JP3361183B2 - Correlation detection type transmission line search device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correlation for obtaining a search signal by correlating a received signal obtained through a transmission line in order to detect the state of the transmission line between two predetermined fixed points. Type transmission path exploration apparatus, for example, a correlation detection type transmission path exploration apparatus for exploring the geological condition between points in the ground by the passage characteristics of electromagnetic waves, that is, a correlation detection type borehole radar.

[0002]

2. Description of the Related Art As an apparatus of this type, a transmission path may be a cable, a dielectric, underground, etc., and a transmission signal for exploration may be an electric signal, an ultrasonic signal, an electromagnetic wave, etc. Then, in order to simplify the explanation, the transmission path is underground, and the transmission signal for exploration is used as a transmitted wave of electromagnetic waves (also called a passing wave). A specific example will be described by taking a borehole radar for exploring the geological condition of the above as an example.

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 configuration of such a borehole radar is, for example, a borehole radar 100 shown in FIG. In FIG. 9, exploration holes 203 provided at two locations
-204 is the underground 2 corresponding to the transmission line for conducting the exploration
It is a hole drilled vertically in 02.

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.

In other words, the electromagnetic wave 501 corresponds to a transmission signal for exploring the underground 202, and the transmitting unit 402 and the transmitting antenna 403 serve as a transmitting portion for exploring the underground 202.
In addition, the receiving antenna 601 and the receiving unit 602 are
Corresponds to the receiving part for exploring.

Then, the received signal 701a is used as a correlated signal and the promised waveform signal 401a is used as a correlation signal, and correlation is detected by a correlation processing function provided in the control processing / display unit 301 at predetermined intervals. The target search signal is displayed by the display function provided in the control processing / display unit 301. By searching the transmission antenna 403 and the reception antenna 601 while moving up and down,
We are making it possible to investigate the geology at various depths.

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 has a frequency f ₀ to a frequency (f ₀ + Δf) between time 0 and time T, as in the frequency change of FIG.
Is a signal that repeats a variable frequency f ₄₀ that changes linearly up to, and the swept continuous FM signal by stepwise continuous frequency modulation has a frequency f from time 0 to time T as shown in the frequency change of FIG. It is a signal that repeats a variable frequency f ₄₀ in which the frequency slightly changes stepwise from ₀ to time (f ₀ + Δf) every time Δt.

In the correlation detection type transmission line exploration apparatus 100 using the promised waveform signal by 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 amplitude component or the phase component due to the characteristics of the transmission path. The configuration that obtains the signal for the change is
It is disclosed by Japanese Patent Application Laid-Open No. 4-152286 based on the application of the applicant of the present application.

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 amplitude change and the phase change by the expansion by Fourier transform is performed by the orthogonal function expansion. Also called correlation detection.

In the above configuration, the amplitude change and the phase change are detected by the multiplication correlation. In the present invention, the correlation means the amplitude change and the phase change by the configuration other than the multiplication correlation in the same manner as described above. It also includes a configuration for detecting, for example, a correlation configuration for sampling the correlated signal with a pulsed signal of the correlation signal.

[0015]

In the above-mentioned conventional technique, the sweep type continuous FM signal is used as the promised waveform signal. Generally, it is necessary to use the sweep type continuous FM signal for sweeping over a wide frequency range. When exploring road conditions, particularly geological conditions in the ground, it is often desirable to use a swept continuous FM signal that sweeps over as wide a frequency range as possible in the lowest frequency band.

Therefore, firstly, the correlation processing is performed by the continuous FM.
Since a wide frequency band is provided, various harmonic components are generated, and this harmonic component causes unnecessary and complicated interference to other components.

Secondly, a swept-type continuous FM signal is used as the promise waveform signal, and the promise waveform signal is converted into a two-phase correlation signal to perform two-phase correlation processing. That is, as compared with the case where the correlation processing is performed using one correlation signal, a correlation result having a large amplitude can be obtained by the processing based on the two correlation detection signals, so that there is a lot of attenuation in the transmission path and there are many noise signals. In the case of, S
/ N is good, but the phase shift operation in the 90 ° phase shift circuit for obtaining two-phase correlation signals is continuous FM.
Stable and accurate over a wide frequency band
There is an inconvenience that a measurement error occurs due to the 0 ° phase shift operation not being performed.

