound waves.

[0164] Even when observing the distance R between two points or the change ΔR therein outdoors for a long period of time, the first acoustic waveguide 101 made of metal, resin, rubber, etc. is unlikely to be damaged. This also makes it possible to stably and easily measure the distance R between any two points or the change ΔR therein using sound waves.

[0165] Furthermore, if there is a risk of damage to the first acoustic waveguide 101, the measurement system 100 may further include a protective tube that houses the first acoustic waveguide 101 therein. This makes it possible to provide a more reliable measurement system 100.

[0166] According to this embodiment, the first reflecting portion 105 is movable inside the first acoustic waveguide 101. This allows the first reflecting portion 105 to be easily positioned in relation to the measurement point P2. Therefore, it becomes possible to easily measure the distance R between any two points or the change therein ΔR using sound waves.

[0167] In particular, when observing the distance R between two points or the change ΔR therein multiple times, it is advisable to leave the first acoustic waveguide 101 placed during the initial measurement with the first transmitting / receiving unit 102 attached and the first reflecting unit 105 placed inside. Since the first reflecting unit 105 moves, it is possible to easily repeat the measurement of the distance R between the same two points or the change ΔR therein. Therefore, it becomes possible to easily measure the distance R between any two points or the change ΔR therein multiple times using sound waves.

[0168] According to the present embodiment, a first fixing member 103 for fixing the first transmitting / receiving unit 102 to the reference point P1 is provided. This makes it possible to easily relate the first transmitting / receiving unit 102 to the reference point P1. Therefore, it becomes possible to easily measure the distance R between any two points or the change therein ΔR by using sound waves.

[0169] In particular, when observing the distance R between two points or the change ΔR therein multiple times, the first transmitting / receiving unit 102 can be fixedly positioned with respect to the reference point P1. Therefore, it becomes possible to easily measure the distance R between any two points or the change ΔR therein multiple times using sound waves.

[0170] According to this embodiment, the first reflecting portion 105 is disposed inside the first acoustic waveguide 101, and a second fixing member 104 is provided for fixing the first reflecting portion 105 to the measurement point P2. This allows the first reflecting portion 105 to be easily associated with the measurement point P2. Therefore, it becomes possible to easily measure the distance R between any two points or the change therein ΔR using sound waves.

[0171] In particular, when observing the distance R between two points or the change ΔR therein multiple times, the first reflecting portion 105 can be fixedly positioned with respect to the measurement point P2. Therefore, it becomes possible to easily measure the distance R between any two points or the change ΔR therein multiple times using sound waves.

[0172] According to this embodiment, the first acoustic waveguide 101 has flexibility. This allows the first acoustic waveguide 101 to be easily arranged even in a location with unevenness, obstacles, etc. Therefore, it becomes possible to easily measure the distance R between any two points or the change therein ΔR using sound waves.

[0173] According to this embodiment, the time TR1 at which the first reflected wave RW1 is received is the time at which the first transceiver 102 receives the center of the first reflected wave RW1 on the time axis. The measuring device 106 detects the center of the first reflected wave RW1 received by the first transceiver 102 on the time axis, based on the first received signal RS1 output from the first transceiver 102.

[0174] This allows the reception time TR1 of the first reflected wave RW1 to be accurately obtained. Furthermore, when measurements are repeated, the reception time TR1 can be determined based on the center of the first reflected wave RW1 on the time axis in each measurement. Therefore, the reception time TR1 of the first reflected wave RW1 is rarely determined based on a different point on the time axis of the first reflected wave RW1 for each measurement, so that the reception time TR1 of the first reflected wave RW1 can be stably obtained. Therefore, it becomes possible to accurately and stably measure the distance R between any two points or the change ΔR therein using sound waves.

[0175] According to this embodiment, the first transmitting / receiving unit 102 includes a piezoelectric element. A piezoelectric element is generally a relatively inexpensive element. Therefore, it is possible to provide an economically superior measurement system 100.

[0176] According to this embodiment, a communication unit 112 is provided that transmits measurement information 111a including at least one of distances DT, R and distance changes ΔDT, ΔR to an external device 107. This makes it possible to easily manage the measurement information 111a even in a location away from the reference point P1 and the measurement point P2. Therefore, it becomes possible to easily manage the distance R between any two points or the change ΔR therein by using sound waves.

