JPH07120559A - Borehole radar - Google Patents

Abstract

PURPOSE:To cut down the excavation cost by reducing the diameter of a survey hole by miniaturizing an antenna part and to provide a borehole radar which can survey a slight difference in geology by detecting a very small difference in propagation of electromagnetic waves. CONSTITUTION:The borehole radar 100 surveys difference in geology by detecting a slight change in transmitting time of electromagnetic waves 501 transmitted through a ground. By providing a transmitter 402 and an operating battery 9 in a cylindrical transmitting antenna 403, and a receiver 602 and an operating battery 11 in a cylindrical antenna 601, induced interference is prevented to miniaturize the antenna part. A correlation signal of a promised waveform signal 1a delayed by transmitting time tau1+tau3 by a transmitting conductor 401 and a receiving conductor 701 is multiplied by and correlated with 19, 20 a correlation target signal by a receiving signal 17a, thereby, it is made possible that only a frequency change part by transmitting time tau2 in a ground is detected.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A borehole radar is a type of transmitting and receiving on-the-fly detection radar that searches for the status of buried objects, changes in the stratum, etc. in an underground transmission line between required points by means of transmitted waves of electromagnetic waves (also called passing waves).

In this type of borehole radar, in order to improve the search capability, a signal of a promise waveform that repeats at a required detection cycle is transmitted to the ground as a transmission signal, and a reception signal obtained by transmitting the ground is received. There is a configuration in which a correlation signal is used and a desired detection signal is obtained by performing correlation with the same signal as the promised waveform as a correlation signal for each detection cycle.

The arrangement of such a borehole radar is, for example, a borehole radar 100 shown in FIG. In FIG. 7, exploration holes 203 and 204 are holes drilled vertically in the ground 202.

A transmitting antenna 403 is provided in one exploration hole 203, and a receiving antenna 6 is provided in the other exploration hole 204.
01 is placed and the control process is placed on the ground 201.
From the display unit 301, while repeating the promised waveform signal 401a at a predetermined detection cycle, the transmission unit 4 via the transmission lead wire 401.
02, the electromagnetic wave 501 having the promised waveform signal is transmitted to the ground 202 at a predetermined detection cycle.

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 wire 701. give.

With the received signal 701a as the correlated signal and the promised waveform signal 401a as the correlation signal, the correlation processing function provided in the control processing / display unit 301 performs correlation at predetermined intervals to detect the object. Control processing of exploration signal /
A display function provided in the display unit 301 is used for displaying, and a transmitting antenna 403 and a receiving antenna 601 are provided.
By moving the and up and down while exploring, it is possible to investigate the geology at each mid-depth.

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 line in detail, the promised waveform signal 401a is converted into a signal having a large number of frequency components, and the received signal 70 for each frequency is
It is necessary to detect the difference in changes in 1a.

Therefore, 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 promise signal 401a.

Sweep type continuous F by linear continuous frequency modulation
The M signal is a signal in which the variable frequency f ₁ that linearly changes from the frequency f ₀ to the frequency (f ₀ + Δf) is repeated from time 0 to time T, like the frequency change in FIG. In the swept continuous FM signal by the stepwise continuous frequency modulation, the frequency gradually changes stepwise from the frequency f ₀ to the time Δt between the time 0 and the time T as in the frequency change in FIG. It is a signal that repeats the variable frequency f ₁ that changes to the frequency (f ₀ + Δf).

In the correlation detection type transmission line exploration apparatus 100 which uses the promised waveform signal based on such a swept continuous FM signal, in addition to the promised waveform signal 401a as the correlation signal,
The promised waveform signal 401a is shifted by π / 2, that is, 90 °, to form a promised waveform signal.
That is, two multiply correlated signals obtained by multiplying the two-phase correlation signal and the received signal 701a are inversely Fourier-transformed to obtain a target search signal, that is, a change in the frequency component or a phase component due to the characteristics of the transmission path. A configuration for obtaining a signal for requesting a change is based on the application of the applicant of the present application.
6 and the like.

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

[0013]

According to the above-mentioned prior art, firstly, the transmitting conductor wire 401 and the receiving conductor wire 7 are provided.
Since 01 is very long, unless the grounding configuration of each part is carefully performed, the ground imbalance between the transmission conductor wire 401 and the reception conductor wire 701, the ground imbalance between the transmission part 402 and the transmission antenna 403, the reception part 602, Due to the ground imbalance between the receiving antennas 601, the high-frequency signals in the respective unbalanced portions are inductively interfered with each other, which hinders the intended operation.

Secondly, between the transmitting portion 402 and the transmitting antenna 403 and between the receiving portion 602 and the receiving antenna 601, respectively, are provided in order to avoid harmful effects due to direct leakage or mutual interference. The outer diameter of the structure of this part becomes large because it is necessary to shield it, and it is necessary to mechanically connect and integrate these parts. However, there is an inconvenience that excavation of these holes requires a considerable amount of money and exploration requires a huge amount of money.

Thirdly, since the lengths of the transmission wire 401 and the reception wire 701 are very long, the phase change component in the detection signal detected by the correlation detection depends on the difference in the target geology. Since the phase change component based on the lengths of these conducting wires is contained in a much larger amount than the phase change component, there is a disadvantage that the phase change component due to geology cannot be detected accurately.

[0016] Therefore, there is a problem that it is desired to provide a simple and inexpensive structure that does not have such inconvenience.