Third, the length of the conducting wire portion connecting the correlation processing portion to the transmitting portion and the receiving portion is long, and in particular, it is very long in a correlation detection type transmission line survey device such as a borehole radar. Therefore, the phase change component in the detection signal detected by the correlation detection is longer than the phase change component based on the situation of the target transmission line, for example, the difference in the geological condition in the ground. Since the phase change component based on the signal is included in a very large amount, there is a disadvantage that the phase change component based on the state of the transmission line cannot be detected accurately.

Therefore, there is a problem that it is desired to provide an apparatus having a simple and inexpensive structure that does not have such inconvenience.

[0020]

According to the present invention, a transmitting portion is arranged at one of two places of a transmission path such as the above-mentioned correlation detecting type borehole radar, and a receiving portion is arranged at the other side thereof. Sweep-type continuous FM signal, that is, the first
Signal of the received signal obtained in the receiving part by transmitting the swept continuous FM signal as the correlated signal, and the required search is performed based on the signal obtained by performing the correlation process on the correlated signal with the predetermined correlated signal. In a correlation detection type transmission path exploration device for obtaining a signal, a correlating means for performing a correlation process using a constant frequency signal as the predetermined correlation signal, and the correlation signal or a constant frequency signal based on the correlation signal Frequency conversion means for obtaining the first swept continuous FM signal by performing frequency conversion with a second swept continuous FM signal having a variable frequency range higher than the variable frequency range of the swept continuous FM signal of An inverse frequency conversion method for obtaining a correlated signal having a frequency similar to that of the above correlation signal by performing frequency conversion of the above reception signal in the reverse of the above frequency conversion. First configuration providing bets,

In the correlation detection type transmission path exploration apparatus for performing the correlation processing in the first configuration by the two-phase correlation processing, the constant frequency signal and the constant frequency signal are replaced by 90 instead of the correlation means in the first configuration. A second configuration in which a correlation means for performing the above-described two-phase correlation processing with the phase-shifted signal obtained by phase-shifting as a predetermined correlation signal;

The part of the frequency conversion means in the above-mentioned first configuration or second configuration is a constant frequency signal based on the above-mentioned correlation signal, which is higher than the frequency of the above-mentioned correlation signal and which is above the first frequency. A signal having a constant frequency higher than the maximum frequency of the sweeping continuous FM signal, that is, a high constant frequency signal is used, and the second sweeping continuous FM described above is used.
A third configuration in which frequency conversion means is provided that uses a signal having a variable frequency range higher than the frequency of the high constant frequency signal as a signal;

The portion of the frequency conversion means in the third configuration is the above-mentioned first sweep type continuous FM signal, which is a variable frequency range wide enough that it cannot be stably generated by one variable frequency generation circuit, that is, A signal having a wide variable frequency range is used, a signal having a frequency within the wide variable frequency range is used as the correlation signal, and one variable frequency generating circuit is used as the second swept continuous FM signal. A fourth configuration in which frequency conversion means that uses a signal having a variable frequency range that can be stably generated by

In the above-mentioned first to fourth configurations, the first swept continuous FM signal obtained on the side performing the above-mentioned correlation processing is converted into an optical signal and guided by the light guide line, that is, the light guide line on the transmission side. Conducting wire means for giving to the transmitting portion, guiding wire means for converting the received signal into an optical signal and giving it to the side for performing the above correlation processing by the receiving side light guide wire, and the above frequency conversion Second sweep type continuous F for performing
The M signal is at least the time amount obtained by adding the transmission time of the first sweep type continuous FM signal in the transmission side light guide line portion and the transmission time of the reception signal in the reception side light guide line portion. A fifth configuration for providing a delay means for delaying a corresponding amount of time;

In the fifth configuration, the above delay is
A sixth configuration in which the delay means is provided, which is obtained by a light guide line having a length corresponding to at least the length of the transmission side light guide line and the reception side light guide line.

In the above-mentioned first to fourth structures, a seventh structure is provided in which a frequency conversion portion arrangement means for arranging a part or all of the frequency conversion means on the reception portion side is provided.

In the seventh structure, the above delay is
The above problem can be solved by providing an eighth configuration or the like in which the above-mentioned delay means obtained by a light guide line having a length corresponding to at least the length of the above-mentioned transmission side light guide line is provided. is there.

[0028]

According to the first configuration, since the transmission line is searched for with a signal having a wide variable frequency, it is possible to obtain a received signal containing information corresponding to a fine change such as geological condition, and from this received signal. In the part where the search signal is obtained, the received signal is converted into a signal having a constant frequency, that is, a single frequency, so that it can be passed through a filter circuit having an extremely narrow bandwidth. / N can be improved significantly.

