System and method for specifying distance between two points

Abstract

To provide a system and a method for specifying a distance between two points, in which constraints related to an installation place and installation time of a measuring machine are restricted, and in which a distance between two points can be specified with high accuracy, while reducing time and labor required for the measurement.SOLUTION: A system 500 for specifying a distance between two points includes: a transmitter 200 being a target; and a receiver 100 being a measuring machine. The receiver 100 includes: a transmitting unit 120 for transmitting a transmission wave; a microphone 140 for receiving a sound wave; a first circuit 112; and a control unit 110. The transmitter 200 includes: a receiving unit 220 for receiving a transmission wave; a speaker 240 for transmitting a sound wave; and a second circuit 212. The transmitter 200 transmits a sound wave when receiving a transmission wave. The control unit 110 specifies a peak value of the received sound wave, and specifies a distance between two points of the receiver 100 and the transmitter 200, on the basis of time from transmission of a transmission wave until a peak value of a sound wave is specified, a circuit delay time when each circuit is passed through by an electric signal, and speed of the sound wave.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a system and a method for specifying a distance between two points. [Background technology]

[0002] In a method for determining the distance between two measurement points installed on various structures to be measured, such as those used to measure the displacement of retaining walls during construction, the displacement of the inner walls of mountain tunnels, and the level of roads and railway tracks, a measuring device such as an optical rangefinder is installed at the measurement position and the measuring device is used to sight the measurement point to determine the distance between the two points.

[0003] For example, with regard to measuring the displacement of the inner wall surface of a mountain tunnel, one of the examples given above, a tunnel measurement system is proposed in Patent Document 1, which automatically measures specified control dimensions inside the tunnel shaft during construction and manages the measurement data centrally at a specified management center. Specifically, the system is equipped with a number of measuring devices that are installed inside the tunnel during construction of the tunnel and measure specified control dimensions inside the tunnel, a communication means for transmitting the measurement data of these measuring devices to a specified control center, and a control device that operates the multiple measuring devices from the specified control center via the communication means. More specifically, the measurement device is composed of a laser transmitter / receiver with the function of emitting and receiving a laser horizontally from the inner wall surface of the tunnel, and a laser reflector with the function of reflecting the laser light emitted by the laser transmitter / receiver toward the laser transmitter / receiver. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-304531 A Summary of the Invention [Problem to be solved by the invention]

[0005] The tunnel measurement system described in Patent Document 1 uses laser light as a means of displacement measurement, but since measurement is impossible if there is an obstacle in the path of the laser light, the installation location of the measurement device is naturally limited. For example, in the mountain tunnel mentioned above, since large heavy machinery passes through the tunnel, the installation location of the measuring device is further restricted to avoid the route taken by the large heavy machinery, and measurements often have to be taken at times that avoid the times when the large heavy machinery is passing through, which poses the problem of restrictions on both the measurement location and the measurement time.

[0006] In addition, in actual measurements, the laser rangefinder is set up horizontally and sighted into each point to perform measurements. Therefore, in measurement environments where it is difficult to see the mirrors and targets, such as mountain tunnels, it becomes necessary to repeatedly rearrange the laser rangefinder and perform the survey within the limitations of measurement locations mentioned above, which creates issues such as requiring a lot of time and effort.

[0007] The present invention aims to provide a two-point distance determining system and a two-point distance determining method that can determine the distance between two points with high accuracy while minimizing constraints on the installation location and installation time of the measuring instrument and reducing the time and effort required for measurement. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the two-point distance specification system according to the present invention comprises: A two-point distance determination system that determines a distance between a measurement point installed on a structure and a measurement device that measures the measurement point, comprising: A transmitter as a target installed at the measurement point; a receiver that is the measuring device and that measures the distance to the target; The receiver includes at least a transmitter that transmits a transmission wave, a microphone that receives a sound wave, a first circuit that connects the transmitter and the microphone, and a control unit; the transmitter includes at least a receiving unit that receives the transmission wave, a speaker that transmits the sound wave, and a second circuit that connects the receiving unit and the speaker; The transmitter transmits the sound wave from the speaker when the receiving unit receives the transmission wave, The control unit is characterized in that it identifies the peak value of the sound wave received by the microphone, and determines the point-to-point distance between the receiver and the transmitter based on the time from the transmission of the transmitted wave to the identification of the peak value of the sound wave, the circuit delay time when an electrical signal passes through the first circuit and the second circuit, and the speed of the sound wave.

[0009] According to this embodiment, a transmitter which is a target is installed at a measurement point of a structure, a receiver is applied to a measuring device which measures the distance to the target, and when the transmission wave transmitted from the transmitting unit of the receiver is received by the receiving unit of the transmitter, a sound wave is transmitted from the speaker of the transmitter to the microphone of the receiver, and the control unit of the receiver identifies the peak value of the received sound wave and determines the distance between the two points between the receiver and the transmitter based on the time from the transmission of the transmission wave to the determination of the peak value of the sound wave, the circuit delay time when an electrical signal passes through the circuits of the transmitter and receiver, and the speed of the sound wave.This reduces constraints on the installation location and installation time of the measuring device, and makes it possible to determine the distance between the two points with high accuracy while reducing the time and effort required for measurement.

[0010] Another aspect of the two-point distance specification system according to the present invention is The sound wave is an ultrasonic wave, and the transmission wave is either an infrared ray or a visible light ray.

[0011] According to the present embodiment, since the sound waves are ultrasonic waves and the transmission waves are either infrared rays or visible light, and since both infrared rays and visible light are significantly faster than sound waves, it is preferable that when determining the distance between two points in the control unit, there is no need to take into account the time it takes for the transmission waves to be transmitted from the transmitting unit to the receiving unit (transmission time is zero).

[0012] Another aspect of the two-point distance specification system according to the present invention is In the first circuit, a peak hold circuit and a signal detection circuit are interposed in parallel between the microphone and the control unit; a pulse generating circuit is interposed between the transmitting unit and the control unit, and the transmission wave is pulse-transmitted from the pulse generating circuit to the transmitting unit; a counter circuit is interposed between the signal detection circuit and the control unit; the signal detection circuit has a sonic threshold set; the signal detection circuit generates a detection pulse when the peak value of the sound wave reaches the sound wave threshold; The counter circuit counts a transmission time from a pulse transmission time in the pulse transmission circuit to a detection pulse generation time in the signal detection circuit.

[0013] According to this embodiment, the peak value (maximum input value) of the sound wave received by the microphone is identified by a peak hold circuit and the peak value is transmitted to a control unit. The control unit then transmits the peak value of the sound wave to a signal detection circuit. When the peak value reaches a sound wave threshold value set in the signal detection circuit, the signal detection circuit generates a detection pulse. The counter circuit counts the transmission time from the pulse transmission time in the pulse transmission circuit to the detection pulse generation time in the signal detection circuit, thereby making it possible to identify the distance between the two points between the receiver and the transmitter with high accuracy.

[0014] Another aspect of the two-point distance specification system according to the present invention is In the first circuit, a rectifying and detecting circuit is interposed between the microphone and the peak hold circuit and between the microphone and the signal detection circuit, The rectification detection circuit is characterized in that it inverts the negative waveform or the positive waveform of the sine wave of the sound wave received by the microphone to the other.

