JPH0384489A - Buried body detecting device - Google Patents

Abstract

PURPOSE:To prevent unnecessary data from being inputted by putting a pulse generating circuit in an operation stop state when it is decided that reception intensity found from the received signal of a reflected wave is less than specific permissible reception intensity. CONSTITUTION:The buried body detecting device sets the reception intensity corresponding to the 0.24 intensity rate of the reflected wave in, for example, a comparator 15 as the permissible reception intensity. Then when the intensity rate WRP of the maximum amplitude intensity in the range of the arrival time Tc+ or -DELTAT of the received reflected wave is less than 0.24, an electromagnetic wave transmission stop switch 16 holds an initialized recovery state and the transmission of an electromagnetic wave is carried on. When the intensity rate WRP of the maximum amplitude intensity in the range of the arrival time Tc+ or -DELTAT of the received reflected wave is equal to or less than 0.24, the electromagnetic wave transmission stop switch 16 operates to disconnect a pulse generating circuit 11, stopping the transmission of the electromagnetic wave. Consequently, unnecessary data is prevented from being inputted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a buried object detection device that uses electromagnetic wave method to search for objects buried underground or in structures, and in particular, it relates to a buried object detection device that uses an electromagnetic wave method to search for objects buried underground or in structures. The present invention relates to a buried object detection device that prevents the detection of buried objects.

[Prior Art] FIG. 7 shows a configuration diagram of a conventional buried object detection device using the electromagnetic wave method.

1 is a main unit, 2 is an antenna, and 3 is a signal cable.

The main device section 1 includes a power supply section 4 that supplies electric power, a signal control section 5 that sets the reception time of the reflected signal, conditions of the reception voltage, etc., a signal processing section 6 that performs arithmetic processing of the reflected signal, and a ground surface or TI A storage unit 7 that stores reflected signals due to reflected waves from the structure surface and buried objects, an image display unit 8 that displays arithmetic processing results, a signal output unit 9 that outputs display information of the image display unit 8 to the outside of the device, and It is composed of a control section 10 that controls these component devices.

The antenna section 2 includes a pulse generating circuit 11 that generates electric pulses, and a transmitting antenna 1 that transmits electromagnetic waves generated by the electric pulses sent from the pulse generating circuit 11 underground.
2. Receiving antenna 13 that captures the reflected waves that have reflected from the ground surface, the surface of structures, and buried objects and returned again, and converts the reflected waves captured by the receiving antenna 13 into reflected signals, determines the reception strength, and outputs the signals. The receiver circuit 14 includes a receiving circuit 14. Further, 20 is a measurement surface on which the transmitting antenna 12 and the receiving antenna 13 are arranged, and the measurement surface 20 and the ground surface 2
It is arranged to face 1.

Note that the ground surface 21 can also be referred to as a structure surface, and hereinafter, when the ground surface 21 is simply referred to as the structure surface, it also includes the meaning of the structure surface.

The signal cable 3 serves as a transmission path for transmitting the amount of input and output signals between the main device section 1 and the antenna section 2 .

FIG. 8 shows an explanatory diagram when searching for underground objects using the conventional buried object detection device configured as described above.

Operator A prepares in advance to set the measurement surface 20 of the antenna section 2 at the planned exploration point so as to face the ground surface 21.

After that, the worker A turns on the power supply section 4 in the main device section 1, sets the conditions such as the reception time and reception voltage of the received signal according to the exploration in the signal control section 5, and then By scanning 2,
Exploring buried objects underground or in structures.

The procedure of the above-mentioned operation will be explained along the flowchart shown in FIG.

That is, first, turn on the power of the main unit, and then proceed to step 101.
'), an electric pulse is sent from the pulse generating circuit 11 to the transmitting antenna 12 (step 102), and an electromagnetic wave is sent from the sending antenna 12 (step 103). The reflected wave is reflected back to the receiving antenna and received (step 104), and the reception intensity of the reflected wave is measured by the receiving circuit 14 to detect the presence or absence of a buried object (step 104).
Steps 105.106).

Note that this buried object detection device has a structure in which electromagnetic waves are intermittently emitted from the transmitting antenna 12 when the device is powered on.

[Problem to be solved by the invention] In the conventional buried object detection device described above, the measurement surface 20
is facing the ground surface 21, the leakage electric field strength due to the electromagnetic waves emitted from the transmitting antenna 12 is small, so
The influence on electronic devices such as communication devices existing around the antenna section 2 is negligible.

However, if you lift the antenna part 2 to move it, or tilt the antenna part 2 for some reason,
If the device falls over, the strength of the leakage electric field due to the electromagnetic waves emitted from the transmitting antenna 12 becomes large, which poses a problem in that there is concern that it may affect nearby electronic devices such as communication devices.

