JP6706296B2 - Measuring method and underground radar device - Google Patents

Description

The present invention relates to the technique of underground radar.

As a conventional ground radar technology, for example, the technology described in Non-Patent Document 1 is known. The underground radar technique described in Non-Patent Document 1 will be described with reference to FIG. FIG. 37 shows a cross-sectional view of an object in the ground and a radar image by the ground radar. FIG. 37(a) shows an antenna arrangement and electromagnetic wave reflection from the stratum boundary. The electromagnetic wave velocity in the ground changes depending on the relative permittivity and the electrical conductivity, which are the material constants of the medium (soil). Since the ground radar measures in the frequency region of 10 MHz or more, the properties of the medium mainly depend on the relative permittivity. Generally, when the relative permittivity of soil is ε _r , the electromagnetic wave velocity v [meter/sec: m/s] is represented by the following equation (1). However, c is the speed of light in a vacuum.

When the above equation (1) is modified, the following equation (2) is obtained. From the equation (2), the relative permittivity ε _r can be calculated from the electromagnetic wave velocity v.

When the depth d[m] of the buried reflector is known as shown in FIG. 37(a), the electromagnetic wave velocity v can be estimated from the arrival time τ of the reflected wave. Alternatively, when there is a reflector such as a metal tube whose existence is clear even if the depth of the buried reflector is unknown, the depth d of the reflector and the electromagnetic wave velocity v can be determined from the reflection waveform of the underground radar. And can be estimated at the same time. The right side of FIG. 37(b) shows the condition of the buried iron pipe. The left diagram of FIG. 37(b) shows an underground radar image. In the example of the buried pipe shown in FIG. 37B, when the transmitting antenna and the receiving antenna are at the horizontal position x, the arrival time τ of the reflected wave is expressed by the following formula (3) from the result of profile measurement. It Profile measurement is a measurement in which both the transmitting antenna and the receiving antenna of an underground radar are scanned on the ground.

The unknown parameters in the above equation (3) are the buried position (depth d and horizontal position x ₀ ) of the metal pipe and the electromagnetic wave velocity v. The horizontal position x ₀ in which the metal pipe is embedded is usually clear from the ground-penetrating radar image shown in the left diagram of FIG. 37(b), as the apex position of the upwardly convex hyperbola is the horizontal position x ₀ of the metal pipe. Is. Then, while changing the depth d in which the metal pipe is embedded and the electromagnetic wave velocity v, the parameters are determined so that the theoretical arrival time fits to the hyperbolic curve of the measurement waveform as shown in FIG. 37(b). It is possible to simultaneously estimate the depth d and the electromagnetic wave velocity v in which is embedded. From this estimated electromagnetic wave velocity v, the relative permittivity ε _r can be calculated by the above equation (2).

The underground radar technology with reference to FIG. 37 described above is described in Non-Patent Document 1.

Next, a method of operating (calibrating and measuring) the ground radar will be described. In the measurement using the ground-penetrating radar, the relative permittivity of soil in the range where the target buried object exists is acquired in advance. Then, by setting the relative permittivity acquired in advance in the ground radar before measurement and calibrating it, the response time axis of the ground radar image is measured during the measurement while scanning the transmitting antenna and the receiving antenna. It can be observed by mapping to the depth. Here, the accuracy of the relative permittivity acquired in advance affects the accuracy of measurement in the depth direction by the ground radar.

FIG. 38 is a flowchart of a conventional ground radar measurement method.
(Step S1001) The transmitting antenna and the receiving antenna of the ground radar are arranged at the measurement position.
(Step S1002) An electromagnetic wave is transmitted from the transmitting antenna.
(Step S1003) The reflected wave is received by the receiving antenna.
Steps S1001 to S1003 are the reflected wave measurement steps. The step of measuring the reflected wave corresponds to the time when the electromagnetic wave is emitted from the transmitting antenna and the reflected wave is received by the receiving antenna in FIG. 37(a).

(Step S1004) The relative permittivity is calculated from the received signal of the reflected wave received by the receiving antenna. The received signal of the reflected wave received by the receiving antenna represents the reflection of a known buried object buried in the ground.
(Step S1005) The reflected wave is processed using the calculated relative permittivity.
(Step S1006) The position and condition of the buried object are calculated from the processed reflected waves.
(Step S1007) The calculated position and status of the buried object are displayed.
Steps S1004 to S1007 are the steps of calculating the relative permittivity and grasping the condition of the buried object. This step of calculating the relative permittivity corresponds to the point of deriving the relative permittivity from the depth and arrival time in FIG. 37(a) and from the hyperbolic curve in FIG. 37(b).

As the calculation of the relative permittivity in the step S1004, the calculation of the equation (2) may be performed from the known depth d in FIG. 37(a) and the arrival time τ measured, or The electromagnetic wave velocity v may be acquired by fitting the underground radar image of b) and the hyperbolic formula (3), and the calculation of the formula (2) may be performed using the acquired electromagnetic wave velocity v.

Motoyuki Sato, "Physics Exploration Seminar "Underground Radar"", Center for Northeast Asian Studies, Tohoku University, July 2001, [Search April 17, 2015], Internet <URL: http://cobalt.cneas. tohoku.ac.jp/users/sato/%92n%92%86%83%8C%81%5B%83_%82%C9%82%E6%82%E9%92n%89%BA%8Cv%91%AA (2001)revised.pdf＞

When measuring with ground-penetrating radar to grasp the condition of buried objects from the ground, the accuracy of the relative permittivity of the soil in which the buried objects are buried is important. However, various unnecessary scatterers exist in the ground where the buried objects are buried, and the reflected waves from the unnecessary scatterers deteriorate the accuracy of the measurement of the relative permittivity of soil using the ground radar. For this reason, the accuracy of the relative permittivity of the soil becomes insufficient, and the accuracy of the condition of the buried object that can be grasped from the result of measurement by the ground radar may not be sufficiently obtained.

With reference to FIG. 39, a problem in the relative permittivity measuring method relating to FIG. FIG. 39A shows the antenna arrangement, the electromagnetic wave reflection from the stratum boundary, and the electromagnetic wave reflection from the unnecessary scatterer. Unnecessary scatterers include multiple rocks. FIG. 39B shows the time response of the reflection intensity by the received signal of the reflected wave received by the receiving antenna under the situation of FIG. 39A. In the graph of FIG. 39(b), the horizontal axis represents time (t) and the vertical axis represents reflection intensity (I). In the graph of FIG. 39( b ), in addition to the reflection component from the formation boundary surface, there is an unnecessary scattering component having the same level as the reflection intensity of the reflection from the formation boundary surface. In this case, it is difficult to specify the reflection at the boundary layer of the measurement object with high accuracy. For this reason, the accuracy of the arrival time τ of the reflected wave from the stratum boundary surface cannot be increased, and the accuracy of the measurement of the relative permittivity of the soil deteriorates. Therefore, the burden of separately examining the relative permittivity of the soil occurs.

Further, also in the conventional method for measuring the relative permittivity of FIG. 37(b) among the underground radar techniques, the presence of the unnecessary scatterers adversely affects the underground radar image, and the accuracy of the relative permittivity of the soil is reduced. to degrade. In the ground-penetrating radar image shown in FIG. 37(b), the three pipes can be confirmed as a convex hyperbolic pattern serving as an image of reflection. However, if the unnecessary scatterer is present above the pipe (on the ground side), the image is disturbed, so the buried position of the pipe (depth d and horizontal position x ₀ ) becomes unclear, and the relative permittivity of the soil is accurately measured. I can't ask.

In view of the above circumstances, an object of the present invention is to provide a technique capable of improving the accuracy of measurement using an underground radar.

One aspect of the present invention is a measurement method using an underground antenna, the first step of radiating an electromagnetic wave of the underground radar toward the ground from a transmission antenna arranged on the ground, and the transmission antenna. The second step of receiving the reflected wave of the electromagnetic wave by the receiving antenna arranged on the ground on the circumference centered on the position of, and the receiving antennas being respectively received by the receiving antennas in a plurality of positions where the positions of the receiving antennas are different. The third step of recording the reception signal indicating the intensity of the reflected wave and the mutual comparison of the reception signals recorded in the third step to obtain information about the scatterer existing in the ground And a fourth step of performing.

According to one aspect of the present invention, a transmitting antenna which is arranged on the ground and radiates an electromagnetic wave toward the ground, and a circular ground around the position of the transmitting antenna are arranged to receive a reflected wave of the electromagnetic wave. And a reception information recording unit that records reception signals indicating the intensities of the reflected waves respectively received by the reception antennas in a plurality of arrangements in which the positions of the reception antennas are different, and is recorded in the reception information recording unit. And a comparison unit that obtains information about the scatterers existing in the ground by performing mutual comparison of the received signals.

According to the present invention, it is possible to improve the accuracy of measurement using an underground radar.

The figure which shows the known information regarding the buried object which is a measurement object. Sectional drawing which shows a pair of antenna arrangement|positioning of 1st Embodiment. The top view which shows the antenna arrangement|positioning on the circumference of 1st Embodiment. Sectional drawing which shows a pair of antenna arrangement|positioning of 1st Embodiment. The figure which shows the example of the time response of the reflected wave of each antenna pair of 1st Embodiment. The figure which shows the result which synthesize|combined the time response of the reflected wave about four antenna pairs of 1st Embodiment. FIG. 3 is a bird's-eye view showing an arrangement of four pairs of antennas according to the first embodiment. The figure which shows the example of the time response of the reflected wave of the four antenna pairs of 1st Embodiment. The figure which shows the structure of the underground radar apparatus 130 of 1st Embodiment. The flowchart of the underground radar measuring method of 1st Embodiment. The figure which shows the structure of the underground radar apparatus 200 of 2nd Embodiment. The flowchart of the underground radar measuring method of 2nd Embodiment. The bird's-eye view which shows the example of a movement of the transmitting antenna and receiving antenna of 3rd Embodiment. The figure which shows the example of the time response of the reflected wave in three measurement positions of 3rd Embodiment. The bird's-eye view which shows the example of a movement of the transmitting antenna and receiving antenna of 3rd Embodiment. The top view which shows the example of a movement of the transmitting antenna and receiving antenna of 3rd Embodiment. The figure which shows the result of having synthesize|combined the time response of the reflected wave of 3rd Embodiment. The bird's-eye view which shows the example of a movement of the transmission antenna and reception antenna of the comparison object of 3rd Embodiment. The top view which shows the example of a movement of the transmitting antenna and receiving antenna of the comparison object of 3rd Embodiment. The figure which shows the result of having synthesize|combined the time response of the reflected wave of the comparison object of 3rd Embodiment. The figure which shows the structure of the underground radar apparatus 350 of 3rd Embodiment. The flowchart of the underground radar measuring method of 3rd Embodiment. The figure which shows the example of arrangement|positioning of the transmitting antenna of the modification of 3rd Embodiment, and a receiving antenna. The figure which shows the example of arrangement|positioning of the transmitting antenna of the modification of 3rd Embodiment, and a receiving antenna. The figure which shows the example of arrangement|positioning of the transmitting antenna of the modification of 3rd Embodiment, and a receiving antenna. The bird's-eye view which shows the arrangement|positioning of the transmitting antenna and receiving antenna of the modification of 3rd Embodiment. The top view which shows the arrangement|positioning of the transmitting antenna and receiving antenna of the modification of 3rd Embodiment. The figure which shows the result of having synthesize|combined the time response of the reflected wave of the modification of 3rd Embodiment. Explanatory drawing of the underground radar measuring method of 4th Embodiment. The figure which shows the structure of the underground radar apparatus 400 of 4th Embodiment. The figure which shows the example of arrangement|positioning of the transmission antenna of the modification of 4th Embodiment, and a receiving antenna. The figure which shows the example of arrangement|positioning of the transmission antenna of the modification of 4th Embodiment, and a receiving antenna. The figure which shows the example of arrangement|positioning of the transmission antenna of the modification of 4th Embodiment, and a receiving antenna. The flowchart of the underground radar measuring method of the modification of 4th Embodiment. Explanatory drawing of 5th Embodiment. Explanatory drawing of 5th Embodiment. Explanatory drawing of the conventional underground radar technology. The flowchart of the conventional underground radar measurement method. Explanatory drawing of the conventional underground radar technology.