[0177] <Variation 1> When it is not known where in the first received signal RS1 the first reflected signal FS1 is contained, the reflected wave detector 114 needs to search a wide range of the first received signal RS1 along the time axis in order to detect the first reflected wave RW1. Therefore, the first generator 113 and the second generator 116 may change the pulse widths PT2, PT3 between a search mode for searching for the first reflected wave RW1 and a ranging mode for accurately detecting the first reflected wave RW1.

[0178] For example, the pulse widths PT2 and PT3 in the search mode may be larger than the pulse widths PT2 and PT3 in the ranging mode, and may be, for example, about twice the pulse width of the first reflected wave RW1.

[0179] In detail, for example, the initial values ​​of the pulse widths PT2 and PT3 may be set to the pulse widths PT2 and PT3 in the search mode. Then, while the first reflected wave RW1 is not detected, the first generating unit 113 and the second generating unit 116 may generate the first pulse PA1 and the second pulse PA2 with the pulse widths PT2 and PT3 in the search mode. After detecting the first reflected wave RW1, the first generating unit 113 and the second generating unit 116 may generate the first pulse PA1 and the second pulse PA2 with the pulse widths PT2 and PT3 in the distance measurement mode.

[0180] FIG. 12 is a flowchart showing a detailed example of the detection process (step S102) according to this modified example.

[0181] After step S111 similar to that of the first embodiment, the first generating section 113 and the second generating section 116 generate a first pulse PA1 and a second pulse PA2 in the search mode, respectively (step S112a).

[0182] The reflected wave detector 114 determines whether or not the first reflected wave RW1 is detected based on the first received signal RS1 acquired in step S111 and the first pulse PA1 generated in step S112a (step S113a). The method of detecting the first reflected wave RW1 here may be the same as that in step S113.

[0183] If it is determined that the reflected wave RW1 is not detected (step S113a; No), the reflected wave detection unit 114 returns to step S112a. If it is determined that the first reflected wave RW1 is detected (step S113a; Yes), the first generation unit 113 and the second generation unit 116 generate the first pulse PA1 and the second pulse PA2, respectively, in the distance measurement mode (step S112b).

[0184] The reflected wave detector 114 determines whether or not the first reflected wave RW1 has been detected based on the first received signal RS1 determined in step S113a to have detected the first reflected wave RW1 and the first pulse PA1 generated in step S112b (step S113b). The method of detecting the first reflected wave RW1 here may be the same as in step S113.

[0185] If it is determined that the reflected wave RW1 has not been detected (step S113b; No), the first generating unit 113 and the second generating unit 116 execute step S112b again.

[0186] If it is determined that the first reflected wave RW1 has been detected (step S113b; Yes), the pulse control unit 117 determines whether or not the center of the first reflected wave RW1 on the time axis has been detected based on the first received signal RS1 determined in step S113b to have detected the first reflected wave RW1 and the second pulse PA1 generated in step S112b (step S114). The method for detecting the center of the first reflected wave RW1 on the time axis here may be the same as in step S114 in the first embodiment.

[0187] Subsequently, steps S115 to S116 similar to those in the first embodiment may be executed.

[0188] According to this modification, the pulse widths PT2 and PT3 before the detection of the first reflected wave RW1 are made larger than the pulse widths PT2 and PT3 after the detection of the first reflected wave RW1. This allows the first reflected wave RW1 to be detected quickly. Therefore, it becomes possible to quickly measure the distance R between any two points or the change ΔR therein using sound waves.

[0189] <Embodiment 2> As described in the first embodiment, the sound speed v is used to calculate the propagation distance DT based on the first time. However, particularly when the first acoustic waveguide 101 is placed outdoors, it may be difficult to measure the overall temperature inside the first acoustic waveguide 101 because part of the first acoustic waveguide 101 is exposed to direct sunlight and the remaining part is in the shade, and as a result, it may be difficult to accurately calculate the sound speed v.

[0190] In the second embodiment, an example will be described in which a second acoustic waveguide provided next to the first acoustic waveguide 101 is used to determine the sound speed v inside the first acoustic waveguide 101. In this embodiment, for the sake of brevity, differences from the first embodiment will be mainly described, and overlapping descriptions will be omitted as appropriate.

