JP3779808B2 - Underground concealment detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an underground concealment detection device that detects electromagnetic concealment that already exists in the ground.
[0002]
[Prior art]
  In Japanese Patent Application No. 9-65066, the present applicant has proposed an obstacle detection apparatus using an underground propulsion method. The proposed device includes a propulsion body that propels the soil. This propulsion body has a propulsion body main body, and a propulsion tip is attached to the tip of the propulsion body main body. A blade for excavating the soil is provided at the tip of the propulsion, and a discharge hole that opens forward is provided in the vicinity of the blade.GNight mud is supplied. In addition, a driving means is provided in association with the propulsion body, and this driving means drives the propulsion body to rotate in a predetermined direction and pushes the propulsion body into the soil. Therefore, when the propulsion body is rotationally driven by the driving means and a force in the propulsion direction is applied, the blade mounted thereon excavates the soil, and the propulsion body advances while excavating the soil.
[0003]
  Such a propulsion body is equipped with an underground concealment detection device for detecting an underground concealment such as a gas pipe. This detection apparatus includes a transmission antenna that transmits electromagnetic waves, a reception antenna that receives reflected electromagnetic waves from the concealment, and signal processing means that processes the electromagnetic waves received by the reception antenna, and processes the received electromagnetic waves. The position of the concealment buried in the ground is detected by processing as required by means. And by detecting the position of the underground concealment in this way, the propulsion body can be propelled to avoid the underground concealment, thereby preventing the damage of the underground concealment during the excavation work can do. Although the transmission antenna and the reception antenna can be composed of separate antennas, the transmission antenna and the reception antenna can be distinguished from each other by distinguishing the operation time by composing the common antenna.do itCan function.
[0004]
[Problems to be solved by the invention]
The proposed detection apparatus has the following problems to be solved. First, the combined resistance value of the antenna body composed of the transmitting antenna and the receiving antenna is set to a relatively large value. Therefore, the combined resistance value of the antenna body and the impedance value of the soil excavated by the propulsion body are In contrast, due to this, the transmission efficiency of the transmission antenna and the reception efficiency of the reception antenna are lowered, and the position detection accuracy of the underground concealment is lowered.
[0005]
Second, the antenna body has a plate-shaped dielectric substrate and an antenna element provided on the surface of the dielectric substrate, so that the dielectric substrate is in contact with the soil, in other words, the antenna element is on the inside. It is attached to the propulsion rotating body. However, in the proposed detection device, the relative permittivity of the dielectric substrate is relatively small. Therefore, the relative permittivity of the dielectric substrate and the relative permittivity of the soil excavated by the propellant are different. When a part of the electromagnetic wave transmitted from the transmitting antenna through the dielectric substrate is reflected at the boundary surface with the soil, and a part of the reflected electromagnetic wave from the soil is received by the receiving antenna through the dielectric substrate. Reflected at the interface with the dielectric substrate, the transmission efficiency of the transmission antenna and the reception efficiency of the reception antenna are lowered, and the position detection accuracy of the underground concealment is lowered.
[0006]
Thirdly, the proposed detection device includes a high-frequency amplifier for amplifying the received electromagnetic wave, and the high-frequency generator is disposed at a position away from the antenna body. Are electrically connected via a cable. Therefore, noise is received in the cable for this connection, multiple reflection occurs in the cable, and the noise component is included in the signal for detecting the underground concealment. The position detection accuracy is reduced.
[0007]
An object of the present invention is to provide an underground concealment detection apparatus capable of increasing the transmission efficiency and reception efficiency of an antenna body.
[0008]
Another object of the present invention is to provide an underground concealment detection device that can reduce the reflection of electromagnetic waves at the interface between the antenna body and the soil to be excavated.
[0009]
Still another object of the present invention is to provide an underground concealment detection device that can reduce noise components contained in a signal for detecting an underground concealment.
[0010]
[Means for Solving the Problems]
  The present invention is provided at the tip of a propulsion body for propelling in the soil, transmits an electromagnetic wave and receives an electromagnetic wave reflected by a concealing object, and processes and conceals the received electromagnetic wave received by the antenna body. In the underground concealed object detection device comprising signal processing means for detecting the buried position of the object,
  The antenna body has a bow-tie antenna loaded with a plurality of resistors having a combined resistance value of 20 to 100Ω,
  The antenna includes a dielectric substrate having a relative dielectric constant r of 5 ≦ r ≦ 81, and an antenna element provided on the surface of the dielectric substrate,
  The dielectric base is provided in an opening, and has an antenna housing that houses the antenna,
  An intermediate body made of a material having a relative permittivity r of 2 ≦ r ≦ 5 is interposed between the antenna housing and the antenna element of the antenna, and an electromagnetic shield is interposed between the intermediate body and the antenna housing. An underground concealed object detection device characterized in that a member is provided.
[0011]
According to the present invention, the antenna body is constituted by a bow-tie antenna, and the combined resistance value of a plurality of resistors loaded on the antenna body is 20 to 100Ω. Therefore, depending on the combined resistance value of the antenna body and the propulsion body The impedance value of the soil to be excavated becomes substantially equal, and thereby the transmission efficiency and reception efficiency of electromagnetic waves between the antenna body and the soil can be increased.