Hereinafter, a measuring method and an underground radar device according to embodiments will be described with reference to the drawings. In the following embodiments, the case of calculating the relative permittivity will be described, but the same can be applied to the case of calculating the permittivity.

(First embodiment)
The first embodiment will be described with reference to FIGS. 1 to 10. FIG. 1 shows known information about an embedded object to be measured. The underground buried object (measurement target) shown in FIG. 1 is a manhole 100 provided for communication. The manhole 100 is a cylindrical portion having a radius a [m] and a height (depth) d [m], and a portion of the doorway to the ground (called a neck), and the manhole 100 has a rectangular parallelepiped shape in the ground. And a part of the space of. The main body of the manhole 100 is made of reinforced concrete and has a rectangular parallelepiped shape having a length L [m] and a width W [m]. The lid 101 on the neck portion of the manhole 100 has a disk shape with a radius a [m]. The ceiling of the manhole 100 (called the upper floor plate) has a thickness d ₀ [m]. The upper floor plate of the manhole 100 is a plate (concrete plate) made of reinforced concrete in each range 102 and 103 on both sides of the manhole cover 101. Each of the ranges 102 and 103 has a rectangular shape with a length “L/2−a” and a width W. The upper floor plate of the manhole 100 is buried at a depth d from the ground. It is assumed that the detailed condition of the upper floor plate of the manhole 100 is grasped from the ground by using an underground radar. If the detailed condition of the upper floor plate of the manhole 100 is known, the burden of maintenance and inspection work of the manhole 100 can be significantly reduced. In order to grasp the condition of the upper floor plate of the manhole 100 in detail by using the ground radar, it is necessary to accurately measure the relative permittivity of the ground (soil) in which the electromagnetic wave transmitted from the ground radar propagates. is important. The method for measuring the relative permittivity will be described below by taking the case where the manhole 100 shown in FIG. 1 is the measurement target as an example.

FIG. 2 is a sectional view showing a pair of antenna arrangements. FIG. 2 shows a pair of transmitting antenna A1-1 and receiving antenna A1-2. The transmitting antenna A1-1 and the receiving antenna A1-2 are arranged on the ground at an interval X[m]. The transmitting antenna A1-1 radiates the electromagnetic wave of the underground radar toward the ground. The receiving antenna A1-2 receives the electromagnetic wave of the underground radar in order to measure the reflected wave of the electromagnetic wave emitted from the transmitting antenna A1-1. The places where the transmitting antenna A1-1 and the receiving antenna A1-2 are respectively arranged are in the ranges 102 and 103 corresponding to the concrete plate existing at the depth d in the ground shown in FIG. Both the transmitting antenna A1-1 and the receiving antenna A1-2 are arranged in the same one of the ranges 102 and 103. The reason for this is that when the transmitting antenna A1-1 and the receiving antenna A1-2 are separately arranged in the range 102 and the range 103, the electromagnetic waves radiated from the transmitting antenna A1-1 toward the ground are manholes. This is because propagation is blocked by the neck portion of the manhole 100 until it is reflected by the concrete surface of the upper floor plate of 100 or on the way to the reception antenna A1-2 after being reflected. The electromagnetic wave emitted from the transmitting antenna A1-1 toward the ground propagates through the soil and reaches the concrete surface of the upper floor plate of the manhole 100. Electromagnetic waves that have reached the concrete surface of the upper floor plate of the manhole 100 and are reflected by the concrete surface are received by the receiving antenna A1-2.

FIG. 3 is a top view showing the antenna arrangement on the circumference. FIG. 3 shows four sets of transmitting antennas and receiving antennas as an example of antenna arrangement on the circumference. In FIG. 3, a set of a transmitting antenna A1-1 and a receiving antenna A1-2, a set of a transmitting antenna A2-1 and a receiving antenna A2-2, and a set of a transmitting antenna A3-1 and a receiving antenna A3-2. And the set of the transmitting antenna A4-1 and the receiving antenna A4-2 are arranged on the circumference of the same circle 111. In one set, the transmitting antenna is arranged at one end on one diameter of the circle 111, and the receiving antenna is arranged at the other end. In circle 111, each set of transmit and receive antennas is placed on a different diameter. The diameter of the circle 111 is X, and the antenna spacing of each set is X. FIG. 2 described above is a cross-sectional view taken along the alternate long and short dash line 112 in FIG. The center of the circle 111 corresponds to the alternate long and short dash line 110 in FIG. In each set, the electromagnetic wave of the underground radar radiated toward the ground from the transmitting antenna propagates through the soil, reaches the concrete surface of the upper floor plate of the manhole 100, is reflected by the concrete surface, and is received as a reflected wave. Received by the antenna.

FIG. 4 is a cross-sectional view showing a pair of antenna arrangements, electromagnetic wave reflection from a concrete surface, and electromagnetic wave reflection from an unnecessary scatterer. FIG. 4 shows a pair of transmitting antenna A2-1 and receiving antenna A2-2 shown in FIG. In FIG. 4, the electromagnetic wave is reflected by the concrete surface of the upper floor plate of the manhole 100 and the electromagnetic wave is reflected by an unnecessary scatterer such as rock.

Here, the reflection of electromagnetic waves by the concrete surface of the upper floor plate of the manhole 100 and the reflection and scattering of electromagnetic waves by the unnecessary scatterer will be described. The depth d in which the upper floor plate of the manhole 100 is buried is known. The arrangement of the transmitting antenna A2-1 and the receiving antenna A2-2 and the antenna distance X between the transmitting antenna A2-1 and the receiving antenna A2-2 are also known. The electromagnetic wave of the underground radar radiated toward the ground from the transmitting antenna A2-1 propagates through the soil and is reflected by the concrete surface of the upper floor plate of the manhole 100 and reaches the receiving antenna A2-2 as a reflected wave. The propagation distance l[m] of is expressed by the following equation (4).

In the ranges 102 and 103 shown in FIG. 1 where the upper floor plate of the manhole 100 exists, the reflection by the unnecessary scatterer does not satisfy the above formula (4). The above formula (4) is established for each set of the transmitting antenna and the receiving antenna shown in FIG. Therefore, it can be said that there is no unnecessary scatterer that satisfies the above equation (4) for each set of the transmitting antenna and the receiving antenna shown in FIG.

It is assumed that the unnecessary scatterer satisfies the above formula (4) for only one set of the transmitting antenna A2-1 and the receiving antenna A2-2 shown in FIG. In this case, the unnecessary scatterers are arranged around the ellipse whose focal points are the transmitting antenna A2-1 and the receiving antenna A2-2. Then, considering the reflection intensity in that case, it is necessary to have a reflecting surface along the ellipsoid. Therefore, it is considered that there are almost no unnecessary scatterers having the reflecting surface along the ellipsoid under the condition that the above expression (4) is satisfied and the reflection intensity is relatively strong. Furthermore, "a set of a transmitting antenna A1-1 and a receiving antenna A1-2" which is a set of another transmitting antenna and a receiving antenna, and "a set of a transmitting antenna A3-1 and a receiving antenna A3-2", The positions satisfying all the conditions that the unnecessary scatterers are present around each ellipse whose focus is the “set of the transmitting antenna A4-1 and the receiving antenna A4-2” are extremely limited or all Since there is no position that satisfies the conditions at the same time, it can be said that there is no unnecessary scatterer at such a position.

Next, the electromagnetic wave of the underground radar radiated toward the ground from the transmitting antenna A2-1 propagates through the soil and is reflected by the concrete surface of the upper floor plate of the manhole 100, and is reflected by the receiving antenna A2-2. Let τ be the arrival time to reach. The relative permittivity ε _r of soil is represented by the following equation (5). However, c is the speed of light in vacuum “3.0×10 ⁸ [m/s]”.

From the propagation distance 1 and the arrival time τ, the relative permittivity ε _r of soil can be calculated by the above equation (5). However, it is generally difficult to accurately calculate the propagation distance 1 and the arrival time τ due to the influence of the unnecessary scatterer shown in FIG.

FIG. 5 shows an example of the time response of the reflected wave of each antenna pair. In the graph of FIG. 5, the horizontal axis represents time (t) and the vertical axis represents reflection intensity (I). In FIG. 5, four antenna pairs shown in FIG. 3, “A1 pair: a set of transmission antenna A1-1 and reception antenna A1-2” and “A2 pair: transmission antenna A2-1 and reception antenna” are shown. A2 pair", "A3 pair: transmitting antenna A3-1 and receiving antenna A3-2 pair", and "A4 pair: transmitting antenna A4-1 and receiving antenna A4-2 pair". The time response of the reflected wave for each of The graph of each antenna pair is based on the reception signal received by each reception antenna in the underground state shown in FIG. 4 above. That is, each graph of FIG. 5 shows the transmitting antennas of each antenna pair in the underground state in which the reflection of electromagnetic waves by the concrete surface of the upper floor plate of the manhole 100 and the reflection of electromagnetic waves by unnecessary scatterers such as rocks occur. The time change of the received signal received by the receiving antenna of each antenna pair of the reflected wave of the electromagnetic wave of the underground radar radiated toward the ground from is shown.

The solid line graph in FIG. 5 shows the time response of the reflection of electromagnetic waves by the concrete surface of the upper floor plate of the manhole 100. The graph of the broken line in FIG. 5 shows the time response of the reflection of the electromagnetic wave by the unnecessary scatterer. Regarding the reflection of electromagnetic waves by the concrete surface of the upper floor plate of the manhole 100, all the antenna intervals of the four antenna pairs are the same at X, and the same reflection point (at the depth d of the d surface of the concrete surface of the upper floor plate of the manhole 100). Since they are reflected at the same position), the arrival time τ is the same for all four antenna pairs.

FIG. 6 shows the result of combining the time responses of the reflected waves for the four antenna pairs shown in FIG. In the graph of FIG. 6, the horizontal axis represents time (t) and the vertical axis represents combined reflection intensity (Ic). In FIG. 5, the time responses of the reflected waves for the four antenna pairs are individually shown in a graph, but in FIG. 6, the time responses of the reflected waves at the same time for each antenna pair are superimposed and combined. .. The combination of the reflected waves by this superposition is performed by the process of adding the reflection intensity every time. A point to be noted in the process of synthesizing the reflected waves is to match the time axis of the reflected waves of each antenna pair with the reflection of the buried object whose depth is known, in this case, the concrete surface of the upper floor plate of the manhole 100 (depth It is to adjust the time of reflection according to d). As a result, at the same time τ as the arrival time value, the reflected waves from the concrete surface of the upper floor plate of the manhole 100 are overlapped with each other, and the combined reflection intensity (Ic) is strengthened (a solid line in FIG. 6).

On the other hand, in the result of the synthesis of the reflected waves by the unnecessary scatterers (the graph of the broken line in FIG. 6), since the arrival time is different in each antenna pair, the antennas are synthesized while being dispersed temporally. ). The reason for this is that the unnecessary scatterer shown in FIG. 4 above does not exist in the intermediate position between the transmitting antenna and the receiving antenna of each antenna pair, so that as shown in FIG. This is because the arrival time of the reflected wave by the unnecessary scatterer changes when the position of the receiving antenna changes.