Further, since the multiplication correlation is performed by the correlated signal obtained by converting the received signal to a constant frequency and the correlation signal of the constant frequency signal in this way, the correlation function part can be the same as the multiplication operation of single frequencies. It is possible to reduce the harmonic signal components generated by the multiplication operation, and it is possible to drastically reduce unnecessary interference given to other components.

In the second configuration, in addition to the operation of the first configuration, the two-phase correlation signal used for the two-phase multiplication correlation for facilitating fine exploration of the geological condition etc. is transferred to the constant frequency signal. Since it can be performed by phase, the correlation signal on the phase shift side can be made to be an accurate phase shift signal, so that the cause of the error in the correlation operation can be reduced and the search information in the search signal can be made highly accurate.

In the third configuration and the fourth configuration, in addition to the actions of the first configuration and the second configuration, the sweep type continuous FM used from the constant frequency signal used for the correlation signal to the transmission signal is used.
Until the signal is obtained, there is two frequency conversions: once raising the frequency to a frequency higher by one digit and then returning to the lower frequency band. Therefore, in the low frequency band, one variable frequency generating circuit stabilizes. In general, a variable frequency generation circuit can generate a stable signal in a high frequency band even in a variable frequency range that cannot be generated in a high frequency range. Therefore, the transmission signal used for exploration is set to an extremely wide variable frequency range in a low frequency band. Thus, the search can be performed finely over a wide range of frequencies, and the multiplication correlation for this search can be performed by a constant frequency signal.

In the fifth and sixth configurations, first to fourth
In addition to the operation in the configuration of, in order to convert each signal transmitted between the portion performing the correlation processing and the transmitting unit and between the portion performing the correlation processing and the receiving unit into light and transmitting the light by the light guide line, The group delay caused by the variable frequency component of the swept continuous FM signal can be accurately and easily delayed, and the portion for processing the delay amount can be easily processed only by the length of the light guide line.

In the seventh configuration and the eighth configuration, a commercially available light guide line with a reinforcing cord is a bundle of a plurality of light guiding lines, for example, about four light guiding lines bundled with the reinforcing cord as a core. Therefore, one of them can be used as the delay conductor and the other one can be used as the reception conductor, so that the substantial structure can be simplified, and the same commercially available light guide line can be used as the transmission conductor. By using the same, the transmission conductor and the delay conductor can have the same characteristics, so that the delay amount due to the transmission conductor and the delay amount due to the delay conductor can be accurately matched only by making the lengths of the conductors the same. Therefore, it works to ensure the cancellation of the delay amount by the transmission conductor.

[0034]

EXAMPLES Examples will be described below with reference to FIGS.
In the configurations of FIGS. 1 to 8, the portions denoted by the same reference numerals as those in FIGS. 9 to 11 indicate the portions having the same functions as the portions having the same reference numerals described in FIGS. 9 to 11. Further, the parts (1) and (2) of FIG. 1 are connected to and (1) of FIG.

[First Embodiment] The first embodiment will be described below with reference to FIGS. In the control processing / display unit 301 of FIG. 1, the first local signal generation circuit 1 produces a first constant frequency signal 1a used as a correlation signal, for example, a signal of 10 MHz, and a first conversion circuit 2 and a multiplication circuit 31 Give to.

The second local signal generating circuit 3 produces a second constant frequency signal 3a having a frequency higher than that of the first constant frequency signal 1a used as a frequency conversion signal by one digit or more, for example, a signal of 270 MHz. 1 conversion circuit 2 and 4
And the conversion circuit 30.

The first conversion circuit 2 performs frequency conversion between the first constant frequency signal 1a and the second constant frequency signal 3a, and the frequency of the first constant frequency signal 1a and the second constant frequency signal 3a. Frequency of the sum of the frequencies, for example, 2
A signal of 80 MHz is created as the third constant frequency signal 2a and given to the second conversion circuit 4.

The variable frequency generation circuit 5 is a first swept continuous FM signal 4a, which will be described later and corresponds to a transmission signal for exploration.
Of the variable frequency generating circuit as a second swept continuous FM signal 5a having a variable frequency which is higher than the variable frequency range of 1) and can be stably generated by one variable frequency generating circuit, for example, a PLL. A VCO circuit having a synthesizer configuration or a variable frequency oscillating circuit using a variable capacitance element, for example, a varicap or the like, and the generated second swept continuous FM signal 5a is converted into a second conversion circuit 4
And the delay circuit 29.