[0013]
  AlsoSince the relative dielectric constant of the dielectric substrate of the antenna body is 5 to 81, the relative dielectric constant of the dielectric substrate and the relative dielectric constant of the soil excavated by the propulsion body are substantially equal, thereby the dielectric substrate and the soil. Reflection of electromagnetic waves at the boundary surface between the electromagnetic waves can be suppressed, and electromagnetic waves can be transmitted efficiently.
  Furthermore, since an intermediate body having a relative dielectric constant r of 2 ≦ r ≦ 5 is interposed between the antenna housing and the antenna element, resonance of electromagnetic waves transmitted from the antenna element can be suppressed by this intermediate body. A wide frequency band can be covered as an electromagnetic wave for detecting the underground concealment, and a broad band of electromagnetic waves to be transmitted and received can be achieved.
  In addition, since an electromagnetic shielding member is provided between the antenna housing and the intermediate body, it is possible to prevent external electromagnetic waves from being received by the antenna through the antenna housing, and to reduce noise components included in the received signal. Can do.
[0014]
  The present invention also provides a dielectric constant r of the dielectric substrate.Is 10 ≦ r ≦ 30It is characterized by being.
[0015]
  According to the present invention, the dielectric constant of the dielectric substrater10≦ r ≦Therefore, the relative dielectric constant is, for example, BenGWhen the soil is dug while squirting knight mud, it becomes substantially equal to the relative permittivity of the soil, which can greatly suppress the reflection of electromagnetic waves at the interface between the dielectric substrate and the soil.
[0018]
The present invention further includes a transmission pulse generator for supplying a transmission pulse signal for generating an electromagnetic wave to the antenna body, and the transmission pulse generator is directly attached to the antenna housing. It is characterized by.
[0019]
According to the present invention, since the transmission pulse generator is directly attached to the antenna housing, a cable for electrically connecting the transmission pulse generator and the antenna body can be substantially omitted. In this regard, the noise component contained in the signal for detecting the underground concealment can be reduced.
[0020]
The present invention further includes a high-frequency amplifier for amplifying the received electromagnetic wave received by the antenna body, and the high-frequency amplifier is directly attached to the antenna housing.
[0021]
According to the present invention, since the high-frequency amplifier is directly provided on the antenna housing, a cable for electrically connecting the high-frequency amplifier and the antenna body can be substantially omitted. Even when related, the noise component contained in the signal for detecting the underground concealment can be reduced.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, with reference to an accompanying drawing, one embodiment of a detection device for underground concealment according to the present invention is described. FIG. 1 shows a propulsion unit equipped with an embodiment of the underground concealment detection device according to the present invention.Key points ofFIG. 2 is a block diagram schematically showing a circuit system of a detection device installed in the propulsion body of FIG. 1.
[0023]
In FIG. 1, the illustrated propulsion body 2 includes a propulsion body main body 4 that propels the soil, and a propulsion tip portion 6 that is attached to the tip of the propulsion body main body 4. The propulsion body 2 is propelled into the soil from a start shaft (not shown) formed on the ground, for example. In relation to the propulsion body 2, the starting shaft is provided with driving means (not shown) such as a hydraulic motor. This driving means is drivingly connected to the propulsion body 2 and rotationally drives the propulsion body 2 in a predetermined direction and pushes the propulsion body 2 into the soil.
[0024]
  The propulsion body 2 penetrates the propulsion tip 6 from the starting shaft into the soil, press-fits while propelling a propulsion pipe constituting a part of the propulsion body 4, and advances while excavating. From the front end of the propulsion tip 6, for example,GThe muddy water is jetted to facilitate excavation by the propulsion tip 6 and stabilize the hole wall formed by the propulsion tip 6. In such a propulsion body 2, as shown in FIG. 1, the front end portion of the propulsion tip section 6 is inclined with respect to the central axis 8 of the propulsion body 2, that is, is inclined outward toward the rear side of the propulsion tip section 6. Thus, the inclined surface 10 is provided, so that the propulsion body 2 can be driven straight to the left in FIG. 1 by being pushed in the propulsion direction while being driven to rotate, and the propulsion body 2 can be pushed without being driven to rotate. 1 and can be moved to the left in FIG. 1. By propelling in this way, the propulsion body 2 avoids underground conceals (not shown) such as gas pipes in the soil. Can dig up.
[0025]
  In this way, holes are formed in the soil by the propulsion body 2, and then a buried member (not shown) such as a gas pipe is laid. That is, a hole is formed by the propulsion body 2 to, for example, a reaching vertical hole, the propulsion body 2 is removed by this reaching vertical hole, an expanded reamer corresponding to the outer diameter of the embedded member to be installed is attached, and then the embedded member to be installed Connect the vent reamer from BenGThe propulsion pipe is pulled back while expanding the required diameter while reinjecting the night mud, and the burying member is drawn up to the start up hole to finish the laying operation of the burying member.