This invention solves the above-mentioned conventional problems,
When surveying, the measurement surface 20 of the antenna section 2 is on the ground surface 21.
The purpose is to transmit electromagnetic waves only when facing the earth surface 21, and to stop transmitting electromagnetic waves when the measurement surface 20 is lifted up without facing the ground surface 21 due to tilting or falling of the antenna part 2.

[Means to solve the problem] The buried object detection device of this invention has the following means.

(a) Comparison means for comparing the received intensity of reflected waves from the ground surface or the surface of a structure with a predetermined standard received intensity; (b) When the comparing means determines that the received intensity is below a predetermined allowable received intensity; (c) Electromagnetic wave stop canceling means for manually releasing the stopped state of the pulse generating circuit when the pulse generating circuit is in a stopped state.

[Operation] When the comparison means determines that the reception strength obtained from the reception signal of the reflected wave from the ground surface or the surface of a structure is less than the predetermined permissible reception strength, the pulse generation circuit is stopped by the electromagnetic wave stop means. state, the transmission of electromagnetic waves from the transmitting antenna is stopped. Therefore, it is possible to prevent unnecessary electromagnetic waves from being transmitted when the angle of inclination between the measurement surface and the surface of the ground or structure becomes larger than a predetermined angle.

[Example] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the buried object detection device of the present invention, and the same reference numerals as in FIG. 7 indicate the same or corresponding parts, and the explanation thereof will be omitted.

In the antenna unit 2, a reference numeral 15 compares the intensity of the electromagnetic wave sent out from the transmitting antenna 12, reflected by the underground object 22, and returned to the ground surface with the reflected wave returned from the ground surface 21. It is a comparator. 16 is an electromagnetic wave sending stop switch that stops sending out electromagnetic waves from the pulse generating circuit 11 according to the result of the comparator 15, and 17 is an electromagnetic wave sending stop switch that cancels the electromagnetic wave sending stop state of the pulse generating circuit 11 and starts sending out electromagnetic waves from the pulse generating circuit 11 again. This is a manually operated electromagnetic wave transmission stop reset switch that starts the process. In addition, similarly to the buried object detection device shown in FIG.
0 is arranged so as to face the ground surface 21.

Next, the operation of the electromagnetic wave transmission stop switch 16 will be explained.

FIG. 2 shows that the electromagnetic waves transmitted from the transmitting antenna 12 are reflected by the ground surface 21 and the buried object 22, and the receiving antenna 13
It is a principle diagram showing the situation captured by. In FIG. 2, the solid line is the orthogonal path of the electromagnetic waves reflected by the ground surface 21, and the broken line is the orthogonal path of the electromagnetic waves reflected by the buried object 22. L
is the ground surface 21, the transmitting antenna 12 and the receiving antenna 1
3, L' is the distance between the buried object 22 and the transmitting antenna 12 and the receiving antenna 13, Ll is the distance between the transmitting antenna 12 and the receiving antenna 13 at the distance L',
L2' is the distance between the ground surface 21 and the buried object 22 at distance L'.

Further, the arrival time Ts of the electromagnetic waves reflected by the ground surface 21 and the arrival time T' of the electromagnetic waves reflected by the buried object 22 are expressed as follows.

Ts = 2 L/V (1)
T2 = 2 L2'/V' = 2 (L' - Lt')/V' ζ2 (L' - L)/V' (2) (However,
L volume L1'') T'''Ts +T2 = (2L/V) + (2(t,'-L)/V') (3) However, V Propagation speed of electromagnetic waves in the middle V': underground or Propagation speed T2 of electromagnetic waves in the medium in the structure: Of the electromagnetic waves reflected by the buried object 22, the propagation time in the ground or the structure, that is, the position of the reflected wave from the ground surface 21 in the time domain. I can do it. The comparator 15 compares the maximum amplitude intensities in a range of T±ΔT using an arbitrary time T as a reference. In addition, since the reflected wave from the buried object 22 appears at time T', as described in Japanese Patent Application No. 62254738, the obtained reflected wave is converted into a frequency domain, and the frequency domain obtained by the conversion is Buried objects can be detected and identified using their characteristics.

FIG. 3 shows that in the buried object detection device of the present invention, when the measurement surface 20 of the antenna section 2 faces the ground surface 21, the reflected waves of the electromagnetic waves sent out from the transmitting antenna 2 are received by the receiving antenna 13. The reflected wave WR from the buried object 22 clearly appears at the point at time 0 T' in the waveform diagram showing the waveform at that time.

Here, the waveform of the reflected wave shown in FIG. 3 will be explained in detail.

When the pulse generation circuit 11 generates a pulse waveform of time @TA, the transmitting antenna 12 sends out one cycle of a SIN wave-like electromagnetic wave with a period of 2TA.
Let TB (Ta = 2TA) be the period of one cycle of the electromagnetic wave sent out from this transmitting antenna (2).