If the unnecessary scatterer is present at the center of the circle 111 shown in FIG. 3, the unnecessary scatterer is present at an intermediate position between the transmitting antenna and the receiving antenna of the plurality of antenna pairs, and therefore the reflection by the unnecessary scatterer is caused. As a result of combining the waves, the combined reflection intensities (Ic) are strengthened. However, it is rare that the unnecessary scatterer exists at the position of such a condition. Further, if an unnecessary scatterer is present at the position of that condition, the reflection by the buried object of known depth is greatly affected. For example, with respect to a reflected wave from a buried object having a known depth, a phenomenon occurs such that the reflected wave does not exist around the calculated arrival time. As a result, when the positions of the transmitting antenna and the receiving antenna of the antenna pair are changed and re-measurement is performed, as a result of the synthesis of the reflected waves by the unnecessary scatterers, the synthetic reflected intensity (Ic) does not strengthen each other, which is a problem. There is no.

As described above, by overlapping and synthesizing the time responses of the reflected waves at the same time for each antenna pair, the reflected waves by the unnecessary scatterers do not strengthen each other as the combined reflection intensity (Ic). The reflected waves from the concrete surface of the upper floor plate of the manhole 100 are strengthened as a combined reflection intensity (Ic). Therefore, in the graph of FIG. 6, the component (unnecessary scattering component) of the reflected wave by the undesired scatterer can be easily distinguished and separated. Thereby, from the graph of FIG. 6, it is possible to extract only the component of the reflected wave by the concrete surface of the upper floor plate of the manhole 100. Then, the arrival time τ for the reflected wave by the concrete surface of the upper floor plate of the manhole 100 can be accurately known. The propagation distance l can be calculated by the above equation (4) from the antenna distance X and the depth d common to each antenna pair. Then, the relative permittivity ε _r of the soil can be accurately calculated from the arrival time τ and the propagation distance 1 by the above equation (5). By using the calculated relative permittivity ε _r to calibrate the underground radar, the accuracy of measurement by the underground radar can be improved.

FIG. 7 is a bird's-eye view showing four pairs of antenna arrangements, the situation from the ground to the concrete surface in the ground, and each electromagnetic wave reflection. Four antenna pairs “A1 pair: a set of transmission antenna A1-1 and reception antenna A1-2” and “A2 pair: a set of transmission antenna A2-1 and reception antenna A2-2” shown in FIG. , "A3 pair: set of transmitting antenna A3-1 and receiving antenna A3-2" and "A4 pair: set of transmitting antenna A4-1 and receiving antenna A4-2" are shown in FIG. This is the arrangement. Further, the reflection of electromagnetic waves by the concrete surface of the upper floor plate of the manhole 100 and the reflection of electromagnetic waves by unnecessary scatterers such as rocks shown in FIG. 7 are the same as those shown in FIGS. 2 and 4 above. ..

FIG. 8A shows an example of the time response of the reflected waves of the four antenna pairs shown in FIG. 7. In the graph of FIG. 8A, the horizontal axis represents time (t) and the vertical axis represents reflection intensity (I). FIG. 8B shows a result of combining the time responses of the reflected waves for the four antenna pairs shown in FIG. 8A. In the graph of FIG. 8B, the horizontal axis represents time (t) and the vertical axis represents combined reflection intensity (Ic). From the graph of FIG. 8B, a process of removing unnecessary scattering components is performed. In this removal processing of unnecessary scattered components, other reflected waves other than the time response (solid line graph) of the reflected wave appearing at the time τ that strengthens as the combined reflected intensity (Ic) by combining the reflected waves of the four antenna pairs. Delete the time response of (dotted line graph). As a result, from the graph of FIG. 8B, the arrival time τ for the wave reflected by the concrete surface of the upper floor plate of the manhole 100 can be accurately known as the time τ for strengthening the combined reflection intensity (Ic). Then, the propagation distance 1 is calculated by the above equation (4) from the antenna spacing X and the depth d common to the four antenna pairs, and the propagation time 1 is calculated from the arrival time τ and the propagation distance 1 by the above equation (5). , The relative permittivity ε _r of soil in the ground shown in FIG. 7 can be calculated accurately. By using the calculated relative permittivity ε _r to calibrate the ground radar, the ground radar shown in FIG. 7 can be accurately measured by the ground radar after the calibration.

Next, the device configuration of the underground radar according to the present embodiment will be described. FIG. 9 shows the structure of the underground radar device 130. The underground radar device 130 shown in FIG. 9 includes a transmitting unit 150, a receiving unit 170, four antenna pairs “A1 pair: a pair of transmitting antenna A1-1 and receiving antenna A1-2” and “A2 pair: transmitting. "A pair of antenna A2-1 and receiving antenna A2-2", "A3 pair: pair of transmitting antenna A3-1 and receiving antenna A3-2", and "A4 pair: transmitting antenna A4-1 and receiving antenna A4-2. And a group”. Each of the transmitting antenna and the receiving antenna of the four antenna pairs is arranged on the circumference of the same circle 111, as shown in FIG. The transmission unit 150 includes a transmission selection control unit 151 and an electromagnetic wave generation unit 152. The reception unit 170 includes a reception detection unit 171, a reception synthesis unit 172, a comparison unit 173, an unnecessary scattered wave removal/dielectric constant calculation unit 174, and a calibration/received signal reprocessing unit 175.

In the transmission unit 150, the transmission selection control unit 151 sequentially selects transmission antennas that radiate electromagnetic waves from the transmission antennas A1-1, A2-1, A3-1, A4-1 of the four antenna pairs. The transmission selection control unit 151 outputs a selection signal indicating the selected transmission antenna to the electromagnetic wave generation unit 152 and the reception unit 170. The selection signal input to the reception unit 170 is input to the reception synthesis unit 172 and the comparison unit 173. The electromagnetic wave generation unit 152 is connected to each of the transmission antennas A1-1, A2-1, A3-1, A4-1 of the four antenna pairs. The electromagnetic wave generation unit 152 outputs an electromagnetic wave to the transmission antenna indicated by the selection signal input from the transmission selection control unit 151. As a result, the electromagnetic wave of the underground radar is radiated toward the ground from the transmission antenna indicated by the selection signal by the transmission selection control unit 151.

In the reception unit 170, the reception detection unit 171 is connected to each of the reception antennas A1-2, A2-2, A3-2, A4-2 of the four antenna pairs. The reception detection unit 171 receives the signals from the reception antennas A1-2, A2-2, A3-2, A4-2 for each reception antenna A1-2, A2-2, A3-2, A4-2. Detects electromagnetic waves from ground-penetrating radar. The reception signal of the electromagnetic wave of the ground radar detected by the reception detection unit 171 for each of the reception antennas A1-2, A2-2, A3-2, A4-2 is the reception antennas A1-2, A2-2, A3-2. , A4-2, and are output to the reception combining unit 172 and the comparing unit 173.

The reception combining unit 172 is a selection signal input from the transmission selection control unit 151 among the reception signals of the receiving antennas A1-2, A2-2, A3-2, A4-2 input from the reception detection unit 171. Record the received signal at the receive antenna paired with the transmit antenna shown. The reception combining unit 172 combines the recorded reception signals of the respective reception antennas A1-2, A2-2, A3-2 and A4-2. In the synthesis of the received signals, as described with reference to FIG. 5, FIG. 6, and FIG. 8 described above, the received signals of the respective receiving antennas A1-2, A2-2, A3-2, A4-2 of the four antenna pairs are received. The reflection intensity (I) of is added every time. In the addition of the reflection intensity (I), the time axes are matched by the time of reflection of an embedded object having a known depth, here, the time of reflection by the concrete surface (depth d) of the upper floor plate of the manhole 100.

The comparison unit 173 indicates the selection signal input from the transmission selection control unit 151 among the reception signals of the reception antennas A1-2, A2-2, A3-2, A4-2 input from the reception detection unit 171. The received signal from the receiving antenna paired with the transmitting antenna is recorded. The comparing unit 173 performs mutual comparison on the received signals of the respective receiving antennas A1-2, A2-2, A3-2 and A4-2 which are recorded. As a result of this comparison, when there is a received signal that satisfies a predetermined abnormality determination condition for determining that the received signal is abnormal, the comparing unit 173 determines that the receiving antenna of the received signal is the receiving combining unit 172. Notify to. The reception combining unit 172 excludes the reception signal of the reception antenna notified from the comparison unit 173 from the above-described reception signal combining target. This is for the following reason. Statistical processing is performed when a received signal having an abnormality in which the reflection due to the buried object as the measurement target, here the concrete surface of the upper floor plate of the manhole 100, is significantly different is included in the target of the reception signal synthesis (for example, Even if the average value and the median value are calculated), the processing result may be greatly affected. Therefore, a more accurate processing result can be obtained by excluding the reception signal determined to be abnormal from the target of the synthesis of the reception signals. Further, the accuracy of the ground-penetrating radar image is improved by the processing (removal of unnecessary scattered waves/dielectric constant calculation processing, calibration/reception signal reprocessing) after the synthesis of the received signals.

The unnecessary scattered wave removing/permittivity calculating unit 174 removes the unnecessary scattered wave from the result of combining the reception signals by the reception combining unit 172, and calculates the relative permittivity based on the result of removing the unnecessary scattered wave. The method of calculating the relative permittivity is the method described with reference to FIGS. 6 and 8 described above. The calibration/received signal reprocessing unit 175 performs calibration using the relative permittivity calculated by the unnecessary scattered wave removing/dielectric constant calculating unit 174. The calibration/received signal reprocessing unit 175 reprocesses the received signal based on the result of the calibration.

The operation of the underground radar device 130 shown in FIG. 9 will be described with reference to FIG. 10. FIG. 10 is a flowchart of the underground radar measuring method of this embodiment.

(Step S101) The transmission selection control unit 151 selects one of the four transmission antennas A1-1, A2-1, A3-1, A4-1 that emit electromagnetic waves.

(Step S102) The electromagnetic wave generation unit 152 outputs the electromagnetic wave to the transmission antenna selected by the transmission selection control unit 151. As a result, the electromagnetic wave of the ground radar is radiated toward the ground from the transmission antenna selected by the transmission selection control unit 151.

(Step S103) The reception detection unit 171 receives the reflected wave which is the electromagnetic wave of the underground radar by the receiving antenna paired with the transmitting antenna that radiated the electromagnetic wave.

(Step S104) The reception combining unit 172 and the comparison unit 173 record the reception signal of the reflected wave received by the reception detection unit 171. When the same transmitting antenna radiates the electromagnetic waves a plurality of times, the reception signals of the reflected waves received by the reception detecting unit 171 are combined each time, and the combined result is recorded. The reflected waves are combined by adding the intensities of the reflected waves received by the transmitting antenna and the receiving antenna arranged at different positions.

(Step S105) The transmission selection control unit 151 determines whether the emission of electromagnetic waves from all of the four transmission antennas A1-1, A2-1, A3-1, A4-1 of the antenna pair has been completed. As a result, if completed, the process proceeds to step S106. On the other hand, if the transmission is not completed, the process proceeds to step S101, and the transmission selection control unit 151 selects the transmission antenna that has not been radiated.

(Step S106) The reception combining unit 172 combines the recorded reception signals of the respective reception antennas A1-2, A2-2, A3-2, A4-2. The reception combining unit 172 removes the unnecessary scattered wave that is the reflected wave by the unnecessary scatterer from the combined result.

(Step S107) The comparing unit 173 records each reception based on the “time of reflection by the concrete surface of the upper floor plate of the manhole 100 (comparison target time)” obtained from the result of removal of the unnecessary scattered wave in step S106. The received signals of the antennas A1-2, A2-2, A3-2, A4-2 are compared and evaluated. The "time of reflection by the concrete surface of the upper floor plate of the manhole 100" in the received signals of the respective receiving antennas A1-2, A2-2, A3-2, A4-2 recorded is significantly different from the comparison target time. To judge. For example, it is determined whether or not the difference differs by a predetermined ratio (for example, 10%). As a result of this determination, when the comparison target time is largely different, the comparison unit 173 notifies the reception combining unit 172 of the reception antenna of the reception signal determined to be significantly different from the comparison target time. Upon receiving this notification, the reception combining unit 172 excludes the notified reception antenna from the target of the reception signal combination, and combines the recorded reception signals of the respective reception antennas. The result of combining the received signals is used for the subsequent processing.