[0026]
The propulsion tip 2 of the propulsion body 2 is provided with a mounting seat 12 corresponding to the inclined surface 10, and an antenna body 14 is mounted on the mounting seat 12. Since the antenna body 14 is fixed to the mounting seat 12 inclined with respect to the central axis 8 of the propulsion body 2, when the propulsion body 2 is driven to rotate, electromagnetic waves are emitted toward a relatively wide range in front of the propulsion direction. It is possible to detect underground concealment that originates and thus exists in this range. The configuration of the antenna body 14 will be described later.
[0027]
  A cutter 16 for excavating soil is fixed to the front surface of the propulsion tip 6, in this embodiment, in the vicinity of the mounting seat 12, and a discharge hole 18 opening forward is formed in the vicinity of the cutter 16. Has been. The discharge hole 18 is bent through a pipe line 20 during the excavation.GNight mud etc. are pumped.
[0028]
The pipe line 20 is connected to a pipe line 24 in the propelling body 4 through a pipe joint 22. The propulsion tip 6 and the propelling body 4 are provided with power supply lines 28 and 30 and signal lines 32 and 34, respectively.
[0029]
  The propulsion body 2 is equipped with a detection device shown in FIG. The illustrated detection apparatus includes an oscillator 52 and a transmission pulse generator 54. DepartureShakeThe device 52 is constituted by a crystal oscillator, for example, and generates a transmission signal P1 having a predetermined frequency. This departureShakeThe transmission signal P1 from the device 52 may be, for example, a sine wave (see FIG. 3). DepartureShakeBy using a crystal oscillator as the device 52, the frequency of the transmission signal can be stabilized, and the peak value of the high-frequency transmission signal can be set to about 3V, for example. In order to detect an underground concealment such as a gas pipe buried in the ground at high speed and with high accuracy, it is desirable that the frequency of the transmission signal P1 be as large as possible, for example, set to 1 megahertz (MHz) or more. Is preferred. DepartureShakeThe transmission signal P1 from the device 52 is generated as a transmission pulse.LivingThe transmission pulse generator 54 generates a transmission pulse signal P4 when the transmission signal P1 rises from the zero point and reaches a predetermined value V1 (see FIG. 3). Therefore, the transmission pulse signal P4 generated by the transmission pulse generator 54 is the transmission signal.P1It is generated with a delay of time T1 from the zero point of the rise.
[0030]
  The detection device also includes an antenna body 14. The antenna body 14 of this embodiment includes an antenna housing, and a transmitting antenna 56 and a receiving antenna 58 are provided on the antenna housing. Transmission pulse signal from transmission pulse generator 54P4Is sent to the transmitting antenna 56, which transmits this transmitted pulse signal.P4Based on this, the electromagnetic wave for detection is transmitted toward the underground concealment (not shown). The receiving antenna 58 is transmitted from the transmitting antenna 56.,Receive electromagnetic waves reflected by underground concealment. The transmitting antenna 56 and the receiving antenna 58 are configured by bow-tie antennas having substantially the same configuration, and may be planar or three-dimensional (see FIG. 4). In this embodiment, the antenna body 14 is composed of separate dedicated transmission antennas 56 and reception antennas 58. However, the antenna body 14 is composed of a common dual-purpose antenna, and by distinguishing the operation time of the dual-purpose antenna, Both functions of the receiving antenna can be provided.
[0031]
  The detection apparatus further includes a high frequency amplifier 60 and sampling means 62. The reception signal P5 received by the reception antenna 58 is sent to the high frequency amplifier 60. Since the reception signal P5 of the reception antenna 58 is a reception signal of the electromagnetic wave reflected from the underground concealment, the transmission pulse signalP4thanT2This signal becomes a time delay (see FIG. 3), and this time delay T2 becomes longer as the distances between the transmitting antenna 56 and the receiving antenna 58 and the underground concealment pipe are larger. The high frequency amplifier 60 receives a signal received from the receiving antenna 58.P5Is amplified at high frequency, and the amplified received signal is sent to the sampling means 62.
[0032]
  DepartureShakeSignal from the instrument 52P1Is fed to the phase shift means 64. The illustrated phase shift means 64 includes a phase shift circuit voltage control means 66 and a voltage variable phase shift circuit 68. The phase shift circuit voltage control means 66 composed of the phase shift circuit voltage control circuit changes the voltage supplied to the voltage variable phase shift circuit 68. Further, the voltage variable phase shift circuit 68 is configured to transmit the transmission signal based on the control voltage from the phase shift circuit voltage control means 66.P1The phase shift of is variable. That is, the voltage variable phase shift circuit 68 is configured to transmit the transmission signal as the control voltage from the phase shift circuit voltage control means 66 increases, for example.P1Is increased (in other words, the delay time is increased), while the transmission signal is increased as the control voltage from the phase shift circuit voltage control means 66 decreases, for example.P1(In other words, the delay time is shortened). As such a voltage variable phase shift circuit 68, for example, a circuit incorporating about five varicaps of about 30 to 200 pF can be used. In such a circuit, the voltage is changed by, for example, 0 to 5 V. For example, the phase of the transmission signal P1 is set to 0 to 60 × 10.^-9Seconds (0-60 ns) can be delayed. The circuit using the varicap described above has good temperature characteristics of the circuit, and the characteristics are stable even when the temperature changes, and the fluctuation of the zero point of the phase shift signal output from the phase shift means 64 is reduced. Can be reduced.
