JPH0436688A - Underground installation detector - Google Patents

Abstract

PURPOSE:To detect even a nonmetallic material to be retrieved with high accuracy by converting output from a transmitter to an electromagnetic wave by an antenna for transmission in the material to be retrieved, and tansmitting it to an antenna for transmission installed on the ground. CONSTITUTION:A pulse signal with narrow width outputted from the transmitter 2 is sent to a small antenna 41 for transmission inserted from the manhole 50 of a road to the PVC tube 40 of the material to be retrieved via a fork signal transmission cable 31, and it is converted to the electromagnetic wave, and is directly transmitted toward a ground level 10. The signal is propagated under the ground 20, and is received with an antenna 5 for reception on the ground level 10. A reception signal is sent to a receiver 6 via the cable 31. When measurement is performed, the antenna 5 is moved and scanned in a direction of arrow head X, and such retrieval operation is repeated at every travel interval. Those signals are displayed 7 from the receiver 6 via a controller 8, and the installing position of the PVC tube 40 can be measured. In such a way, the material to be measured can be detected with high accuracy even when it is the nonmetallic one.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an underground object detection device that uses electromagnetic waves to detect the buried position of an object buried underground.

(Prior Art) As a conventional underground object detection device, there is one shown in FIG. 3, for example. In the figure, 1 is the underground radar body (detection device body) installed on the ground, and transmitter 2
, a receiver 6, a display 7, and a controller 8 for controlling these devices. 4.5 are a transmitting antenna and a receiving antenna installed on the ground, and the transmitting antenna 4 is connected to the transmitter 2 and the receiving antenna 5 is connected to the receiver 6 via the signal transmission cable 3. has been done.

A narrow pulse signal with a half-width number n5ec outputted from the transmitter 2 is sent to the transmitting antenna 4 via the signal transmission cable 3, where it is converted into an electromagnetic wave. The converted electromagnetic waves enter the underground 20 from the earth's surface 10, propagate through the underground 20, and if there is a buried pipe 30, which is an object to be detected, it is reflected there. The buried pipe 30 is a metal pipe, hereinafter referred to as a PS pipe.

Further, 40 is a non-metallic pipe, which will hereinafter be referred to as a PvC pipe. The reflected electromagnetic waves are received by the receiving antenna 5 and sent to the receiver 6 via the signal transmission cable 3. During actual measurement, the transmitting antenna 4 and the receiving antenna 5 are moved and scanned in the direction of the arrow X in FIG. 3, for example, by 2 cm.
The above detection operation is repeated at every movement interval. The plurality of received signals thus obtained are temporarily stored in the receiver 6, and after scanning is completed, they are color-modulated according to the amplitude under the control of the controller 8, and are displayed two-dimensionally on the display 7. By displaying, a ground plane pattern can be obtained.

FIG. 4 shows a received signal received when the receiving antenna 5 is located directly above the PS tube 30. The horizontal axis is time and the vertical axis is amplitude. The reflected wave 101 is a signal reflected by the ground surface 10. Hereinafter, this will be referred to as a ground surface reflected wave. The reflected wave 102 is a reflected wave from the PS tube 30. FIG. 5 shows an example of a ground plane pattern obtained when the transmitting and receiving antenna 4.5 is moved and scanned in the direction of the arrow X in FIG. In this figure, time positions corresponding to amplitudes of the amplitude level A1 or higher or -A1 or lower in the received signal shown in FIG. 4 are represented by a diagonal line pattern. pattern 201
is a pattern corresponding to the ground surface reflected wave 101, pattern 2
02 is the cross-sectional pattern of the PS tube 30, and pattern 203 is the P
It is a cross-sectional pattern of the vC tube 40. Since the electromagnetic waves transmitted from the transmitting antenna 4 spread at a certain angle, the obtained images of the buried pipes 30 and 40 have a hyperbolic shape. Therefore, the buried position of the buried pipe 30, 40 corresponds to the vertex of the hyperbola.

Although the horizontal position of the vertex can be read directly from the image, the burial depth is given as the electromagnetic wave propagation time T. Therefore, the burial depth L (m) is determined by the propagation time TI
It is calculated from (s e c).

L-v 11Tl/2”
41) Here, ■ is the underground propagation velocity of electromagnetic waves (m/5ec).

Thereby, the buried position of the buried pipe 30, 40 is detected.

(Problems to be Solved by the Invention) In the conventional underground buried object detection device, electromagnetic waves from the transmitting antenna 4 installed on the ground are reflected very well from metal buried objects, but when it is reflected from non-metal buried objects, It is difficult to reflect against. Therefore, as shown in FIG.
02 can be seen very clearly, but the cross-sectional pattern 203 due to the reflected wave from the PvC pipe 40 is difficult to see. As described above, the conventional technology has a problem in that it is difficult to detect the buried position of a buried pipe that is not made of metal.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems, and to provide an underground buried object detection device that can accurately detect the buried position of a non-metallic object. Our goal is to provide the following.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention is an underground object detection device that uses electromagnetic waves to detect the buried position of objects to be detected buried underground. , a transmitter installed on the ground, a transmitting antenna installed in the object to be detected and transmitting electromagnetic waves by the output from the transmitter transmitted via a signal transmission cable, and a transmitting antenna installed on the ground for transmitting electromagnetic waves. The gist of the present invention is to include a reception antenna that receives electromagnetic waves transmitted from the antenna, and a detection section that detects the buried position of the object based on the reception signal received by the reception antenna.

