JPS59794B2 - Buried object detection device with rotating antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a buried object detection device having a rotating antenna.

A conventional device of this type is shown in FIG.

In the figure, 1 is an oscillator, 2 is a transmitting antenna, 3 and 9 are receiving antennas, 4 and 10 are detectors with opposite polarities,
5 is an indicator, 6 is a foreign object or a buried object, 7 is a homogeneous object, 8 is a container for storing and fixing the transmitting antenna 2 and receiving antennas 3 and 9, and 11 is a differential comparator.

Next, the operation of the above conventional device will be explained.

Radio waves generated by an oscillator 1 are transmitted from a transmitting antenna 2 and received by receiving antennas 3 and 9.

The radio waves received by the receiving antennas 3 and 9 are the radio waves reflected from the homogeneous object 7 and the radio waves directly received from the transmitting antenna 2 if there is no buried object 6.

At this time, the intensities of the radio waves of the receiving antennas 3 and 9 change by the same amount at the same time even if the distance changes equally.

Radio waves received by receiving antennas 3 and 9 are converted into DC signals with different polarities and the same magnitude by detectors 4 and 10, which have opposite polarities, and these two signals are added to a differential comparator 11, which The output will always be 0 if there is no buried object 6.

Next, when the container 8 is moved in the direction of the arrow (■), if there is a buried object 6, the reception antenna 3 is affected, causing a change in the indicator 5, which has been in an equilibrium state until now.

Further, when the transmitting antenna 2 is near the buried object 6, the receiving antennas 3 and 9 are again in an equilibrium state, and the indicator 5 becomes 0.

Furthermore, where the buried object 6 approaches the receiving antenna 9, it becomes unbalanced, causing a change in the indicator 5.

Therefore, the presence of the buried object 6 can be known from the change in the indicator 5.

The conventional buried object detection device described above is configured as described above, so even if the distance between the container 8 and the homogeneous object 7 changes, if the buried object 6 is not present, the indicator 5 will indicate O. When the container 8 and the homogeneous object 7 are no longer parallel, the propagation length of the radio waves emitted from the transmitting antenna 2, reflected by the homogeneous object 7, and reaching the receiving antennas 3 and 9 becomes different, resulting in a difference in the strength of the radio waves. Due to the imbalance, the indicator 5 changes even though there is no buried object 6, which makes it appear as if there is a buried object 6.
This could be mistaken as indicating the existence of

Therefore, there was a drawback that the effect could not be obtained unless the container 8 was moved while always being kept parallel to the homogeneous object 7.

Furthermore, if the receiving system is arranged symmetrically on both sides of the transmitting system using a large number of antennas, and the detection polarities of the signals obtained from each of these systems are made to be opposite to each other, mutual interference will occur between the large number of antennas. There were disadvantages such as difficulty in achieving the objectives.

The present invention was made in order to eliminate the drawbacks of the conventional device as described above, and includes a signal generating section consisting of at least an oscillator, one transmitting antenna for transmitting a signal from the signal generating section, and the above-mentioned one transmitting antenna. an antenna section consisting of two receiving antennas paired with a transmitting antenna; an antenna rotation drive section consisting of an antenna rotation drive device for rotating the antenna section; Two circuits for detection and amplification, two band-elimination filter circuits for blocking only frequency components corresponding to the rotation period of the antenna section rotated by the antenna rotation drive device, and the two band-elimination filter circuits. A signal processing section consisting of a differential circuit that takes a difference in output and a rectifier circuit that takes out only a positive signal component, and a display section consisting of at least one of an indicator and a receiver,
A buried object detection device with a rotating antenna that can detect signals only from buried objects by removing the signal generated when the container that houses and fixes the antenna section is no longer parallel to the surface to be detected. is intended to provide.

An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 2, a is a signal generation section, b is an antenna section, and C
is the antenna rotation drive unit, d is the signal processing unit, e is the display unit,
20 is an oscillator, 21 is an attenuator, 22o is a transmitting antenna,
22a and 22b are receiving antennas, 23 is an antenna rotation drive device, 24a and 24b are detection/amplification circuits, 25a and 2
5b is a band rejection filter circuit, 26 is a differential circuit, 27 is a rectifier circuit, 28a is an indicator conversion circuit, -28b is an indicator, 2
9a is an acoustic conversion circuit, and 29b is a receiver.