[0017]

According to the present invention, a transmitting section and a transmitting antenna are arranged in one of the facing exploratory holes in the ground as described above, and a receiving section and a receiving antenna are provided in the other exploratory hole. Arranged, the electromagnetic wave based on the promised waveform signal is transmitted from the transmitting antenna, the signal based on the received signal received by the receiving antenna is used as the correlated signal, and the above-mentioned promised waveform signal is multiplied as the correlation signal. In the borehole radar to obtain a required search signal based on, the above-mentioned transmitting antenna is a hollow cylindrical body, that is, formed with a transmitting cylindrical body, the above-mentioned transmitting unit, a power supply battery for operating the transmitting unit, That is, the transmitting battery, the transmitting cylinder means arranged inside the transmitting cylinder, and the receiving antenna are formed by a hollow cylindrical body, that is, the receiving cylinder. And the receiving section, a power supply battery for operating the receiver unit, i.e., a reception cell, a first and a structure provided with a receiving cylinder means disposed inside the reception cylinder,

In the first structure, the transmitting antenna is formed as a transmitting dipole antenna having two hollow cylindrical bodies as respective antenna elements, and one cylindrical body of the transmitting dipole antenna is formed. A transmitting cylindrical body means for arranging the transmitting section inside and the transmitting battery for arranging the transmitting battery inside the other cylindrical body, and the receiving antenna for receiving using two hollow cylindrical bodies as respective antenna elements. A dipole antenna is formed, and a receiving cylinder means for arranging the above-mentioned receiving section inside one cylinder of this receiving dipole antenna and arranging the above-mentioned receiving battery inside the other cylinder is provided. And a second configuration,

In addition, the transmitting section and the transmitting antenna are arranged in one of the respective exploratory holes facing each other in the ground as described above, and the receiving section and the receiving antenna are disposed in the other exploratory hole so that the transmitting antenna promises. An electromagnetic wave based on a waveform signal is transmitted, the signal based on the received signal received by the receiving antenna is used as the correlated signal, and the required exploration signal is obtained based on the multiplied correlation signal obtained by multiplying the promised waveform signal as the correlation signal. In the borehole radar to be obtained, the above-mentioned promise waveform signal is converted into an optical signal into a light guide line, that is, a transmitting conductor means for giving to the transmitting section by the transmitting side light guide line, and the above received signal is converted into an optical signal into a light guide line. That is, at least at least the transmission-side light guide line is provided with the above-mentioned promise waveform signal and the receiving conductor means for giving to the processing unit for performing the above-mentioned multiplication correlation by the reception-side light guide line. Of the above-mentioned correlation signal based on the delay signal obtained by delaying the amount of time corresponding to the amount of time obtained by adding the transmission time of the promised waveform signal and the transmission time of the reception signal in the above-mentioned light guide line on the receiving side. A third configuration provided with the obtained correlation signal means,

In the third structure, the delay is caused by a light guide line having a length corresponding to at least the sum of the length of the transmission side light guide line and the length of the reception side light guide line. A fourth configuration provided with the obtained correlation signal means, and further, a transmitting unit and a transmitting antenna are arranged in one of the facing exploration holes in the ground, and a receiving unit and a receiving antenna are provided in the other exploration hole. , And sends an electromagnetic wave based on the promised waveform signal from the above-mentioned transmitting antenna, and the signal based on the received signal received by the above-mentioned receiving antenna is used as the correlated signal, and the above-mentioned promised waveform signal is multiplied as the correlation signal. In a borehole radar that obtains a required exploration signal based on a correlated multiplication correlation signal, converts the above-mentioned promise waveform signal into an optical signal and applies it to a light guide line, that is, a transmission side light guide line, and sends it to a transmission unit. At least a portion of the processing unit for performing the multiplication correlation and the above-mentioned exploration signal to perform the multiplication processing is arranged integrally with the reception unit, and the rest of the processing unit is arranged on the ground. Separately from the multiplying correlation part setting means and the transmitting light guide line means, the promise waveform signal is converted into an optical signal and the light guide line, that is,
The delay light guide line converts the promise waveform signal into a delay signal obtained by delaying at least a time amount corresponding to the time amount of the transmission time of the promise waveform signal in the transmission side light guide line portion, and Delaying lead wire means provided to the processing unit for performing the multiplication correlation, and receiving light guiding line means for converting the signal obtained by the above multiplication processing portion into an optical signal and giving it to the above-mentioned remaining portion arranged on the ground by the light guide line. And a correlation signal in which the delay light guide line is formed by a light guide line having at least the same length as the transmission side light guide line in the fifth configuration. A sixth configuration provided with means is provided to solve the above problems.

[0021]

According to the first configuration and the second configuration, the transmitter and the battery for the power source are arranged inside the cylindrical body forming the transmitting antenna, and the receiving section is arranged inside the cylindrical body forming the receiving antenna. Since these parts and the battery for the power supply are arranged, these parts are integrated inside the antenna itself, so there is no mutual interference in the antenna parts, and the outer diameter can be made smaller. You can finish the hole with a thin hole. Therefore, the device itself can be provided at a low cost, and the work of excavating the exploration hole can be reduced, so that the exploration cost can be reduced.

According to the third configuration, the fourth configuration, the fifth configuration, and the sixth configuration, since the transmission lead wire and the reception lead wire are formed by the light guide wires, the control processing / display unit This means that the electrical connection between ground-based equipment components such as this and ground-based equipment components such as transmitters and receivers is cut off, so even if the ground is unbalanced, induced interference may occur. It is not affected by exploration obstacles due to the fact that the promised waveform signal is delayed so that only the signal part corresponding to the transmission time in the ground is correlated and detected. Since the rate of change of the part is improved, the change component due to geology can be detected with high accuracy.