[0191] A measurement system 200 according to a second embodiment of the present invention has a configuration example as shown in FIG. The measurement system 200 includes a first acoustic waveguide 101, a first transmitting / receiving section 102, a first fixing member 103, a first reflecting section 105, a second fixing member 104, and an external device 107 similar to those of the first embodiment. The measurement system 200 includes a measurement device 206 replacing the measurement device 106 of the first embodiment. The measurement system 200 further includes a second acoustic waveguide 220, a second transmitting / receiving section 221, and a fixing member 222 including a second reflecting section 223.

[0192] The second acoustic waveguide 220 is an acoustic waveguide. The second acoustic waveguide 220 is arranged next to the first acoustic waveguide 101 in order to propagate the pulsed second sound wave SW2. The length of the second acoustic waveguide 220 may be approximately the same as the length of the first acoustic waveguide 101, but may be changed as appropriate.

[0193] The second acoustic waveguide 220 may be arranged adjacent to the first acoustic waveguide 101, but may be accommodated together with the first acoustic waveguide 101 in a common accommodation tube (not shown). This makes it possible to protect the first acoustic waveguide 101 and the second acoustic waveguide 220. In addition, it becomes easy to arrange the first acoustic waveguide 101 and the second acoustic waveguide 220 side by side.

[0194] The second acoustic waveguide 220 is desirably made of the same material as the first acoustic waveguide 101 so that the environment in which the sound waves propagate is as similar as possible to that of the first acoustic waveguide 101. In addition, the second acoustic waveguide 220 is desirably of the same diameter as the first acoustic waveguide 101.

[0195] The second transceiver 221 transmits the second sound wave SW2 into the second acoustic waveguide 220, and receives a second reflected wave RW2 that is formed by the second sound wave SW2 being reflected by a second reflecting portion 223 inside the second acoustic waveguide 220. The details of the configuration of the second transceiver 221 may be similar to those of the first transceiver 102.

[0196] That is, the second transceiver 221 receives a transmission signal from the measurement device 206 and generates a second sound wave SW2. When the second transceiver 221 receives the sound wave, it outputs a second reception signal RS2 corresponding to the received sound to the measurement device 206. When the second transceiver 221 receives the second reflected wave RW2, the second reception signal RS2 output from the second transceiver 221 includes a second reflected signal FS2 corresponding to the second reflected wave RW2. Similarly to the first transceiver 102, the second transceiver 221 may receive noise other than the second reflected wave RW1 and output a second reception signal RS2 including a noise signal corresponding to the noise.

[0197] Second transceiver 221 is disposed, for example, at or near one end of second acoustic waveguide 220. In this embodiment, second transceiver 221 is fixed to one end of second acoustic waveguide 220.

[0198] The second reflecting section 223 is a section that reflects the second sound wave SW2 sent out from the second transmitting / receiving section 221, and is disposed inside the second acoustic waveguide 220. The second reflecting section 223 may be configured similarly to the first reflecting section 105 according to the first embodiment, but in this embodiment, it is included in the fixed member 222. The fixed member 222 is a disk-shaped member, and is disposed at or near the other end of the second acoustic waveguide 220.

[0199] In this embodiment, the fixing member 222 is fitted into and fixed to the other end of the second acoustic waveguide 220. The second reflecting portion 223 is a portion that forms one of the two main surfaces of the fixing member 222 that faces the second transmitting / receiving portion 221. The second reflecting portion 223 forms, for example, a flat surface. Note that the second reflecting portion 223 may have any shape that reflects the second sound wave SW2, and is not limited to a flat surface, and may be a curved surface or the like. Note that the shape of the fixing member 222 is not limited to a flat plate shape, and may be changed as appropriate.

[0200] Since the second transceiver 221 and the second reflector 223 are fixed to the second acoustic waveguide 220, a reference distance RD, which is the distance between the second transceiver 221 and the second reflector 223, is approximately constant. The reference distance RD is measured in advance and is known.

[0201] (Example of Functional Configuration of Measuring Device 206) The measuring device 206 has the same functions as the measuring device 106 according to the embodiment 1. The measuring device 206 further obtains a sound speed v based on a second time and a reference distance RD. The second time is the time from when the second transceiver 221 transmits the second sound wave SW2 to when the second reflected wave RW2 is received.

[0202] In this embodiment, a function that measuring device 206 has in addition to the function that measuring device 106 according to embodiment 1 has in order to obtain the sound speed v will be mainly described.