[0033]
  The phase shift means 64 generates the phase shift signal P2 (see FIG. 3) as described above. This phase shift signal P2 is a signal whose T phase is delayed by a predetermined time from the transmission signal P1, and the phase delay time with respect to the transmission signal P1 is controlled by changing the control voltage supplied to the voltage variable phase shift circuit 68. The The amount of delay of such a phase shift signal P2 is the amount of transmission signal P1.ShakeAlthough it is related to the frequency, it is desirable to set to an appropriate range of 1 to 1000 ns.
[0034]
  The phase shift signal P2 from the phase shift means 64 is sent to the pulsing circuit 70, and the pulsing circuit 70 pulsates the phase shift signal P2. Pulsed phase shift signalP2Is then fed to the sampling pulse generator 72, which receives the phase shift signalP2In this embodiment, when the output value of the phase shift signal P2 from the phase shift means 64 reaches the predetermined value V2, the sampling pulse signal P3 (FIG. 3) is generated.
  That is, as shown in FIG. 3, the sampling pulse generator 72 generates the sampling pulse signal P3 when it reaches the predetermined value V2 from the time of the rising zero point of the phase shift signal P2, and this sampling pulse signal P3 is sent to the sampling means 62. To send. Sampling pulse signal generated by the sampling pulse generator 72P3Is set very short. The sampling pulse signal P3 from the sampling pulse generator 72 functions as a gate signal for the sampling means 62, and the sampling means 62 composed of a sampling circuit receives the sampling pulse signal P3 from the sampling pulse generator 72. Received signal received by receiving antenna 58P5And is fed to the signal processing means 74.
[0035]
  In this embodiment, the frequency of the transmission signal P1 is set to 20 MHz, for example, and its period is 50 ns. In such a case, for example, during the first measurement period set to 312.5 μs, the phase shift means 64 causes the phase shift signal P delayed by a predetermined time T from the transmission signal P1.2The sampling pulse generator 72 generates 6250 sampling pulse signals P3 based on the phase shift signal P2.
  Therefore, during the first measurement period, the sampling means 62 receives the received signal from the receiving antenna 58.P5Is measured 6250 times based on the sampling pulse signal P3, and the measured sampling signal P6 (FIG. 3) is sent to the signal processing means 74. The signal processing means 74 includes an integration circuit and a memory. The sampling signal P6 in the first measurement period is integrated by the integration circuit, and the integration value obtained by the integration processing is stored in the memory. By integrating the measurement values measured many times in this way, noise components can be reduced and highly accurate measurement can be performed.
  When the first measurement period ends, the phase shift circuit voltage control means 66 increases the voltage supplied to the voltage variable phase shift circuit 68, for example, so that the phase shift signal P2 from the phase shift means 64 becomes the transmission signal P1. The time (T + ΔT) phase is delayed. During the second measurement period of 312.5 μs following the first measurement period, the phase shift means 64 causes the phase shift signal P whose time (T + ΔT) phase is delayed from the transmission signal P1.2Based on the phase shift signal P2, the sampling pulse generator 72 generates 6250 sampling pulse signals P3 as in the first measurement period. Note that the delay time ΔT is set to 0.117 ns, for example.
  Similarly, in the second measurement period, the sampling means 62 receives the received signal from the receiving antenna 58.P5Is measured 6250 times based on the sampling pulse signal P3, and the measured sampling signal P6 (FIG. 3) is sent to the signal processing means 74. Next, the signal processing means 74 integrates the sampling signal P6 in the second measurement period by the integration circuit, and the integration value obtained by the integration processing is recorded in the memory.ToRemembered.
[0036]
  In this embodiment, as shown in FIG. 3, one cycle of measurement is set to 80 ms. Therefore, the measurement of each measurement period described above is performed from the start of measurement in the first measurement period until reaching 80 ms, during which time the transition is performed. The phase means 64 is a phase shift signal that is sequentially delayed by ΔT from the transmission signal P1.P2The sampling signal P6 for each measurement period is integrated by the integration circuit of the signal processing means 74, and each integration value subjected to the integration processing is stored in the memory. The period of one cycle of measurement and each measurement period can be set as appropriate according to the frequency of the transmission signal P1.
[0037]
  The signal processing means 74 further integrates the integrated value for one cycle stored in the memory, lowers the frequency, and generates a detection signal P7 (FIG. 3). Detection signal obtained in this wayP7Is sent to a display means 76 such as a liquid crystal display device, and a detection signalP7The embedded position information included in the display means 76 is displayed on the display means 76, and thus the operator can easily know the embedded position of the concealed object by looking at the detection information displayed on the display means 76.
[0038]
  In such a detection device, for example,Shake52, a transmission pulse generator 54, an antenna body 14, a high frequency amplifier 60, a phase shift means 64, a pulsing circuit 70, a sampling pulse generator 72 and a sampling means 62 are provided in the propulsion body 2 and the remaining signal processing means 74. And the display means 76 is provided on, for example, a start stand or on the ground, and the operator views the position information of the underground concealment displayed on the display means 76 within the start stand or on the ground. It can be mined as desired.