[0023]

EXAMPLES Examples will be described below with reference to FIGS.
In the configurations of FIGS. 1 to 6, the portions denoted by the same reference numerals as those in FIGS. 7 to 9 indicate the portions having the same functions as the portions having 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 creates a swept continuous FM signal by linear frequency modulation as shown in the frequency change of FIG. It is given to the amplifier circuit 2 and the fixed delay circuit 18. Promising waveform signal 1a
Specifically, for example, f ₀ = 10 MHz to f ₀ +
A signal having a variable frequency f ₁ up to Δf = 80 MHz.

The preamplifier circuit 2 performs preamplification for amplifying the promised waveform signal 1a to the extent that it can be transmitted to the transmission section 402, and supplies the amplified promised waveform signal 2a to the electrical / optical conversion circuit 3. .

The electric / optical conversion circuit 3 is a circuit for converting the promised waveform 2a by an electric signal into an optical signal, for example, a circuit for obtaining a target optical signal by a laser diode, and the optical signal of the converted promised waveform is used. Conductor 401 for transmitting signal 3a
Give to.

The operation power supply 26 is provided with a control processing / display unit 30.
1 is a power supply for operating each circuit, for example,
A power supply circuit that obtains a required voltage from a storage battery or a commercial power supply.

The transmission lead 401 is a light guide line, for example, a light guide line made of an optical fiber, and has a promise waveform.
a is a conducting wire for giving the photoelectric conversion circuit 5 of the transmitter 402 arranged remotely. Here, the optical signal 3a is transmitted through the transmission wire 4
The transmission time required to transmit the length L _{1 of} 01 is τ ₁
And

The optical / electrical conversion circuit 5 uses the optical signal 3 of the promised waveform.
It is a circuit for converting a into an electric signal, for example, a circuit for obtaining a target electric signal by a phototransistor, and the promise waveform signal 5a by the electric signal obtained by the conversion is given to the transmission circuit 6.

The transmission circuit 6 is a power amplification circuit that amplifies the promised waveform signal 5a to a required power required for transmission, and is, for example, a transistor amplification circuit, and the transmission signal 6a obtained by amplification is matched with a matching transformer. Give to 7. The battery 9 is a power supply independently provided for operating each circuit arranged in the transmission unit 402 including the transmission circuit 6, and is, 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, and the unbalanced side is connected to the transmitting circuit 6 and the balanced side is connected to the transmitting antenna 403. The electric power of the transmission signal 6a is converted from the transmission antenna 403 into the electromagnetic wave 501 having the promised waveform signal, and the electromagnetic wave 501 is transmitted to the transmission path in the ground 202.

The transmitting antenna 403 is a kind of dipole antenna, and each antenna element is formed on the 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, and the upper and lower arrangement intervals L are set.
₁₁ is adjusted to the feeding impedance, and the lengths L ₁₂ and L ₁₃ of the cylindrical bodies 403a and 403b are set to the transmission signal 3a.
Frequency, that is, a frequency slightly higher than the maximum frequency 80 MHz of the signal of the promised waveform, for example, 100
By setting the length so as to resonate at a wavelength of about MHz, each frequency component included in the promise waveform signal can be transmitted by an electromagnetic wave having a power as uniform as possible.

Cylindrical body 40 forming the transmitting antenna 403
3a and 403b, that is, in the hollow portion, inside the one cylindrical body 403a, the photoelectric conversion circuit 5 and the transmission circuit 6 are provided.
The parts constituting the transmission unit 402 such as
Inside the other cylindrical body 403b, a power supply battery for the transmitter 402, that is, the battery 9 is housed and arranged.

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 an FRP resin material, and a gland packing 10a for waterproofly penetrating the transmission conductor 401 is provided above the cylindrical body.

The structure in which the transmitting antenna 403 and the like are housed inside the outer cover 10 is, for example, a structure that can withstand water pressure at a deep depth in the exploration hole 203, and therefore has high-frequency insulation inside if necessary. It is filled with insulating oil or silicone rubber.

The electromagnetic wave 501 has power enough to reach the exploration hole 204 at a point separated by an underground transmission distance d suitable for the purpose of the underground exploration. Here, the electromagnetic wave 501 is equal to the underground transmission distance d. The transmission time required for transmission is τ ₂ .

The receiving antenna 601 is the transmitting antenna 40.
A dipole antenna having the same configuration as that of 3
It is formed by the conductor of two hollow cylindrical bodies 601a and 601b, is made of the same material as the transmitting antenna 403, and the arrangement interval L ₁₄ , the length L ₁₅ and the length L ₁₆ are the arrangement interval L ₁₁ and the length. The electromagnetic wave 501, which has the same structure as L ₁₂ and the length L ₁₃ , reaches through the transmission path in the ground 202.
The received signal obtained by receiving the signal 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, and the receiving antenna 601 receives the signal. The wave output is given from the matching transformer 12 to the receiving circuit 13 as a received signal 12a having a promised waveform.

The receiving circuit 13 pre-amplifies the received signal 12a so that the received signal 12a can be transmitted to the control processing / display section 301, and the electric / optical conversion circuit 14
Give to. The battery 11 is a power supply independently provided for operating each circuit arranged in the receiving unit 602 including the receiving circuit 13, and is, for example, an alkaline manganese dry battery.

The electric / optical conversion circuit 14 is a circuit for converting the received signal 13a by an electric signal into an optical signal, for example, a circuit for obtaining a target optical signal by a laser diode, and the converted received signal light is used. The signal 14a is applied to the receiving conductor 701.

