JP3322462B2 - Borehole radar - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for exploring the geology between two predetermined points in the ground by means of electromagnetic wave transmission characteristics, that is, a borehole radar.

[0002]

2. Description of the Related Art A borehole radar is a type of transmission / reception opposing detection radar for detecting the state of a buried object, the state of change in a stratum, and the like in an underground transmission line between required points by a transmitted wave (also referred to as a passing wave) of an electromagnetic wave.

[0003] In this type of borehole radar, a signal of a promised waveform that repeats at a required detection cycle is transmitted underground as a transmission signal in order to improve the search capability, and a reception signal obtained by transmitting through the ground is received. There is a configuration in which a desired detection signal is obtained by correlating the same signal as the promised waveform as a correlation signal at each detection cycle as a correlation signal.

The arrangement of such a borehole radar is, for example, like the borehole radar 100 shown in FIG. In FIG. 7, search holes 203 and 204 are holes excavated in the underground 202 in the vertical direction.

[0005] One of the search holes 203 is provided with a transmission antenna 403, and the other search hole 204 is provided with a reception antenna 6.
01 and the control processing /
While repeating the promised waveform signal 401a from the display unit 301 at a predetermined detection cycle, the transmitting unit 4
02, the electromagnetic wave 501 having the signal of the promised waveform is transmitted to the underground 202 at a predetermined detection cycle.

[0006] A reception signal 701a obtained by receiving an electromagnetic wave 501 transmitted through the underground 202 as a transmission path by a reception antenna 601 is transmitted from a reception unit 602 to a control processing / display unit 301 on the ground 201 via a reception lead 701. give.

The received signal 701a is used as a correlated signal, and the signal 401a of the promised waveform is used as a correlation signal, and the correlation processing function provided in the control processing / display unit 301 performs correlation for each predetermined period and detects the correlation signal. Control processing of search signals /
The display is provided by a display function provided in the display unit 301, and the transmission antenna 403 and the reception antenna 601 are provided.
It is possible to investigate the geology at mid-depth in each place by exploring while moving up and down.

The distance between the exploration holes 203 and 204 is about 50 m, and the depth of the exploration holes 203 and 204 is 300 to 10
In order to investigate the characteristics of the transmission path in detail, the above-described promised waveform signal 401a is converted into a signal having a large number of frequency components, and the reception signal 70
It is necessary to detect the difference in the change of 1a.

For this reason, a signal subjected to linear continuous frequency modulation or stepwise continuous frequency modulation (in the present invention,
A swept continuous FM signal) is used as the promised signal 401a.

Swept continuous F by linear continuous frequency modulation
The M signal is a signal that repeats a variable frequency f ₁ that changes linearly from the frequency f ₀ to the frequency (f ₀ + Δf) from time 0 to time T, as shown in the frequency change of FIG. As shown in FIG. 9, the frequency of the sweep-type continuous FM signal generated by the step-like continuous frequency modulation changes stepwise from the frequency f ₀ to the time Δt slightly from time f to time Δt. The signal is a signal that repeats the variable frequency f ₁ that changes to the frequency (f ₀ + Δf).

In such a correlation detection type transmission path searching apparatus 100 using a promised waveform signal based on a swept continuous FM signal, in addition to the promised waveform signal 401a,
The promised waveform signal 401a is phase-shifted by π / 2, that is, a promised waveform signal is shifted by 90 °, and these two correlation signals are
That is, two multiplication correlation signals obtained by multiplying the two-phase correlation signal and the reception signal 701a are inversely Fourier-transformed, and the target search signal, that is, the change of the frequency component and the phase component due to the characteristics of the transmission path. A configuration for obtaining a signal for determining a change or the like is disclosed in Japanese Patent Application Laid-Open No. HEI 4-15228 based on the application of the present applicant.
6 and the like.

By performing the multiplication correlation using such two-phase correlation signals, the S / N of the detection signal is improved, and the operation of precisely detecting a phase change or a frequency change by expansion by Fourier transform is performed by orthogonal function expansion. Also called correlation detection.

In the above configuration, firstly, the transmitting wire 4
01. Since the receiving conductor 701 is very long, if the grounding configuration of each part is not carefully considered, the ground unbalance between the transmitting conductor 401 and the receiving conductor 701 and the ground unbalance between the transmitting part 402 and the transmitting antenna 403 will be described. In addition, due to grounding unbalance between the receiving unit 602 and the receiving antenna 601, there occurs a disadvantage that each high-frequency signal in each unbalanced portion induces interference and hinders the intended operation. Second, between the transmitting section 402 and the transmitting antenna 403, and between the receiving section 602 and the receiving antenna 60.
1 means that it is necessary to provide a shield for avoiding adverse effects due to direct leakage or mutual interference, and it is necessary to mechanically combine and integrate these parts. For this reason, since the outer diameter of the structure of this part becomes large, the inside diameter of the exploration holes 203 and 204 has to be enlarged, so that excavation of these holes requires considerable cost, and the exploration requires enormous cost. There is an inconvenience that costs are required.

[0014] In order to solve such inconveniences,
The conductor 401 and the reception conductor 701 are connected by an optical fiber.
The transmission antenna 403 and the reception antenna 60
1 is formed of a hollow cylindrical body, and
In Japanese Patent Application Laid-Open
It is disclosed by Hei 4-80684.

[0015]

SUMMARY OF THE INVENTION The above prior art configuration
Then, first, the transmitting antenna 40 of a hollow cylindrical body
3. Configuration without providing anything outside the receiving antenna 601
The transmission antenna 403 and the reception antenna 6
01 comes into contact with the inner surfaces of the
The inconvenience of changing the electrical characteristics of the antenna
Occurs. Secondly, in the case of deep depth exploration
Means that the exploration holes 203 and 204 are filled with groundwater,
Each of the internal circuit components is submerged and destroys the electrical characteristics.
The inconvenience of being lost occurs. And third,
Since the length of the transmission wire 401 and the length of the reception wire 701 are very long, the phase change component in the detection signal detected by the correlation detection is larger than the phase change component due to the target geological difference. Since the phase change component based on the length of the conductor is included much more, there is a disadvantage that the phase change component due to the geology cannot be accurately detected.

For this reason, there is a problem that provision of a simple and inexpensive configuration free of such inconveniences is desired.