[0015] According to this embodiment, a rectifier detection circuit is interposed between the microphone and the peak hold circuit and signal detection circuit, and the rectifier detection circuit corrects the waveform by inverting the negative or positive waveform of the sine wave of the sound wave received by the microphone to the other side, and then transmitting the corrected waveform to the peak hold circuit, which is preferable because it makes it easier to identify the peak value of the sound wave in the peak hold circuit.

[0016] In another aspect of the two-point distance specifying system according to the present invention, The receiver is equipped with a temperature and humidity sensor, a wind direction sensor, and a wind speed sensor. The control unit corrects the speed of the sound waves based on the measurement data from the temperature and humidity sensor, the wind direction sensor, and the wind speed sensor.

[0017] According to this embodiment, the control unit corrects the speed of the sound waves based on the measurement data from the temperature and humidity sensor, the wind direction sensor, and the wind speed sensor, thereby enabling distance determination using sound waves that takes into account the environmental conditions of the point-to-point distance determination area, making it possible to determine the point-to-point distance between the receiver and the transmitter with even greater accuracy.

[0018] In another aspect of the two-point distance specifying system according to the present invention, The receiver further comprises a first radio unit; The transmitter further comprises a second radio unit; The second circuit is provided with an ON / OFF switch, When a measurement start signal is transmitted from the first wireless device to the second wireless device, the ON / OFF switch is turned ON.

[0019] According to this aspect, when a measurement start signal is transmitted from the first radio of the receiver to the second radio of the transmitter, the ON / OFF switch provided in the second circuit is turned ON. For example, when there are multiple transmitters at multiple measurement points on a structure, it is possible to select only the transmitter at the measurement point to be measured and determine the distance between the two points and the receiver.

[0020] Another aspect of the two-point distance specification system according to the present invention is The structure is an inner wall surface of a mountain tunnel, The transmitter is installed on the inner wall surface of the mountain tunnel, The receiver is installed at another position on the inner wall surface of the mountain tunnel or on the roadbed of the mountain tunnel, It is characterized in that it is used to measure the displacement of the inner wall surface by determining the distance between a plurality of two points over time.

[0021] According to this embodiment, even in mountain tunnels, where the measurement environment is difficult to see the target, by transmitting and receiving sound waves between the transmitter (the target) and the receiver (the measuring device) to determine the distance between the two points, it is possible to reduce constraints on the location and installation time of the measuring device when measuring the displacement of the inner wall surface of a mountain tunnel, thereby reducing the time and effort required for measurement.

[0022] Further, one aspect of the two-point distance specifying method according to the present invention is to A method for determining a distance between two points, the method comprising: determining a distance between a measurement point installed on a structure and a measurement device that measures the measurement point, the method comprising the steps of: A transmitter serving as a target is installed at the measurement point, and a receiver serving as the measurement device for measuring the distance to the target is installed; Here, the receiver includes at least a transmitting unit that transmits a transmission wave, a microphone that receives a sound wave, a first circuit that connects the transmitting unit and the microphone, and a control unit, and the transmitter includes at least a receiving unit that receives the transmission wave, a speaker that transmits the sound wave, and a second circuit that connects the receiving unit and the speaker; an installation process; a transmitting / receiving step of transmitting the transmission wave from the transmitting unit, transmitting the sound wave from the speaker when the receiving unit receives the transmission wave, and receiving the sound wave by the microphone; The control unit is characterized by having a distance determination process in which it determines the peak value of the sound wave received by the microphone, and determines the two-point distance between the receiver and the transmitter based on the time from the transmission of the transmitted wave to the determination of the peak value of the sound wave, the circuit delay time when an electrical signal passes through the first circuit and the second circuit, and the speed of the sound wave.

[0023] According to this embodiment, a transmitter which is a target is installed at a measurement point of a structure, a receiver is applied to a measuring device which measures the distance to the target, and when the transmission wave transmitted from the transmitting unit of the receiver is received by the receiving unit of the transmitter, a sound wave is transmitted from the speaker of the transmitter to the microphone of the receiver, and the control unit of the receiver identifies the peak value of the received sound wave and determines the distance between the two points between the receiver and the transmitter based on the time from the transmission of the transmission wave to the determination of the peak value of the sound wave, the circuit delay time when an electrical signal passes through the circuits of the transmitter and receiver, and the speed of the sound wave.This reduces constraints on the installation location and installation time of the measuring device, and makes it possible to determine the distance between the two points with high accuracy while reducing the time and effort required for measurement.

[0024] Another aspect of the two-point distance specifying method according to the present invention is to In the first circuit, a peak hold circuit and a signal detection circuit are interposed in parallel between the microphone and the control unit; a pulse generating circuit is interposed between the transmitting unit and the control unit, and the transmission wave is pulse-transmitted from the pulse generating circuit to the transmitting unit; a counter circuit is interposed between the signal detection circuit and the control unit; A set of the steps of the transmission and reception step and the distance determination step is executed twice; In the first process set, the peak value of the sound wave received by the microphone is acquired by the peak hold circuit, and the control unit reduces the peak value based on a reduction ratio for reducing the peak value to determine a sound wave threshold value, and then sets the sound wave threshold value in the signal detection circuit; In the second process set, when the peak value of the sound wave reaches the sound wave threshold value, a detection pulse is generated in the signal detection circuit, and the transmission time from the pulse transmission time in the pulse transmission circuit to the detection pulse generation time in the signal detection circuit is counted by the counter circuit.

[0025] According to this aspect, in the first process set, which is the calibration measurement, the peak value of the sound wave received by the microphone is identified by the peak hold circuit and the peak value is transmitted to the control unit, and the control unit reduces the peak value based on the reduction ratio for reducing the peak value, determines the sound wave threshold value, and sets it in the signal detection circuit. Then, in the second process set, which is the actual measurement, the sound wave is transmitted again from the speaker to the microphone, and when the sound wave transmitted to the signal detection circuit reaches the sound wave threshold value, the signal detection circuit generates a detection pulse, and the counter circuit counts the transmission time from the pulse transmission time in the pulse transmission circuit to the detection pulse generation time in the signal detection circuit, thereby preventing the occurrence of time errors that may occur when the threshold level fluctuates when the sound wave threshold value is set near the peak value, and the distance between the two points between the receiver and the transmitter can be determined with high accuracy. For example, in the calibration measurement, the reduction ratio can be set within the range of 30% to 60%, and the peak value of the identified sound wave can be reduced to set the sound wave threshold value.

[0026] In another aspect of the method for specifying a distance between two points according to the present invention, In the first process set, the peak value is reduced based on a reduction ratio for reducing the peak value, and then a plurality of provisional acoustic thresholds are set; performing the set of steps under each of the pseudo sonic thresholds to identify the circuit delay time at each pseudo sonic threshold; For each of the tentative sound thresholds, the second set of steps is performed a plurality of times to identify a plurality of two-point distances, and an average value of a plurality of two-point distances in the middle of the identified plurality of two-point distances is further identified as the two-point distance for each tentative sound threshold, and further, the variance of each two-point distance for each tentative sound threshold is identified; The control unit is characterized in that it specifies the provisional sound threshold having the smallest variance as the formal sound threshold, and specifies the average value at the provisional sound threshold as the formal two-point distance.