The receiving conductor 701 is a light guide line, for example, a light guide line made of an optical fiber, and has a promise waveform.
4a is a lead wire for giving the photoelectric conversion circuit 16 of the control processing / display unit 301 arranged remotely. Where the optical signal 14
Let τ ₃ be the transmission time required to transmit a for the length L ₃ of the receiving conductor 701.

A cylindrical body 60 forming the receiving antenna 601.
In the inside of 1a and 601b, that is, in the hollow portion, a portion of the cylindrical portion 601a that constitutes the receiving portion 602 such as the electric / optical conversion circuit 14 and the receiving circuit 13 is housed and arranged, and Inside the cylindrical body 601b of the transmitter 402
The battery for power supply, 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 an FRP resin material, and a gland packing 15a for waterproofly penetrating the receiving conductor 701 is provided above the cylindrical body.

The structure in which the receiving antenna 601 and the like are housed inside the outer cover 15 is the same as the structure 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 desired electric signal by a phototransistor, and an electric signal obtained by the conversion. The received signal 16a as a signal is given to the post-stage amplifier circuit 17.

The post-stage amplifier circuit 17 is an amplifier circuit that amplifies the received signal 16a to a required voltage necessary for performing the multiplication correlation, and is, for example, a transistor amplifier circuit, and the amplified received signal 17a is multiplied by the multiplier circuit 19. It is given as one multiplication input of.

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

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

However, in this case, in the beat component, the total amount of transmission time τ ₁ , transmission time τ ₂ and transmission time τ ₃ is τ ₁₁ τ ₁₁ = τ ₁ + τ ₂ + τ ₃ , Preamplifier circuit 2, electric / optical conversion circuit 3, optical / electrical conversion circuit 5, transmission circuit 6, reception circuit 13, electric / optical conversion circuit 14
The time of the sum of the delay time in each circuit of the optical / electrical conversion circuit 16 and the post-stage amplification circuit 17 and the time amount τ ₁₂ , that is, the component due to the total delay time τ ₁₃ τ ₁₃ = τ ₁₁ + τ ₁₂ is included. Therefore, the change rate of the change of the beat component due to the change of the transmission time τ ₂ in the ground 202 is
Since the rate of change is with respect to this total delay time τ ₁₃ , the rate of change to be detected will eventually decrease.

Therefore, the promised waveform signal 1a is given to the fixed delay circuit 18 to delay it. Ideally, this delay is calculated from the above total delay time τ ₁₃ to the transmission time τ ₂ in the ground 202.
The delay signal 18a delayed by the amount of time τ ₁₄ τ ₁₄ = τ ₁₃ −τ ₂ should be applied to the multiplication circuit 19 as a multiplication input. However, in order to simplify the configuration, the delay circuit 18 The delay time amount τ _s is at least a time amount τ ₁₅ τ _s = τ ₁ + τ ₃ = τ ₁₅ that is the sum of the transmission time τ ₁ and the transmission time τ ₃ , and preferably up to the above time amount τ _14. Delay time. However, here we briefly describe the transmission time τ
It is delayed by the amount of time τ ₁₅ , which is the sum of ₁ and the transmission time τ ₃ .

The delay circuit 18 is, for example, a delay line using a light guide line made of an optical fiber similar to the transmission line configured by the electric / optical conversion circuit 3, the transmission conductor 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 was done like this. That is, the light guide line used for the delay circuit 18, the light guide line used for the transmission conductor 401, and the light guide line used for the reception conductor 701 are all made of the same material or the same standard, that is, the same material or the same standard optical fiber. As a result, each transmission time and delay time can be easily matched by simply setting the length to a predetermined length.

The multiplication circuit 19 is, for example, a multiplication circuit (also referred to as a double balance type multiplication circuit) using a double balance mixer (DBM) and multiplies the amplitude value of one multiplication input and the amplitude value of the other multiplication input. Is a circuit for outputting a signal of an amplitude value obtained as a multiplication signal, and low-pass filters a multiplication signal 19a obtained by multiplying a received signal 17a corresponding to a correlated signal and a delayed signal 18a corresponding to a correlation signal. It is given to the circuit 20.

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

The processor 21 is, for example, a processor that performs a Fourier transform by a microcomputer, and performs a Fourier transform on the basis of the digital value data obtained by sampling the multiplied correlation signal 20a to obtain the multiplied correlation signal 20a. By calculating the main frequency component, that is, the beat frequency f _b obtained by beat detection, a calculated value corresponding to the substantial amount of change in the transmission time τ ₂ is calculated, which is obtained based on this calculated value. The signal is given to the display 22 as the calculated value signal 21a.

The winch 801 includes a cable 802 (not shown) or a transmission lead 401 connected to the outer cover 10 and the outer cover 15 for moving the outer cover 10 and the outer cover 15 up and down.
And the lead wire 701 for receiving and winding up or down, and the cable 802 or the lead wire 401 for transmitting
A depth signal 801a indicating the depths of the transmitting antenna 403 and the receiving antenna 601 is given to the processor 21 based on the detected amount of movement of the receiving conductor 701 and the receiving conductor 701.

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

The processing steps of the arithmetic processing for obtaining the calculated value corresponding to the substantial change amount of the transmission time τ ₂ by the Fourier transform in the processor 21 will be described below.

Here, in order to easily and easily understand the arithmetic processing, the preamplification circuit 2, the electric / optical conversion circuit 3, the optical / electrical conversion circuit 5, the transmission circuit 6, the reception circuit 13, the electric / optical conversion circuit 1 are provided.
4. The delay time in each circuit of the optical / electrical conversion circuit 16 and the post-amplification circuit 17 is ignored, and the received signal 17 from the promised waveform 1a
The delay time up to a is the transmission time τ ₁ and the transmission time τ
₂ and the transmission time τ _{3 are} considered as the total amount of time τ ₁₁ , and the delay time τ _s of the fixed delay circuit 18 is set to the amount of time τ ₁₅ which is the sum of the transmission time τ ₁ and the transmission time τ _3. To do.