Next, the operation of the above embodiment will be explained.

The radio waves oscillated by the oscillator 20 are attenuated by the attenuator 21, or are sent to the transmitting antenna 22o and emitted without attenuating the attenuator 21.

Radio waves emitted from this transmitting antenna 22o are received by receiving antennas 22a and 22b, and sent to detection/amplification circuits 24a and 24b, respectively.

In the detection/amplification circuits 24a and 24b, the signal is converted into a combined signal of the DC and AC components or a signal of only the DC component, amplified, and sent to the band-elimination filter circuits 25a and 25b.

Since the band rejection filter circuits 25a and 25b act to block only the frequency component corresponding to one rotation of the container A that houses and fixes the antenna part 6 rotated by the antenna rotation driving device 23, the detection/amplification circuits 24a and 24b
In the signal outputted from the band stop filter circuits 25a and 25b, only the frequency component caused by the rotation of the container A is blocked and sent to the differential circuit 26.

Here, the transmitting antenna 22o, the receiving antenna 22a and 2
The operation of the antenna rotation driving section C consisting of the antenna section 6 constituted by the antenna section 2b and the antenna rotation driving device 23 will be explained.

FIG. 3 shows a transmitting antenna 22o and a receiving antenna 22a.
2b is a plan view showing the arrangement of the parts 2b.

In the embodiment shown in FIG. 3, receiving antennas 22a and 22b
are arranged in a straight line at equal intervals on both sides of the transmitting antenna 22o, and the transmitting antenna 22o and the receiving antenna 2
The container A that stores and fixes the antenna part 6 composed of the receiving antennas 2a and 22b has a middle point 30 between the receiving antennas 22a and 22b,
That is, the transmitting antenna 22o is rotated in the direction of arrow W by the antenna rotation drive device 23.

Figure 4 shows the transmitting antenna 22° and the receiving antennas 22a and 2.
A case is shown in which the container A that houses and fixes the antenna section 6 constituted by the antenna section 2b has stopped rotating and is parallel to the ground 40 as the surface to be detected.

In this case, when container A is horizontally rotated in the direction of arrow W by antenna rotation drive device 23, the positions of receiving antennas 22a and 22b are alternately switched.

Next, the case of detecting buried objects is shown in Figures 4, 5, and 6.
This will be explained using figures.

In FIG. 4, container A is at a distance from the ground 40.

The transmitting antenna 22o
The strength of the radio waves propagated from → ground 40 → receiving antennas 22a and 22b is the same, and the strength of the radio waves does not change even if container A is rotated in the direction of arrow W by antenna rotation drive device 23.

Therefore, the signal output from the detection/amplification circuit 24a becomes a DC component 60a shown in FIG. 5, and similarly, the signal output from the detection/amplification circuit 24b becomes a DC component 61a shown in FIG.

These signals are transmitted to bandpass IL filter circuits 25a and 2, respectively.
Sent to 5b.

Since the band-elimination filter circuits 25a and 25b are designed to block only the frequency component corresponding to one rotation of the container A, the DC components 60a and 61a, which are the respective outputs of the detection/amplification circuits 24a and 24b, are band-eliminated. Filter circuits 25a and 2
5b, and each is sent to the differential circuit 26.

The differential circuit 26 is configured to take the difference between the output signals of the band rejection filter circuits 25a and 25b.

Therefore, since the DC components 60a and 61a, which are the outputs of the band-elimination filter circuits 25a and 25b, are the same, the output of the differential circuit 26 becomes zero.

In this case, the signal passing through the rectifier circuit 27 is zero,
Display section e does not operate.

Next, the container A moves in the X direction and the receiving antenna 22a
Or, when 22b comes near the top of the buried object 50, the container A is being rotated by the antenna rotation drive device 23, so the strength of the radio waves propagated from the transmitting antenna 22o to the ground 40 to the receiving antennas 22a and 22b increases. is buried object 5
Changes occur once per revolution of container A under the influence of o.

Therefore, the output signals of the detection/amplification circuit 24a are 62a and 62c shown in FIG. 5, and the output signals of the detection/amplification circuit 24b are 63a and 63c shown in FIG. sent to.