If there is no notification from the comparing unit 173 of the receiving antennas to be excluded from the target of the reception signal combination, the reception combining unit 172 does not combine the reception signals in step S107. In this case, the result of combining the received signals in step S106 is used in the subsequent processing.

(Step S108) The unnecessary scattered wave removing/permittivity calculating unit 174 removes the unnecessary scattered wave from the result of combining the reception signals by the receiving combining unit 172, and calculates the relative permittivity based on the result of removing the unnecessary scattered wave. To do. Here, the result of combining the received signals is the result of adding the intensities of the reflected waves, and the arrival time of the reflected wave from the object is determined based on this result. The relative permittivity of soil is calculated using this arrival time, the depth of the object, and the antenna interval.

(Step S109) The calibration/received signal reprocessing unit 175 performs calibration using the relative permittivity calculated by the unnecessary scattered wave removing/permittivity calculating unit 174. The calibration/received signal reprocessing unit 175 reprocesses the received signal of the reflected wave based on the result of the calibration.

(Steps S110 and S111) The ground radar device 130 calculates the position and the condition of the buried object from the received signal of the reflected wave reprocessed by the calibration/received signal reprocessing unit 175. The underground radar device 130 displays the calculated position and status of the buried object.

According to the above-described first embodiment, the electromagnetic wave of the underground radar is radiated from the transmitting antenna arranged on the ground toward the ground where the target object whose depth is known is buried. The reflected wave of the electromagnetic wave is received by a receiving antenna placed on the ground at a constant antenna distance from the transmitting antenna. Next, the intensities of the reflected waves respectively received by the receiving antennas are added in a plurality of arrangements in which at least one of the transmitting antenna and the receiving antenna has different positions among the arrangements of the transmitting antenna and the receiving antenna. Next, the arrival time of the reflected wave from the object is determined based on the result of the addition of the reflected wave intensities. Next, the relative permittivity of the soil is calculated using the result of the arrival time determination, the depth of the object, and the antenna interval. Thereby, the relative permittivity of the soil can be calculated by reducing the influence of the reflected wave due to the unnecessary scatterer existing in the soil. Therefore, the accuracy of measurement of the relative permittivity using the ground radar can be improved.

According to the first embodiment, the transmitting antenna and the receiving antenna are arranged on the same circumference whose center lies on the ground just above the object. Accordingly, it is possible to easily realize that the reflected wave radiated from the transmitting antenna and reflected at one point of the object is received at a plurality of positions.

(Second embodiment)
The second embodiment will be described with reference to FIGS. 11 and 12. Also in the second embodiment, the underground manhole 100 shown in FIG. 1 is an object to be measured, as in the above-described first embodiment.

FIG. 11 shows the configuration of an underground radar device 200 according to the second embodiment. The underground radar device 200 illustrated in FIG. 11 includes a transmitter 210, a receiver 230, and one antenna pair “A1 pair: a set of a transmitting antenna A1-1 and a receiving antenna A1-2”. In the ground-penetrating radar device 130 of the first embodiment shown in FIG. 9 described above, four antenna pairs “A1 pair: a set of transmission antenna A1-1 and reception antenna A1-2” and “A2 pair: transmission antenna A2” are used. -1 and a receiving antenna A2-2", "A3 pair: transmitting antenna A3-1 and receiving antenna A3-2 pair" and "A4 pair: transmitting antenna A4-1 and receiving antenna A4-2. And the transmitting antenna and the receiving antenna of each antenna pair are arranged on the circumference of the same circle 111, as shown in FIG. 3 above. In the present embodiment, only “A1 pair: a set of a transmitting antenna A1-1 and a receiving antenna A1-2” is provided as an antenna pair, and the transmitting antenna A1-1 and the receiving antenna A1-2 are shown in FIG. The measurement is performed by sequentially moving to the position of each antenna pair shown. In FIG. 11, the positions of the transmission antenna and the reception antenna for the A2 pair, the A3 pair, and the A4 pair are shown in parentheses.

The transmission unit 210 includes a transmission control unit 211, an electromagnetic wave generation unit 212, and an antenna position control unit 213. The reception unit 230 includes a reception detection unit 231, a reception information recording unit 232, a reception synthesis unit 233, a comparison unit 234, an unnecessary scattered wave removal/dielectric constant calculation unit 235, and a calibration/reception signal reprocessing unit 236.

In the transmission unit 210, the transmission control unit 211 issues an instruction to transmit an electromagnetic wave of the underground radar to the electromagnetic wave generation unit 212 and the antenna position control unit 213. The electromagnetic wave generation unit 212 is connected to the transmission antenna A1-1. The electromagnetic wave generation unit 212 outputs an electromagnetic wave to the transmission antenna A1-1 according to the instruction from the transmission control unit 211 and the input of the antenna position information from the antenna position control unit 213. The antenna position control unit 213 sequentially moves the transmission antenna A1-1 and the reception antenna A1-2 to the positions of the respective antenna pairs shown in FIG. The antenna position control unit 213 moves the transmitting antenna A1-1 and the receiving antenna A1-2 to the measurement position among the positions of each antenna pair shown in FIG. 3 above, and then outputs the antenna position information indicating the measurement position. The signal is output to the electromagnetic wave generation unit 212 and the reception unit 230. The antenna position information input to the reception unit 230 is input to the reception information recording unit 232 and the comparison unit 234. The transmitting unit 210 radiates an electromagnetic wave of an underground radar toward the ground from the transmitting antenna A1-1 at the measurement position indicated by the antenna position information among the positions of the respective antenna pairs shown in FIG. .. In addition, the measurement position is sequentially moved.

The transmission antenna A1-1 and the reception antenna A1-2 may be automatically moved by an antenna moving device (not shown in FIG. 11), or manually according to a movement instruction from the antenna position control unit 213. May be done in.

In the reception section 230, the reception detection section 231 is connected to the reception antenna A1-2. The reception detection unit 231 detects the electromagnetic wave of the ground radar from the signal received by the reception antenna A1-2. The received signal of the electromagnetic wave of the ground radar detected by the reception detection unit 231 is output to the reception information recording unit 232 and the comparison unit 234.

The reception information recording unit 232 records the reception signal input from the reception detection unit 231 in association with the antenna position information input from the transmission unit 210 to the reception unit 230. The reception combining unit 233 uses the antenna position information and the reception signal recorded in the reception information recording unit 232 to combine the reception signals of the measurement positions indicated by the antenna position information. In the synthesis of the reception signals, the measurement positions of the reception antennas A1-2, A2-2, A3-2, A4-2 of the four antenna pairs shown in FIG. The reflection intensity (I) of each received signal is added every time. In the addition of the reflection intensity (I), the time axes are matched by the time of reflection of an embedded object having a known depth, here, the time of reflection by the concrete surface (depth d) of the upper floor plate of the manhole 100.

The comparison unit 234 uses the antenna position information recorded in the reception information recording unit 232 and the received signal to perform mutual comparison between the received signals at the measurement positions indicated by the antenna position information. As a result of this comparison, when there is a received signal that satisfies a predetermined abnormality determination condition for determining that the received signal is abnormal, the comparison unit 234 determines the measurement position of the received signal as the reception combining unit 233. Notify to. The reception combining unit 233 excludes the reception signal at the measurement position notified from the comparison unit 234 from the above-described reception signal combining target. The reason for this is the same as the description of the comparison unit 173 of the first embodiment described above.

The unnecessary scattered wave removing/permittivity calculating unit 235 removes the unnecessary scattered wave from the result of combining the reception signals by the reception combining unit 233, and calculates the relative permittivity based on the result of removing the unnecessary scattered wave. The method of calculating the relative permittivity is the same as in the first embodiment described above. The calibration/received signal reprocessing unit 236 performs calibration using the relative permittivity calculated by the unnecessary scattered wave removing/dielectric constant calculating unit 235. The calibration/received signal reprocessing unit 236 reprocesses the received signal based on the result of the calibration.

The operation of the ground radar device 200 shown in FIG. 11 will be described with reference to FIG. FIG. 12 is a flowchart of the underground radar measuring method of this embodiment.

(Step S201) The antenna position control unit 213 arranges the transmitting antenna A1-1 and the receiving antenna A1-2 at the first measurement position. The first measurement position is, for example, the position of A1 pair. The reception information recording unit 232 records the first measurement position based on the antenna position information.

(Step S202) The electromagnetic wave generation unit 212 outputs an electromagnetic wave to the transmission antenna A1-1. As a result, the electromagnetic wave of the ground radar is radiated from the transmitting antenna A1-1 set at the measurement position toward the ground.

(Step S203) The reception detection unit 231 receives the reflected wave which is the electromagnetic wave of the ground radar by the reception antenna A1-2.

(Step S204) The reception information recording unit 232 records the reception signal of the reflected wave received by the reception detection unit 231. When electromagnetic waves are emitted from the same measurement position a plurality of times, the reception signals of the reflected waves received by the reception detection unit 231 are combined each time, and the combined result is recorded.

(Step S205) The antenna position control unit 213 determines whether or not the emission of the electromagnetic wave from the transmitting antenna A1-1 is completed at all the positions of the four antenna pairs shown in FIG. As a result, if completed, the process proceeds to step S208. On the other hand, if not completed, the process proceeds to step S206.

(Step S206) The reception information recording unit 232 records the reception signal recorded in step S204 in association with the measurement position.

(Step S207) The antenna position control unit 213 moves the transmitting antenna A1-1 and the receiving antenna A1-2 to the next measurement position. For example, as shown in FIG. 11, from the position of the A1 pair to the position of the A2 pair, that is, at the positions (A2-1) and (A2-2) in FIG. 11, the transmitting antenna A1-1 and the receiving antenna A1-2 are located. And move. The reception information recording unit 232 records the next measurement position based on the antenna position information. Then, the process returns to step S202.

(Step S208) The reception synthesizing unit 233 synthesizes the reception signals at the respective measurement positions recorded in the reception information recording unit 232. The reception combining unit 233 removes the unnecessary scattered wave that is the reflected wave by the unnecessary scatterer from the combined result.

(Step S209) The comparison unit 234 receives the information recorded by the reception information recording unit 232 based on the “reflection time of the concrete surface of the upper floor plate of the manhole 100 (comparison target time)” obtained from the result of the removal of the unnecessary scattered waves at Step S208. The received signals at each measurement position recorded in 1 are compared and evaluated. It is determined whether the “time of reflection of the upper floor plate of the manhole 100 on the concrete surface” in the received signal at each measurement position is significantly different from the comparison target time. This comparative evaluation method is the same as the method of step S107 of FIG. 10 of the above-described first embodiment. As a result of the comparison evaluation, if the comparison target time is largely different, the comparison unit 234 notifies the reception combining unit 233 of the measurement position determined to be significantly different from the comparison target time. Receiving the notification, the reception combining unit 233 excludes the notified measurement position from the target of the reception signal combination, and combines the reception signals of the respective measurement positions recorded in the reception information recording unit 232. The result of combining the received signals is used for the subsequent processing.

If the comparison unit 234 does not notify the measurement position to be excluded from the received signal combining target, the reception combining unit 233 does not combine the received signals in step S209. In this case, the result of combining the received signals in step S208 is used in the subsequent processing.

(Step S210) The unnecessary scattered wave removing/permittivity calculating unit 235 removes the unnecessary scattered wave from the result of combining the reception signals by the receiving combining unit 233, and calculates the relative permittivity based on the result of removing the unnecessary scattered wave. To do.

(Step S211) The calibration/received signal reprocessing unit 236 performs calibration using the relative permittivity calculated by the unnecessary scattered wave removing/permittivity calculating unit 235. The calibration/received signal reprocessing unit 236 reprocesses the received signal of the reflected wave based on the result of the calibration.