Therefore,

[Equation 1] Is.

Then, the promise waveform signal 1a is e ₁ , the signal output from the transmitting section 402, that is, the signal output from the transmitting circuit 6 is e ₂ , the signal output from the receiving section 602, that is, the receiving circuit 13 The signal output from e ₃ ,
If 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]

Further, the multiplication correlation signal 20a is represented by E ₁ .
If the low-pass filtering function is represented by LPF [],

[Equation 3]

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

[Equation 4] Can be expressed as

The promised waveform signal 1a is a swept continuous FM signal having a variable frequency f ₁ such as the frequency change of FIG. 8, for example, a concrete waveform shows that the signal has the waveform of FIG. Then, ω ₁ in the equation can be expressed as the following equation.

[0065]

[Equation 5] However, 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

From the formula and the formula,

[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 that accompanies the change in the geology of the ground 202, is

[Equation 9] And when we introduce the formula, finally,

[Equation 10] The beat frequency component of this equation is included in the frequency signal E ₁ of the multiplication correlation signal 20a.

Then, τ ₁ · τ ₃ · τ _s in the equation is the transmission time τ ₁ by the transmission conductor 401, the transmission time τ ₃ by the reception conductor 701, and the promised waveform signal 1 a by the fixed delay circuit 18. Since they are delay time amounts τ _s , all of them are fixed values, so the frequency signal E ₁ output as the multiplication correlation signal 20a, that is, the signal of the equation is converted into digital value data by A / D conversion by the processor 21. Based on the Fourier transform, the beat frequency f _b can be obtained by calculating the power spectrum, that is, the frequency power distribution.

Here, the Fourier transform is

[Equation 11] And the power spectrum

[Equation 12] Then,

[Equation 13] Therefore, if you express the relationship of this formula in a graph,
For example, as shown in FIG. 3, by obtaining the phase change rate or frequency that maximizes the power spectrum, the beat frequency f _b corresponding to the geology at the depth of the underground 202 currently being searched, that is, the beat frequency It will be possible to obtain a value representing the frequency of the signal or its phase change.

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

[Equation 14] Since it is set to, the actual value in () of the right term in the equation is

[Equation 15] Therefore, the change in the beat frequency f _b is
It can be seen as the rate of change with respect to the frequency corresponding to ₂ .

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

[Equation 16] become.

Therefore, the change of the beat frequency f _b is
Compared with the case of looking at the rate of change with respect to the frequency corresponding to τ ₁₁ ,

[Equation 17] Since it will be seen in the ratio enlarged by the ratio of 2
Therefore, the change in the transmission time τ ₂ due to the change in the geology of No. 02 can be explored with the accuracy increased by the ratio of the formula.

[Second Embodiment] A second embodiment will be described below with reference to FIG. Parts in FIG. 4 that are the same as the parts in FIG. 1 to FIG. 3 have the same functions as the parts in FIG. 1 to FIG.

The second embodiment shown in FIG. 4 is obtained by modifying the multiplication correlation portion of the first embodiment shown in FIG. 1 into a multiplication configuration using two orthogonal phases, and the promise waveform signal 18a is shifted by 90 °.
The promised waveform signal 23a phase-shifted by 90 ° in 3 is used as a correlation signal, the received signal 17a is used as a correlated signal, and the multiplication signal 24a multiplied by the multiplication circuit 24 is filtered by the low-pass filtering circuit 25 to obtain a 90 ° multiplication correlation signal 25a. This is an additional configuration.

[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 processor 2
By giving it to 1, the Fourier transform in the processor 21 is performed by the Fourier transform by the orthogonal function expansion.

In summary of the first and second embodiments described above, the transmitting section 402 and the transmitting antenna 40 are provided in one of the exploratory holes 203 and 204 in the ground facing each other.
3 and the receiving portion 6 in the other exploration hole 204.
02 and the receiving antenna 601 are arranged, the transmitting antenna 403 transmits the electromagnetic wave 501 based on the promised waveform signal 1a, and the receiving antenna 601 receives the received signal 13a.
In the borehole radar, the transmitting antenna 403 is hollow in the borehole radar in which the signal based on the signal is a correlated signal 17a, and the required correlation signal 17a is the correlation signal, and the required correlation signal 20a is obtained based on the multiplied correlation signal 20a or 20a · 25a. Of the transmission cylinder, and the transmission unit 402 and the power supply battery 9 for operating the transmission unit, that is, the transmission battery, are arranged inside the transmission cylinder. Body means and receiving antenna 6
01 is formed of a hollow cylinder, that is, a receiving cylinder, and the receiving unit 602 and the power supply battery 11 for operating the receiving unit, that is, the receiving battery are arranged inside the receiving cylinder. And a receiving cylinder means for

In the first structure, the transmitting antenna 403 is formed as a transmitting dipole antenna having two hollow cylindrical bodies 403a and 403b as respective antenna elements, and one cylinder of the transmitting dipole antenna is formed. Transmitting section 402 is arranged inside body 403a and transmitting battery 9 is arranged inside the other cylindrical body 403b, and receiving antenna 601 and two hollow cylindrical bodies 601a and 601b are provided as antenna elements. The receiving portion 602 is formed inside the cylindrical body 601a of the receiving dipole antenna, and the receiving battery 11 is arranged inside the other cylindrical body 601b of the receiving dipole antenna. A second arrangement having a cylindrical body means;