[0203] 14, the measuring device 206 includes a measuring unit 110, a history storage unit 111, and a communication unit 112 similar to those in the first embodiment. The measuring device 206 includes a sonic wave control unit 208 and a detection unit 209 instead of the sonic wave control unit 108 and the detection unit 109 according to the first embodiment. The measuring device 206 further includes a sound speed measurement unit 224.

[0204] The sonic wave control unit 208 has the same functions as the sonic wave control unit 108 according to the first embodiment. The sonic wave control unit 208 further causes the second transceiver unit 221 to transmit a pulsed second sonic wave SW2. The second sonic wave SW2 is the same as the first sonic wave SW1. However, one or both of the magnitude and pulse width of the second sonic wave SW2 may be different from the magnitude A1 and pulse width PT1 of the first sonic wave SW1.

[0205] The detector 209 has the same function as the detector 109 according to embodiment 1. The detector 209 further detects that the second transceiver 221 has received the second reflected wave RW2. For example, the detector 209 detects that the second transceiver 221 has received the second reflected wave RW2, based on the second received signal RS2 output from the second transceiver 221.

[0206] The detection unit 209 further has the function of replacing the "first transmission / reception unit 102" and the "first reflected wave RW1" in the description of the detection unit 109 (first generation unit 113, reflected wave detection unit 114, center identification unit 115, second generation unit 116, pulse control unit 117) in embodiment 1 with a "second transmission / reception unit 221" and a "second reflected wave RW2", respectively.

[0207] As a result, the detector 209 detects the second reflected wave RW2 based on the second received signal RS2 and the first pulse PA1, for example. Also, for example, the detector 209 identifies the center of the second reflected wave RW2 received by the second transmitter / receiver 221 on the time axis.

[0208] The sound speed measurement unit 224 obtains the sound speed v based on the second time and the reference distance RD.

[0209] In detail, the sound speed measurement unit 224 obtains the second time based on the transmission time TS2 of the second sound wave SW2 and the reception time TR2 of the second reflected wave RW2. The transmission time TS2 is the time when the second transceiver 221 transmits the second sound wave SW2, for example, the time when the second transceiver 221 transmits the center of the second sound wave SW2 on the time axis. The reception time TR2 is the time when the second transceiver 221 receives the second reflected wave RW2, for example, the time when the second transceiver 221 receives the center of the second reflected wave RW2 on the time axis.

[0210] Up to this point, the functional configuration of measurement system 200 according to the second embodiment of the present invention has been mainly described. From now on, the operation of measurement system 200 according to this embodiment will be described.

[0211] (Operation of Measurement System 200) The measurement system 200 executes the same measurement process as in embodiment 1. In addition, the measurement system 200 executes a sound speed measurement process, an example of which is shown in the flowchart of Fig. 15. The sound speed measurement process is a process for measuring the sound speed v.

[0212] Before starting the measurement process, the second acoustic waveguide 220 is disposed between the reference point P1 and the measurement point P2 together with the first acoustic waveguide 101. The second transmitting / receiving unit 221 is fixed to one end of the second acoustic waveguide 220. The fixed member 222 (the second reflecting unit 223) is fixed to the other end of the second acoustic waveguide 220.

[0213] After such preparation, the measurement device 206 starts the sound speed measurement process in response to, for example, an instruction from a user.

[0214] The sonic wave control unit 208 causes the second transceiver unit 221 to emit the second sonic wave SW2. For example, the sonic wave control unit 208 outputs a transmission signal for causing the second transceiver unit 221 to emit the second sonic wave SW2 to the second transceiver unit 221. In response to this, the second transceiver unit 221 emits the second sonic wave SW2 (step S201).

[0215] In step S201, similarly to step S101, the second transceiver 221 may transmit a single pulsed second sound wave SW2. After executing step S201, the second transceiver 221 receives the sound wave inside the second acoustic waveguide 220, and outputs a second reception signal RS2 corresponding to the received sound wave.

[0216] The detector 209 detects, based on the second received signal RS2 output from the second transmitter / receiver 221, that the second transmitter / receiver 221 has received the second reflected wave RW2 (step S202).

[0217] Details of the detection process (step S202) may be generally similar to the detection process (step S102) according to embodiment 1. That is, in the detection process (step S202), a process is executed in which the "first transceiver 102", "first received signal RS1", "first reflected wave RW1", "step S101", and "first time" in the description of the detection process (step S102) according to embodiment 1 are replaced with "second transceiver 221", "second received signal RS2", "second reflected wave RW2", "step S201", and "second time", respectively.