[0017]

According to the present invention, a transmitting section and a transmitting antenna are arranged in one of the above-described underground exploring holes, and a receiving section and a receiving antenna are arranged in the other exploring hole. An electromagnetic wave based on a promised waveform signal is transmitted from a transmitting antenna, and a signal based on a received signal received by a receiving antenna is used as a correlated signal, and a multiplied correlation signal obtained by multiplying and correlating the above-described promised waveform signal as a correlation signal. In a borehole radar that obtains a required search signal based on the transmission antenna, the transmission antenna is formed of a hollow cylinder, that is, a transmission cylinder, and the transmission unit, a power supply battery for operating the transmission unit, That is, the transmitting battery and the transmitting cylindrical means arranged inside the transmitting cylindrical body and the receiving antenna are formed of a hollow cylindrical body, that is, a receiving cylindrical body. And the receiving section, a power supply battery for operating the receiver unit, i.e., a reception cell, a receiving cylinder means disposed inside the reception cylinder, feeding of the
The outer circumference of the receiving cylinder and the outer circumference of the receiving cylinder are
Covered with a waterproof cover made of high-frequency insulation,
Insulation filling to fill high frequency insulating filler inside the water cover
A first configuration provided with means ;

The borehole array in the first configuration described above.
In the same borehole radar as the above, the transmitting antenna is formed as two hollow cylinders , that is, a transmitting dipole antenna having a pair of transmitting cylinders as antenna elements, and one of the transmitting dipole antennas is formed. A transmitting cylinder means for disposing the transmitting section inside the cylindrical body and disposing the transmitting battery inside the other cylindrical body, and the receiving antenna, the two hollow cylindrical bodies ,
The receiving cylinder pair is formed as a receiving dipole antenna with each antenna element, and the receiving section is arranged inside one cylinder of the receiving dipole antenna, and inside the other cylindrical body. The receiving cylinder means for arranging the receiving battery, the outer circumference of the transmitting cylinder pair and the
Of the pair of receiving cylinders of
In addition to covering with waterproof cover, high frequency
An insulating filling means for filling an insulating filler .
Configuration and

Further, a transmitting unit and a transmitting antenna are disposed in one of the above-described underground exploring holes, and a receiving unit and a receiving antenna are disposed in the other exploring hole. An electromagnetic wave based on the waveform signal is transmitted, a signal based on the received signal received by the receiving antenna is used as a correlated signal, and a required exploration signal is generated based on the multiplied correlation signal obtained by multiplying and correlating the above-mentioned promised waveform signal as a correlation signal. In the borehole radar to be obtained, the above-mentioned promised waveform signal is converted into an optical signal to be a light guide, that is, a transmission wire means provided to a transmitting unit by a transmission-side light guide, and the above-mentioned received signal is converted into an optical signal by a light guide. That is, the receiving wire means to be provided to the processing unit for performing the above-mentioned multiplication correlation by the receiving light guide, and the above-mentioned promised waveform signal, at least, in the portion of the above-mentioned transmitting light guide A time amount corresponding to a time amount obtained by adding the transmission time of the promised waveform signal and the transmission time of the reception signal in the above-described light-receiving-side light guide portion is calculated based on the delayed signal obtained by delaying the correlation signal. A third configuration provided with a correlation signal means for obtaining;

In the third configuration, the delay is provided by a light guide having a length corresponding to at least the sum of the length of the transmitting light guide and the length of the receiving light guide. A fourth configuration provided with a correlation signal means for obtaining, and further, a transmitting unit and a transmitting antenna are arranged in one of the opposing exploration holes in the ground, and a receiving unit and a receiving antenna are disposed in the other exploration hole. To transmit an electromagnetic wave based on the promised waveform signal from the transmitting antenna, a signal based on the received signal received by the receiving antenna as a correlated signal, and multiply the promised waveform signal as a correlation signal. In a borehole radar that obtains a required search signal based on a correlated multiplied correlation signal, the above-mentioned promised waveform signal is converted into an optical signal and transmitted to a transmitting unit by a light guide, that is, a transmission side light guide. Conducting means, and at least a portion of the processing unit for performing the multiplying correlation to obtain the above-described search signal is arranged integrally with the receiving unit, and the rest of the processing unit is arranged on the ground. The multiplying correlation section setting means and the transmission light guide means are separately converted from the promised waveform signal into an optical signal to guide the light, that is,
By the delay light guide, the promised waveform signal is converted into a delay signal obtained by delaying at least a time amount corresponding to the time amount of the transmission time of the promised waveform signal in the above-described transmission light guide portion, Delay wire means to be applied to a processing unit for performing multiplication correlation, and reception light beam means to convert a signal obtained by the above-mentioned multiplication processing part into an optical signal and to provide the above-mentioned remaining part arranged on the ground with a light guide light And a correlation signal that forms the delay light guide at least by a light guide having the same length as the length of the transmission-side light guide in the fifth structure. By providing a sixth configuration provided with means, the above-mentioned problem can be solved.

[0021]

According to the first and second configurations, the transmission address
Antenna and receiving antenna on the inner surface of each exploration hole
The electrical characteristics of the antenna do not touch
Has the effect of stabilizing and improving
Also, because it is filled with a high-frequency insulating filler,
Destruction of electrical characteristics of each internal circuit component due to flooding
Stable exploration even in deep water holes
It works so that the effect that can be performed is obtained .

According to the third, fourth, fifth, and sixth configurations, the transmission conductor and the reception conductor are constituted by light guides, so that the control processing / display unit This means that the electrical connection between such equipment components on the ground and underground equipment components such as the transmitter and receiver is interrupted, so even if the ground becomes unbalanced, inductive interference will occur. This eliminates the risk of exploration faults caused by geological conditions, and delays the promised waveform signal so that only the signal portion corresponding to the transmission time under the ground is detected. Since the rate of change of the portion is improved, it works so that a change component due to geology can be detected with high accuracy.

[0023]

An embodiment will be described below with reference to FIGS.
In the configurations of FIGS. 1 to 6, portions denoted by the same reference numerals as those in FIGS. 7 to 9 indicate portions having the same functions as the portions denoted by the same reference numerals described in FIGS. 7 to 9.

First Embodiment A first embodiment will be described below with reference to FIGS. In the control processing / display unit 301 of FIG. 1, the variable frequency generation circuit 1 generates a swept continuous FM signal by linear frequency modulation as shown in the frequency change of FIG. The signal is supplied to the amplifier circuit 2 and the fixed delay circuit 18. Promised waveform signal 1a
Specifically, for example, from f ₀ = 10 MHz to f ₀ +
Δf = a signal having a variable frequency f ₁ up to 80 MHz.

The preamplifier circuit 2 performs preamplification for amplifying the promised waveform signal 1a to such an extent that the promised waveform signal 1a can be transmitted to the transmitting section 402, and supplies the amplified promised waveform signal 2a to the electro-optical conversion circuit 3. .