(Steps S212 and S213) The subsurface radar device 200 calculates the position and status of the buried object from the received signal of the reflected wave reprocessed by the calibration/received signal reprocessing unit 236. The underground radar device 200 displays the calculated position and status of the buried object.

According to the above-described second embodiment, the relative permittivity of soil can be calculated by reducing the influence of reflected waves due to unnecessary scatterers existing in soil, as in the first embodiment. Therefore, the accuracy of measurement of the relative permittivity using the ground radar can be improved. Further, similarly to the second embodiment, it is possible to easily realize that the reflected wave radiated from the transmitting antenna and reflected at one point of the object is received at a plurality of positions.

Further, according to the second embodiment, the pair of transmission antennas and reception antennas are moved on the same circumference whose center lies on the ground just above the object. By this means, only a pair of transmitting antenna and receiving antenna need be provided, so that the cost can be reduced.

(Third Embodiment)
The third embodiment will be described with reference to FIGS. 13 to 22. Also in the third embodiment, the manhole 100 in the ground shown in FIG. 1 is a measurement target, as in the above-described first embodiment.

FIG. 13 is a bird's-eye view showing an example of movement of the transmission antenna and the reception antenna of this embodiment. In the present embodiment, only one antenna pair “Aa pair: a set of a transmitting antenna Aa-1 and a receiving antenna Aa-2” is provided, and a transmitting antenna Aa-1 and a receiving antenna Aa-2 are provided at each measurement position. The measurement is performed by sequentially moving. In FIG. 13, as the three measurement positions, the position of “Aa pair” in which the transmitting antenna Aa-1 and the receiving antenna Aa-2 are shown and “Ab pair: transmitting antenna position Ab-1” shown in parentheses. And the position of the receiving antenna position Ab-2” and the positions of “Ac pair: transmitting antenna position Ac-1 and receiving antenna position Ac-2” shown in parentheses.

The transmitting antenna Aa-1 moves on the same line 301. Therefore, each measurement position of the transmitting antenna Aa-1 is on the line 301. The receiving antenna Aa-2 moves on the same line 302. Therefore, each measurement position of the receiving antenna Aa-2 is on the line 301. At each measurement position, the antenna interval between the transmitting antenna Aa-1 and the receiving antenna Aa-2 is X and is constant. The lines 301 and 302 may be straight lines or curved lines. The transmitting antenna Aa-1 and the receiving antenna Aa-2 are arranged on the ground. Each measurement position exists within the range of the buried object to be measured. In FIG. 13, each measurement position exists within the range 102 or 103 of the upper floor plate of the manhole 100 shown in FIG. 1 described above. The depth from the ground to the concrete surface of the upper floor plate of the manhole 100 is d, which is common to each measurement position.

FIG. 14A shows an example of the time response of the reflected wave at the three measurement positions “Aa pair”, “Ab pair”, and “Ac pair” shown in FIG. 13. In the graph of FIG. 14A, the horizontal axis represents time (t) and the vertical axis represents reflection intensity (I). FIG. 14B shows the result of combining the time responses of the reflected waves for the three measurement positions “Aa pair”, “Ab pair”, and “Ac pair” shown in FIG. 14(a). In the graph of FIG. 14B, the horizontal axis represents time (t) and the vertical axis represents combined reflection intensity (Ic). From the graph of FIG. 14B, a process of removing unnecessary scattering components is performed. In the removal processing of the unnecessary scattering component, the reflections appearing at the time τ which strengthens as the combined reflection intensity (Ic) by combining the reflected waves at the three measurement positions “Aa pair”, “Ab pair”, and “Ac pair”. Delete the time response of the reflected wave (broken line graph) other than the wave time response (solid line graph). Thus, from the graph of FIG. 14B, the arrival time τ of the reflected wave from the concrete surface can be accurately known as the time τ of strengthening the combined reflection intensity (Ic). Then, the propagation distance l is calculated by the above equation (4) from the antenna distance X and the depth d common to the three measurement positions “Aa pair”, “Ab pair”, and “Ac pair”, and the arrival time τ From the above and the propagation distance l, the relative permittivity ε _r of soil in the ground shown in FIG. 13 can be calculated accurately by the above equation (5). By using the calculated relative permittivity ε _r to calibrate the ground-penetrating radar, the ground-penetrating radar after the calibration can accurately perform the underground measurement shown in FIG.

Here, the features of the present embodiment will be described with reference to FIGS. 15 to 20. 15 to 17 are explanatory diagrams of the present embodiment. 18 to 20 are explanatory diagrams of objects to be compared with the present embodiment.

First, the object to be compared with the present embodiment will be described with reference to FIGS. 18 to 20. 18 and 19 show an example of movement of a transmission antenna and a reception antenna to be compared with this embodiment, FIG. 18 is a bird's-eye view, and FIG. 19 is a top view. The transmission antenna and the reception antenna in FIG. 18 are, for example, the transmission antenna and the reception antenna in the case shown in FIG. In FIG. 18 and FIG. 19, the transmitting antenna and the receiving antenna, which are one antenna pair, are moved on the same line 331. In FIG. 18 and FIG. 19, the three measurement positions are “Ai pair: transmission antenna position Ai-1 and reception antenna position Ai-2” and “Aii pair: transmission antenna position Aii-1 and reception antenna position Aii. -2" and the positions of "Aiii pair: transmitting antenna position Aiii-1 and receiving antenna position Aiii-2". At each measurement position, the antenna spacing between the transmitting antenna and the receiving antenna is the same. Each measurement position exists directly above the object (horizontal buried plate) buried in the ground. 18 and 19, the propagation path of the reflected wave (electromagnetic wave) by the object is shown by a solid line arrow and the propagation path of the reflected wave (electromagnetic wave) by the unnecessary scatterer is shown by a broken line arrow at each measurement position.

In FIG. 19, the dashed-dotted ellipse indicates that the propagation paths of the reflection by the object at each measurement position are equidistant. The dashed ellipse has a longer propagation distance than the dashed-dotted ellipse, and shows the equidistant range in the propagation path of the reflection by the unnecessary scatterer at each measurement position. The unnecessary scatterers are shown at the points where the broken-line ellipses at the respective measurement positions overlap.

FIG. 20 shows the result of combining the time responses of the reflected waves at the respective measurement positions of FIGS. 18 and 19. In the graph of FIG. 20, the horizontal axis represents time (t) and the vertical axis represents combined reflection intensity (Ic). Regarding the reflection on the target object, since the target object is a horizontal embedded plate, the arrival time of the reflected wave is the same at τ ₂ at each measurement position. However, as shown in FIG. 20, both the reflected wave from the object and the reflected wave (unnecessary scattering) from the unnecessary scatterer are strengthened as a combined reflection intensity (Ic) depending on the result of the combination. Therefore, it is impossible to determine which of the time τ ₁ related to unnecessary scattering and the time τ ₂ related to the object is the arrival time of the reflected wave by the object.

Next, this embodiment will be described with reference to FIGS. 15 and 16 show an example of movement of the transmitting antenna and the receiving antenna of the present embodiment, FIG. 15 is a bird's-eye view, and FIG. 16 is a top view. In FIG. 15 and FIG. 16, among the transmitting antenna and the receiving antenna of one antenna pair, the transmitting antenna is moved on the line 301 and the receiving antenna is moved on the line 302, as shown in FIG. In FIGS. 15 and 16, the three measurement positions are “Aa pair: transmission antenna position Aa-1 and reception antenna position Aa-2”, and “Ab pair: transmission antenna position Ab-1 and reception antenna position Ab. The position of "-2" and the position of "Ac pair: transmitting antenna position Ac-1 and receiving antenna position Ac-2" are shown. At each measurement position, the antenna spacing between the transmitting antenna and the receiving antenna is the same. Each measurement position exists directly above the object (horizontal buried plate) buried in the ground. 15 and 16, the propagation path of the reflected wave (electromagnetic wave) by the object is indicated by a solid line arrow and the propagation path of the reflected wave (electromagnetic wave) by the unnecessary scatterer is indicated by a broken line arrow at each measurement position.

In FIG. 16, the dashed-dotted ellipse indicates that the propagation paths of the reflection by the object at each measurement position are equidistant. The dashed ellipse indicates the equidistant range of the propagation path of the reflection by the unnecessary scatterer at each measurement position. The dashed ellipse has a longer propagation path than the dashed ellipse. In the case of the present embodiment, as shown in FIG. 16, the propagation distance of the reflected wave by the unnecessary scatterer greatly varies depending on each measurement position. For example, at the measurement position of the Ab pair, the propagation distance of the reflected wave by the unnecessary scatterer is shorter than that at the measurement position of the Aa pair and the measurement position of the Ac pair. The variation of the propagation distance of the reflected wave due to the unnecessary scatterer is caused by the method of moving the measurement position according to the present embodiment.

FIG. 17 shows the result of combining the time responses of the reflected waves at the respective measurement positions of FIGS. 15 and 16. In the graph of FIG. 17, the horizontal axis represents time (t) and the vertical axis represents combined reflection intensity (Ic). Regarding the reflection on the target object, since the target object is a horizontal embedded plate, the arrival time of the reflected wave is the same at τ at each measurement position. On the other hand, regarding the reflected wave (unnecessary scattering) by the unnecessary scatterer, since the propagation distance varies at each measurement position as described above, the arrival time varies. As a result, the reflected wave from the object remarkably strengthens as the combined reflection intensity (Ic) according to the result of the combination, and it can be determined that the arrival time of the reflected wave from the object is the time τ.

FIG. 21 shows the structure of an underground radar device 350 of the third embodiment. The underground radar device 350 shown in FIG. 21 includes a transmitting unit 360, a receiving unit 380, and one antenna pair “Aa pair: a set of a transmitting antenna Aa-1 and a receiving antenna Aa-2”. In the present embodiment, only an “Aa pair: a set of a transmitting antenna Aa-1 and a receiving antenna Aa-2” is provided as an antenna pair, and the transmitting antenna Aa-1 is on the line 301 and the receiving antenna Aa-2 is on the line 302. Above, the measurement is carried out by sequentially moving to each measurement position. In FIG. 21, as three measurement positions, a position of “Aa pair” in which a transmitting antenna Aa-1 and a receiving antenna Aa-2 are shown and “Ab pair: transmitting antenna position Ab-1” shown in parentheses. And the position of the receiving antenna position Ab-2” and the positions of “Ac pair: transmitting antenna position Ac-1 and receiving antenna position Ac-2” shown in parentheses. Each measurement position is within the range of the buried object to be measured, here, in the range 102 or 103 of the upper floor plate of the manhole 100 shown in FIG. 1 above, “the rectangular shape having the length “L/2−a” and the width W””. Exists in.

The transmitter 360 includes a transmission controller 361, an electromagnetic wave generator 362, and an antenna position controller 363. The reception unit 380 includes a reception detection unit 381, a reception information recording unit 382, a reception synthesis unit 383, a comparison unit 384, an unnecessary scattered wave removal/dielectric constant calculation unit 385, and a calibration/received signal reprocessing unit 386.

In the transmission unit 360, the transmission control unit 361 outputs an instruction to transmit an electromagnetic wave of the ground radar to the electromagnetic wave generation unit 362 and the antenna position control unit 363. The electromagnetic wave generation unit 362 is connected to the transmission antenna Aa-1. The electromagnetic wave generation unit 362 outputs an electromagnetic wave to the transmission antenna Aa-1 in response to an instruction from the transmission control unit 361 and input of antenna position information from the antenna position control unit 363. The antenna position control unit 363 sequentially moves the transmitting antenna Aa-1 and the receiving antenna Aa-2 to each measurement position. After moving the transmitting antenna Aa-1 and the receiving antenna Aa-2 to the measurement position, the antenna position control unit 363 outputs antenna position information indicating the measurement position to the electromagnetic wave generation unit 362 and the reception unit 380. The antenna position information input to the reception unit 380 is input to the reception information recording unit 382 and the comparison unit 384. The transmitting unit 360 radiates an electromagnetic wave of an underground radar toward the ground from the transmission antenna Aa-1 at the measurement position indicated by the antenna position information among the measurement positions. In addition, the measurement position is sequentially moved.