[0039]
  Next, the illustrated antenna body 14 will be described with reference to FIGS. 4 and 5.
  The illustrated antenna body 14 includes a transmission antenna body 82 including a transmission antenna 56 and a reception antenna body 84 including a reception antenna 58. The transmission antenna body 82 and the reception antenna body 84 have substantially the same configuration, and the configuration of the transmission antenna body 82 (or the reception antenna body 84) will be described below.
  The transmitting antenna body 82 (or the receiving antenna body 84) includes a substantially rectangular antenna housing 86. The antenna housing 86 has a bottom wall 88 and four side walls 90 provided on the edge of the bottom wall 88. A housing space is defined by the bottom wall 88 and the four side walls 90.
  The transmitting antenna 56 (or the receiving antenna 58) includes a dielectric substrate 92 and an antenna element 94 provided on the surface of the dielectric substrate 92. The dielectric base 92 is formed in a rectangular shape and is disposed in the opening of the accommodation space of the antenna housing 86 as shown in FIG. 5, and the outer surface of the dielectric base 92 is in contact with the soil where the propelling body 2 excavates. . This dielectric substrate 92 has a dielectric constant r5≦ r ≦ 81'sPreferably it is formed from a material, and its relative dielectric constant rIs 10 ≦ r ≦ 3ZeroIt is more desirable to form from material.
  As a material having such a relative dielectric constant, for example, alumina-based or titanium-based ceramics can be used. By using a material having a relative dielectric constant r of 5 to 81 as the dielectric base 92, the relative dielectric constant of the dielectric base 92 can be made substantially equal to the relative dielectric constant of various soils that the propelling body 2 digs. Thus, reflection of electromagnetic waves at the interface between the dielectric substrate 92 and the soil can be suppressed, and the transmission efficiency of the electromagnetic waves from the transmitting antenna 56 to the soil (or from the soil to the receiving antenna 58) can be increased.
  In particular, by using a material having a relative dielectric constant r of 10 to 30 as the dielectric substrate 92, the dielectric constant of the dielectric substrate 92 can beGIt can be made substantially equal to the relative dielectric constant of the soil when digging while expelling knight mud.GReflection of electromagnetic waves at the boundary surface when using knight mud can be greatly suppressed.
[0040]
The antenna element 94 has a pair of first portions 96 and 97 having a substantially rectangular shape disposed opposite to each other, and a second portion 98 provided so as to surround the pair of first portions 96 and 97. is doing. These first and second portions 96, 97, and 98 are made of copper, and are provided on the inner surface of the dielectric substrate 92 (the upper surface in FIG. 5). Such an antenna element 94 can be formed by an etching process.
[0041]
  In the illustrated antenna element 94, four resistors 100 are electrically connected in parallel between a first portion 96 and a portion 98a of the second portion 98 facing each other. Similarly, the other first part 97 and second part98The four resistors 102 are electrically provided in parallel with the portion 98b facing this. Further, a connector 99 such as a balun is electrically connected to a portion where the pair of first portions 96 and 97 are opposed to each other, and the transmission pulse signal from the transmission pulse generator 54 is transmitted.P4Is sent to the antenna element 94 of the transmitting antenna 56 via the connector 99 (or the received signal from the antenna element 94 of the receiving antenna 58).P5Is fed to the high-frequency amplifier 60 through the connector 99.
[0042]
  In this embodiment, the resistance value R of each of the resistors 100 and 102 is set to 100Ω, so that the combined resistance value RT of the resistors 100 and 102 loaded on the antenna element 94 is 50Ω. In this manner, by setting the combined resistance value RT of the resistors 100 and 102 loaded on the antenna element 94 to 50Ω, the combined resistance value RT is bent.GThe impedance value of the soil in the case of digging while jetting knight mud is substantially equal, and the transmission efficiency (reception efficiency) of electromagnetic waves from the transmission antenna 56 to the soil (from the soil to the reception antenna 58) can be increased. . The combined resistance value RT of the resistors 100 and 102 does not necessarily need to be set to 50Ω, and by setting the combined resistance value RT to 20 to 100Ω, the impedance value becomes almost equal to the soil impedance value. The effect of can be achieved.
[0043]
An intermediate body 104 is interposed in a housing space between the bottom wall 88 of the antenna housing 86 and the dielectric substrate 92 and the antenna element 94. The intermediate body 104 can be formed of a material having a relative dielectric constant r of 2 to 5, such as rubber, polyvinyl chloride (PVC), polyethylene (PE), glass fiber reinforced plastic (FRP), and the like. The space is filled. By interposing the intermediate body 104 made of such a material, it is possible to suppress resonance of the antenna element 94 that occurs during transmission and reception of electromagnetic waves (especially easily generated at the corners of the antenna element 94), and concealment in the ground. A wider band of electromagnetic waves used for detecting an object can be achieved.
[0044]
  In this embodiment, an electromagnetic shield member 106 is further provided between the bottom wall 88 of the antenna housing 86 and the intermediate body 104. The electromagnetic shield member 106 is made of, for example, ferrite, and electromagnetic waves from the outside are received by the transmitting antenna 56 (or the receiving antenna 58) through the bottom wall 88.ThisThe reception signal of the reception antenna 58P5The noise component contained in can be reduced.