[0218] The sound speed measurement unit 224 obtains the second time based on the sending time TS2 and the receiving time TR2 (step S203).

[0219] Details of step S203 may be substantially similar to step S103 according to embodiment 1. That is, in step S203, the sound speed measurement unit 224 executes a process in which the "first transmission / reception unit 102," "first sound wave SW1," "first reflected wave RW1," "step S101," and "first time" in the description of step S103 according to embodiment 1 are replaced with "second transmission / reception unit 221," "second sound wave SW2," "second reflected wave RW2," "step S201," and "second time," respectively.

[0220] The sound speed measurement unit 224 obtains the sound speed v by dividing the reference distance RD by the second time obtained in step S203 (step S204), and ends the sound speed measurement process.

[0221] By executing the sound speed measurement process, the sound speed v in the second acoustic waveguide 220 can be obtained. The first acoustic waveguide 101 is arranged next to the second acoustic waveguide 220. Therefore, the sound speed v in the second acoustic waveguide 220 is usually approximately equal to the sound speed v in the first acoustic waveguide 101. Therefore, the sound speed v in the first acoustic waveguide 101 can be obtained.

[0222] In the measurement process, the propagation distance DT may be calculated using the sound speed v calculated in the sound speed measurement process.

[0223] Physically, the second transceiver 221 and the measurement device 206 may be configured similarly to the first transceiver 102 and the measurement device 106, respectively.

[0224] The second embodiment of the present invention has been described above.

[0225] (Action and effect) According to this embodiment, the measurement system 200 includes a second acoustic waveguide 220, a second reflecting section 223, and a second transmitting / receiving section 221. The measurement device 206 includes a sound speed measuring section 224.

[0226] The second acoustic waveguide 220 is arranged next to the first acoustic waveguide 101, and is a member for propagating the pulsed second sound wave SW2. The second reflecting section 223 is arranged in the second acoustic waveguide 220, and reflects the second sound wave SW2. The second transmitting / receiving section 221 sends the second sound wave SW2 into the second acoustic waveguide 220, and receives a second reflected wave RW2 resulting from the second sound wave SW2 being reflected by the second reflecting section 223. The sound speed measuring section 224 obtains a sound speed v based on a second time from when the second sound wave SW2 is sent to when the second reflected wave RW2 is received, and the distance (reference distance RD) between the second transmitting / receiving section 221 and the second reflecting section 223.

[0227] It is possible to obtain the speed of sound v in the second acoustic waveguide 220. As described above, the speed of sound v in the second acoustic waveguide 220 is usually approximately equal to the speed of sound v in the first acoustic waveguide 101, so it is possible to obtain the speed of sound v in the first acoustic waveguide 101. Therefore, it is possible to accurately measure the distance between any two points or the change therein by using sound waves.

[0228] <Embodiment 3> In the first embodiment, an example has been described in which the measurement system 100 includes the first reflecting unit 105 (second fixing member 104). However, the first reflecting unit may be the liquid surface. In the third embodiment, an example in which the first reflecting unit is the liquid surface will be described. In this embodiment, for the sake of brevity, differences from the first embodiment will be mainly described, and overlapping descriptions will be omitted as appropriate. do.

[0229] A measurement system 300 according to a third embodiment of the present invention has a configuration example as shown in FIG. The present embodiment includes a first acoustic waveguide 301 instead of the first acoustic waveguide 101 according to the first embodiment, and a first transmitting / receiving section 102, a measuring device 106, and an external device 107 similar to those in the first embodiment.

[0230] The first acoustic waveguide 301 is a hollow tube for propagating sound waves, similar to the first embodiment. The first acoustic waveguide 301 according to the present embodiment is installed differently from the first acoustic waveguide 101 according to the first embodiment. The first acoustic waveguide 301 is filled with liquid from the bottom end to partway inside, and the liquid surface serves as the reflecting section 305. The reflecting section 305 is movable inside the first acoustic waveguide 301, similar to the first reflecting section 105 according to the first embodiment.