[0027] According to this embodiment, when the peak value of the sound wave is reduced based on the reduction ratio in the first process set, which is the calibration measurement, to set the sound threshold, multiple temporary sound thresholds are set, the process set is performed under all temporary sound thresholds to identify the circuit delay time at each temporary sound threshold, and the process set is performed multiple times for each temporary sound threshold to identify multiple two-point distances, and the average value of the multiple two-point distances in the middle of the identified multiple two-point distances is set as the two-point distance for each temporary sound threshold, and after identifying the variance of the two-point distances for each of all temporary sound thresholds, the temporary sound threshold with the smallest variance is identified as the official sound threshold, and the average value of this temporary sound threshold is set as the official two-point distance.By doing this, the two-point distance between the receiver and the transmitter can be identified with high accuracy while preventing the occurrence of time errors that may occur when the sound threshold with the reduced peak value or the received waveform related to the sound wave fluctuates. That is, this aspect is another embodiment of the method for setting a sound threshold value, for preventing occurrence of a time error that may occur when the threshold level fluctuates when the sound threshold value is set near the peak value.

[0028] Another aspect of the two-point distance specifying method according to the present invention is to In the first circuit, a peak hold circuit and a signal detection circuit are interposed in parallel between the microphone and the control unit; a pulse generating circuit is interposed between the transmitting unit and the control unit, and the transmission wave is pulse-transmitted from the pulse generating circuit to the transmitting unit; a counter circuit is interposed between the signal detection circuit and the control unit; A set of the steps of the transmission and reception step and the distance determination step is executed twice; In the first process set, the peak value of the sound wave received by the microphone is acquired by the peak hold circuit, and this is performed multiple times. The control unit selects the most frequently occurring peak value, reduces the peak value based on a reduction ratio for reducing the selected peak value, and determines a sound wave threshold value. The sound wave threshold value is set in the signal detection circuit. In the second process set, when the peak value of the sound wave reaches the sound wave threshold value, a detection pulse is generated in the signal detection circuit, and the transmission time from the pulse transmission time in the pulse transmission circuit to the detection pulse generation time in the signal detection circuit is counted by the counter circuit.

[0029] According to this embodiment, in the first process set, which is the calibration measurement, the peak values ​​of the sound waves received by the microphone are obtained multiple times using a peak hold circuit, the control unit selects the most frequently occurring peak value and determines the sound wave threshold based on the reduction ratio for reducing the selected peak value, and the signal detection circuit generates a detection pulse based on this sound wave threshold.This makes it possible to determine the distance between the two points between the receiver and the transmitter with high accuracy while preventing the occurrence of time errors that may occur when the threshold level fluctuates when the threshold is set near the peak value. That is, this aspect is yet another embodiment of the method for setting a sound threshold, for preventing the occurrence of time errors that may occur when the threshold level fluctuates when the sound threshold is set near the peak value.

[0030] Another aspect of the two-point distance specifying method according to the present invention is to In the first circuit, a peak hold circuit and a signal detection circuit are interposed in parallel between the microphone and the control unit; a pulse generating circuit is interposed between the transmitting unit and the control unit, and the transmission wave is pulse-transmitted from the pulse generating circuit to the transmitting unit; a counter circuit is interposed between the signal detection circuit and the control unit; A set of the steps of the transmission and reception step and the distance determination step is executed twice; In the first process set, the peak value of the sound wave received by the microphone is acquired by the peak hold circuit, and this is performed multiple times to measure the rise time until the peak value is reached. The control unit selects the peak value whose rise time is within a time threshold related to the rise time, reduces the peak value based on a reduction ratio for reducing the selected peak value to determine a sound wave threshold, and sets the sound wave threshold in the signal detection circuit. In the second process set, when the peak value of the sound wave reaches the sound wave threshold value, a detection pulse is generated in the signal detection circuit, and the transmission time from the pulse transmission time in the pulse transmission circuit to the detection pulse generation time in the signal detection circuit is counted by the counter circuit.

[0031] According to this embodiment, in the first process set, which is the calibration measurement, the peak value of the sound wave received by the microphone is obtained multiple times using a peak hold circuit, the rise time to reach the peak value is measured, the control unit selects a peak value whose rise time is within the time threshold and determines a sound wave threshold based on a reduction ratio for reducing the selected peak value, and the signal detection circuit generates a detection pulse based on this sound wave threshold, thereby making it possible to determine the distance between the two points between the receiver and the transmitter with high accuracy while preventing the occurrence of time errors that may occur when the threshold level fluctuates when the threshold is set near the peak value. That is, this aspect is yet another embodiment of the method for setting a sound threshold, for preventing the occurrence of time errors that may occur when the threshold level fluctuates when the sound threshold is set near the peak value. Effect of the Invention

[0032] The two-point distance determination system and method of the present invention can determine the distance between two points with high accuracy while minimizing constraints on the installation location and installation time of the measuring instrument and reducing the time and effort required for measurement. [Brief description of the drawings]

[0033] [Figure 1]This is an oblique view showing an example of a two-point distance specifying system according to an embodiment installed on the inner wall surface of a mountain tunnel, a see-through view of the interior of the mountain tunnel, and also a diagram showing the installation process of the two-point distance specifying method according to an embodiment. [Diagram 2] This is an example of a configuration block diagram of a receiver and a transmitter that constitute a point-to-point distance determination system according to an embodiment, and also shows the state in which wireless communication is being performed between the receiver and the transmitter to be measured. [Diagram 3] 1 is a diagram illustrating a process set including a transmission / reception process and a distance specifying process of a two-point distance specifying method according to an embodiment. FIG. [Figure 4] 10A and 10B are diagrams illustrating a method of updating a sound waveform in a rectification detection circuit. [Diagram 5] 5A and 5B are diagrams illustrating a method for acquiring a peak value of a sound waveform in a peak hold circuit. [Figure 6] 4A and 4B are diagrams illustrating a method for generating a detection pulse in a signal detection circuit. [Figure 7] 10A and 10B are diagrams illustrating a method for counting a transmission time in a counter circuit. [Figure 8] 4 is a diagram illustrating a signal flow from pulse transmission to generation of a detection pulse. FIG. [Figure 9] 1 is a diagram illustrating how the frequency of a sound wave does not change while the amplitude of the sound wave attenuates as it travels through space. [Figure 10A] 10 is a diagram for explaining the occurrence of a time error until signal detection when the input level differs from a fixed sound wave threshold. FIG. [Figure 10B] FIG. 10 is a diagram for explaining an example of a method for correcting a time error until signal detection, and explains detection of a signal based on a sound wave threshold determined by the peak value (maximum value) of the sound wave and a reduction ratio. [Figure 10C] 10 is a diagram illustrating the difference in time error until signal detection when the peak value (maximum value) of a sound wave is used as the sound wave threshold and when the peak value is reduced to use the sound wave threshold. FIG. [Figure 11A]FIG. 13 is a diagram for explaining another example of a method for correcting a time error until signal detection, and is a diagram for explaining a sound threshold setting method by a method of setting a plurality of temporary sound thresholds. [Figure 11B] 11B is a diagram for explaining a method for setting a sound threshold value by setting a plurality of temporary sound threshold values, similar to FIG. 11A. FIG. [Figure 11C] 11A and 11B, this is a diagram for explaining a method for setting a sound threshold value by setting a plurality of temporary sound threshold values. [Figure 11D] 11A to 11C, this is a diagram for explaining a method for setting a sound threshold value by setting a plurality of temporary sound threshold values. [Figure 12A] FIG. 13 is a diagram for explaining yet another example of a method for correcting the time error until signal detection, and explains that a time error until signal detection occurs due to differences in the rising gradient until the waveform reaches a peak value. [Figure 12B] 11A and 11B are diagrams illustrating a method of correcting a time error based on the rise time until the waveform reaches a peak value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Hereinafter, a two-point distance specifying system and a two-point distance specifying method according to an embodiment will be described with reference to the accompanying drawings. Note that in this specification and the drawings, substantially identical components may be denoted by the same reference numerals to avoid redundant description.