The electric / optical conversion circuit 3 is a circuit for converting the promised waveform 2a based on an electric signal into an optical signal, for example, a circuit for obtaining a target optical signal by a laser diode. The signal 3a is transmitted to the transmission wire 401.
Give to.

The operation power supply 26 is connected to the control processing / display unit 30.
1 is a power supply for operating each circuit, for example,
A power supply circuit for obtaining a required voltage from a storage battery or a commercial power supply.

The transmission wire 401 is a light guide, for example, a light guide made of an optical fiber, and has an optical signal 3 having a predetermined waveform.
"a" is a conducting wire that gives a to the optical / electrical conversion circuit 5 of the transmission unit 402 remotely located. Here, the optical signal 3a is transmitted to the transmission conductor 4
01 length L ₁ by a transmission time required to transmit tau ₁
And

The optical / electrical conversion circuit 5 generates an optical signal 3 having a promised waveform.
is a circuit for converting a into an electric signal, for example, a circuit for obtaining a target electric signal by a phototransistor, and supplies a promised waveform signal 5a based on the converted electric signal to the transmission circuit 6.

The transmitting circuit 6 is a power amplifying circuit for amplifying the promised waveform signal 5a to a required power required for transmission. For example, the transmitting circuit 6 is a transistor-based amplifying circuit, and converts the amplified transmission signal 6a to a matching transformer. Give 7 The battery 9 is a power supply provided independently for operation of each circuit arranged in the transmission unit 402 including the transmission circuit 6, and includes, for example,
It is an alkaline manganese dry battery.

The matching transformer 7 is, for example, a high-frequency transformer for matching between unbalanced / balanced circuits, that is, a balun. The unbalanced side is connected to the transmission circuit 6, and the balanced side is connected to the transmission antenna 403. Then, the power of the transmission signal 6a is converted from the transmission antenna 403 into an electromagnetic wave 501 having a promised waveform signal and transmitted to the transmission path of the underground 202.

The transmitting antenna 403 is a kind of dipole antenna, and each antenna element is formed on a conductor of two hollow cylindrical bodies 403a and 403b.
The conductor from the matching transformer 7 is screwed to the end of a circular pipe made of aluminum material.
₁₁ is adjusted to the feed impedance, and the lengths L ₁₂ and L ₁₃ of the cylindrical bodies 403a and 403b are determined by the transmission signal 3a
, That is, a frequency slightly higher than the highest frequency 80 MHz of the frequency of the signal of the promised waveform, for example, 100
By setting the length to resonate at a wavelength of about MHz, each frequency component included in the promised waveform signal can be transmitted by an electromagnetic wave having as uniform power as possible.

The cylindrical body 40 forming the transmitting antenna 403
3a and 403b, that is, in the hollow portion, an optical / electrical conversion circuit 5 and a transmission circuit 6 are provided inside one cylindrical body 403a.
And the like, which accommodates the parts constituting the transmission unit 402,
The power supply battery of the transmission unit 402, that is, the battery 9 is housed and arranged inside the other cylindrical body 403b.

The outer cover 10 is a waterproof cover formed of a high-frequency insulating material that covers the outside of the transmitting antenna 403.
A cylindrical body whose upper and lower sides are closed is formed of FRP resin material, and a gland packing 10a for waterproofly penetrating the transmission wire 401 is provided above.

The structure in which the transmitting antenna 403 and the like are housed inside the outer cover 10 is, for example, a structure that withstands water pressure at a deep depth in the exploration hole 203. It is filled with insulating oil or silicone rubber.

The electromagnetic wave 501 has a power that can reach the search hole 204 located at a point separated by an underground transmission distance d suitable for the purpose of the underground exploration. The transmission time required for transmission is τ ₂ .

The receiving antenna 601 is connected to the transmitting antenna 40
A dipole antenna having the same configuration as
One of the hollow is obtained by forming a conductor of the cylindrical body 601a · 601b, and a transmission antenna 403 and the material in the same, and the arrangement interval L ₁₄ and length L ₁₅ and length L _16, the arrangement interval L ₁₁ and length L ₁₂ and be one configured by the same as the length L _13, the electromagnetic wave 501 arriving via the transmission path of the ground 202
Is given to the receiving circuit 13 via the matching transformer 12.

The matching transformer 12 is a high-frequency transformer similar to the matching transformer 7, for example, a balun. The balanced side is connected to the receiving antenna 601 and the unbalanced side is connected to the receiving circuit 13. The wave output is supplied from the matching transformer 12 to the receiving circuit 13 as a received signal 12a having a promised waveform.

The receiving circuit 13 converts the pre-amplified received signal 13a for amplifying the received signal 12a to such an extent that the received signal 12a can be transmitted to the control processing / display unit 301.
Give to. The battery 11 is a power source provided independently for the operation of each circuit arranged in the receiving unit 602 including the receiving circuit 13, and is, for example, an alkaline manganese dry battery.

The electrical / optical conversion circuit 14 is a circuit for converting the received signal 13a based on an electrical signal into an optical signal, for example, a circuit for obtaining a target optical signal by a laser diode. The signal 14a is supplied to the receiving conductor 701.

The receiving conductor 701 is a light guide, for example, a light guide made of an optical fiber.
4a is a lead wire which is provided to the optical / electrical conversion circuit 16 of the control processing / display unit 301 which is remotely arranged. Here, the optical signal 14
The transmission time required to transmit a by the length L ₃ of the receiving conductor 701 is τ ₃ .

The cylindrical body 60 forming the receiving antenna 601
In the inside of 1a and 601b, that is, in the hollow part, the part constituting the receiving unit 602 such as the electro-optical conversion circuit 14 and the receiving circuit 13 is housed and arranged inside one cylindrical body 601a, and The transmission unit 402 is provided inside the cylindrical body 601b.
, That is, the battery 11 is housed and arranged.

The outer cover 15 is a waterproof cover formed of a high-frequency insulating material that covers the outside of the receiving antenna 601.
A cylindrical body whose upper and lower sides are closed is formed of FRP resin material, and a gland packing 15a for waterproofly penetrating the receiving conductor 701 is provided above.

The configuration in which the receiving antenna 601 and the like are housed inside the outer cover 15 is the same as the configuration in which the transmitting antenna 403 and the like are housed inside the outer cover 10, for example.

The optical / electrical conversion circuit 16 is a circuit for converting the optical signal 14a of the received signal into an electric signal, for example, a circuit for obtaining a target electric signal by a phototransistor. The received signal 16a by the signal is given to the rear-stage amplifier circuit 17.