In addition, the transmitting unit 402 is installed in one of the facing search holes 203 and 204 in the ground as described above.
And a transmitting antenna 403 are arranged, and a receiving section 602 and a receiving antenna 601 are arranged in the other exploration hole 204, and an electromagnetic wave 501 based on the promised waveform signal 1a is transmitted from the transmitting antenna 402 and received by the receiving antenna 601. A signal based on the received signal 13a that has been waved is used as a correlated signal,
In a borehole radar that obtains a required exploration signal 21a based on a multiplied correlation signal 20a or 20a and 25a that has been subjected to multiplication correlation using the promised waveform signal 1a as a correlation signal, the promised waveform signal 1a is converted into an optical signal by a light guide line, that is, transmission. A transmission conductor means for giving to the transmission unit 401 by the side light guide line 401, and a reception conductor given to the processing unit 301 for converting the received signal 13a into an optical signal and conducting the light guide line, that is, the reception side light guide line 701. The conductor means and the promised waveform signal 1a are transmitted at least at the transmission side light guide line 401 at the transmission time τ ₁ of the promised waveform signal 1a and the reception side light guide line 70.
Correlation signal means for obtaining a correlation signal based on the delay signal 18a obtained by delaying the time amount τ _s corresponding to the 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 It has a fourth configuration in which correlation signal means obtained by a light guide line having a height is provided.

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

In the configuration of the third embodiment, the structural points different from those of the first embodiment are mainly the multiplication correlations arranged in the control processing / display unit 301 in the first embodiment of FIG. The first part of the processing part that performs
In the third embodiment of FIG. 5, in the third embodiment of FIG. 5, the multiplication circuit 19 and the low-pass filtering circuit 20 corresponding to the multiplication processing part are moved to the receiving unit 602 side, and the promised waveform signal A path for giving the delayed signal 18a obtained by delaying 1a as a correlation signal is controlled from the control processing / display unit 301 to the receiving unit 602.
This is the part changed to give to the side.

The components of the configuration of FIG. 5 different from the configuration of FIG. 1 will be specifically described below. The multiplying circuit 19 and the low-pass filtering circuit 20 'are arranged integrally with the receiving section 602 so that they can be operated by the power supply battery 11.
The reception circuit 13 gives the reception signal 13a as one multiplication input of the multiplication circuit 19.

The delay signal 18a 'provided as the other multiplication input of the multiplication circuit 19 is converted into the optical signal 181a by the electric / optical conversion circuit 181 arranged in the control processing / display unit 301, and the optical signal 181a is obtained. Is delayed by an optical / electrical conversion circuit 183 and an amplification circuit 184 arranged integrally with the receiving unit 602 via a delay conductor 182.

The delay time τ _s is determined by the electro-optical conversion circuit 1
81. Optical / electrical conversion circuit 183 is converted to electric / optical conversion circuit 3 / optical /
The optical signal 3a in the transmission conductor 401 is constituted by the same structure as the electrical conversion circuit 5 and the delay conductor 182 is made of the same material or the same standard as the transmission conductor 401 and has the same length L _1. Is the same as the transmission time τ ₁ . Further, the amplifier circuit 184 uses the optical signal 181a.
Signal 183a converted by the optical / electrical conversion circuit 183
Is amplified to an amplitude value suitable as the other input of the multiplication circuit 19.

However, the delay time τ _s is ideally the transmission time τ ₁ for the same reason as described in the first embodiment.
And the delay time by the preamplification circuit 2, the electric / optical conversion circuit 3, the optical / electrical conversion circuit 5, the transmission circuit 6, and the reception circuit 13 are preferably set.

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

The electric / optical conversion circuit 14 'is the same as the electric / 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. ′
Via the receiving lead wire 701 '.
6 ', and the optical / electrical conversion circuit 16' supplies the optical signal 14a '.
Is converted into a multiplied correlation signal 16a 'by an electric signal and given to a post-stage amplification circuit 17'. The post-stage amplification circuit 17 'is configured to give a multiplication correlation signal 20a amplified to a required amplitude value to a processor 21. The specific circuit components in each of these components are the same as those in the first embodiment shown in FIG.

Therefore, in the configuration of the third embodiment, the first
The processing is performed by removing the portion corresponding to the time amount τ ₃ in each of the expressions (1) to ( ₃₎ in the embodiment.

[Fourth Embodiment] The fourth embodiment will be described below with reference to FIG. The parts in FIG. 6 that are the same as the parts in FIG. 1 to FIG. 5 have the same functions as the parts in FIG.

The fourth embodiment of FIG. 6 is a modification of the multiplication correlation portion of the third embodiment of FIG. 5 into a multiplication structure with orthogonal two phases, similarly to the second embodiment of FIG. ° A circuit similar to the phase shift circuit 23 / multiplication circuit 24 is provided in the receiving unit 602.
And a low pass filter circuit 20 ', an electric / optical conversion circuit 14', a receiving conductor 701 ', and an optical / electric conversion circuit 16'.
-A circuit system similar to the circuit system by the post-stage amplification circuit 17 'is used as a low-pass filter circuit 20 ", an electric / optical conversion circuit 14", a receiving conductor 701 ", an optical / electric conversion circuit 16", and a post-stage amplification circuit 17 ". By providing the following amplification circuit 17 ″
Is added to the configuration for obtaining the 90 ° multiplication correlation signal 25a by the output.

Since the 90 ° multiplication correlation signal 25a becomes a signal E ₂ having a 90 ° phase difference with respect to the signal E _{1 of the} equation, by making the subsequent configuration similar to that of the second embodiment of FIG. The Fourier transform in the processor 21 is performed by the Fourier transform by the orthogonal function expansion.