[0231] 16, for example, the first acoustic waveguide 301 is buried in the ground. In this case, the liquid that fills the first acoustic waveguide 301 partway is, for example, groundwater. Also, for example, although not shown, the first acoustic waveguide 301 may be a part of a communicating pipe into which liquid is injected, and in this case, the liquid that fills the first acoustic waveguide 301 partway may be an appropriate liquid such as water.

[0232] Except for the installation mode, the first acoustic waveguide 301 may be configured similarly to the first acoustic waveguide 101 according to embodiment 1. For example, the shape, dimensions, material, composition, etc. of the first acoustic waveguide 301 may be similar to those of the first acoustic waveguide 101 according to embodiment 1, or may be changed as appropriate.

[0233] In this embodiment, the first transceiver 102 is fixed to or near the upper end of the first acoustic waveguide 301. As a result, the first transceiver 102 transmits a first sound wave SW1 into the first acoustic waveguide 101, and receives a first reflected wave RW1 that is formed by the first sound wave SW1 being reflected by a first reflecting section 105 inside the first acoustic waveguide 101, as in the first embodiment.

[0234] Measurement system 300 according to this embodiment may operate in the same manner as measurement system 100 according to the first embodiment.

[0235] The first sound wave SW1 sent from the first transmitting / receiving unit 102 is reflected by the first reflecting unit 305 inside the first acoustic waveguide 301. The first transmitting / receiving unit 102 then receives the first reflected wave RW1 reflected by the first reflecting unit 305. Therefore, similar to the first embodiment, the measuring device 106 can obtain the distance DT between the first transmitting / receiving unit 102 and the first reflecting unit 305 or the change ΔDT therein based on the first time from when the first sound wave SW1 is sent to when the first reflected wave RW1 is received. The change ΔDT in the propagation distance DT can be obtained based on the propagation distance DT obtained in the past and the current propagation distance DT, similar to the first embodiment.

[0236] In the example shown in FIG. 16, the propagation distance DT is the distance between the first transmitting / receiving unit 102 (e.g., a part that transmits and receives sound waves) and the liquid surface, which is the reflecting unit 305. When measuring the distance R from the ground surface to the groundwater surface, for example, it is advisable to measure in advance the length of the part protruding upward from the ground surface (above ground length L). Then, the distance acquiring unit 119 holds the above ground length L in advance, and can measure the distance R by performing a calculation to subtract the above ground length L from the propagation distance DT. When calculating the change ΔR in the distance R, the change ΔR in the distance R is calculated based on the previously calculated distance R and the current distance R, as in the first embodiment.

[0237] The third embodiment of the present invention has been described above.

[0238] (Action and effect) According to this embodiment, first reflecting portion 305 is the liquid surface of a liquid that fills the inside of first acoustic waveguide 301 partway.

[0239] This makes it possible to measure the distance from the first transmitting / receiving unit 102 to the liquid surface, etc., simply by filling the inside of the first acoustic waveguide 301 partway with liquid. Therefore, it becomes possible to measure the distance between the first transmitting / receiving unit 102 and the liquid surface or the change therein using sound waves.

[0240] For example, when measuring changes in the groundwater level, the first acoustic waveguide 301 to which the first transmitting / receiving unit 102 is attached may be left buried in the ground. Since it is not necessary to bury the first acoustic waveguide 301 in the ground every time a measurement is made, changes in the groundwater level can be easily measured.

[0241] As described above, the first acoustic waveguide 301 may be a part of a communicating tube into which liquid is poured. This allows it to be used as a water cup for measuring the height difference between two distant points. This makes it possible to easily measure the height difference between two distant points.

[0242] Although the embodiment and the modified examples of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above may be adopted. For example, the present invention includes a form in which some or all of the embodiments and modified examples described so far are appropriately combined, and a form in which the forms are appropriately modified. For example, the order of multiple steps included in a method, process, etc. may be changed as long as the change does not affect the content.