The post-amplifying circuit 17 is an amplifying circuit for amplifying the received signal 16a to a required voltage necessary for performing the multiplying correlation, and is, for example, a transistor-based amplifying circuit, and multiplies the amplified received signal 17a by the multiplying circuit 19a. Is given as one of the multiplication inputs.

Here, in the first embodiment, the received signal 1
6a is a signal to be correlated, a multiplication correlation with the correlation signal as a promised waveform signal 1a is performed by a kind of beat detection, and a correlation detection signal obtained by the multiplication correlation, that is, a beat detection signal is Fourier-transformed to obtain a power spectrum. From
By determining the beat frequency f _b and knowing the change in the transmission time τ ₂ of the electromagnetic wave 501 in the underground 202, the geology of the underground 202 is determined.

Therefore, the promised waveform signal 1a is given as the other multiplication input of the multiplication circuit 19,
If only beat detection is performed, the purpose can be achieved by directly providing the promised waveform signal 1a as a multiplication input.

However, in this case, the beat component includes the total amount of transmission time τ ₁ , transmission time τ _2, and transmission time τ ₃ τ ₁₁ τ ₁₁ = τ ₁ + τ ₂ + τ ₃ , Preamplifier circuit 2, electric / optical conversion circuit 3, optical / electric conversion circuit 5, transmission circuit 6, reception circuit 13, electric / optical conversion circuit 14
The time of the sum of the total amount of delay time in each circuit of the optical / electrical conversion circuit 16 and the post-amplifier circuit 17 with the time amount τ ₁₂ , that is, a component due to the total delay time τ ₁₃ τ ₁₃ = τ ₁₁ + τ ₁₂ is included. The rate of change of the beat component due to the change of the transmission time τ ₂ in the underground 202 is
Because becomes the rate of change for the total delay time tau _13, after all, change the ratio to be detected is not made to be lowered.

[0050] Therefore, promises waveform signal 1a a is delayed by applying a fixed delay circuit 18, the delay Ideally, transmission time tau ₂ of in the ground 202 from total delay time tau ₁₃ of the
Should be given as a multiplication input to the multiplication circuit 19 by delaying the time amount τ ₁₄ τ ₁₄ = τ ₁₃ −τ _2. However, in order to simplify the configuration, The delay time amount τ _s is a time amount of at least τ ₁₅ τ _s = τ ₁ + τ ₃ = τ ₁₅ which is the sum of the transmission time τ ₁ and the transmission time τ ₃ , and is preferably up to the time amount τ ₁₄ described above. Delay time. However, here, simply, the transmission time τ
Only ₁ and transmission time tau ₃ times the amount of time tau ₁₅ plus those that are delayed.

The delay circuit 18 is, for example, a delay line using a light guide made of an optical fiber similar to the transmission line having the configuration of the optical / optical conversion circuit 3, the transmission line 401, and the optical / electrical conversion circuit 5. the length of the beam, by be of a length L ₁ and the length L ₃ and a length obtained by adding the reception conductors 701 of the transmission conductor 401, to obtain a delay time amount corresponding to the amount of time tau ₁₅ It is like that. That is, the light guide used for the delay circuit 18, the light guide used for the transmission wire 401, and the light guide used for the reception wire 701 are all made of the same material or the same standard light guide, that is, the same material or the same standard optical fiber. In this way, each transmission time and the delay time can be easily matched just by setting the length to a predetermined length.

The multiplying circuit 19 is, for example, a multiplying circuit (also called a double-balanced multiplying circuit) using a double balance mixer (DBM), and multiplies the amplitude value of one multiplication input by the amplitude value of the other multiplication input. And outputs a signal having an amplitude value obtained as a multiplication signal. The multiplication signal 19a obtained by multiplying the reception signal 17a corresponding to the correlated signal and the delay signal 18a corresponding to the correlation signal is low-pass filtered. To the circuit 20.

The low-pass filtering circuit 20 passes a frequency lower than the lowest frequency component of the promised waveform signal 1a and higher than the highest frequency predicted as a beat detection output, that is, in this embodiment, a frequency of 1 kHz or less. This is a filtering circuit for filtering as a frequency, and provides a multiplying correlation signal 20a obtained by filtering to a processing processor 21.

The processing processor 21 is, for example, a processor for performing a Fourier transform by a microcomputer, and performs a Fourier transform on the basis of digital value data obtained by sampling the multiplied correlation signal 20a, thereby obtaining the multiplied correlation signal 20a. the main frequency components, that is, by obtaining the beat frequency f _b obtained by the beat detection, which seek to calculate values corresponding to the substantial variation of transmission time tau _2, obtained on the basis of the calculation value The signal is given to the display 22 as the calculated value signal 21a.

The winch 801 is provided with a cable 802 (not shown) or a transmission wire 401 connected to the outer cover 10 and the outer cover 15 to move the outer cover 10 and the outer cover 15 up and down.
And the receiving wire 701 are wound up or down, and the cable 802 or the transmitting wire 401 is wound up.
A depth signal 801a indicating the depth of the transmitting antenna 403 and the receiving antenna 601 is provided to the processor 21 based on the detected amount of movement between the receiving antenna 701 and the receiving wire 701.

The display 22 displays the data of the depth value based on the depth signal 801a from the processor 21 and the data of the calculated value corresponding to the substantial change amount of the transmission time τ ₂ based on the calculated value signal 21a. In addition to performing digital display by character display, analog display by graph-like graphic display is performed.

Hereinafter, a description will be given of a processing procedure of an arithmetic processing for obtaining a calculated value corresponding to a substantial change amount of the transmission time τ ₂ by Fourier transform in the processor 21.

Here, in order to easily understand the arithmetic processing, a preamplifier circuit 2, an electric / optical conversion circuit 3, an optical / electric conversion circuit 5, a transmission circuit 6, a reception circuit 13, and an electric / optical conversion circuit 1
4. Disregarding the delay time in each circuit of the optical / electrical conversion circuit 16 and the post-amplifier circuit 17, the received signal 17
The transmission time τ ₁ and the transmission time τ
Considering the time amount τ ₁₁ of the sum of ₂ and the transmission time τ ₃ , the delay time τ _s of the fixed delay circuit 18 is set to the time amount τ ₁₅ obtained by adding the transmission time τ ₁ and the transmission time τ _3. I do.

Therefore,

(Equation 1) It is.

The promised waveform signal 1a is denoted by e ₁ , the signal output from the transmission unit 402, ie, the signal output from the transmission circuit 6 is denoted by e ₂ , the signal output from the reception unit 602, ie, the reception circuit 13 E ₃ ,
Assuming that the received signal 17a corresponding to the correlated signal is represented by e ₄ and the delayed signal 18a corresponding to the correlated signal is represented by e ₅ , each signal can be represented by the following equation.