[0035] [Point-to-point distance specification system and point-to-point distance specification method according to the embodiment] An example of a two-point distance specifying system and a two-point distance specifying method according to the embodiment will be described with reference to FIGS. Here, FIG. 1 is a perspective view showing a state where an example of a two-point distance specification system according to the embodiment is installed on the inner wall surface of a mountain tunnel, and is a see-through view of the inside of the mountain tunnel, and is also a diagram showing an installation process of a two-point distance specification method according to the embodiment. Also, FIG. 2 is an example of a configuration block diagram of a receiver and a transmitter constituting a two-point distance specification system according to the embodiment, and is a diagram showing a state where wireless communication is performed between the receiver and the transmitter to be measured, and FIG. 3 is a diagram explaining a process set of a transmission / reception process and a distance specification process of a two-point distance specification method according to the embodiment. Also, FIG. 4 is a diagram explaining a method of updating a sound wave waveform in a rectification detection circuit, FIG. 5 is a diagram explaining a method of acquiring a peak value of a sound wave waveform in a peak hold circuit, FIG. 6 is a diagram explaining the generation of a detection pulse in a signal detection circuit, and FIG. 7 is a diagram explaining a method of counting a transmission time in a counter circuit. Furthermore, FIG. 8 is a diagram explaining a signal flow from pulse transmission to generation of a detection pulse.

[0036] In the following illustrated example, the structure for which the distance between two points is to be specified is a mountain tunnel, and more specifically, the distance between each of several targets set up on the inner wall of the mountain tunnel and the measuring device is measured multiple times over time to measure the displacement of each target (measurement A), which is used to measure the displacement of the inner wall of the mountain tunnel.However, in addition to mountain tunnels, the structure for which the distance between two points is to be specified can be various other structures such as roads, railway tracks, bridges, retaining walls, etc.

[0037] When measuring the displacement of the inner wall surface Ta of a mountain tunnel T that is extended by excavating the ground G, a receiver 100, which is a measuring device, is installed on a support S such as an H-shaped steel that supports the tunnel together with sprayed concrete. Here, the receiver 100 may be erected on the roadbed of the mountain tunnel T.

[0038] In mountain tunnel T, a new tunnel face K is constructed as the tunnel is excavated, and multiple measurement points (four in the illustrated example) are set at intervals in the circumferential direction of the tunnel on the inner wall Ta at a distance d2 (the distance d2 changes from time to time as the tunnel is excavated) from the tunnel face K, and transmitters 200A to 200D are installed as targets at each measurement point. Note that there are various numbers of targets installed other than the illustrated example.

[0039] A point-to-point distance determining system 500 is formed by receiver 100, which is a measuring device installed on a support structure S, and transmitters 200, which are multiple targets installed on the inner wall surface Ta of a mountain tunnel T. In the following explanation, a method for determining the point-to-point distance d1 between receiver 100 and transmitter 200A will be described, but the method for determining the point-to-point distances between receiver 100 and other transmitters 200B to 200D is similar.

[0040] In specifying the point-to-point distance between the receiver 100 and each of the transmitters 200A to 200D, transmission and reception of transmission waves and sound waves are performed in the X1 to X4 directions between the receiver 100 and each of the transmitters 200A to 200D.

[0041] In other words, unlike conventional measurement methods in which a measuring device such as an optical rangefinder is installed on the roadbed and the measuring device is used to measure a mirror or target, the distance between two points between the measuring device and the target, etc., this system automatically determines the distance between two points between receiver 100 and transmitter 200 after receiver 100 and transmitter 200 are installed in their respective designated positions.

[0042] In the two-point distance specifying method according to the embodiment, as shown in FIG. 1, an installation step is performed in which transmitter 200, which is a target, is installed at a measurement point, and receiver 100, which is a measuring device that measures the distance to the target, is installed.

[0043] As shown in FIG. 2, the receiver 100 constituting the point-to-point distance determination system 500 has a first control unit 110 (an example of a control unit), a transmitting unit 120, and a microphone 140, which are electrically connected by a first circuit 112.

[0044] A peak hold circuit 160 and a signal detection circuit 170 are arranged in parallel between the microphone 140 and the first control unit 110. A counter circuit 180 and a pulse transmission circuit 190 are arranged between the transmission unit 120 and the first control unit 110, and the counter circuit 180 is arranged between the signal detection circuit 170 and the first control unit 110.

[0045] The receiver 100 is composed of a computer, and the first control unit 110 is a CPU (Central Processing Unit). Around the first control unit 110 there are a main memory device 115, an auxiliary memory device 116, a communication IF (interface) 117, and an input / output IF 118, each of which is connected to the first control unit 110 via a connection bus 111.

[0046] The first control unit, CPU 110, is also called an MPU (Microprocessor) or a processor, and CPU 110 may be a single processor or a multiprocessor. CPU 110 is a central processing unit that performs overall control of receiver 100, which is a computer. CPU 110 provides functions that meet a predetermined purpose by, for example, expanding a program stored in auxiliary storage device 116 in an executable manner in a working area of ​​main storage device 115, and controlling peripheral devices through the execution of the program.

[0047] The main memory device 115 stores computer programs executed by the CPU 110, data processed by the CPU 110, etc. The main memory device 115 includes, for example, a flash memory, a RAM (Random Access Memory), and a ROM (Read Only Memory). The auxiliary memory device 116 stores various programs and various data in a readable and writable recording medium, and is also called an external memory device. The auxiliary memory device 116 stores, for example, an OS (Operating System), various programs, various tables, etc. The OS includes, for example, a communication interface program that transfers data to and from external devices connected via the communication IF 117. The external devices include, for example, a temperature and humidity sensor 310, a wind direction sensor 320, and a wind speed sensor 330.

[0048] The auxiliary storage device 116 is used, for example, as a storage area that supplements the main storage device 115, and stores computer programs executed by the CPU 110, data processed by the CPU 110, etc. The auxiliary storage device 116 is a silicon disk including a non-volatile semiconductor memory (flash memory, EPROM (Erasable Programmable ROM)), a hard disk drive (HDD: Hard Disk Drive) device, a solid state drive device, etc. Examples of the auxiliary storage device 116 include drives for removable recording media such as a CD drive device, a DVD drive device, and a BD drive device, and examples of the removable recording media include a CD, a DVD, a BD, a USB (Universal Serial Bus) memory, and an SD (Secure Digital) memory card, etc.