To summarize the configurations of the above-described third and fourth embodiments, the transmitting section 402 and the transmitting antenna 403 are provided in one of the facing exploration holes 203 and 204 in the ground.
And the receiving section 60 in the other exploration hole 204.
2 and the receiving antenna 601 are arranged, and the transmitting antenna 4
An electromagnetic wave 501 based on the promised waveform signal 1a is transmitted from 02, a signal based on the received signal 13a received by the receiving antenna 601 is used as a correlated signal, and the promised waveform signal 1a is used as a correlation signal. Two
In the borehole radar that obtains the required search signal 21a based on 0a and 25a, the promise waveform signal 1a is converted into the optical signal 3a, and a light guide line, that is, a transmission lead wire unit that is provided to the transmission unit 402 by the transmission side light guide line 401. , At least the multiplication processing part of the processing part 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 part 402,
The remaining part of the processing section, that is, the multiplication correlation partial setting means for arranging the processor 21 on the ground, and the transmission light guide line means are separately provided to convert the promise waveform signal 1a into the optical signal 181a to guide the light guide line 182, that is, the delay. The delay signal 18a ′ obtained by delaying the promised waveform signal 1a by at least a time amount corresponding to the transmission time τ ₁ time amount of the promised waveform signal 1a in the transmission side light guide line 401 portion by the light guide line for Then, the processing unit for performing the above-described multiplication correlation, that is, the delay lead means provided to the multiplication correlation processing unit by the multiplication circuit 19 and the low-pass filtering circuit 20 ', and the portion for performing the multiplication processing, that is,
A signal obtained by the multiplication circuit 19 and the low-pass filtering circuit 20 'is converted into an optical signal 14a' and the remaining portion arranged on the ground by the light guide line 701 ', that is, a light guide line means for reception given to the processor 21 is provided. A fifth configuration provided,

In the fifth structure, the delaying light guide line 182 is at least the length L of the transmitting side light guide line 401.
The sixth configuration is provided with the correlation signal means formed by the light guide line having the same length as ₁ .

[Modified Implementation] The present invention includes the following modified implementations. (1) The promise waveform signal 1a is changed to a swept continuous FM signal by stepwise continuous frequency modulation shown in FIG.

(2) As shown in FIG. 10, the promise waveform signal 1a is the same signal as the linear variable frequency f ₁ of FIG. 8 during a short time Ta in the period TA, or FIG. A signal similar to the stepped variable frequency f _{1 of} FIG. Further, as shown by a thick dotted line in FIG. 10, the period in which frequency modulation is not performed is changed to a signal which is held at a constant frequency, for example, the frequency f ₀ .

(3) All or 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 or a fixed delay circuit using an electric distributed constant circuit. To do.

(4) The multiplication components by the multiplication circuits 19, 24 and the low-pass filtering circuits 20, 20 ', 20 ", 25 are
The delay signals 18a and 18a 'and the 90 ° phase shift delay signal 23a
The pulsed signals are used as sampling pulses, and the sampled hold circuit is used to obtain a multiplied correlation signal from the output obtained by sample-holding the received signals 17a and 13a.

(5) The processing processor and the display are constituted by a personal computer with a printer added, and the processing results can be printed and stored.

(6) Transmission conductor 401, reception conductor 70
1.701 ′ · 701 ″, a winch 8 for winding up and down a light guide wire that constitutes the delay conductor 182
The light guide line is divided into a rotating side and a fixed side by relay connection at the center of rotation of the rotary drum 01, and an optical rotary coupler such as an optical fiber rotary joint is provided at this relay connection part. To do.

[0101]

According to the present invention, the transmitter and its power supply battery are arranged inside the transmitting antenna cylinder, and the receiver and its power supply battery are arranged inside the receiving antenna cylinder.
Since the part that enters the exploration hole is integrated, mutual interference in the antenna part can be eliminated and the outer diameter can be reduced, and it is possible to perform exploration even with a thin exploration hole. In addition, since the transmission lead wire and the reception lead wire are used as light guide wires to cut off the electrical connection between the ground equipment component and the ground equipment component, even if the ground is unbalanced, induction is required. There is no interference such as interference,
Also, by delaying the promised waveform signal and correlating only the signal part corresponding to the transmission time in the ground, the rate of change of the phase change or frequency change part due to geology is improved, so geological exploration can be performed accurately. It has the features of being able to detect the device, providing the device at low cost, and reducing the cost of exploration.

[Brief description of drawings]

1 to 6 show an embodiment of the present invention, and FIG.
10 shows the prior art, 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 essential parts.

FIG. 3 is a signal waveform diagram of essential parts.

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

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

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

FIG. 7 is an overall block configuration diagram.

FIG. 8 is a signal waveform diagram of essential parts.

FIG. 9 is a signal waveform diagram of essential parts.

FIG. 10 is a signal waveform diagram of essential parts.