[0061]

(Equation 2)

[0062] In addition, it represents a multiplication correlation signal 20a at E _1,
If the function for low-pass filtering is represented by LPF [],

(Equation 3)

Here, the second term of the equation of the last floor is eliminated by the low-pass filtering circuit 20, so that the multiplication correlation signal 20a output from the low-pass filtering circuit 20 is

(Equation 4) Can be expressed as

[0064] The promise waveform signal 1a, the sweep-type continuous FM signal having a variable frequency f _1, such as the frequency change of the FIG. 8, for example, indicating a concrete waveform, when there was a signal like the waveform of FIG. 2 Then, ω ₁ in the equation can be expressed as the following equation.

[0065]

(Equation 5) However, it is assumed that 0 ≦ t ≦ T.

Here,

(Equation 6) In other words, the frequency signal E ₁ output as the multiplication correlation signal 20a is

(Equation 7) Becomes

Then, from the equations and the equations,

(Equation 8) Is obtained.

Therefore, the beat frequency component f _b of the frequency signal E ₁ , that is, the beat frequency component that changes due to the change in the transmission time τ ₂ caused by the change in the geology of the underground 202 is:

(Equation 9) Introducing the formula, eventually,

(Equation 10) Can represent as the beat frequency component of this equation is not made to be included in the frequency signal E ₁ of the multiplication correlation signal 20a.

Τ ₁ τ ₃ τ _s in the equation is the transmission time τ ₁ by the transmission wire 401, the transmission time τ ₃ by the reception wire 701, and the promised waveform signal 1 a by the fixed delay circuit 18. Since the delay time amount τ _s , these are all fixed values. Therefore, the frequency signal E ₁ output as the multiplication correlation signal 20 a, that is, the signal of the equation is converted into digital value data obtained by A / D conversion by the processor 21. based, the power spectrum by Fourier transform, that is, it is possible to determine the beat frequency f _b when calculating the frequency power distribution.

Here, the Fourier transform is

[Equation 11] And the power spectrum

(Equation 12) Then

(Equation 13) Therefore, if the relationship of this equation is represented by a graph,
For example, by obtaining the phase change rate or frequency at which the power spectrum is maximized as shown in FIG. 3, the beat frequency f _b corresponding to the geology at the depth of the underground 202 currently being searched, that is, the beat frequency f _b , A value representing the frequency of the signal or its phase change can be determined.

In the above operation, the delay time value τ _s in the fixed delay circuit 18 is

[Equation 14] , The effective value in parentheses in the right term of the equation is

(Equation 15) And the change in beat frequency f _b is
It can be seen as the rate of change for the frequency corresponding to ₂ .

On the other hand, when the fixed delay circuit 18 is not provided, the value in parentheses is

(Equation 16) become.

Therefore, the change of the beat frequency f _b is
As compared with the case where viewed as the rate of change with respect to frequency corresponding to the tau _11,

[Equation 17] Underground 2
In other words, the change of the transmission time τ ₂ due to the change of the geology of 02 can be searched with the accuracy increased by the ratio of the equation.

[Second Embodiment] Hereinafter, a second embodiment will be described with reference to FIG. 4 have the same functions as those described with reference to FIGS. 1 to 3.

The second embodiment shown in FIG. 4 is a modification of the first embodiment shown in FIG. 1 in which the multiplication-correlation portion is changed to a multiplication configuration using two orthogonal phases.
3. A 90 ° multiplied correlation signal 25a obtained by filtering the multiplied signal 24a multiplied by the multiplying circuit 24 by the multiplying circuit 24 with the received signal 17a as the correlated signal using the promised waveform signal 23a shifted by 90 ° in 3 with the low-pass filter 25 is obtained. The configuration has been expanded.

[0076] 90 ° multiplied correlation signals 25a, since for the signal E ₁ of the formula equation becomes different signal E ₂ of 90 ° phase signal by the signal E ₂ and multiplied correlation signals 20a by the 90 ° multiplication correlation signals 25a E ₁ and the processor 2
1, the Fourier transform in the processor 21 is performed by the Fourier transform by orthogonal function expansion.

The first and second embodiments described above can be summarized as follows. The transmitting unit 402 and the transmitting antenna 40 are provided in one of the opposing searching holes 203 and 204 in the ground.
3 and the receiver 6 in the other search hole 204.
02 and the receiving antenna 601 are arranged, the electromagnetic wave 501 based on the promised waveform signal 1a is transmitted from the transmitting antenna 403, and the receiving signal 13a received by the receiving antenna 601 is transmitted.
In the borehole radar that obtains a required search signal 21a based on a multiplied correlation signal 20a or 20a / 25a obtained by multiplying and correlating the above-described promised waveform signal 1a as a correlation signal, the transmitting antenna 403 is hollow. A transmission cylinder in which the transmission unit 402 and the power source battery 9 for operating the transmission unit, that is, the transmission battery, are disposed inside the transmission cylinder. Body means and receiving antenna 6
01 is formed of a hollow cylindrical body, that is, a receiving cylindrical body, and the receiving unit 602 and the power supply battery 11 for operating the receiving unit, that is, the receiving battery are disposed inside the receiving cylindrical body. Receiving cylinder means and the transmitting cylinder described above
Of the receiving cylinder and the outer circumference of the receiving cylinder,
When the waterproof insulation of the wave insulation material, that is, when it is covered with the outer jackets 10 and 15,
In addition, a high-frequency insulating filler is placed inside each of the above waterproof covers.
A first configuration provided with an insulating filling means for filling ;

The borehole array in the first configuration described above
In a borehole radar similar to
03, two hollow cylindrical bodies 403a and 403b ,
The transmission cylinder pair is formed as a transmission dipole antenna using each antenna element, and the transmission section 402 is arranged inside one cylinder 403a of this transmission dipole antenna, and inside the other cylinder 403b. Transmission cylinder means for disposing the transmission battery 9 in the
To two hollow cylinders 601a and 601b ,
The receiving cylinder pair is formed as a receiving dipole antenna having each antenna element, and a receiving unit 60 is provided inside one cylindrical body 601a of the receiving dipole antenna.
2 Place a receiving cylinder means for arranging the reception battery 11 to the interior of the other of the cylindrical body 601b, the above transmission cylinder
The outer circumference of the body pair and the outer circumference of the receiving cylinder
And a high-frequency insulating waterproof cover, that is, an outer cover
Cover and high-frequency insulation inside each waterproof cover
A second configuration provided with insulating filling means for filling the filler ,