The transmission antenna Aa-1 and the reception antenna Aa-2 may be moved automatically by an antenna moving device not shown in FIG. 21, or manually according to a movement instruction from the antenna position control unit 363. May be done in.

In the reception unit 380, the reception detection unit 381 is connected to the reception antenna Aa-2. The reception detection unit 381 detects the electromagnetic wave of the ground radar from the signal received by the reception antenna Aa-2. The received signal of the electromagnetic wave of the ground radar detected by the reception detection unit 381 is output to the reception information recording unit 382 and the comparison unit 384.

The reception information recording unit 382 records the reception signal input from the reception detection unit 381 in association with the antenna position information input from the transmission unit 360 to the reception unit 380. The reception combining unit 383 uses the antenna position information and the reception signal recorded in the reception information recording unit 382 to combine the reception signals of the measurement positions indicated by the antenna position information. In the synthesis of the received signals, the reflection intensities (I) of the received signals at the respective measurement positions are added every time, as in the above-described first embodiment. In the addition of the reflection intensity (I), the time axis is aligned with the reflection of the buried object having a known depth, here, the reflection by the concrete surface (depth d) of the upper floor plate of the manhole 100 shown in FIG. 1 above. Match at the time of.

The comparison unit 384 uses the antenna position information recorded in the reception information recording unit 382 and the received signal to perform mutual comparison between the received signals at the measurement positions indicated by the antenna position information. As a result of this comparison, when there is a received signal that satisfies a predetermined abnormality determination condition for determining that the received signal is abnormal, the comparison unit 384 determines the measurement position of the received signal by the reception combining unit 383. Notify to. The reception combining unit 383 excludes the reception signal at the measurement position notified from the comparing unit 384 from the above-described reception signal combining target. The reason for this is the same as the description of the comparison unit 173 of the first embodiment described above.

The unnecessary scattered wave removing/permittivity calculating unit 385 removes the unnecessary scattered wave from the result of combining the reception signals by the reception combining unit 383, and calculates the relative permittivity based on the result of removing the unnecessary scattered wave. The method of calculating the relative permittivity is the same as in the first embodiment described above. The calibration/received signal reprocessing unit 386 performs calibration using the relative permittivity calculated by the unnecessary scattered wave removing/permittivity calculating unit 385. The calibration/received signal reprocessing unit 386 reprocesses the received signal based on the result of the calibration.

The operation of the underground radar device 350 shown in FIG. 21 will be described with reference to FIG. FIG. 22 is a flowchart of the underground radar measuring method of this embodiment.

(Step S301) The antenna position control unit 363 arranges the transmitting antenna Aa-1 and the receiving antenna Aa-2 at the first measurement position. The first measurement position is, for example, the Aa pair position. The reception information recording unit 382 records the first measurement position based on the antenna position information.

(Step S302) The electromagnetic wave generation unit 362 outputs an electromagnetic wave to the transmission antenna Aa-1. As a result, the electromagnetic wave of the ground radar is radiated toward the ground from the transmission antenna Aa-1 set at the measurement position.

(Step S303) The reception detection unit 381 receives the reflected wave which is the electromagnetic wave of the ground radar by the reception antenna Aa-2.

(Step S304) The reception information recording unit 382 records the reception signal of the reflected wave received by the reception detection unit 381. When electromagnetic waves are emitted from the same measurement position a plurality of times, the reception signals of the reflected waves received by the reception detection unit 381 are combined each time, and the combined result is recorded.

(Step S305) Whether the antenna position control unit 363 has completed the emission of the electromagnetic wave from the transmitting antenna Aa-1 at all the positions of “Aa pair”, “Ab pair”, and “Ac pair”. To judge. As a result, if completed, the process proceeds to step S308. On the other hand, if not completed, the process proceeds to step S306.

(Step S306) The reception information recording unit 382 records the reception signal recorded in step S304 in association with the measurement position.

(Step S307) The antenna position control unit 363 moves the transmitting antenna Aa-1 and the receiving antenna Aa-2 to the next measurement position. For example, as shown in FIG. 21, from the position of the Aa pair to the position of the Ab pair, that is, from the positions of the transmitting antenna Aa-1 and the receiving antenna Aa-2 to the positions (Ab-1) and (Ab-2), respectively, The transmitting antenna Aa-1 and the receiving antenna Aa-2 are moved. The reception information recording unit 382 records the next measurement position based on the antenna position information. Then, the process returns to step S302.

(Step S308) The reception synthesizing unit 383 synthesizes the reception signals at the respective measurement positions recorded in the reception information recording unit 382. The reception combining unit 383 removes the unnecessary scattered wave that is the reflected wave by the unnecessary scatterer from the combined result.

(Step S309) The comparing unit 384 receives the information from the receiving information recording unit 382 based on “the time of reflection by the concrete surface of the upper floor plate of the manhole 100 (comparison target time)” obtained from the result of removing the unnecessary scattered waves in Step S308. The received signals at each measurement position recorded in 1 are compared and evaluated. It is determined whether the “time of reflection of the upper floor plate of the manhole 100 on the concrete surface” in the received signal at each measurement position is significantly different from the comparison target time. This comparative evaluation method is the same as the method of step S107 of FIG. 10 of the above-described first embodiment. As a result of the comparative evaluation, when the comparison target time is largely different, the comparing unit 384 notifies the reception combining unit 383 of the measurement position determined to be significantly different from the comparison target time. Upon receiving this notification, the reception combining unit 383 excludes the notified measurement position from the reception signal combining target, and combines the reception signals of the respective measurement positions recorded in the reception information recording unit 382. The result of combining the received signals is used for the subsequent processing.

If the comparison unit 384 does not notify the measurement position to be excluded from the received signal combining target, the reception combining unit 383 does not combine the received signals in step S309. In this case, the result of combining the received signals in step S308 is used for the subsequent processing.

(Step S310) The unnecessary scattered wave removing/permittivity calculating unit 385 removes the unnecessary scattered wave from the result of combining the received signals by the receiving combiner 383, and calculates the relative permittivity based on the result of removing the unnecessary scattered wave. To do.

(Step S311) The calibration/received signal reprocessing unit 386 performs calibration using the relative permittivity calculated by the unnecessary scattered wave removing/permittivity calculating unit 385. The calibration/reception signal reprocessing unit 386 reprocesses the reception signal of the reflected wave based on the calibration result.

(Steps S312 and S313) The subsurface radar device 350 calculates the position and status of the buried object from the received signal of the reflected wave reprocessed by the calibration/received signal reprocessing unit 386. The underground radar device 350 displays the calculated position and status of the buried object.

Next, a modification of the third embodiment will be described with reference to FIGS. 23 to 28. 23 to 25 are explanatory diagrams of modified examples of the third embodiment. FIG. 23A, FIG. 24A, and FIG. 25A are plan views showing examples of the arrangement of the transmitting antenna and the receiving antenna. 23(b), 24(b), and 25(b) are bird's-eye views showing an example of the arrangement of the transmitting antenna and the receiving antenna. In this modification, the position of the transmitting antenna is fixed to Ao-1. The receiving antenna moves on the circumference of a circle 390 whose center is the position Ao-1 of the transmitting antenna. In the present modification, the reception antenna is moved by 30 degrees as the central angle and the measurement is performed. In FIG. 23, the measurement position Aa-2 is shown as the first (first) measurement position of the receiving antenna. In FIG. 24, the measurement position Ab-2 is shown as the second measurement position of the receiving antenna. In FIG. 25, the measurement position Al-2 is shown as the last (12th) measurement position of the receiving antenna.

As shown in FIGS. 23(b), 24(b), and 25(b), the electromagnetic wave of the underground radar radiated toward the ground from the transmitting antenna at the position Ao-1 is at the position Ao-1. Is the center and is half the antenna distance between the transmitting antenna and the receiving antenna (that is, half the radius of the circle 390) is reflected on the circumference of the circle whose radius is The measurement positions Aa-2, Ab-2,..., Al-2 are received.

Also in the modification of the third embodiment of FIGS. 23 to 25, the device configuration is the same as that of the ground radar device 350 of FIG. 21, and the same as the ground radar measuring method of FIG. This is an underground radar measurement method. However, the antenna position control unit 363 sequentially moves the position of the reception antenna from the first measurement position Aa-2 to the twelfth measurement position Al-2. Then, the electromagnetic wave generation unit 362 receives the antenna position information, and after the reception antennas are arranged at the respective measurement positions Aa-2, Ab-2,..., Al-2, the electromagnetic wave generation unit 362 becomes the transmission antenna at the position Ao-1. It outputs electromagnetic waves and radiates the electromagnetic waves of the ground radar from the transmitting antenna toward the ground.

Features of the modified example of the above-described third embodiment will be described with reference to FIGS. 26 to 28. 26 to 28 are explanatory diagrams of modified examples of the above-described third embodiment. 26 and 27 show the arrangement of the transmitting antenna and the receiving antenna of the modification of the third embodiment, FIG. 26 is a bird's eye view, and FIG. 27 is a top view.

26 and 27, the transmission antenna is fixed at the position Ao-1. Each measurement position Aa-2, Ab-2,..., Al-2 of the reception antenna exists on the circumference of a circle 390 whose center is the position Ao-1 of the transmission antenna. Therefore, at each measurement position of the receiving antenna, the antenna spacing between the transmitting antenna and the receiving antenna is the same as the radius of the circle 390. The position Ao-1 of the transmitting antenna and the measurement positions Aa-2, Ab-2,..., Al-2 of the receiving antenna are directly above the object (horizontal buried plate) buried in the ground. Exists. 26 and 27, the propagation path of the reflected wave (electromagnetic wave) by the object is shown by a solid arrow, and the propagation path of the reflected wave (electromagnetic wave) by the unnecessary scatterer is shown by a dashed arrow.

In FIG. 27, the alternate long and short dash line indicates that the propagation paths of the reflection by the object at the respective measurement positions of the receiving antenna are equidistant. However, the propagation distance of the reflected wave by the unnecessary scatterer greatly varies depending on each measurement position of the receiving antenna. For example, at the measurement position Ai-2 of the reception antenna, the propagation distance of the reflected wave by the unnecessary scatterer is shorter than at the measurement position Aa-2 of the reception antenna. At the measurement position Ad-2 of the receiving antenna, the propagation distance of the reflected wave by the unnecessary scatterer becomes longer and becomes the longest. The variation in the propagation distance of the reflected wave due to the unnecessary scatterer is caused by the method of moving the measurement position according to the modification of the third embodiment.

FIG. 28 shows the result of combining the time responses of the reflected waves at the respective measurement positions of the receiving antennas of FIGS. 26 and 27. In the graph of FIG. 28, the horizontal axis represents time (t) and the vertical axis represents combined reflection intensity (Ic). Regarding the reflection at the target object, since the target object is a horizontal embedded plate, the arrival time of the reflected wave is the same at τ at each measurement position of the receiving antenna. On the other hand, regarding the reflected wave (unnecessary scattering) by the unnecessary scatterer, since the propagation distance changes at each measurement position of the receiving antenna as described above, the arrival time varies. As a result, the reflected wave from the object remarkably strengthens as the combined reflection intensity (Ic) according to the result of the combination, and it can be determined that the arrival time of the reflected wave from the object is the time τ.

23 to 25, the transmitting antenna is fixed as the center position of the circle 390 and the receiving antenna is moved on the circumference of the circle 390, but the moving method may be reversed. That is, the receiving antenna may be fixed as the center position of the circle 390 and the transmitting antenna may be moved on the circumference of the circle 390.

According to the above-described third embodiment, the relative permittivity of soil can be calculated by reducing the influence of reflected waves due to unnecessary scatterers existing in soil, as in the first embodiment. Therefore, the accuracy of measurement of the relative permittivity using the ground radar can be improved.