[Explanation of symbols]

 1 variable frequency circuit 1a promise signal 2 preamplifier circuit 2a promise waveform signal 3 electrical / optical conversion circuit 3a optical signal 5 optical / electrical conversion circuit 5a promise waveform signal 6 transmission circuit 6a transmission signal 7 matching transformer 9 battery 10 outer cover 10a Ground packing 11 Battery 12 Matching transformer 12a Received signal 13 Received circuit 13a Received signal 14 Electro-optical conversion circuit 14 'Electro-optical conversion circuit 14 "Electro-optical conversion circuit 14a Optical signal 14a' Optical signal 14a" Optical signal 15 Outer cover 15a gland 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 post-stage amplification circuit 17 'post-stage amplification circuit 17 "post-stage amplification circuit 17a reception Signal 18 delay circuit 18a delay signal 18a 'delay signal 19 multiplication circuit 19a Calculation signal 20 Low-pass filtering circuit 20 'Low-pass filtering circuit 20 "Low-pass filtering circuit 20a Multiplication correlation signal 21 Processing processor 21a Calculated value signal 22 Display 23 90 ° Phase shift circuit 23a Promise waveform signal 24 Multiplication circuit 24a Multiplication signal 25 Low-pass filtering circuit 25a Multiplying correlation signal 26 Power supply 100 Borehole radar 181 Electric / optical conversion circuit 181a Optical signal 182 Delay lead wire 183 Optical / electrical conversion circuit 183a Delay signal 184 Amplification circuit 201 Ground 202 Underground 203 Exploration hole 301 Exploration hole 301 Control processing / display unit 401 Transmission conductor 401a Promising waveform signal 402 Transmission unit 403 Transmission antenna 403a Cylindrical body 403b Cylindrical body 501 Electromagnetic wave 601 Reception antenna 601a Cylindrical body 601b Cylindrical body 602 Reception unit 701 Reception conductor 701 'Reception conductor 70 1 ″ reception conductor 701a reception signal 801 winch 801a depth signal

Claims (6)

[Claims] 1. A transmission unit and a transmitting antenna are arranged in one of the facing exploration holes in the ground, and a receiving unit and a receiving antenna are arranged in the other exploration hole so that the transmission antenna promises. An electromagnetic wave based on a waveform signal is transmitted, and a signal based on the received signal received by the receiving antenna is set as a correlated signal, and the required exploration signal is obtained based on a multiplied correlation signal obtained by multiplying and correlating the promised waveform signal as a correlation signal. In the obtained borehole radar, the transmitting antenna is formed of a hollow cylinder (hereinafter referred to as a transmitting cylinder), and the transmitting unit and a power supply battery for operating the transmitting unit (hereinafter referred to as a transmitting battery). )
And transmitting cylinder means arranged inside the transmitting cylinder, and forming the receiving antenna with a hollow cylindrical body (hereinafter referred to as receiving cylinder), and operating the receiving section and the receiving section. Battery for power supply (hereinafter referred to as receiving battery)
And a receiving cylinder means disposed inside the receiving cylinder, the borehole radar. 2. The borehole radar according to claim 1, wherein the transmitting antenna is formed as a transmitting dipole antenna using two hollow cylindrical bodies as respective antenna elements, and one of the transmitting dipole antennas is formed. The transmitting cylindrical body means for arranging the transmitting section inside the cylindrical body and the transmitting battery inside the other cylindrical body, and the receiving antenna for receiving two hollow cylindrical bodies as respective antenna elements. A receiving dipole antenna, the receiving dipole antenna includes the receiving portion disposed inside one cylindrical body of the receiving dipole antenna, and the receiving battery means disposed inside the other cylindrical body of the receiving battery. A borehole radar characterized by: 3. A transmission unit and a transmission antenna are arranged in one of the facing exploration holes in the ground, and a receiving unit and a receiving antenna are arranged in the other exploration hole, so that the transmission antenna promises. An electromagnetic wave based on a waveform signal is transmitted, and a signal based on the received signal received by the receiving antenna is set as a correlated signal, and the required exploration 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 obtaining, comprising: a transmission conductor means for converting the promised waveform signal into an optical signal and giving it to the transmitter by a light guide line (hereinafter, referred to as a transmission side light guide line); and converting the received signal into an optical signal. Light guide line (hereinafter, referred to as “receiver-side light guide line”) to the processing section, and the promise waveform signal, at least the promise wave signal in the transmission side light guide line. Correlation signal for obtaining the correlation signal based on a delay signal obtained by delaying a time amount corresponding to the time amount obtained by adding the transmission time of the shape signal and the transmission time of the reception signal in the receiving side light guide line portion. A borehole radar comprising: 4. The borehole radar according to claim 3, wherein the delay has a length corresponding to at least a length obtained by adding a length of the transmission side light guide line and a length of the reception side light guide line. A borehole radar comprising the correlation signal means obtained by 5. The transmission antenna and the receiving antenna are arranged in one of the opposite exploration holes in the ground, and the receiving unit and the receiving antenna are arranged in the other exploration hole, so that the transmission antenna promises. An electromagnetic wave based on a waveform signal is transmitted, and a signal based on the received signal received by the receiving antenna is set as a correlated signal, and the required exploration 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 obtaining, wherein the promise waveform signal is converted into an optical signal, and is provided to the transmitting unit by a light guide line (hereinafter, referred to as a transmission side light guide line); At least a portion of the processing unit for performing the multiplication is arranged integrally with the receiving unit, and the remaining part of the processing unit is arranged on the ground. Separately from the transmission light guide line means, the promise waveform signal is converted into an optical signal, and the promise waveform signal is promised at least at the transmission side light guide line by a light guide line (hereinafter, referred to as a delay light guide line). The delay signal is obtained by delaying a time amount corresponding to the time amount of the transmission time of the waveform signal and is given to the processing unit for carrying out the multiplication correlation, and is obtained by the multiplication processing unit. A borehole radar for receiving, which comprises: a receiving light guide line means for converting a signal into an optical signal and giving it to the remaining portion arranged on the ground by a light guide line. 6. The borehole radar according to claim 5, further comprising the correlation signal means for forming the delay light guide line by a light guide line having at least the same length as the transmission side light guide line. Borehole radar characterized by.