Further, the transmitting unit 402 is provided in one of the opposing search holes 203 and 204 in the ground as described above.
And a transmitting antenna 403, and a receiving unit 602 and a receiving antenna 601 are disposed in the other exploration hole 204. An electromagnetic wave 501 based on the promised waveform signal 1 a is transmitted from the transmitting antenna 402 and received by the receiving antenna 601. A signal based on the waved received signal 13a is set as a correlated signal,
In a borehole radar that obtains a required search signal 21a based on a multiplied correlation signal 20a or 20a and 25a obtained by multiplying and correlating the promised waveform signal 1a as a correlation signal, the promised waveform signal 1a is converted into an optical signal to guide light, that is, transmitted. A transmission wire means provided to the transmission unit 401 by the side light guide 401 and a reception light provided to the processing unit 301 for converting the reception signal 13a into an optical signal and performing a multiplication correlation by the reception light guide 701. The conductor means and the promised waveform signal 1a are compared at least with the transmission time τ ₁ of the promised waveform signal 1a in the portion of the transmission side light ray 401 and the reception side light ray 70.
A correlation signal means for obtaining a correlation signal based on a delay signal 18a obtained by delaying a time amount τ _s corresponding to a time amount obtained by adding the transmission time τ ₃ of the reception signal 13a in the portion 1 A third configuration,

[0080] In the third configuration described above, the delay length corresponding to the length obtained by adding at least the length L ₁ of the transmission side guide light 401 and the length L ₃ of the receiving side guide light 701 This is a fourth configuration provided with a correlation signal means obtained by a light guide having an appropriate length.

[Third Embodiment] The third embodiment will be described below with reference to FIG. The portions having the same reference numerals as those in FIGS. 1 to 4 in FIG. 5 are portions having the same functions as the portions having the same reference numerals described in FIGS.

In the structure of the third embodiment, the different points from the structure of the first embodiment are mainly the multiplication correlations arranged in the control processing / display unit 301 in the first embodiment of FIG. Of the processing part that performs
In the third embodiment shown in FIG. 5, the multiplying circuit 19 and the low-pass filtering circuit 20 corresponding to the part for performing the multiplying process are relocated and arranged on the receiving section 602 side. From the control processing / display unit 301 to the receiving unit 602, a path for providing the delay signal 18a obtained by delaying the signal 1a as a correlation signal is provided.
It is a part changed to give to the side.

Hereinafter, components of the configuration of FIG. 5 that are different from the configuration of FIG. 1 will be described in detail. The multiplying circuit 19 and the low-pass filtering circuit 20 ′ are arranged integrally with the receiving unit 602, and are operated by the power supply battery 11.
The receiving circuit 13 gives the received signal 13 a as one multiplication input of the multiplication circuit 19.

The delayed signal 18a 'given as the other multiplication input of the multiplication circuit 19 converts the promised waveform signal 1a into an optical signal 181a by an electro / optical conversion circuit 181 arranged in the control / display section 301, and outputs the optical signal 181a. Is delayed by an optical / electrical conversion circuit 183 and an amplification circuit 184 disposed integrally with the reception unit 602 via a delay conductor 182.

The amount of time τ _{s to be} delayed depends on the electrical / optical conversion circuit 1
81. The optical / electrical conversion circuit 183
As well as consists of the same photoelectric conversion circuit 5, by configuring in the same length L ₁ of the same material or the same standards and transmission conductor 401 a delay conductor 182, the optical signal 3a in the transmission conductor 401 And the same transmission time τ ₁ as shown in FIG. In addition, the amplifier circuit 184 includes the optical signal 181a.
Signal 183a obtained by converting the
Is amplified to an amplitude value suitable as the other input of the multiplication circuit 19.

However, the amount of time τ _{s to be} delayed is ideally equal to the transmission time τ ₁ for the same reason as described in the first embodiment.
And the delay time of the preamplifier circuit 2, the electrical / optical conversion circuit 3, the optical / electrical conversion circuit 5, the transmission circuit 6, and the reception circuit 13 are preferably set to the amount of time.

The multiplication circuit 19 is the same as the multiplication circuit 19 in the first embodiment shown in FIG.
In addition to performing the operation of the low-pass filtering circuit 20 in the first embodiment of FIG. 1, an amplifying function for obtaining an output obtained by amplifying the multiplying correlation signal 20a so that the electro-optical conversion circuit 14 can perform a required operation. Is added.

The electrical / optical conversion circuit 14 'is the same as the electrical / optical conversion circuit 14 of the first embodiment shown in FIG. 1, but in the third embodiment, the optical signal 14a of the multiplication correlation signal 20a' is used. ′
To the optical / electrical conversion circuit 1 via the receiving conductor 701 '.
6 ', the optical / electrical conversion circuit 16' outputs an optical signal 14a '.
Is converted into a multiplication correlation signal 16a 'by an electric signal and supplied to the subsequent amplification circuit 17'. The rear amplification circuit 17 'is configured to supply the multiplication correlation signal 20a amplified to a required amplitude value to the processor 21. The specific circuit components in these components are the same as those in the first embodiment shown in FIG.

Therefore, in the configuration of the third embodiment, the first
In the embodiment, the processing is performed in which the portion corresponding to the time amount τ ₃ of each of the equations (1) to ( ₃₎ is excluded.

[Fourth Embodiment] The fourth embodiment will be described below with reference to FIG. 6 have the same functions as those of FIGS. 1 to 5 and have the same functions as those of FIGS. 1 to 5.

The fourth embodiment shown in FIG. 6 is obtained by modifying the multiplication-correlation part in the third embodiment shown in FIG. 5 into a quadrature two-phase multiplication structure as in the second embodiment shown in FIG. ° A circuit similar to the phase shift circuit 23 and the multiplication circuit 24
And a low-pass filter circuit 20 ', an electric / optical conversion circuit 14', a receiving conductor 701 ', and an optical / electrical conversion circuit 16'.
A circuit system similar to the circuit system of the post-amplifier circuit 17 'is provided by a low-pass filter circuit 20 ", an electric / optical conversion circuit 14", a receiving wire 701 ", an optical / electric conversion circuit 16", and a post-amplifier circuit 17 ". To provide the latter-stage amplifier circuit 17 ″.
The configuration for obtaining a 90 ° multiplication correlation signal 25a by the output of (1) is added.

[0092] 90 ° multiplied correlation signals 25a, since for the signal E ₁ of the formula equation becomes different signal E ₂ of 90 ° phase, by the same manner as in the second embodiment of FIG. 4 the subsequent configuration, The Fourier transform in the processor 21 is performed by Fourier transform by orthogonal function expansion.