[0243] For example, the second embodiment can be applied to the third embodiment. By arranging the second acoustic waveguide 220 next to and embedding it in the first acoustic waveguide 301, the accurate sound speed v inside the first acoustic waveguide 301 can be obtained, and measurements can be made more accurately. [Explanation of symbols]

[0244] 100,200,300 Measurement System 101,301 First acoustic waveguide 102 First transmitter / receiver 103 First fixing member 104 Second fixing member 104a Fixed part 104b Disc section 105,305 1st reflection section 106,206 Measuring equipment 107 External device 108,208 Sonic control unit 109,209 Detector 110 Measuring section 111 History memory unit 111a Measurement Information 112 Communications Department 113 1st generation part 114 Reflected wave detector 115 Center specific part 116 Second generation part 117 Pulse control section 118 Time Acquisition Department 119 Distance acquisition part 220 Second Acoustic Waveguide 221 Second Transmitter / Receiver 222 Fixing member 223 Second reflection part 224 Sonic velocity measurement part

Claims

1. a first acoustic waveguide; and a first transceiver that transmits a pulsed first sound wave into the first acoustic waveguide and receives a first reflected wave that is the first sound wave reflected by a first reflecting section inside the first acoustic waveguide; a measuring device that determines the distance or change in the distance between the first transmitting / receiving unit and the first reflecting unit based on a first time period from when the first sound wave is transmitted until when the first reflected wave is received and the speed of sound; a second acoustic waveguide arranged next to the first acoustic waveguide for propagating a pulsed second acoustic wave; a second reflecting portion disposed in the second acoustic waveguide and reflecting the second sound wave; a second transceiver that transmits the second sound wave into the second acoustic waveguide and receives a second reflected wave that is the second sound wave reflected by the second reflector, the measurement device includes a sound speed measurement unit that calculates the sound speed based on a second time period from when the second sound wave is transmitted until when the second reflected wave is received and a distance between the second transmitting / receiving unit and the second reflecting unit, The first acoustic waveguide and the second acoustic waveguide are made of the same material. Measurement system.

2. The first reflecting portion is disposed inside the first acoustic waveguide. The measurement system of claim 1 .

3. The first reflecting portion is movable within the first acoustic waveguide. The measurement system of claim 2 .

4. a first acoustic waveguide; and a first transceiver that transmits a pulsed first sound wave into the first acoustic waveguide and receives a first reflected wave that is the first sound wave reflected by a first reflecting section inside the first acoustic waveguide; a measuring device that determines the distance or a change therein between the first transmitting / receiving unit and the first reflecting unit based on a first time period from when the first sound wave is transmitted to when the first reflected wave is received, The first reflecting portion is a liquid surface that partially fills the inside of the first acoustic waveguide. Measurement system.

5. The first acoustic waveguide is a part of a communicating tube into which the liquid is injected. The measurement system of claim 4 .

6. The first transceiver is fixed relative to a reference point.

6. A measurement system according to any one of claims 1 to 5.

7. The first acoustic waveguide is flexible.

7. A measurement system according to any one of claims 1 to 6.

8. the time when the first reflected wave is received is the time when the first transmitting / receiving unit receives the center of the first reflected wave on the time axis, The measurement device detects the center on the time axis of the first reflected wave received by the first transceiver, based on a first received signal output from the first transceiver.

8. A measurement system according to any one of claims 1 to 7.

9. The first transceiver includes a piezoelectric element.

9. A measurement system according to any one of claims 1 to 8.

10. a communication unit that transmits measurement information including the distance or a change therein to an external device; 10. A measurement system according to any one of claims 1 to 9.

11. transmitting a pulsed first acoustic wave into the first acoustic waveguide; a first transmitting / receiving unit receiving a first reflected wave that is the first sound wave reflected by a first reflecting unit inside the first acoustic waveguide; a second acoustic wave having a pulse shape is transmitted to the inside of the second acoustic waveguide, the second acoustic waveguide being arranged next to the first acoustic waveguide and made of the same material as the first acoustic waveguide; The second sound wave is reflected by the second reflecting unit, and a second reflected wave is received by a second transmitting / receiving unit; calculating a speed of sound based on a second time period from when the second sound wave is transmitted until when the second reflected wave is received and a distance between the second transmitting / receiving unit and the second reflecting unit; The distance or the change therein between the first transmitting / receiving unit and the first reflecting unit is calculated based on a first time from when the first sound wave is transmitted until when the first reflected wave is received and the speed of sound. Measurement method.

12. transmitting a pulsed first acoustic wave into the first acoustic waveguide; the first acoustic wave is reflected by a first reflecting portion, which is a liquid surface of a liquid that fills partway inside the first acoustic waveguide, and the first reflected wave is received by a first transmitting / receiving portion; The distance between the first transmitting / receiving unit and the first reflecting unit or a change therein is calculated based on a first time from when the first sound wave is transmitted until when the first reflected wave is received. Measurement method.

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