Furthermore, according to the third embodiment, the transmitting antenna and the receiving antenna are arranged on different lines. Thereby, the reflected waves radiated from the transmitting antenna and reflected at a plurality of positions of the object can be separately received.

(Fourth Embodiment)
The fourth embodiment will be described with reference to FIGS. 29 and 30. Also in the fourth embodiment, the manhole 100 in the ground shown in FIG. 1 is an object to be measured, as in the above-described first embodiment.

FIG. 29 is an explanatory diagram of the underground radar measuring method according to the fourth embodiment. In the fourth embodiment, the same measurement target is measured by changing the antenna spacing between the transmission antenna and the reception antenna. FIG. 29A shows the first (first) antenna spacing X _α and the propagation distance l _α of the reflected wave due to the concrete surface (depth d) of the upper floor plate of the manhole 100. FIG. 29B shows the second antenna spacing X _β and the propagation distance l _β of the reflected wave due to the concrete surface (depth d) of the upper floor plate of the manhole 100. FIG. 29C shows the last (third) antenna spacing X _γ and the propagation distance l _γ of the reflected wave due to the concrete surface (depth d) of the upper floor plate of the manhole 100. The magnitude relationship between the antenna intervals is “X _α <X _β <X _γ ”. Further, the depth d is common and the same at each antenna interval. As a result, the magnitude relationship of the propagation distance at each antenna interval is "l _α <l _β <l _γ ".

FIG. 29D shows an example of the time response of the reflected wave at the first (first) antenna interval X _α . At the antenna interval X _α , the arrival time of the reflected wave by the concrete surface of the upper floor plate of the manhole 100 is τ _α . FIG. 29E shows an example of the time response of the reflected wave at the second antenna interval X _β . Arrival time of the reflected wave by the concrete surface of the floor plate above the antenna spacing X in the _beta manhole 100 is tau _beta. FIG. _29F shows an example of the time response of the reflected wave at the last (third) antenna interval X _γ . Arrival time of the reflected wave by the concrete surface of the floor plate above the antenna spacing X in the _gamma manhole 100 is tau _gamma. Since the depth d is the same for each antenna interval, the propagation distances l _α , l _β , l _{γ of} the electromagnetic waves radiated from the transmitting antenna vary depending on the antenna intervals X _α , X _β , X _γ. .. As a result, the arrival times τ _α , τ _β , and τ _γ of the reflected waves from the concrete surface of the upper floor plate of the manhole 100 change according to the antenna intervals X _α , X _β , and X _γ . The size relation of the arrival time at each antenna interval is “τ _α <τ _β <τ _γ ”.

FIG. 29(g) shows the result of synthesizing the time responses of the reflected waves at the antenna intervals of FIGS. 29(d), (e), and (f). In this reflected wave synthesizing process, the time axis is adjusted according to each antenna interval. From the antenna intervals X _α , X _β , X _γ and the common depth d, the propagation distances l _α , l _β , l _γ can be calculated by the above equation (4). From this, according to the antenna intervals X _α , X _β , and X _γ , the time axes of the reflected waves at the antenna intervals are aligned with the time of reflection by the concrete surface of the upper floor plate of the manhole 100. As a result, as shown in FIG. 29(g), the reflected waves from the concrete surface of the upper floor plate of the manhole 100 at the respective arrival times τ _α , τ _β , and τ _γ are overlapped with each other, and the combined reflection intensity (Ic) is strengthened. Will result. As a result, it is possible to easily distinguish and separate the component of the reflected wave by the unnecessary scatterer (unnecessary scattered component), so that only the component of the reflected wave by the concrete surface of the upper floor plate of the manhole 100 can be extracted. , The arrival times τ _α , τ _β , τ _γ corresponding to each of the antenna intervals X _α , X _β , X _γ can be accurately known. Therefore, from the arrival times τ _α , τ _β , τ _γ and the propagation distances l _α , l _β , l _γ corresponding to the antenna intervals X _α , X _β , X _γ , respectively, according to the above equation (5), The relative permittivity ε _r of can be calculated accurately. By using the calculated relative permittivity ε _r to calibrate the underground radar, the accuracy of measurement by the underground radar can be improved.

FIG. 30 shows the structure of an underground radar device 400 according to the fourth embodiment. The underground radar device 400 shown in FIG. 30 includes a transmitting unit 410, a receiving unit 430, three antenna pairs “a set of a transmitting antenna having an antenna interval X _α and a receiving antenna”, and “a transmitting antenna having an antenna interval X _β. A set of a receiving antenna" and a "set of a transmitting antenna and a receiving antenna having an antenna interval X _γ ". The transmitting antenna and the receiving antenna of each antenna pair are in the range of the buried object to be measured, here in the range 102 or 103 of the upper floor plate of the manhole 100 shown in FIG. 1 above, “length “L/2-a””. It is arranged on the ground in a “rectangular shape with a width W”. The transmission unit 410 includes a transmission selection control unit 411 and an electromagnetic wave generation unit 412. The reception unit 430 includes a reception detection unit 431, a reception synthesis unit 432, a comparison unit 433, an unnecessary scattered wave removal/dielectric constant calculation unit 434, and a calibration/received signal reprocessing unit 435.

In the transmission unit 410, the transmission selection control unit 411 selects from among “a transmission antenna with an antenna interval X _α ”, “a transmission antenna with an antenna interval X _β ”, and “a transmission antenna with an antenna interval X _γ ” among three antenna pairs. The transmitting antennas that emit electromagnetic waves are sequentially selected. The transmission selection control unit 411 outputs antenna spacing information indicating the antenna spacing of the selected transmission antennas to the electromagnetic wave generation unit 412 and the reception unit 430. The selection signal input to the reception unit 430 is input to the reception synthesis unit 432 and the comparison unit 433. The electromagnetic wave generation unit 412 is connected to each of the three antenna pairs of “transmission antenna with antenna spacing X _α ”, “transmission antenna with antenna spacing X _β ”, and “transmission antenna with antenna spacing X _γ ”. The electromagnetic wave generation unit 412 outputs an electromagnetic wave to the transmission antenna having the antenna spacing indicated by the antenna spacing information input from the transmission selection control unit 411. As a result, the electromagnetic waves of the underground radar are radiated toward the ground from the transmission antennas having the antenna spacing indicated by the antenna spacing information by the transmission selection control unit 411.

In the reception unit 430, the reception detection unit 431 is connected to each of the “reception antenna with the antenna interval X _α ”, the “reception antenna with the antenna interval X _β ”, and the “reception antenna with the antenna interval X _γ ” of the three antenna pairs. To be done. The reception detection unit 431 detects the electromagnetic wave of the ground radar for each reception antenna of each antenna interval from the signal received by the reception antenna of each antenna interval. The reception signal of the electromagnetic wave of the ground radar detected by the reception detection unit 431 for each reception antenna at each antenna interval is output to the reception combining unit 432 and the comparison unit 433 for each antenna interval.

The reception synthesizing unit 432 uses the antenna spacing indicated by the antenna spacing information input from the transmission selection control unit 411 among the received signals at the respective antenna spacings X _α , X _β , and X _γ input from the reception detection unit 171. Record the received signal of. The reception combining unit 432 combines the recorded reception signals at the respective antenna intervals X _α , X _β , and X _γ . In the synthesis of the received signal, as described by the above FIG. 29, the antenna spacing X _alpha, X _beta, and adjust the time axis in accordance with the X _gamma, the antenna spacing X _alpha, X _beta, received by the X _gamma The reflection intensity (I) of the signal is added every time.

The comparing unit 433 detects, among the reception signals at the antenna intervals X _α , X _β , and X _γ input from the reception detecting unit 431, the antenna intervals indicated by the antenna interval information input from the transmission selection control unit 411. Record the received signal. The comparison unit 433 performs mutual comparison on the received signals at the respective antenna intervals X _α , X _β , and X _γ recorded. As a result of this comparison, when there is a received signal satisfying a predetermined abnormality determination condition for determining that the received signal is abnormal, the comparison unit 433 determines the antenna interval of the received signal as the reception combining unit 432. Notify to. The reception combining unit 432 excludes the reception signals at the antenna intervals notified from the comparison unit 433 from the above-described reception signal combining targets. The reason for this is the same as the description of the comparison unit 173 of the first embodiment described above.

The unnecessary scattered wave removing/permittivity calculating unit 434 removes the unnecessary scattered wave from the result of combining the reception signals by the reception combining unit 432, and calculates the relative permittivity based on the result of removing the unnecessary scattered wave. The method of calculating the relative permittivity is the same as in the first embodiment described above. The calibration/received signal reprocessing unit 435 performs calibration using the relative permittivity calculated by the unnecessary scattered wave removing/permittivity calculating unit 434. The calibration/received signal reprocessing unit 435 reprocesses the received signal based on the result of the calibration.

Next, a modification of the fourth embodiment will be described with reference to FIGS. 31 to 34. 31 to 33 are explanatory views of a modified example of the fourth embodiment. FIG. 31A, FIG. 32A, and FIG. 33A are plan views showing an example of the arrangement of the transmitting antenna and the receiving antenna. 31(b), 32(b), and 33(b) are bird's-eye views showing an example of the arrangement of the transmitting antenna and the receiving antenna. In this modification, the transmitting antenna and the receiving antenna of each of the three antenna pairs are arranged on the circumference of the same circle (center 451 of the circle) whose antenna distance is the diameter.

In FIG. 31, the measurement positions of each of the three sets of transmitting antennas and receiving antennas are provided on the circumference of the same circle whose antenna spacing X _α is the diameter. In FIG. 31, a set of a transmission antenna position A1-1 and a reception antenna position A1-2, a set of a transmission antenna position A2-1 and a reception antenna position A2-2, and a transmission antenna position A3- The measurement is performed on each of the three sets of 1 and the position A3-2 of the receiving antenna. In FIG. 32, the measurement positions of each of the three sets of transmitting antennas and receiving antennas are provided on the circumference of the same circle whose antenna spacing X _β is the diameter. In FIG. 32, a set of a transmission antenna position A4-1 and a reception antenna position A4-2, a set of a transmission antenna position A5-1 and a reception antenna position A5-2, and a transmission antenna position A6- The measurement is performed on each of the three sets of 1 and the position A6-2 of the receiving antenna. In FIG. 33, the measurement positions of each of the three transmitting antennas and the receiving antennas are provided on the circumference of the same circle whose antenna spacing X _γ is the diameter. In FIG. 33, a set of a transmission antenna position A7-1 and a reception antenna position A7-2, a set of a transmission antenna position A8-1 and a reception antenna position A8-2, and a transmission antenna position A9- The measurement is performed on each of the three sets of 1 and the position A9-2 of the receiving antenna.

For example, first, a transmitting antenna and a receiving antenna are sequentially arranged in each of the three sets of antenna spacing X _α shown in FIG. 31, and the measurement is sequentially performed in each arrangement. Secondly, a transmitting antenna and a receiving antenna are sequentially arranged in each of the three sets of antenna intervals X _β shown in FIG. 32, and the measurement is sequentially performed in each arrangement. Finally, a transmitting antenna and a receiving antenna are sequentially arranged in each of the three sets of antenna spacing X _γ shown in FIG. 33, and the measurement is sequentially performed in each arrangement.

The arrangement of the transmitting antenna and the receiving antenna at each antenna interval X _α , X _β , X _γ is all in the range of the buried object to be measured, here, the upper floor plate of the manhole 100 shown in FIG. 1 above. It is arranged on the ground within the range 102 or 103 “rectangular shape of length “L/2−a” and width W”.