That is, the signals 62a and 63a are signals that are not affected by the buried object 50 while the container A is rotating, and the signals 62c and 63a are signals that are not affected by the buried object 50 while the container A is rotating.
3c is a signal generated every time the container A rotates due to the influence of the buried object 50.

At this time, the receiving antennas 22a and 22b are connected to the transmitting antenna 22. Since they are arranged symmetrically around the center, the signal 62C of the output of the detection/amplification circuit 24a and the signal 63c of the output of the detection/amplification circuit 24b are generated with a shift of half a rotation of the container A from each other. .

The outputs 62a and 62c of the detection/amplification circuit 24a and the outputs 63a and 63c of the detection/amplification circuit 24b are connected to the container A.
Since the signal has a frequency component different from the frequency component corresponding to one rotation of the signal, it passes through the band-elimination filter circuits 25a and 25b and is sent to the differential circuit 26, respectively.

In this differential circuit 26, band rejection filter circuits 25a and 25
Since the difference between the respective signals of b is taken, the outputs of the differential circuit 26 become 64c and 65c in FIG. 5, and are sent to the rectifier circuit 27.

Here, only the positive signal 64c passes through and becomes the signal 66C, and this signal 66G activates the display section e to notify the presence of the buried object 50.

Here, 64a and 66a are at zero level.

Suddenly, container A moves in the X direction and the transmitting antenna 22o
When the center of is near the top of the buried object 50, the transmitting antenna 2
The radio waves emitted from 2o are reflected from the ground 40 and the buried object 50 and reach the receiving antennas 22a and 22b, so the strength of the radio waves received by the receiving antennas 22a and 22b is higher than when there is no buried object 50. become stronger.

However, the transmitting antenna 22. Since the center of the container A is located near the top of the buried object 50, the strength of the radio waves received by the receiving antennas 22a and 22b is the same, and even if the container A is rotated by the antenna rotation drive device 23, Since the influence of the object 50 is the same, no change occurs.

Therefore, the output signal of the detection/amplification circuit 24a becomes a DC component 70a shown in FIG. 6, and the output signal of the detection/amplification circuit 24b becomes a DC component 71a shown in FIG. and 25b, and is sent to the differential circuit 26.

Since the differential circuit 26 is configured to take the difference between the outputs of the band rejection filter circuits 25a and 25b, the output of the differential circuit 26 is zero.

Therefore, since the signal sent to the rectifier circuit 27 is zero,
Its output does not activate display section e.

Furthermore, the container A moves in the X direction and the receiving antenna 2
When 2a or 22b comes near the top of the buried object 50, since the container A is being rotated by the antenna rotation drive device 23, the strength of the radio waves propagated from the transmitting antenna 22o to the ground 40 to the receiving antennas 22a and 22b increases. The height changes once per rotation of the container A due to the influence of the buried object 50.

Therefore, the output of the detection/amplification circuit 24a is 7 as shown in FIG.
2a and 72c, and the outputs of the detection/amplification circuit 24b become 73a and 73c shown in FIG.

In this way, each of the above outputs is transmitted to the band rejection filter circuit 25.
sent to a and 25b.

That is, 72a and 73a are signals that are not affected by the buried object 50 while the container A is rotating, and 72c and 73c are signals that are generated every time the container A rotates due to the influence of the buried object 50.

Since the outputs 72a and 7201 of the detection/amplification circuit 24a and the outputs 73a and 73c of the detection/amplification circuit 24a have a frequency component different from the frequency component corresponding to one rotation of the container A, the band Rejection filter circuits 25a and 2
5b and are sent to the differential circuit 26, respectively.

In this differential circuit 26, the band rejection filter circuits 25a and 2
5b, the outputs of the differential circuit 26 become 74c and 75c shown in FIG. 6, and are sent to the rectifier circuit 27.

Here, only the positive signal 74C passes through and the signal 76c
This signal 76c activates the display section e to notify the presence of the buried object 50.

Here, 74a and 76a are at zero level.

On the other hand, FIG. 7 shows the transmitting antenna 22o and the receiving antenna 22.
A case is shown in which the container A that houses and fixes the antenna section 6 composed of a and 22b has stopped rotating and is tilted with respect to the ground 40 as the surface to be detected.