In Fig. 3, ■ waveform of cycle (time O to TB)
is created by superimposing the following two types of components, and this is called a waveform due to direct coupling.

■Direct coupling: Components due to electromagnetic waves that directly reach the receiving antenna from the transmitting antenna. ■Surface reflection: Components due to electromagnetic waves reflected from the ground surface or the surface of a structure.

Next, the waveform of the second cycle (time T8 to 2TB>) includes, in addition to the ringing component of the waveform of the first cycle, reflection at the surface layer of the underground or structure. It is created by the contribution of components from electromagnetic waves reflected at relatively shallow depths.

Note that Tc is the time domain of the second cycle (Ts ~ 2Ts)
The reception strength corresponding to an arbitrary time position, IC is T, is Δ
T is a predetermined time less than or equal to the pulse width T^. However, Tc
±ΔT is within the time domain of the second cycle.

FIG. 4 shows the result when the receiving antenna 13 receives the reflected waves of the electromagnetic waves transmitted from the transmitting antenna 12 when the measurement surface 20 of the antenna section 2 is not facing the ground surface 21 but is floating above the ground surface 21. FIG. 3 is a waveform diagram showing waveforms. The measurement surface 20 is not facing the ground surface 21 and is
1, the electromagnetic waves sent out from the transmitting antenna 12 do not sufficiently enter the ground or structures, so unlike the case in Fig. 3, reflected waves from the buried object 22 do not appear. The same symbols as in Figure 3 indicate corresponding parts.

In FIG. 4, compared to FIG. 3, it can be seen that the amplitude of the waveform in the second cycle has significantly decreased, and the reception intensity IC at the same time position Tc has also decreased. This is because the measurement surface 20 of the antenna section 2 is not opposed to the ground surface 21 but is inclined, so that the electromagnetic wave components reflected underground or on the surface of the structure are reduced.

Therefore, the reception intensity I
. When is extremely small, it can be determined that the measurement surface 20 of the antenna section 2 is inclined with respect to the ground surface 21.

Moreover, FIG. 5(a) is a characteristic diagram showing the relationship between the inclination angle θ formed by the measurement surface 20 of the antenna part 2 and the ground surface 2, and the intensity ratio of the reflected waves at that time, and the horizontal axis The angle of inclination θ is plotted on the graph, and the intensity ratio k is plotted on the vertical axis. However, the intensity ratio is at an inclination angle of O°
In this case, it is the reception strength at a predetermined time position, that is, the ratio of the reception strength when the reference reception strength is set to 1.

FIG. 5(b) shows the inclination angle θ that the measurement surface 20 makes with the ground surface 21.
FIG.

When the measurement surface 20 of the antenna section 2 faces the ground surface 21, that is, when the inclination angle θ is Oo, the intensity ratio of the reflected waves is 1, and when the inclination angle is 3°, it is 0.24, When the inclination angle θ is 90'', it is 0.13.

It can be seen that the intensity ratio of reflected waves tends to decrease as the inclination angle θ increases, and in particular, the intensity ratio decreases rapidly when the inclination angle θ is in the range of 3° from Oo.

Therefore, using this relationship, for example, in FIG. When the intensity ratio WRP of the maximum amplitude intensity in the range of ΔT is 0.24<WRP, the electromagnetic wave transmission stop switch 16 maintains the initial setting recovery state, keeps the pulse generation circuit 11 in the connected state, and transmits the electromagnetic wave. to continue.

On the other hand, the arrival time T of the received reflected waves. When the intensity ratio WRp of the maximum amplitude intensity in the range of ±ΔT is 0.24≧WRP, the electromagnetic wave transmission stop switch 16 is activated to disconnect the pulse generation circuit 11 and stop the transmission of electromagnetic waves.

In the above-described operation, the received strengths are compared by comparing the intensity ratios determined from the received strengths, and the operation of the pulse generation circuit 11 is controlled based on this result. However, it goes without saying that the same result as described above can be obtained even if the received intensity values themselves are compared instead of comparing the intensity ratios.

Next, the operation of the buried object detection device of the present invention will be explained according to the flowchart shown in FIG. 6. In FIG. 6, the broken line portion indicates a portion corresponding to the operation added to FIG. 9, which shows the conventional example. .

First, turn on the power of the main unit (Step 201), and the electromagnetic wave transmission stop switch becomes connected (Step 202).
> , the pulse generation circuit 11 starts up (step 20
3). At this time, as explained in FIG. 5, the antenna section 2 is tilted in advance, and the reception strength at the point where the reception strength of the reflected wave suddenly changes is defined as the reference reception strength. The electromagnetic waves excited by the pulse generating circuit 11 are sent underground or into structures from the transmitting antenna 12 (step 204),
The reflected waves from the ground surface 21 and the buried object 22 are captured by the receiving antenna 13 (step 205), and the reception strength is measured by the receiving circuit 14 (step 206). It is determined whether the received intensity of the reflected wave is greater than a preset reference received intensity (step 207).