[0045]
  In the illustrated embodiment, the transmission pulse generator 54 is attached to the bottom wall 88 of the antenna housing 86 of the transmission antenna body 82, and the high frequency amplifier 60 is attached to the antenna housing 86 of the reception antenna body 84. As shown in FIG. 5, a transmission pulse generator 54 is fixed to the outer surface of the bottom wall 88 of the antenna housing 86 of the transmission antenna body 82 by, for example, a mounting screw (not shown). It is electrically connected to the connector 99 of the transmitting antenna body 82 via the line 108. By attaching the transmission pulse generator 54 in this way, an electrical cord for electrically connecting the transmission pulse generator 54 and the transmission antenna 56 can be omitted.
  Further, in relation to the receiving antenna 58, the high frequency amplifier 60 is fixed to the outer surface of the bottom wall 88 of the antenna housing 86 of the receiving antenna body 84 by, for example, a mounting screw (not shown), and the connector 99 of the receiving antenna body 84. Is electrically connected to the high-frequency amplifier 60 via a lead wire 108. By attaching the high frequency amplifier 60 in this manner, an electrical cord for electrically connecting the receiving antenna 58 and the high frequency amplifier 60 can be omitted.
  By attaching the transmission pulse generator 54 and the high frequency amplifier 60 in this way, the circuit configuration of the detection device can be simplified, and the reception signal of the reception antenna 58 can be simplified.P5The noise component contained in can be further reduced.
  The antenna housing of the transmitting antenna body 82 and the receiving antenna body 8486And dielectric substrate92The antenna elements 94 of the transmitting antenna 56 and the receiving antenna 58 can be provided on the surface of a common dielectric substrate.
[0046]
  In the embodiment described above, the transmitting antenna 56 and the receiving antenna 58 are configured from separate antennas, but when configured from a dual-purpose antenna,eachAntenna body82,84The antenna housing is a dual-purpose housing, and the transmission pulse generator 54 and the high-frequency amplifier 60 are attached to this common antenna housing.
[0047]
  Antenna body configured as described above82,84Can be used in the same way for the detection device shown in FIG. 6, for example, instead of the detection device having the circuit configuration described above. Referring to FIG. 6, which schematically shows another embodiment of the detection apparatus, the illustrated detection apparatus includes a variable period oscillator 202, a fixed delay circuit 204, a transmitter 206, and a transmission antenna 208.
  The variable period oscillator 202 includes a voltage control oscillator circuit (abbreviated as VCO), and has a variable period that is sequentially expanded by a small amount of time Δt each time in the first period.RawThe variable period pulse signal is sent to the fixed delay circuit 204 as a variable period signal. This variable periodic signal is also a correlation signal generator described later.214To be sent to.
  The fixed delay circuit 204 generates a fixed delay signal obtained by delaying the variable period signal by a predetermined fixed delay amount, and sends the fixed delay signal to the transmitter 206. The transmitter 206 generates a transmission signal based on the fixed delay signal, and sends this transmission signal to the transmission antenna 208. The transmission antenna 208 generates an electromagnetic wave based on the transmission signal, and transmits the electromagnetic wave toward the underground concealment that exists in the ground.
[0048]
  The detection apparatus also includes a reception antenna 210, a high frequency amplifier 212, a correlation signal generator 214, and signal processing means 216. The reception antenna 210 receives the electromagnetic wave transmitted from the transmission antenna 208 and reflected by the underground concealment, and sends the reception signal to the high frequency amplifier 212. The high frequency amplifier 212 amplifies the received signal.
  The correlation signal generator 214 generates a promise waveform signal having a monocycle waveform having a predetermined time length as a correlation signal for each variable period signal from the variable period generator 202, and sends the correlation signal to the signal processing means 216. To do. The signal processing means 216 includes a multiplication circuit, an integration circuit, and an amplification circuit.
  Multiplication circuit is a high frequency amplifier212Received signal and correlation signal generator214 with each correlation signalWidthThe multiplication circuit generates a multiplication signal, and the integration circuit generates an integration signal by integrating the multiplication signal from the multiplication circuit., MaThe amplifier circuit amplifies the integrated signal to generate an amplified signal.
  Signal processing means216 further performs a correlation detection process and a pulse compression process on the amplified signal to generate a detection signal. This detection signal includes information on the position where the obstacle is buried, and display means can be obtained by using this detection signal.2The position where the obstacle is buried can be displayed at 18.
[0049]
The above-described bow-tie antenna body can be used as the transmitting antenna 208 and the receiving antenna 210 in such a detection device, and the same effect as described above can be achieved by using this antenna body. In such a case, the transmitter 206 is attached to the antenna housing of the transmitting antenna body, and the high frequency amplifier 212 is attached to the antenna housing of the receiving antenna body.