In this case, when the container A is rotated in the direction of the arrow W by the antenna rotation drive device 23, the receiving antenna 22a
The positions of and 22b alternate.

Next, the case of detecting buried objects is shown in Figures 7, 8, and 9.
This will be explained using figures.

In FIG. 7, since the container A is located at an angle to the ground 40, when the container A is rotated in the direction of the arrow W by the antenna rotation drive device 23, the transmitting antenna 22o
→The ground 40→The radio waves propagated to and received by the receiving antennas 22a and 22b repeat their strength and weakness every rotation of the container A.

Therefore, the output signal of the detection/amplification circuit 24a has the DC component 80a and the AC component 80b shown in FIG. In this way, each signal is sent to band-elimination filter circuits 25a and 25b, respectively.

The band-elimination filter circuits 25a and 25b are designed to block only the frequency component corresponding to one revolution of the container A.

Therefore, out of the outputs 80a and 80b of the detection/amplification circuit 24a, the output 80b has a frequency component corresponding to one revolution of the container A, so it is blocked by the band-elimination filter circuit 25a, and only the output 80a is transmitted through the differential circuit. Sent to 26.

Further, since the output 81b of the outputs 81a and 81b of the detection/amplification circuit 24b has a frequency component corresponding to one rotation of the container A, it is blocked by the band-elimination filter circuit 25b, and only the output 81a is transmitted to the differential circuit 26. sent to.

In this differential circuit 26, band rejection filter circuits 25a and 25b
Therefore, the output of the differential circuit 26 becomes zero, the output of the rectifier circuit 27 also becomes zero, and the display section e does not operate.

Next, the container A moves in the X direction and the receiving antenna 22a
Or, when 22b comes near the top of the buried object 50, the container A is being rotated by the antenna rotation drive device 23, so the strength of the radio waves propagated from the transmitting antenna 22o to the ground 40 to the receiving antennas 22a and 22b increases. is buried object 50
Under the influence of , each change occurs once per revolution of container A.

Therefore, the output signal of the detection/amplification circuit 24a becomes a DC component 82a and alternating current components 82b and 82c shown in FIG.
Further, the output signal of the detection/amplification circuit 24b becomes a DC component 83a and an alternating current component 83b and 83c shown in FIG. 8, and is sent to band rejection filter circuits 25a and 25b, respectively.

In this band-elimination filter circuit 25a, only the frequency component 82b having a frequency component corresponding to one rotation of the container A is blocked and sent to the differential circuit 26 as 84a and 84c shown in FIG.

Similarly, in the band-elimination filter circuit 25b, only 83b is blocked, resulting in 85a and 85c shown in FIG.
sent to.

In this differential circuit 26, the band rejection filter circuits 25a and 2
5b, the output of the differential circuit 26 becomes the signals 86c and 87c shown in FIG.
This signal 88c activates the display section e to notify the presence of the buried object 50.

Here, 86a and 88a are at zero level.

Further, the container A moves in the X direction and the transmitting antenna 22o
When the center of is near the top of the buried object 50, the transmitting antenna 2
The radio waves emitted from the antenna 2o are reflected from the ground 40 and the buried object 50 and reach the receiving antennas 22a and 22b.

In this way, the strength of the radio waves received by the receiving antennas 22a and 22b becomes stronger than in the case where there is no buried object 50, and the strength repeats each time the container A rotates.

However, since the center of the transmitting antenna 22o is located near the top of the buried object 50, even if the container A is rotated by the antenna rotation drive device 23, the influence of the buried object 50 is always the same, so changes occur. do not have.

Therefore, the output signal of the detection/amplification circuit 24a has a DC component 90a and an alternating current component 90b shown in FIG.
1a and 91b, and these signals are sent to band-elimination filter circuits 25a and 25b, respectively.

Of the outputs 90a and 90b of the detection/amplification circuit 24a, 90b has a frequency component corresponding to one rotation of the container A, so it is blocked by the band-elimination filter circuit 25a, and the signal 9
Only 0a is sent to the differential circuit 26.

Similarly, out of the outputs 91a and 91b of the detection/amplification circuit 24b, 91b has a frequency component corresponding to one rotation of the container A, so it is blocked by the band-elimination filter circuit 25b, and the signal 9
Only 1a is sent to the differential circuit 26.