[0049] The input / output IF 118 is an interface for inputting and outputting data between the receiver 100 and a device connected to the receiver 100. For example, an input device such as a touch panel or a microphone is connected to the input / output IF 118. The receiver 100 receives, via the input / output IF 118, an operation instruction from an operator who operates the input device.

[0050] In addition, the input / output IF 118 is connected to display devices such as a liquid crystal display (LCD) panel or an organic electroluminescence (EL) panel, and output devices such as a speaker, so that the start of measurement, measurement data, etc., are displayed on the screen.

[0051] The communication IF 117 is an interface with a network to which the receiver 100 is connected. The communication IF 117 receives measurement data from the temperature and humidity sensor 310 etc. via various networks such as a public network such as the Internet, a wireless network such as a mobile phone network, a dedicated network such as a Virtual Private Network (VPN), a Local Area Network (LAN), etc., and transmits and receives signals to and from the transmitter 200. Note that the temperature and humidity sensor 310 etc. and the receiver 100 may be connected via a wire to enable data transmission and reception.

[0052] On the other hand, the transmitter 200 constituting the point-to-point distance specifying system 500 has a second control unit 210, a receiving unit 220, and a speaker 240, which are electrically connected by a second circuit 212.

[0053] The second circuit 212 is provided with an ON / OFF switch 214, and when a measurement start signal is not received from the receiver 100, the ON / OFF switch 214 is switched OFF as shown in FIG.

[0054] The transmitter 200 is also composed of a computer, the second control unit 210 is a CPU, and around the second control unit 210 there are a main memory device 215, an auxiliary memory device 216, a communication IF 217, and an input / output IF 218, each of which is connected to the second control unit 210 via a connection bus 211.

[0055] As shown in FIG. 2, when a measurer inputs to the receiver 100 a selection of one transmitter 200A from among multiple transmitters 200 for determining the distance between two points, the first wireless device 130 transmits a measurement start signal in the Y1 direction to the second wireless device 230 having the ID number (identification number) of the transmitter 200A.

[0056] When the transmitter 200A receives a measurement start signal at the second wireless device 230, the ON / OFF switch 214 is turned ON, enabling transmission and reception of electrical signals between the receiver 220 and the speaker 240. That is, the ON / OFF switch 214 of only the transmitter 200A that is the measurement target among the multiple transmitters 200 is turned ON, and the ON / OFF switches 214 of the other transmitters 200B to 200D remain OFF, enabling transmission and reception of wireless signals, infrared rays, sound waves, etc. described below between the receiver 100 and each individual transmitter 200A.

[0057] The transmission section 120 of the receiver 100 is a light emitting section that emits infrared rays, visible light, or the like, and the reception section 220 of the transmitter 200 is a light receiving section that receives the emitted infrared rays, visible light, or the like.

[0058] On the other hand, sound waves such as ultrasonic waves are transmitted from the speaker 240 of the transmitter 200, and the microphone 140 of the receiver 100 receives the transmitted sound waves.

[0059] In the transmitter 200, under the control of the second control unit 210, when the receiving unit 220 receives infrared rays or the like, a received light signal is transmitted to the speaker 240 via the second circuit 212, and the speaker 240, having received the received light signal, transmits sound waves such as ultrasound to the microphone 140.

[0060] Here, the speed of the sound waves emitted from the speaker 240 is corrected based on measurement data from a temperature and humidity sensor 340 electrically connected to the transmitter 200, taking into account the temperature and humidity at the location of the transmitter 200, and the corrected sound wave speed data regarding the sound waves emitted from the speaker 240 is transmitted to the first control unit 110 of the receiver 100.

[0061] 3, in the receiver 100, when a transmission wave is pulsed in the Y3 direction from the pulse generating circuit 190 to the transmitting unit 120 based on a command signal from the first control unit 110, infrared rays are emitted from the transmitting unit 120 to the receiving unit 220 of the transmitter 200A in the Y4 direction. After the receiving unit 220 receives the infrared rays, the receiving unit 220 transmits a light reception signal in the Y5 direction to the speaker 240 via the second circuit 212, and the speaker 240, having received the light reception signal, transmits a sound wave in the Y6 direction to the microphone 140 (the above is the transmitting and receiving process).

[0062] The two-point distance determination system 500 is a system in which the first control unit 110 determines the two-point distance d1 between the transmitter 200A and the receiver 100 based on the transmission time of the sound wave between the speaker 240 of the transmitter 200A and the microphone 140 of the receiver 100 and the speed of the sound wave (ultrasound).In this determination, the first control unit 110 determines a total time consisting of the transmission time (so-called circuit delay (time)) of the signal transmitted through the first circuit 112 of the receiver 100 and the second circuit 212 of the transmitter 200A, the infrared transmission time for infrared rays to be transmitted from the transmitting unit 120 to the receiving unit 220, and the ultrasonic transmission time, and then the ultrasonic transmission time is calculated by subtracting the infrared transmission time and the circuit delay time from the total time.

[0063] The sound wave signal received by the microphone 140 is transmitted via the first circuit 112 to the rectification detection circuit 150 in the Y7 direction.

[0064] 7, the sound wave signal transmitted from the microphone 140 to the first circuit 112 has a sine waveform, but the rectification detection circuit 150 inverts the negative (negative) side waveform to the positive (positive) side to make all waveforms positive, thereby improving the detectability of the sound wave signal. Here, the positive side may be inverted to the negative side to make all waveforms negative.

[0065] The waveform after rectification and detection by the rectification detection circuit 150 is transmitted in the Y8 direction and the Y12 direction at different timings to the peak hold circuit 160 and the signal detection circuit 170, which are in a parallel relationship. The peak hold circuit 160 and the signal detection circuit 170 are circuits for adjusting the above-mentioned circuit delay to a constant value.

[0066] The sound wave signal that has passed through the peak hold circuit 160 is transmitted in the Y9 direction to the first control unit 110. The waveform after passing through the peak hold circuit 160 is, for example, a waveform as shown in Fig. 5, and the maximum value of the waveform is obtained in the peak hold circuit 160.

[0067] 6, the signal detection circuit 170 is set with a sound wave threshold determined by the first control unit 110, and the waveform after rectification detection is transmitted to the signal detection circuit 170 in the Y12 direction, the arrival time t5 of the waveform that reaches the sound wave threshold is detected, a detection pulse is generated at the arrival time t5, and data on the arrival time t5 is transmitted in the Y13 direction and the Y11 direction to the first control unit 110 and the counter circuit 180, respectively. Here, the arrival time t5 is the detection pulse generation time.

[0068] The setting of the sound wave threshold will be described in detail below, but when attempting to identify the maximum value of the input level of the signal acquired by the peak hold circuit 160, the threshold level fluctuates according to the signal near the peak value, and the fluctuation in the threshold level increases the time error, which may reduce the accuracy of the transmission time from the identified pulse emission time to the detection pulse generation time. Therefore, the signal detection circuit 170 sets a sound wave threshold that is multiplied by a reduction ratio to the maximum value of the input level of the signal, thereby suppressing the increase in time error caused by the fluctuation in the threshold level.