To summarize the configuration of the third embodiment and the fourth embodiment, the transmitting section 402 and the transmitting antenna 403 are provided in one of the opposing exploration holes 203 and 204 in the ground.
And the receiving unit 60 in the other search hole 204.
2 and the receiving antenna 601 are arranged, and the transmitting antenna 4
02, an electromagnetic wave 501 based on the promised waveform signal 1a is transmitted, a signal based on the received signal 13a received by the receiving antenna 601 is used as a correlated signal, and the multiplied correlation signal 20a obtained by multiplying and correlating the promised waveform signal 1a as a correlation signal or 2
In a borehole radar that obtains a required search signal 21a based on 0a and 25a, a transmission wire means for converting the promised waveform signal 1a into an optical signal 3a and providing a light beam, that is, a transmission wire means 401 to be provided to the transmission unit 402 by a transmission light beam 401. And at least a multiplication processing part of the processing unit for performing the multiplication correlation to obtain the search signal, that is, the multiplication circuit 19 and the low-pass filtering circuit 20 'are arranged integrally with the transmission unit 402,
Separately from the rest of the processing unit, that is, the multiply-correlation sub-setting means for arranging the processing processor 21 on the ground, and the transmission light guide means, the promised waveform signal 1a is converted into an optical signal 181a and the light guide 182, The promising waveform signal 1a is delayed by the use of the propulsion waveform signal 1a by at least a delay amount 18a 'obtained by delaying at least the time amount corresponding to the transmission time τ ₁ time amount of the promised waveform signal 1a in the portion of the transmission side transmission light beam 401. In addition, a processing unit for performing the above-described multiplication correlation, that is, a delay wire means provided to the multiplication correlation processing unit by the multiplication circuit 19 and the low-pass filtering circuit 20 ', and a part for performing the multiplication processing,
The signal obtained by the multiplying circuit 19 and the low-pass filtering circuit 20 'is converted into an optical signal 14a', and the rest arranged on the ground by the light guide 701 ', that is, the receiving light guide means to be given to the processor 21 is provided. A fifth configuration provided;

In the fifth configuration, the delay light guide 182 is formed at least by the length L of the transmission light guide 401.
_A sixth configuration in which a correlation signal means formed by a light guide beam having the same length as ₁ is provided.

[Modification] The present invention includes the following modifications. (1) The promised waveform signal 1a is changed into a sweep type continuous FM signal by stepwise continuous frequency modulation shown in FIG.

[0096] (2) a commitment waveform signal 1a, as shown in FIG. 10, during a short time Ta during the period TA, linear variable frequency f ₁ and the same signal in FIG. 8 or FIG. 9 configure and change the signal arrangement similar signals and variable frequency f ₁ of the stepped. Further, as shown by a thick dotted line in FIG. 10, a period in which frequency modulation is not performed is changed to a signal that is held at a constant frequency, for example, a frequency f ₀ .

(3) All or a part of the delay circuit 18 in the first and second embodiments is constituted by a fixed delay circuit using a surface acoustic wave element, a fixed delay circuit using an electric distributed constant circuit, or the like. I do.

(4) The multiplication components of the multiplication circuits 19 and 24 and the low-pass filtering circuits 20, 20 ', 20 "and 25 are as follows.
Delay signals 18a and 18a 'and 90 ° phase shift delay signal 23a
Is changed to a multiplication configuration by a sample-and-hold circuit that obtains a multiplication correlation signal by an output obtained by sampling and holding the reception signals 17a and 13a, using a signal obtained by pulsing the above as a sampling pulse.

(5) The processor / display is constituted by a personal computer to which a printer is added so that the processing result can be printed and stored.

(6) Transmission wire 401, reception wire 70
1, 701 ', 701 ", a winch 8 for winding and unwinding a light guide constituting the delay wire 182.
No. 01 is connected to the center of rotation of the rotating drum by relaying these light beams separately on the rotating side and the fixed side, and an optical rotary coupler, for example, a rotary joint for optical fiber is provided at the relay connecting part. I do.

[0101]

According to the present invention, the transmitting antenna and the receiving
Do not touch the inner surface of each hole by covering the antenna
The electrical characteristics of the antenna are stable,
The effect of improving the exploration ability is obtained.
Filled with wave insulating filler material,
The electrical characteristics of each circuit component
It is said that stable exploration can be performed even in deep holes
The effect is obtained. Furthermore, since the transmission conductor and the reception conductor are used as light guides to cut off the electrical connection between the equipment components on the ground and the equipment components under the ground, even if the ground is unbalanced, the induction Eliminate exploration obstacles such as interference
In addition, since the promised waveform signal is delayed and only the signal portion corresponding to the transmission time under the ground is correlated and the change rate of the phase change or frequency change portion due to the geology is improved, the geological exploration can be accurately performed. There are such features that the device can be provided at a low cost, such as detection, and the exploration cost can be reduced.

[Brief description of the drawings]

1 to 6 show an embodiment of the present invention, and FIGS.
10 show a conventional technique, and the contents of each figure are as follows.

FIG. 1 is an overall block configuration diagram

FIG. 2 is a signal waveform diagram of a main part.

FIG. 3 is a signal waveform diagram of a main part.

FIG. 4 is a block diagram of a main part.

FIG. 5 is a block diagram of a main part.

FIG. 6 is a block diagram of a main part.

FIG. 7 is a block diagram of the whole;

FIG. 8 is a signal waveform diagram of a main part.

FIG. 9 is a signal waveform diagram of a main part.

FIG. 10 is a signal waveform diagram of a main part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Variable frequency circuit 1a Promised signal 2 Preamplifier circuit 2a Promised waveform signal 3 Electric / optical conversion circuit 3a Optical signal 5 Optical / electrical conversion circuit 5a Promised waveform signal 6 Transmission circuit 6a Transmission signal 7 Matching transformer 9 Battery 10 Enclosure 10a Ground packing 11 Battery 12 Matching transformer 12a Received signal 13 Received circuit 13a Received signal 14 Electrical / optical converter 14 'Electrical / optical converter 14 "Electrical / optical converter 14a Optical signal 14a' Optical signal 14a" Optical signal 15 Outer sheath 15a Ground packing 16 Optical / electrical conversion circuit 16 'Optical / electrical conversion circuit 16 "Optical / electrical conversion circuit 16a Received signal 16a' Received signal 16a" Received signal 17 Rear-stage amplifier 17 'Rear-stage amplifier 17 "Rear-stage amplifier 17a Signal 18 Delay circuit 18a Delay signal 18a 'Delay signal 19 Multiplication circuit 19a Arithmetic signal 20 low-pass filter circuit 20 'low-pass filter circuit 20 "low-pass filter circuit 20a multiplication correlation signal 21 processor 21a calculated value signal 22 display 23 90-degree phase shift circuit 23a promised waveform signal 24 multiplication circuit 24a multiplication signal 25 Low-pass filtering circuit 25a Multiplied correlation signal 26 Power supply 100 Borehole radar 181 Electric / optical conversion circuit 181a Optical signal 182 Delay conductor 183 Optical / electric conversion circuit 183a Delay signal 184 Amplifying circuit 201 Ground 202 Underground 203 Exploration hole 204 Exploration hole 301 Control processing / display unit 401 Transmission wire 401a Promising waveform signal 402 Transmission unit 403 Transmission antenna 403a Cylindrical body 403b Cylindrical body 501 Electromagnetic wave 601 Receiving antenna 601a Cylindrical body 601b Cylindrical body 602 Receiving wire 701 Receiving wire 701 'Receiving wire 70 1 "lead for reception 701a reception signal 801 winch 801a depth signal