(Function) In the above configuration, the output from the transmitter is sent to the transmitting antenna installed inside the detected object via the signal transmission cable and converted into electromagnetic waves. This electromagnetic wave directly transmitted from the object to be detected is received by a receiving antenna installed on the ground, and the detection unit performs appropriate processing on the received signal to determine if the object to be detected is non-metallic. Even if there is, the buried position can be detected with high accuracy.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

In addition, in FIG. 1, the same or equivalent components as those in FIG. 3 are indicated by the same reference numerals as above,
Omit duplicate explanations.

First, to explain the configuration of the underground buried object detection device, a small transmitting antenna 41 detects PvV from inside a manhole 50 on a road.
C pipe 4 is inserted into pipe 0. A small transmitting antenna 41 is connected to the transmitter 2 and a receiving antenna 5 is connected to the receiver 6 via the bifurcated signal cable 31.

Since the underground buried object detection device of this embodiment is configured as described above, the half-width number n5e output from the transmitter 2
The narrow pulse signal c is sent to the small transmitting antenna 41 via the bifurcated signal transmission cable 31, where it is converted into an electromagnetic wave. The converted electromagnetic wave is detected by P, which is the object to be detected.
The signal is transmitted directly toward the ground surface 10 on the 0 side of the vC pipe 4, propagates underground 20, and is received by the receiving antenna 5 installed on the ground surface 10. The received signal is then sent to the receiver 6 via the bifurcated signal transmission cable 31.

During actual measurement, the receiving antenna 5 is moved and scanned in the direction of the arrow X in FIG. 1, and the above-mentioned detection operation is repeated at every moving interval, for example, every 2 cm.

The plurality of received signals thus obtained are temporarily stored in the receiver 6, and after scanning is completed, they are color-modulated according to their amplitude under the control of the controller 8, and are displayed two-dimensionally on the display 7. By displaying them side by side, a ground plane pattern can be obtained. Due to this ground plane pattern etc., the PvC pipe 40
The horizontal position and depth of the buried object are measured. The receiver 6 and the display 7 constitute a detection section that detects the buried position of the object to be detected.

FIG. 2 shows the pvc pipe 40 obtained by the above-mentioned detection operation.
It shows the ground plane pattern. The horizontal axis is the antenna movement distance, and the vertical axis is time. In this embodiment, the fifth
The cross-sectional pattern due to the ground surface reflected wave 101 shown in the figure does not appear. The cross-sectional pattern 204 of the PVC pipe 40 is obtained based on a received signal directly received by the receiving antenna 5 of an electromagnetic wave transmitted from a small transmitting antenna 41 inserted into the PVC pipe 4 . Cross-sectional pattern 204
has a hyperbolic shape due to the difference in propagation time due to the difference in distance between the small transmitting antenna 41 and the receiving antenna 5. Therefore, the apex position of the cross-sectional pattern 204 corresponds to the buried position of the pvc pipe 40, which is the object to be detected. The buried position in the horizontal direction can be directly determined from the image shown in FIG. 2, but the buried depth L (m) can be determined from the propagation time T2 (sec) at the vertex position of the cross-sectional pattern 204 using the following equation.

L-v-t2...
(2) In this way, the object to be detected is the PvC pipe 40 made of nonmetallic material.
etc., the buried position can be detected with high accuracy.

In this embodiment, the receiving antenna 5 installed on the ground surface can be the same as the receiving antenna in the prior art. Therefore, by replacing the bifurcated signal transmission cable 31 with the conventional signal transmission cable 3 and installing a transmission antenna on the ground surface, it is possible to measure the buried position of the object to be detected using the conventional technique. Therefore, if the detection results are also determined, the measurement accuracy can be further improved.

[Effects of the Invention] As explained above, according to the present invention, a transmitting antenna is installed inside an object to be detected, and the electromagnetic waves directly transmitted from the object to be detected are received by the receiving antenna installed on the ground. Since the detection unit detects the buried position of the object to be detected based on the received signal, even if the object to be detected is non-metallic, the buried position can be detected with high accuracy. be able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the underground buried object detection device according to the present invention, FIG. 2 is a diagram showing an example of the ground plane pattern displayed on the display of the above embodiment, and FIGS. Figure 5 shows a conventional underground buried object detection device, Figure 3 is a configuration diagram, Figure 4 is a signal waveform diagram showing the received signal received by the receiving antenna, and Figure 5 is the signal displayed on the display. FIG. 3 is a diagram showing a ground plane pattern. 2: Transmitter, 5: Receiving antenna, : Receiver, : Display unit that together with the receiver constitutes the detection section, 1: Bifurcated signal transmission cable, Q: PS pipe (object to be detected), Q: PVC pipe (object to be detected) Detected object), 1: Small transmitting antenna. Agent Patent Attorney Hidekazu Miyoshi Figure 3 Figure 211! l[ 4 hours (nsecl 4th W-1 antenna moving distance trend (ml 51st!!ll

Claims (1)

[Claims] This is an underground object detection device that uses electromagnetic waves to detect the buried position of an object buried underground, and transmits signals via a transmitter installed above ground and a signal transmission cable installed inside the object. a transmitting antenna that transmits electromagnetic waves by the output from the transmitter, a receiving antenna that is installed on the ground and receives the electromagnetic waves transmitted from the transmitting antenna, and a receiving signal received by the receiving antenna. An underground buried object detection device, comprising: a detection unit that detects a buried position of the detected object based on the detection unit.