[0069] Furthermore, if time errors due to fluctuations in the threshold level are not a problem, the maximum value (peak value) of the input level of the signal acquired by the peak hold circuit 160 may be used as the sound wave threshold to determine the transmission time from the pulse emission time to the detection pulse generation time.

[0070] As shown in FIG. 3, data relating to pulse transmission time t1 is transmitted to the counter circuit 180 from the pulse transmission circuit 190 in the Y15 direction, and data relating to detection pulse generation time t5 is transmitted from the signal detection circuit 170 in the Y11 direction.

[0071] 7, in the counter circuit 180, a clock input is output from the rising edge of the pulse transmission time t1 (input 1) to the rising edge of the detection pulse generation time t5 (input 2). Then, the number of clocks is counted, and a constant signal is output only for outputs where the bit represented in binary is "1", for example.

[0072] In this way, data regarding the transmission time from pulse transmission time t1 to detection pulse generation time t5, counted in counter circuit 180, is transmitted to first control unit 110 in the Y16 direction.

[0073] The signal flow from pulse transmission in pulse transmission circuit 190 to generation of a detection pulse in signal detection circuit 170 can be summarized as shown in Fig. 8. Data relating to the transmission time t (total time) from pulse transmission time t1 to detection pulse generation time t5 is transmitted to first control unit 110.

[0074] As described above, the first control unit 110 calculates the ultrasonic wave transmission time by subtracting the infrared transmission time and the circuit delay time from the total time (transmission time t).

[0075] Here, in a laboratory or the like, a test system is formed in advance in which receiver 100 and transmitter 200 are separated by a predetermined distance, and the circuit delay time is measured. The measured circuit delay time is stored in first control unit 110.

[0076] For example, as a test system for the point-to-point distance specifying system 500 in FIG. 2, the point-to-point distance d1 is formed at a known distance of 300 mm.

[0077] The known formula for calculating the speed of sound (m / s) is "U = 331.4 + 0.606 x temperature + 0.0124 x humidity + wind speed". Also, the speed of infrared light is the speed of light (3 x 10 8 (m / s), which is much faster than the propagation speed of ultrasound (331.4 + 0.606 × temperature + 0.0124 × humidity + wind speed), the infrared propagation time can be considered zero (it does not need to be taken into consideration).

[0078] The ultrasonic propagation time is calculated from the set distance between the two points d1: 300 mm and the ultrasonic propagation speed, and the total circuit delay time of the first circuit 112 and the second circuit 212 in the receiver 100 and the transmitter 200 is calculated by subtracting the ultrasonic propagation time from the measured total propagation time.

[0079] The first control unit 110 corrects the ultrasonic velocity taking into account the temperature and humidity at the position of the receiver 100, based on the measurement data from the temperature and humidity sensor 310, wind direction sensor 320, and wind speed sensor 330 electrically connected to the receiver 100. More specifically, the second control unit 210 of the transmitter 200A corrects the ultrasonic velocity transmitted from the transmitter 200A side based on the measurement data from the temperature and humidity sensor 340, and receives the corrected ultrasonic velocity. The first control unit 110 calculates the average value of the corrected ultrasonic velocity on the transmitter 200A side and the corrected ultrasonic velocity on the receiver 100 side, and sets this as the ultrasonic velocity transmitted between the two points.

[0080] In the first control unit 110, the two-point distance d1 between the receiver 100 and the transmitter 200A is determined based on the stored circuit delay, the transmission time t from the pulse transmission time t1 to the detection pulse generation time t5, and the corrected ultrasonic wave speed (distance determination process).

[0081] When the transmission and reception process and the distance determination process are considered as a process set, in the two-point distance determination method, a first process set which is a calibration measurement is performed and then a second process set which is a main measurement is performed in order to set the acoustic wave threshold.

[0082] Specifically, in the first process set, the peak value of the sound wave received by the microphone 140 is identified by the peak hold circuit 160 and transmitted to the first control unit 110. The first control unit 110 then reduces the peak value based on the reduction ratio for reducing the peak value to determine the sound wave threshold value and sets it in the signal detection circuit 170 (signal flow of Y7, Y8, Y9, Y10 in the first circuit 112).

[0083] Next, in the second process set, sound waves are again transmitted from the speaker 240 to the microphone 140, and when the sound waves transmitted to the signal detection circuit 170 reach a sound wave threshold, the signal detection circuit 170 generates a detection pulse, and the counter circuit 180 counts the transmission time t from the pulse transmission time t1 in the pulse transmission circuit 190 to the detection pulse generation time t5 in the signal detection circuit 170 (signal flow of Y7, Y12, Y11, and Y15 in the first circuit 112). For example, in the calibration measurement, the reduction ratio is set within the range of 30% to 60%.

[0084] The illustrated two-point distance determination system 500 and the two-point distance determination method using this system make it possible to determine the distance between two points with high accuracy while minimizing constraints on the installation location and installation time of the measuring instrument and reducing the time and effort required for measurement.

[0085] Next, referring to Fig. 9 to Fig. 12, an example of a method (error correction method) for reducing a time error caused by fluctuations in the threshold level near the peak value of a sound waveform will be described. Here, Fig. 9 is a diagram for explaining that the frequency of a sound wave does not change and the amplitude of the sound wave attenuates in the process of transmitting through space. Also, Fig. 10A is a diagram for explaining that a time error occurs until a signal is detected when the input level differs in the case of a fixed sound threshold, Fig. 10B is a diagram for explaining an example of a method for correcting a time error until a signal is detected, which illustrates detecting a signal by a sound threshold determined by a peak value (maximum value) of a sound wave and a reduction ratio, and Fig. 10C is a diagram for explaining the difference in the time error until a signal is detected when the peak value (maximum value) of a sound wave is set as the sound threshold and when the peak value is reduced to set as the sound threshold.

[0086] When an ultrasonic wave propagates from speaker 240 to microphone 140, which are separated by a distance d1 between the two points, the period T of the ultrasonic wave does not change, but the amplitude of the ultrasonic wave attenuates according to the distance d1 between the two points.

[0087] Therefore, if a constant sound wave threshold is set as shown in Figure 10A, due to the difference in the distance between the two points, a large time error δt1 may occur between the time when the upper waveform, where the distance between the two points is relatively short and the attenuation is small, reaches the sound wave threshold, and the time when the lower waveform, where the distance between the two points is relatively long and the attenuation is large, reaches the sound wave threshold.

[0088] Therefore, as shown in FIG. 10B, instead of setting the sound wave threshold (absolute value) to a constant, the sound wave threshold is set by multiplying the peak value (maximum value) of the sound wave by a constant reduction ratio, so that the time at which the sound wave reaches the sound wave threshold can be made the same even if the peak value of the sound wave differs depending on the distance between the two points.

[0089] Figure 10C compares the time error δ2 that occurs when the threshold level fluctuates when setting a sound threshold for signal detection at the sound peak value, with the time error δ3 that occurs when the threshold level fluctuates when setting a sound threshold by multiplying the sound peak value by a reduction ratio.