Continuation of front page (56) References JP-A-4-80684 (JP, A) JP-A-4-130294 (JP, A) JP-A-2-297089 (JP, A) JP-A-4-152286 (JP) , A) JP-A-4-52589 (JP, A) JP-A-63-190985 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01V 3/30 G01S 13/88

Claims (6)

(57) [Claims] 1. A transmitting unit and a transmitting antenna are arranged in one of two opposing exploration holes in the ground, and a receiving unit and a receiving antenna are arranged in the other exploration hole. An electromagnetic wave based on the waveform signal is transmitted, a signal based on the received signal received by the receiving antenna is used as a correlated signal, and a required search signal is generated based on a multiplied correlation signal obtained by multiplying and correlating the promised waveform signal as a correlation signal. A borehole radar, wherein the transmitting antenna is formed of a hollow cylindrical body (hereinafter, referred to as a transmitting cylindrical body), and the transmitting unit, and a power battery (hereinafter, referred to as a transmitting battery) for operating the transmitting unit. )
, A transmission cylinder means disposed inside the transmission cylinder, and the reception antenna formed of a hollow cylinder (hereinafter, referred to as a reception cylinder), and operating the reception section and the reception section. Power supply battery (hereinafter referred to as receiving battery)
A receiving cylinder means disposed inside the receiving cylinder, and an outer periphery of the transmitting cylinder and an outer periphery of the receiving cylinder.
Each is covered with a waterproof cover made of high-frequency insulation,
Insulation filler for filling high-frequency insulation filler inside the waterproof cover
And a filling means . (2)One exploration hole for each opposing exploration hole in the ground
Place the transmitting unit and transmitting antenna in the
A receiver and a receiving antenna are arranged in the hole, and
The antenna transmits an electromagnetic wave based on the promised waveform signal, and
A signal based on the received signal received by the receiving antenna is received.
A correlation signal, and multiply the promised waveform signal as a correlation signal
The required search signal is obtained based on the correlated multiplied correlation signal.
Borehole radar,  The transmitting antenna is a two hollow cylindrical body(Hereafter, send
(Cylinder pair)Transmission dipole with each antenna element
And the transmitting die
The transmitter is arranged inside one cylinder of the pole antenna.
Before placing the transmitting battery inside the other cylinder
The transmitting cylinder means and the receiving antenna are connected to two hollow cylinders.(Hereafter, reception
(Cylinder pair)Receiving die with each antenna element
Antenna, and the receiving die
The receiver is arranged inside one cylinder of the pole antenna.
Before placing the receiving battery inside the other cylinder
A receiving cylinder means;The outer circumference of the pair of transmission cylinders and the outer circumference of the pair of reception cylinders
Are covered with a waterproof covering made of high-frequency insulation, respectively.
Fill the inside of each waterproof cover with a high-frequency insulating filler
Insulation filling means and A borehole comprising:
Radar. 3. A transmitting unit and a transmitting antenna are arranged in one of two opposing exploration holes in the ground, and a receiving unit and a receiving antenna are arranged in the other exploration hole. An electromagnetic wave based on the waveform signal is transmitted, a signal based on the received signal received by the receiving antenna is used as a correlated signal, and a required search signal is obtained based on a multiplied correlation signal obtained by multiplying and correlating the promised waveform signal as a correlation signal. A borehole radar for converting the promised waveform signal into an optical signal, and providing the transmission unit with a light guide (hereinafter, referred to as a transmission light guide) to the transmitting unit; and converting the received signal into an optical signal. Receiving wire means to be provided to the processing unit by a light guide (hereinafter, referred to as a receiving light guide), and the promised waveform signal at least in the portion of the transmission light guide. A correlation signal that obtains the correlation signal based on a delay signal obtained by delaying a time amount corresponding to a time amount obtained by adding a transmission time of a shape signal and a transmission time of the reception signal in the portion of the reception-side light guide. Means, and a borehole radar. 4. The borehole radar according to claim 3, wherein said delay has a length corresponding to at least a sum of a length of said transmission-side guide beam and a length of said reception-side guide beam. A borehole radar comprising the correlation signal means obtained by: 5. A transmitting unit and a transmitting antenna are arranged in one of two opposing exploration holes in the ground, and a receiving unit and a receiving antenna are arranged in the other exploration hole. An electromagnetic wave based on the waveform signal is transmitted, a signal based on the received signal received by the receiving antenna is used as a correlated signal, and a required search signal is obtained based on a multiplied correlation signal obtained by multiplying and correlating the promised waveform signal as a correlation signal. A transmission line means for converting the promised waveform signal into an optical signal and providing the transmission unit with a light guide (hereinafter, referred to as a transmission-side light guide) to the transmission unit; A multiply-correlation part setting means for arranging at least a part of the processing part for obtaining the multiplication processing integrally with the reception part, and arranging the remaining part of the processing part on the ground. Separately from the transmission light guide means, the promised waveform signal is converted into an optical signal, and the promised waveform signal is converted into a light signal (hereinafter referred to as a delay light guide) by at least the promised signal at the transmission side light guide part. A delay amount obtained by delaying a time amount corresponding to the time amount of the transmission time of the waveform signal to a processing unit for performing the multiplication correlation, and a delay signal obtained by delaying the multiplication correlation. Borehole radar comprising: a receiving light guide unit for converting a signal into an optical signal and providing the converted signal to the rest disposed on the ground by a light guide. 6. The borehole radar according to claim 5, further comprising: the correlation signal means for forming the delay light guide by a light guide having at least the same length as the length of the transmitting light guide. Borehole radar characterized by the following.