With reference to FIG. 34, a ground-penetrating radar measuring method according to a modified example of the fourth embodiment will be described. FIG. 34 is a flowchart of a ground radar measurement method according to a modification of the fourth embodiment. Here, only one pair of the transmitting antenna and the receiving antenna is used, and the pair of transmitting antennas and the receiving antennas are sequentially moved to the respective arrangements shown in FIGS. 31 to 33, and the measurement in each arrangement is sequentially performed. In addition, the measurement order of each arrangement is as follows. First, the direction from the center 451 of the circle is fixed, the measurement is performed at each antenna interval X _α , X _β , X _γ , and after the measurement of all antenna intervals, the next direction is measured. The measurement is performed at fixed antenna intervals X _α , X _β , and X _γ .

(Step S401) A pair of a transmitting antenna and a receiving antenna are arranged at a first azimuth and at a first antenna interval.

(Step S402) The electromagnetic wave of the underground radar is radiated toward the ground from the transmitting antenna at the measurement position.

(Step S403) The reception antenna at the measurement position receives the reflected wave which is the electromagnetic wave of the underground radar.

(Step S404) The received signal of the reflected wave received by the receiving antenna at the measurement position is recorded. When electromagnetic waves are emitted from the same measurement position a plurality of times, the received signals of the reflected waves received at each time are combined and the combined result is recorded.

(Step S405) It is determined whether the emission of electromagnetic waves from the transmitting antenna is completed at all antenna intervals. As a result, if completed, the process proceeds to step S408. On the other hand, if not completed, the process proceeds to step S406.

(Step S406) The received signal recorded in step S404 is recorded in association with the measurement position.

(Step S407) The transmitting antenna and the receiving antenna are arranged at the following antenna intervals. At this time, the direction does not change. Then, the process returns to step S402.

(Step S408) The transmitting antenna and the receiving antenna are arranged in the following azimuth and at the initial antenna interval.

(Step S409) It is determined whether the emission of the electromagnetic wave from the transmitting antenna is completed in all directions. As a result, if completed, the process proceeds to step S410. On the other hand, if not completed, the process returns to step S402.

(Step S410) The received signals recorded at the respective measurement positions are combined. The unnecessary scattered wave which is the reflected wave by the unnecessary scatterer is removed from the combined result.

(Step S411) Comparative evaluation of reflected waves is performed. The method of this comparative evaluation is the same as the method of step S107 of FIG. 10 of the first embodiment described above.

(Step S412) The unnecessary scattered wave is removed from the result of combining the received signals, and the relative permittivity is calculated based on the result of removing the unnecessary scattered wave.

(Step S413) Calibration is performed using the calculated relative permittivity. The received signal of the reflected wave is reprocessed based on the calibration result.

(Steps S414 and S415) The position and status of the buried object are calculated from the re-processed reception signal of the reflected wave. Display the calculated location and status of buried objects.

According to the above-described fourth embodiment, the transmitting antenna arranged on the ground radiates the electromagnetic wave of the underground radar toward the ground where the target object whose depth is known is buried. The reflected wave of the electromagnetic wave is received by a receiving antenna arranged on the ground at a known antenna distance from the transmitting antenna. Next, the intensities of the reflected waves respectively received by the plurality of receiving antennas arranged at different antenna intervals are adjusted according to the antenna intervals of the receiving antennas and added. Next, the arrival time of the reflected wave from the object is determined based on the result of the addition of the reflected wave intensities. Next, the relative permittivity of the soil is calculated using the result of the arrival time determination, the depth of the object, and the antenna interval. Thereby, the relative permittivity of the soil can be calculated by reducing the influence of the reflected wave due to the unnecessary scatterer existing in the soil. Therefore, the accuracy of measurement of the relative permittivity using the ground radar can be improved. Further, the relative permittivity can be calculated based on the reflected waves at a plurality of antenna intervals by changing the antenna interval between the transmitting antenna and the receiving antenna. Thereby, the accuracy of measurement of the relative permittivity can be further improved.

According to the fourth embodiment, among the arrangements of the transmitting antenna and the receiving antenna, the intensities of the reflected waves respectively received by the receiving antennas are added in a plurality of different arrangements having the same antenna interval. Thereby, the relative permittivity can be calculated based on the reflected waves received at a plurality of positions at the same antenna interval. Thereby, the accuracy of measurement of the relative permittivity can be further improved.
In the flowchart of the underground radar measuring method shown in FIG. 34, the directions of the transmitting antenna and the receiving antenna are changed after the directions of the transmitting antenna and the receiving antenna are fixed and the antenna spacing is changed. That is, when the movement of the antenna position is specifically shown in FIGS. 31 to 33, the transmission antennas are A1-1, A4-1, A7-1, A2-1, A5-1, A8-1, A3-1. The positions are moved in the order of A6-1 and A9-1, and the receiving antennas correspond to the positions of the transmitting antennas A1-2, A4-2, A7-2, A2-2, A5-2, A8-2. , A3-2, A6-2, A9-2 in this order.
Unlike the method of moving the position of the antenna, the transmitting antenna and the receiving antenna may be changed in the azimuth direction to move in all the azimuth directions with the same antenna distance, and then the antenna interval may be changed. In this case, as specific movements of the antenna positions in FIGS. 31 to 33, the transmission antennas are A1-1, A2-1, A3-1, A4-1, A5-1, A6-1, A7-1, The positions are moved in the order of A8-1, A9-1, and the receiving antennas correspond to the positions of the transmitting antennas A1-2, A2-2, A3-2, A4-2, A5-2, A6-2. , A7-2, A8-2, A9-2 in this order.

(Fifth Embodiment)
The fifth embodiment will be described with reference to FIGS. 35 and 36. The fifth embodiment is an underground radar measuring method when the depth of the buried object to be measured is unknown, for example, when the depth d of the manhole 100 shown in FIG. 1 is unknown.

35 and 36 are explanatory diagrams of the fifth embodiment. FIG. 35(a) and FIG. 36(a) are bird's-eye views showing an example of the arrangement of the transmitting antenna and the receiving antenna. In FIG. 35(a), as in the case of FIG. 31, the measurement positions of each of the three sets of transmitting antennas and receiving antennas are provided on the circumference of the same circle whose antenna spacing X _α is the diameter. In FIG. 36(a), as in the case of FIG. 33 described above, the measurement positions of each of the three sets of transmitting antennas and receiving antennas are provided on the circumference of the same circle whose antenna interval _Xγ is the diameter.

FIG. 35B shows the result of combining the time responses of the reflected waves at the respective measurement positions in FIG. From the result of this synthesis, the arrival time τ _α for the reflected wave by the concrete surface of the upper floor plate of the manhole 100 to be measured is obtained with respect to the antenna interval X _α . FIG. 36B shows the result of combining the time responses of the reflected waves at the respective measurement positions in FIG. From the result of this synthesis, the arrival time τ _γ for the reflected wave from the concrete surface of the upper floor plate of the manhole 100 to be measured is obtained for the antenna interval X _γ .

In the case of the antenna spacing X _α shown in FIG. 35, the relative permittivity ε _r is represented by the following equation (6) from the above equations (4) and (5).

In the case of the antenna spacing X _γ shown in FIG. 36, the relative permittivity ε _r is represented by the following equation (7) from the above equations (4) and (5).

In the above equations (6) and (7), unknown values are the relative permittivity ε _r and the depth d. In the case of the manhole 100 that is the same measurement target, the relative permittivity ε _r , which is an unknown value, and the depth d have the same value. From this, the above equations (6) and (7) can be made into simultaneous equations. Here, the antenna intervals X _α and X _γ are known. The arrival times τ _α and τ _γ are obtained from the result of the above synthesis. As a result, the above equations (6) and (7) are transformed into the following equation (8).

From the above equation (8), the depth d is represented by the following equation (9).

Using the known antenna spacings X _α , X _γ and the arrival times τ _α , τ _γ obtained from the result of the above synthesis, the depth d can be calculated by the above equation (9).

From the above equation (9) and the above equation (5), the relative permittivity ε _r is expressed by the following equation (10).

Using the known antenna spacings X _α , X _γ and the arrival times τ _α , τ _γ obtained from the result of the above synthesis, the relative permittivity ε _r can be calculated by the above equation (10). ..

According to the above-described fifth embodiment, the electromagnetic wave of the underground radar is radiated from the transmitting antenna arranged on the ground toward the ground where the object buried in the soil exists. The reflected wave of the electromagnetic wave is received by a receiving antenna arranged on the ground at a known antenna distance from the transmitting antenna. Next, the intensities of the reflected waves respectively received by the plurality of receiving antennas arranged at different antenna intervals are added for each antenna interval. Next, the arrival time of the reflected wave from the object is determined for each antenna interval based on the result of the addition of the reflected wave intensities. Next, the relative permittivity of soil is calculated using the result of the arrival time determined for each antenna interval and the antenna interval. As a result, even if the depth of the object buried in the soil is unknown, it is possible to calculate the relative permittivity of the soil by reducing the influence of the reflected wave due to the unnecessary scatterer existing in the soil. Therefore, the accuracy of measurement of the relative permittivity using the ground radar can be improved. Further, the depth of the object buried in the soil can also be calculated.

If three or more antenna intervals are used, simultaneous equations can be established with the number of combinations, and it is possible to obtain the relative permittivity corresponding to the number of combinations and statistically process the relative permittivity. .. Thereby, the accuracy of the relative permittivity can be increased.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like within a range not departing from the gist of the present invention.
For example, the above-mentioned underground radar device may be realized by a dedicated hardware, or a program configured by a computer system such as a personal computer for realizing the functions of the respective parts of the underground radar device. The function may be realized by executing.

Moreover, an input device, a display device, and the like may be connected to the ground radar device as peripheral devices. Here, the input device refers to an input device such as a keyboard and a mouse. The display device refers to a CRT (Cathode Ray Tube), a liquid crystal display device, or the like. Further, the peripheral devices may be directly connected to the ground radar device, or may be connected via a communication line.

130, 200, 350, 400... Underground radar device, 150, 210, 360, 410... Transmission unit, 151, 411... Transmission selection control unit, 152, 212, 362, 412... Electromagnetic wave generation unit, 170, 230, 380 , 430... Receiving unit, 171, 231, 381, 431... Receiving detecting unit, 172, 233, 383, 432... Receiving combining unit, 173, 234, 384, 433... Comparing unit, 174, 235, 385, 434... Unnecessary Scattered wave removal/dielectric constant calculation unit, 175, 236, 386, 435... Calibration/reception signal reprocessing unit, 211, 361... Transmission control unit, 213, 363... Antenna position control unit, 232, 382... Reception information recording unit , A1-1, Aa-1... Transmitting antenna, A1-2, Aa-2... Receiving antenna

Claims (2)

A measurement method using an underground radar,
A first step of radiating the electromagnetic wave of the underground radar toward the ground from a transmitting antenna arranged on the ground;
A second step of receiving the reflected wave of the electromagnetic wave with a receiving antenna arranged on the ground on a circumference centered on the position of the transmitting antenna;
A third step of recording received signals indicating the intensities of the reflected waves respectively received by the receiving antennas in a plurality of arrangements in which the positions of the receiving antennas are different,
A fourth step of obtaining information about the scatterers present in the ground by performing a mutual comparison on the received signals recorded in the third step;
Only including,
In the fourth step, a measurement is performed to determine whether or not the received signal recorded in the third step includes a received signal that satisfies an abnormality determination condition for determining that reflection by an object is different. Method. A transmitting antenna that is placed on the ground and emits electromagnetic waves toward the ground,
A receiving antenna arranged on the ground on the circumference of the circumference of the position of the transmitting antenna, and receiving a reflected wave of the electromagnetic wave,
A reception information recording unit that records reception signals indicating the intensities of the reflected waves respectively received by the reception antennas in a plurality of positions where the reception antennas have different positions,
A comparison unit that obtains information about the scatterer existing in the ground by performing a mutual comparison of the reception signals recorded in the reception information recording unit,
Equipped with
The comparing unit determines whether or not the received signal recorded in the received information recording unit includes a received signal that satisfies an abnormality determination condition for determining that reflection by an object is different. apparatus.

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