[0050]
Examples and comparative examples
As an example, an experiment was conducted to confirm the effect of combining the antenna body shown in FIGS. 4 and 5 with the detection apparatus having the configuration shown in FIG. For the convenience of the experiment, the transmission pulse generator and the transmission antenna were connected via a cable, and the reception antenna and the high frequency amplifier were connected via a cable. FIG. 7 simply shows the circuit configuration of the detection apparatus used in the experiment. In this circuit configuration, the first attenuator b is connected to the transmission terminal portion of the controller a of the detection apparatus via the first correction cable c, and the transmission antenna Tx of the antenna body d is connected to the first attenuator b. The attenuation value of the first attenuator b was set to 6 dB, and the length of the first correction cable c was set to 25 cm. Further, the second attenuator f is connected to the receiving antenna Rx of the antenna body d via the second correction cable e, and the second attenuator f is connected to the receiving terminal portion of the controller a of the detection apparatus. The attenuation value of the second attenuator f was set to 6 dB, and the length of the second correction cable e was set to 25 cm.
[0051]
Using such a detection device, the following soil tank experiment was conducted. The used soil tank is as shown in FIG. 8, and the sand tank g was filled in the soil tank, and the antenna body d of the detection device was positioned therein. A vinyl chloride pipe h having a diameter of 2 inches was disposed horizontally at the lower part of the earth tub, and a steel pipe i having a diameter of 1 inch was inserted into the inside of the vinyl chloride pipe h. In such a state, first, the antenna body d is positioned in the pure sand soil so that the distance L between the steel pipe i and the steel pipe i is 50 cm, and then the antenna body d is placed in the pure sand soil in a direction approaching the steel pipe i. The steel pipe i was searched for in the manner described above by moving downward to a position where the distance L was 10 cm. As an example, each of the transmitting antenna Tx and the receiving antenna Rx was loaded with a resistor having a combined resistance value of 50Ω. The dielectric substrate was formed from a synthetic resin having a relative dielectric constant of 10, and the intermediate was formed by filling a rubber material having a dielectric constant of 3.
[0052]
The result shown in FIG. 9 was obtained by the soil tank experiment described above. FIG. 9A is search information obtained when the antenna body d of the example is moved until the distance L to the steel pipe i is changed from 50 cm to 10 cm, and is an image displayed on the display means of the detection device. It is. The vertical axis in FIG. 9A is the current wave arrival time axis, and the horizontal axis is the distance axis indicating the moving length from the uppermost surface of the antenna body d. In FIG. A black-and-white straight line Q1 extending upward indicates the radio wave arrival time from the steel pipe i, and the distance L to the steel pipe i is reduced by pushing the antenna body d into the pure sand soil little by little. Show. FIG. 9B shows the amplitude of the signal waveform cut out from the line L0 in FIG. 9A, that is, the point where the distance from the antenna body d to the steel pipe i is 30 cm. A high portion in the signal waveform in FIG. 9B corresponds to a white line in FIG. 9A, and a low portion in the signal waveform in FIG. 9B corresponds to a black line in FIG. 9A. From the experimental results shown in FIGS. 9 (a) and 9 (b), when the antenna body of the embodiment is used, a reception signal with a large amplitude can be obtained, whereby the steel pipe i can be detected with higher accuracy. found.
[0053]
  For comparison, the above-described experiment similar to the example was performed by combining the antenna body of the comparative example with the detection device similar to the example. In the antenna body of the comparative example, each of the transmitting antenna and the receiving antenna was loaded with a resistor having a combined resistance value of 200Ω. The dielectric substrate was made of a glass epoxy resin having a relative dielectric constant of 3, and was not filled with an intermediate. When the antenna body of the comparative example was used, the experimental result shown in FIG. 10 was obtained.
  FIG. 10 (a) is search information obtained when the antenna body d of the comparative example is moved until the distance L to the steel pipe i is changed from 50 cm to 10 cm, and is an image displayed on the display means of the detection device. This corresponds to FIG. 9A of the embodiment. Also in FIG. 10 (a), a black and white straight line Q2 extending obliquely upward toward the left indicates the steel pipe i, but the density difference is reduced compared to the black and white line Q1 in FIG. 9 (a). ing.
  FIG. 10 (b) shows the amplitude of the signal L0 cut out from the line L0 in FIG. 10 (a), that is, the point where the distance from the antenna body d to the steel pipe i is 30 cm. This corresponds to FIG. 9B. Also in FIG. 10B, the high part in the signal waveform corresponds to the white line in FIG. 10A, and the low part corresponds to the black line in FIG.
  9 (a) and (b) showing the experimental results of the example and FIGS. 10 (a) and (b) showing the experimental results of the comparative example, the antenna body d of the example is compared. The reflection intensity of the electromagnetic wave is larger than that of the example, and the amplitude (peak peak value) of the received signal isWhoCompareExampleIs about twice as large. Also, considering background noiseAn example isComparisonFor exampleIt can be seen that the S / N ratio is improved by about 10 dB. The S / N ratio is
  It calculated | required by S / N = 20log (peak peak value) -20log (average value of a noise component).
[0054]
From the above experimental results, it was found that the use of the antenna body of the example can improve the S / N ratio and the underground concealment can be detected with higher accuracy than that of the comparative example.
[0055]
【The invention's effect】
  Main departureClearlyAccording to the present invention, since the antenna body is constituted by a bow-tie antenna, and the combined resistance value of the plurality of resistors loaded on the antenna body is 20 to 100Ω, the antenna body is excavated by the combined resistance value and the propulsion body. The impedance value of the soil becomes substantially equal, and thereby the transmission efficiency and reception efficiency of electromagnetic waves between the antenna body and the soil can be increased.