In this case, the magnitude of the outputs of the band-elimination filter circuits 25a and 25b are the same, so the output of the differential circuit 26 is zero,
The output of the rectifier circuit 27 also becomes zero, and the display section does not operate.

Furthermore, the container A moves in the X direction and the receiving antenna 2
When 2a or 22b comes near the top of the buried object 50, since the container A is being rotated by the antenna rotation drive device 23, the strength of the radio waves propagated from the transmitting antenna 22o to the ground 40 to the receiving antennas 22a and 22b increases. The height changes by one degree per rotation of the container A due to the influence of the buried object 50.

Therefore, the output of the detection/amplification circuit 24a is the DC component 92a and the alternating current components 92b and 92c shown in FIG. 9, and the output of the detection/amplification circuit 24b is the DC component 93a shown in FIG.
and exchanges 93b and 93c, which are sent to band-elimination filter circuits 25a and 25b, respectively.

In this band-elimination filter circuit 25a, only the frequency component 92b having a frequency component corresponding to one rotation of the container A is blocked and sent to the differential circuit 26 as 94a and 94C shown in FIG.

Similarly, in the band-elimination filter circuit 25b, only 93b is blocked, resulting in 95a and 95c shown in FIG.
sent to.

In this differential circuit 26, band rejection filter circuits 25a and 25b
Therefore, the output of the differential circuit 26 is 9 as shown in FIG.
The signals become signals 6c and 97c and are sent to the rectifier circuit 27.

Here, only the positive signal 96C passes through and becomes the signal 98c, and this signal 98c activates the display section e to notify the presence of the buried object 50.

Here, 96a and 98a are at zero level.

As explained above, according to the present invention, the antenna unit consisting of one transmitting antenna and two receiving antennas is configured to be rotated by the antenna rotation drive device 23, and the signal processing unit d Since the structure is configured to remove unnecessary signals caused by the inclination of the container A with respect to the ground 40 in which the parts are housed and fixed, there is no need to always use this device in parallel with the surface to be detected, making the detection work easier. This has the effect of speeding up the detection work and being able to reliably detect only buried objects such as soil.

[Brief explanation of drawings]

Fig. 1 is a system block diagram showing a conventional buried object detection device, Fig. 2 is a system block diagram of a buried object detection device with a rotating antenna which is an embodiment of the present invention, and Fig. 3 is a system block diagram showing a buried object detection device according to the embodiment. A plan view showing the arrangement of the antenna in the antenna section,
FIGS. 4 and 7 are explanatory diagrams for detecting objects buried in the ground by the apparatus according to the present invention, and FIGS. 5.6, 8, and 9 are explanatory diagrams of the same signal waveforms. a...Signal generation section, b...Antenna section, C...Antenna rotation drive section, d...
Signal processing unit, e...Display unit, 20...
Oscillator, 21... Attenuator, 22o...
Transmitting antenna, 22 a, 22 b...Receiving antenna, 23... Antenna rotation 1 drive device,
24a) 24b...Detection/amplification circuit, 25a
. 25b...Band rejection filter circuit, 26...
・Differential circuit, 27... Rectifier circuit, 28a...
...Indicator conversion circuit, 28b...Indicator, 2
9a... Acoustic conversion circuit, 29b... Receiver, A... Container, 30... Midpoint of two receiving antennas in a set, 40 ...The ground as the surface to be detected.

Claims (1)

[Claims] 1. A signal generating section consisting of at least an oscillator, an antenna section consisting of two receiving antennas paired with one transmitting antenna that transmits the signal from the signal generating section, and an antenna rotation that rotates the antenna section. Corresponds to the rotation period of the antenna rotation drive unit consisting of a drive device, two circuits that detect and amplify the signals received by each of the two receiving antennas, and the antenna rotation drive unit. A signal processing section consisting of two band-elimination filter circuits that block only frequency components, a differential circuit that takes the difference between the outputs of the two band-elimination filter circuits, and a rectifier circuit that extracts only the positive signal component, and an indicator. and a display section consisting of at least one of the receivers, and is configured to remove a signal component generated when the container in which the antenna section is housed and fixed is no longer parallel to the surface to be detected. A buried object detection device having a rotating antenna.