[0090] As is clear from FIG. 10C, by setting the sound wave threshold at a position lower than the top of the peak value, for example at about 40% or 50%, it is possible to minimize the time error, which is preferable, even if the threshold level fluctuates.

[0091] Next, another example of a method (error correction method) for reducing a time error caused by fluctuations in the threshold level near the peak value of a sound waveform will be described with reference to Fig. 11A to Fig. 11D. Here, Fig. 11A to Fig. 11D are diagrams for explaining another example of a method for correcting a time error until signal detection, and are diagrams for explaining a sound threshold setting method by a method of setting multiple provisional sound thresholds.

[0092] As already explained with reference to Fig. 10C, by setting the sound wave threshold at, for example, a position of about 40% or 50% from the top of the peak value, the time error can be made as small as possible even if the threshold level fluctuates. Here, the method of setting the reduction ratio is to detect the peak value of the signal using a peak hold circuit and set the peak value from a wave with a small variation in peak value.

[0093] For example, by setting the reduction ratio to 40% to further minimize the time error, the accuracy of identifying the distance between two points is improved. Therefore, this example shows a method of setting the sound wave threshold that can minimize the time error.

[0094] As shown in FIG. 11A, we will take up reduction ratios of 38%, 39%, 40%, 41%, and 42%, which are around 40%, and explain how to identify the reduction ratio (based on the sound threshold) that minimizes the time error among these.

[0095] Here, in order to obtain the finally determined sound threshold (a reduction ratio that defines the sound threshold), a plurality of tentative sound thresholds (a plurality of reduction ratios that define the tentative sound thresholds) are set.

[0096] The process set (transmission and reception process and distance determination process) is performed multiple times (for example, 20 times or more) under each virtual ultrasonic threshold, and the peak value and the time from the rise to the peak value are collected. Then, the two types of collected data are sorted, and the range of the central 50% of the data is set as the valid range (valid data in the interquartile range).

[0097] FIG. 11B shows example data for interquartile ranges of peak values ​​and rise times at certain acoustic thresholds.

[0098] For each sound threshold based on the five types of reduction ratios, this process set is performed multiple times to obtain valid data, and the circuit delay (time) at each sound threshold is calculated and stored in the first control unit 110.

[0099] For example, the circuit delay (time) for each of the five acoustic thresholds is as shown in FIG. 11C.

[0100] Using the circuit delay at five sonic thresholds, the process set is performed multiple times (e.g., 20 times or more) at each sonic threshold, and the interquartile range of the peak value is obtained as the valid range, as in the case of determining the circuit delay. The upper diagram of Figure 11D shows an example of the measurement result of the interquartile range for each of the five sonic thresholds.

[0101] In addition, the variance of the measurement results at each sound wave threshold was calculated, and the calculation results are shown in the lower diagram of Figure 11D.

[0102] Then, the provisional ultrasonic threshold at which the reduction ratio with the smallest variance is 39% is specified as the formal ultrasonic threshold, and the average value of the interquartile range at this time is specified as the formal two-point distance.

[0103] According to this method, it becomes possible to determine the distance between two points with higher accuracy due to the higher accuracy of the sound wave threshold.

[0104] Next, with reference to Figs. 12A and 12B, a further example of a method (error correction method) for reducing time errors caused by fluctuations in the threshold level near the peak value of the sound waveform will be described.

[0105] As shown in FIG. 12A, the waveform shown by the dashed dotted line, which has a relatively small amplitude, rises more gradually than the solid line waveform, which has a relatively large amplitude, and this can result in a time error when a common acoustic threshold is applied to signal detection.

[0106] Therefore, as shown in FIG. 12B, the rising times t8 and t9 from the time t7 when the received waveform is detected until the respective peak values ​​are reached are measured, and a certain time t th If the measurement result is not within the range of t th If it is within the time threshold, the measurement result is valid.

[0107] This example is a method for suppressing time errors by screening the variation in rise time.

[0108] Also, although not shown in the figure, another method for reducing time errors caused by fluctuations in the threshold level is to obtain the peak value of the sound wave received by the microphone 140 using the peak hold circuit 160, perform this multiple times, and have the first control unit 110 select the peak value that occurs most frequently, and reduce the selected peak value based on a reduction ratio to determine the sound wave threshold.

[0109] [Verification experiment] The inventors conducted verification experiments at three distances (approximately 5 m, 6 m, and 7 m) between the speaker and microphone, within a distance of 5 to 7 m that allows stable distance measurement based on the performance of the current experimental equipment.

[0110] For each distance between two points, 20 measurements were taken for about 4 seconds, and the average of 12 measurements was calculated after removing the 8 measurements that deviated significantly from the average. The experimental results are shown in Table 1 below.

[0111] [Table 1]

[0112] The evaluation distances in the table are shown as reference, based on the results of measurements taken with a laser displacement meter. The "time" in the table is the time difference before circuit delay is removed. Here, the speed of sound is assumed to be 340 m / s, and the distance is calculated from the time difference. For experimental cases 1 to 3, the distances are calculated from the average value of the time difference, resulting in 5247 mm, 6060 mm, and 7017 mm, respectively, which are larger values ​​because they include values ​​close to the reference distance and delay times.

[0113] Regarding distance accuracy, it is believed that various corrections will lead to accurate evaluation of distance in order to reduce the difference between the maximum and minimum values ​​of this time. Currently, the maximum and minimum time difference multiplied by the speed of sound results in a relatively high accuracy of between 4 and 10 mm.

[0114] In addition, the present invention is not limited to the configuration shown here, and may be implemented in other embodiments in which other components are combined with the configurations and the like of the above-mentioned embodiment. In this regard, the present invention may be modified within the scope of the gist of the present invention, and may be appropriately determined according to the application form. [Explanation of symbols]

[0115] 100: Receiver (measuring device) 110: First control unit (control unit, CPU) 112: 1st circuit 120: Transmitter 130: 1st radio 140: Microphone 150: Rectification detection circuit 160: Peak hold circuit 170: Signal detection circuit 180: Counter circuit 190: Pulse generator circuit 200, 200A~200D: Transmitter (target) 210: Second control unit (CPU) 212: 2nd circuit 214: ON / OFF switch 220: Receiving unit 230:Second radio 240: Speaker 310,340: Temperature and humidity sensor 320: Wind direction sensor 330: Wind speed sensor G: Ground T: Mountain tunnel (structure) Ta: Inner wall surface S: Shoring K: Face

Claims

1. A two-point distance specifying system that specifies a distance between a measurement point installed on a structure and a measurement device that measures the measurement point, comprising: A transmitter as a target installed at the measurement point; a receiver that is the measuring device and that measures the distance to the target; The receiver includes at least a transmitter that transmits a transmission wave, a microphone that receives a sound wave, a first circuit that connects the transmitter and the microphone, and a control unit; the transmitter includes at least a receiving unit that receives the transmission wave, a speaker that transmits the sound wave, and a second circuit that connects the receiving unit and the speaker; The transmitter transmits the sound wave from the speaker when the receiving unit receives the transmission wave, The control unit determines the peak value of the sound wave received by the microphone, and determines the two-point distance between the receiver and the transmitter based on the time from the transmission of the transmitted wave to the determination of the peak value of the sound wave, the circuit delay time when an electrical signal passes through the first circuit and the second circuit, and the speed of the sound wave.