If the comparator 15 determines that the received strength of the reflected wave is below the reference received strength (Yes), the electromagnetic wave transmission stop switch 16 operates to disconnect the pulse generation circuit 11 and stop transmitting the electromagnetic waves (step 209).

To cancel this electromagnetic wave transmission stop state, manually operate the electromagnetic wave transmission stop reset switch 17 to restore the electromagnetic wave transmission stop switch 16 to its initial state (step 2
10〉.

On the other hand, if the comparator 15 determines that the received intensity of the reflected wave is greater than the reference received intensity (NO), the electromagnetic wave transmission stop switch 16 maintains the initial setting and the restored state.
The pulse generation circuit 11 is connected, and the electromagnetic waves are continued to be transmitted and measurements are performed (step 208').
.

As is clear from the above results, for some reason the transmitting antenna 12 and receiving antenna 13 placed on the surface facing the ground or the surface of a structure did not face the ground or the surface of the structure during exploration, but instead faced the space. Sometimes, the comparator 15 and the electromagnetic wave transmission stop switch 16 automatically stop the transmission of electromagnetic waves instantly, so that even if the operator makes a mistake, the electromagnetic waves will not be transmitted into the space, and electronic equipment such as communication devices around the exploration site will be protected. The impact on is eliminated.

[Effects of the Invention] As explained above, according to the buried object detection device of the present invention, the reception intensity determined from the reception signal of the reflected wave from the ground surface or the surface of the structure is less than or equal to the predetermined allowable reception intensity. When it is determined by the comparing means, the pulse generating circuit is brought into a stopped state by the electromagnetic wave stopping means, so that the transmission of electromagnetic waves from the transmitting antenna is stopped. Therefore, it is possible to prevent unnecessary electromagnetic waves from being transmitted when the angle of inclination between the meter side and the surface of the ground or structure becomes larger than a predetermined angle.

As a result, the influence on electronic devices such as communication devices around the exploration site is eliminated, ensuring safety. In addition, since electromagnetic waves are not transmitted when the measuring side of the antenna section is lifted from the ground surface or the surface of a structure, unnecessary data is prevented from being captured, allowing for efficient buried object exploration work. .

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the electromagnetic wave transmission stop device for detecting buried objects of this invention, Fig. 2 is a principle diagram of buried object detection using the electromagnetic wave method, and Fig. 3 is a diagram showing the principle of buried object detection using the electromagnetic wave method. A waveform diagram showing reflected waves from underground when the transmitting antenna and receiving antenna received by the device are opposed to the ground surface 21. Figure 4 shows the transmitting antenna and the reflected wave received by the buried object detection device using the electromagnetic wave method. Waveform diagram of reflected waves from underground when the receiving antenna rises from the ground surface 21, 5th
Figure (a) is a relationship diagram between the inclination angle θ that the meter side makes with the ground surface or the surface of a structure and the intensity ratio of the reflected waves at that time.
b) is the inclination angle θ that the measurement surface makes with the ground surface or the surface of the structure
FIG. 6 is a flowchart showing the operating procedure of the buried object detection device of the present invention, FIG. 7 is a schematic diagram of a measurement system for detecting buried objects using the conventional electromagnetic wave method, and FIG. FIG. 9 is a flowchart showing the operating procedure of the conventional buried object detection apparatus. DESCRIPTION OF SYMBOLS 1...Main device part, 2...Antenna part, 3...Signal cable, 4...Power supply part, 5...Signal control part, 6
... Signal processing section, 7... Storage section, 8... Image display section, 9... Signal output section, 10... Control section, 11...
・Pulse generation circuit, 12... Transmission antenna, 13-・
- Receiving antenna, 14... Receiving circuit, 15... Comparator, 16... Electromagnetic wave transmission stop switch, 17... Electromagnetic wave transmission stop reset switch.

Claims (1)

[Claims] A pulse generating circuit that generates electric pulses, a transmitting antenna that transmits electromagnetic waves using the electric pulses, and a transmission antenna that transmits electromagnetic waves when the electromagnetic waves hit the ground surface or the surface of a structure and objects buried underground or in the structure and return. A buried object detection device includes a receiving antenna for receiving reflected waves, a receiving circuit for processing a received signal from the receiving antenna to obtain reception strength, and a means for analyzing the received signal to detect the presence or absence of a buried object. a comparison means for comparing the reception intensity of the reflected wave from the ground surface or the surface of a structure with a predetermined allowable reception intensity; What is claimed is: 1. A buried object detection device comprising: electromagnetic wave stopping means for bringing a pulse generating circuit into a stopped state; and electromagnetic wave stopping canceling means for manually releasing the stopped state of the pulse generating circuit.