[0056]
  Also this departureClearlyAccording to the present invention, since the relative permittivity of the dielectric base of the antenna body is 5 to 81, the relative permittivity of the dielectric base and the relative permittivity of the soil excavated by the propulsion body are substantially equal. Reflection of electromagnetic waves at the boundary surface between soil and soil is suppressed, and electromagnetic waves can be transmitted efficiently.
[0057]
  Also this departureClearlyAccording to this, since the relative permittivity of the dielectric substrate is 10 to 30, this relative permittivity is, for example, BenGWhen the soil is dug while squirting knight mud, the relative permittivity of the soil becomes substantially equal, and this can greatly suppress the reflection of electromagnetic waves at the boundary surface between the dielectric substrate and the soil.
[0058]
  Also this departureClearlyAccording to the present invention, since an intermediate having a relative dielectric constant of 2 to 5 is interposed between the antenna housing and the antenna element, resonance of electromagnetic waves transmitted from the antenna element can be suppressed by this intermediate, A wide frequency band can be covered as an electromagnetic wave for detecting the medium concealment, and a wider band of electromagnetic waves to be transmitted and received can be achieved.
  According to the present invention, since the electromagnetic shield member is provided between the intermediate body and the antenna housing, the noise component of the received signal can be reduced.
[0059]
  Also this departureClearlyAccording to the present invention, since the transmission pulse generator is directly attached to the antenna housing, a cable for electrically connecting the transmission pulse generator and the antenna body can be substantially omitted. The noise component contained in the signal for detecting the underground concealment can be reduced.
[0060]
  Further departureClearlyAccording to this, since the high-frequency amplifier is directly provided on the antenna housing, a cable for electrically connecting the high-frequency amplifier and the antenna body can be substantially omitted. Also, it is possible to reduce the noise component contained in the signal for detecting the underground concealment.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a part of a propulsion body equipped with an embodiment of the underground concealment detection apparatus according to the present invention in cross section.
FIG. 2 is a block diagram schematically showing a detection device installed in the propulsion body of FIG. 1;
3 is a time chart showing various signals generated in various components of the detection apparatus of FIG. 2. FIG.
4 is a cross-sectional view showing an antenna body of the detection device of FIG. 2. FIG.
FIG. 5 is a cross-sectional view taken along line VV in FIG.
FIG. 6 is a block diagram schematically showing another embodiment of the detection apparatus.
FIG. 7 is a cross-sectional view schematically showing a soil tank for conducting a soil tank experiment.
FIG. 8 is a block diagram schematically showing a circuit configuration of a system using a detection apparatus to which an antenna body according to an embodiment is attached.
FIGS. 9 (a) and 9 (b) are diagrams showing the results of a soil tank experiment performed using the antenna body of the example, respectively.
FIGS. 10 (a) and 10 (b) are diagrams showing the results of a soil tank experiment performed using an antenna body of a comparative example, respectively.
[Explanation of symbols]
  2 propulsion bodies
  4 propulsion body
  14 Antenna body
  52 shotsShakevessel
  54 Transmission pulse generator
  56 Transmitting antenna
  58 Receiving antenna
  60 high frequency amplifier
  62 Sampling means
  64 Phase shift means
  74 Signal processing means
  76 Display means
  82 Transmitting antenna body
  84 Receiving antenna body
  86 Antenna housing
  92 Dielectric substrate
  94 Antenna element
  100,102 resistance
  104 Intermediate
  208 Transmitting antenna
  210 Receiving antenna

Claims (4)

An antenna body that is provided at the tip of a propulsion body that propels in the soil, transmits electromagnetic waves and receives electromagnetic waves reflected by the concealment, and a position where the concealment is buried by processing the received electromagnetic waves received by the antenna body In the underground concealment detection device comprising a signal processing means for detecting
The antenna body has a bow-tie antenna loaded with a plurality of resistors having a combined resistance value of 20 to 100Ω,
The antenna includes a dielectric substrate having a relative dielectric constant r of 5 ≦ r ≦ 81, and an antenna element provided on the surface of the dielectric substrate,
The dielectric base is provided in an opening, and has an antenna housing that houses the antenna,
An intermediate body made of a material having a relative permittivity r of 2 ≦ r ≦ 5 is interposed between the antenna housing and the antenna element of the antenna, and an electromagnetic shield is interposed between the intermediate body and the antenna housing. A device for detecting an underground concealment, wherein a member is provided . 2. The underground concealment detection apparatus according to claim 1, wherein a relative dielectric constant r of the dielectric substrate satisfies 10 ≦ r ≦ 30. A transmission pulse generator for supplying a transmission pulse signal for generating an electromagnetic wave to the antenna body is further provided, and the transmission pulse generator is directly attached to the antenna housing. Item 3. The underground concealment detection apparatus according to item 1 or 2. The high frequency amplifier for amplifying the received electromagnetic wave received by the antenna body is further provided, and the high frequency amplifier is directly attached to the antenna housing. The underground concealment detection apparatus described in 1.

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