2. 2. The system for determining a distance between two points according to claim 1, wherein the sound wave is an ultrasonic wave, and the transmission wave is one of an infrared ray and a visible light ray.

3. In the first circuit, a peak hold circuit and a signal detection circuit are interposed in parallel between the microphone and the control unit; a pulse generating circuit is interposed between the transmitting unit and the control unit, and the transmission wave is pulse-transmitted from the pulse generating circuit to the transmitting unit; a counter circuit is interposed between the signal detection circuit and the control unit; the signal detection circuit has a sonic threshold set; the signal detection circuit generates a detection pulse when the peak value of the sound wave reaches the sound wave threshold; 3. The point-to-point distance specifying system according to claim 2, wherein said counter circuit counts a transmission time from a pulse transmission time in said pulse transmission circuit to a detection pulse generation time in said signal detection circuit.

4. In the first circuit, a rectifying and detecting circuit is interposed between the microphone and the peak hold circuit and between the microphone and the signal detection circuit, 4. The point-to-point distance determination system according to claim 3, wherein the rectification detection circuit inverts the negative waveform or the positive waveform of the sine wave of the sound wave received by the microphone to the other.

5. The receiver is equipped with a temperature and humidity sensor, a wind direction sensor, and a wind speed sensor.

5. The point-to-point distance specifying system according to claim 4, wherein the control unit corrects the speed of the sound waves based on the measurement data from the temperature and humidity sensor, the wind direction sensor, and the wind speed sensor.

6. The receiver further includes a first radio unit; The transmitter further comprises a second radio unit; The second circuit is provided with an ON / OFF switch, 6. The point-to-point distance specifying system according to claim 5, wherein the ON / OFF switch is turned ON when a measurement start signal is transmitted from the first wireless device to the second wireless device.

7. The structure is an inner wall surface of a mountain tunnel, The transmitter is installed on the inner wall surface of the mountain tunnel, The receiver is installed at another position on the inner wall surface of the mountain tunnel or on the roadbed of the mountain tunnel, 7. The point-to-point distance determining system according to claim 6, characterized in that it is used to measure the displacement of the inner wall surface by determining a plurality of point-to-point distances over time.

8. A method for determining a distance between two points, the method comprising: determining a distance between a measurement point installed on a structure and a measurement device that measures the measurement point, the method comprising the steps of: A transmitter serving as a target is installed at the measurement point, and a receiver serving as the measurement device for measuring the distance to the target is installed; Here, the receiver includes at least a transmitting unit that transmits a transmission wave, a microphone that receives a sound wave, a first circuit that connects the transmitting unit and the microphone, and a control unit, and the transmitter includes at least a receiving unit that receives the transmission wave, a speaker that transmits the sound wave, and a second circuit that connects the receiving unit and the speaker; an installation process; a transmitting / receiving step of transmitting the transmission wave from the transmitting unit, transmitting the sound wave from the speaker when the receiving unit receives the transmission wave, and receiving the sound wave by the microphone; A method for determining a distance between two points, characterized in that the control unit determines a peak value of the sound wave received by the microphone, and determines the two-point distance between the receiver and the transmitter based on the time from the transmission of the transmitted wave to the determination of the peak value of the sound wave, the circuit delay time when an electrical signal passes through the first circuit and the second circuit, and the speed of the sound wave.

9. In the first circuit, a peak hold circuit and a signal detection circuit are interposed in parallel between the microphone and the control unit; a pulse generating circuit is interposed between the transmitting unit and the control unit, and the transmission wave is pulse-transmitted from the pulse generating circuit to the transmitting unit; a counter circuit is interposed between the signal detection circuit and the control unit; A set of the steps of the transmission and reception step and the distance determination step is executed twice; In the first process set, the peak value of the sound wave received by the microphone is acquired by the peak hold circuit, and the control unit reduces the peak value based on a reduction ratio for reducing the peak value to determine a sound wave threshold value, and then sets the sound wave threshold value in the signal detection circuit; The method for determining a distance between two points described in claim 8, characterized in that in the second process set, a detection pulse is generated in the signal detection circuit when the peak value of the sound wave reaches the sound wave threshold value, and the transmission time from the pulse transmission time in the pulse transmission circuit to the detection pulse generation time in the signal detection circuit is counted by the counter circuit.

10. In the first process set, the peak value is reduced based on a reduction ratio for reducing the peak value, and then a plurality of provisional acoustic thresholds are set; performing the set of steps under each of the pseudo sonic thresholds to identify the circuit delay time at each pseudo sonic threshold; For each of the tentative sound thresholds, the second set of steps is performed a plurality of times to identify a plurality of two-point distances, and an average value of a plurality of two-point distances in the middle of the identified plurality of two-point distances is further identified as the two-point distance for each tentative sound threshold, and further, the variance of each two-point distance for each tentative sound threshold is identified; The method for determining a distance between two points according to claim 9, characterized in that the control unit specifies the provisional sound threshold with the smallest variance as the formal sound threshold, and specifies the average value at the provisional sound threshold as the formal distance between two points.

11. In the first circuit, a peak hold circuit and a signal detection circuit are interposed in parallel between the microphone and the control unit; a pulse generating circuit is interposed between the transmitting unit and the control unit, and the transmission wave is pulse-transmitted from the pulse generating circuit to the transmitting unit; a counter circuit is interposed between the signal detection circuit and the control unit; A set of the steps of the transmission and reception step and the distance determination step is executed twice; In the first process set, the peak value of the sound wave received by the microphone is acquired by the peak hold circuit, and this is performed multiple times. The control unit selects the most frequently occurring peak value, reduces the peak value based on a reduction ratio for reducing the selected peak value, and determines a sound wave threshold value. The sound wave threshold value is set in the signal detection circuit. The method for determining a distance between two points described in claim 8, characterized in that in the second process set, a detection pulse is generated in the signal detection circuit when the peak value of the sound wave reaches the sound wave threshold value, and the transmission time from the pulse transmission time in the pulse transmission circuit to the detection pulse generation time in the signal detection circuit is counted by the counter circuit.

12. In the first circuit, a peak hold circuit and a signal detection circuit are interposed in parallel between the microphone and the control unit; a pulse generating circuit is interposed between the transmitting unit and the control unit, and the transmission wave is pulse-transmitted from the pulse generating circuit to the transmitting unit; a counter circuit is interposed between the signal detection circuit and the control unit; A set of the steps of the transmission and reception step and the distance determination step is executed twice; In the first process set, the peak value of the sound wave received by the microphone is acquired by the peak hold circuit, and this is performed multiple times to measure the rise time until the peak value is reached. The control unit selects the peak value whose rise time is within a time threshold related to the rise time, reduces the peak value based on a reduction ratio for reducing the selected peak value to determine a sound wave threshold, and sets the sound wave threshold in the signal detection circuit. The method for determining a distance between two points described in claim 8, characterized in that in the second process set, a detection pulse is generated in the signal detection circuit when the peak value of the sound wave reaches the sound wave threshold value, and the transmission time from the pulse transmission time in the pulse transmission circuit to the detection pulse generation time in the signal detection circuit is counted by the counter circuit.

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