Here, the first sweep type continuous FM signal 4a
Is, for example, f ₀ from f ₀ = 1 MHz in Fig. 10 +
A signal having a variable frequency f ₄₀ up to Δf = 81 MHz, that is, a signal having a variable frequency of 1 to 81 MHz and having a waveform repeating in a cycle T as shown in FIG. The FM signal 5a is, for example, the sum frequency of the frequency of the first swept-type continuous FM signal 4a and the frequency of the third constant frequency signal 2a, that is, 281 to 36.
It is a signal having a variable frequency of 1 MHz.

The second conversion circuit 4 carries out a frequency conversion by the third constant frequency signal 2a and the second swept continuous FM signal 5a to obtain the frequency of the third constant frequency signal 2a and the second constant frequency signal 2a.
A signal having a frequency different from the frequency of the sweep-type continuous FM signal 5a, for example, the above-mentioned signal of 1 to 81 MHz is formed as the first sweep-type continuous FM signal 4a, and given to the preamplifier circuit 6. The preamplifier circuit 6 is for amplifying the first swept-type continuous FM signal 4a, that is, a signal to be a transmission signal to be given to the ground serving as a transmission path, to the extent that it can be transmitted to the transmission unit 402. Pre-amplification is performed and the amplified signal 6a thus amplified is given to the electric / optical conversion circuit 7.

The electric / optical conversion circuit 7 is a circuit for converting the first swept continuous FM signal 4a by an electric signal into an optical signal, for example, a circuit for obtaining a desired optical signal by a laser diode, The converted first continuous sweep FM signal is converted into the optical signal 7a and is applied to the transmission conductor 401.

The operating power source 38 is used for the 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 formed by an optical fiber, and is a first sweep type continuous F wire.
It is a conducting wire for applying the optical signal 7a obtained by converting the M signal to light to the optical / electrical conversion circuit 8 of the transmitter 402 arranged remotely. Here, the transmission time required to transmit the optical signal 7a by the length L _{1 of the} transmission wire 401 is τ ₁ .

The optical / electrical conversion circuit 8 is a circuit for converting the optical signal 7a into an electric signal, for example, a circuit for obtaining a desired electric signal by a phototransistor, and a circuit for obtaining an electric signal obtained by the conversion. A first sweeping continuous FM signal 8a corresponding to one sweeping continuous FM signal 4a is given to the transmission circuit 9.

The transmission circuit 9 is a power amplification circuit that amplifies the first swept-type continuous FM signal 8a to the required power required for transmission, for example, a transistor amplification circuit,
The transmission output signal 9a obtained by amplification is matched with the matching transformer 10.
Give to. The battery 11 is a power source independently provided for operating each circuit arranged in the transmission unit 402 including the transmission circuit 9, and is, for example, an alkaline manganese dry battery.

The matching transformer 10 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 9 and the balanced side is connected to the transmitting antenna 403. The electric power of the transmission output signal 9a is transmitted from the transmission antenna 403 to the underground 202 serving as a transmission path, using the electromagnetic wave 501 having the first swept continuous FM signal as a transmission signal.

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.
Matching transformer 11 to the end of the circular pipe of aluminum material
The lead wire from the above is screwed, and the upper and lower arrangement intervals L ₁₁ are 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 9
The frequency of a, that is, the frequency that is slightly higher than the highest frequency 81 MHz of the frequency band of the first swept-type continuous FM signal, for example, the length that resonates at a wavelength of about 90 MHz, Each frequency component contained in the FM 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 8 and the transmission circuit 9 are provided.
The parts constituting the transmission unit 402 such as
The power supply battery of the transmitter 402, that is, the battery 11 is housed and arranged inside the other cylindrical body 403b.

The outer cover 12 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 12a 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 12 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 corresponding to the transmission signal for exploring the transmission path is set to the electric power that can reach the exploration hole 204 at a location separated by the transmission distance d corresponding to the purpose of the exploration. Let τ2 be the transmission time required to transmit 501 by the transmission distance d.

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. An electromagnetic wave 501 that has the same configuration as L ₁₂ and the length L ₁₃ and that has reached through the underground 202 of the transmission path.
The received signal obtained by receiving the signal is given to the receiving circuit 23 via the matching transformer 22.

The matching transformer 22 is a high frequency transformer similar to the matching transformer 10, for example, a balun. The balanced side is connected to the receiving antenna 601 and the unbalanced side is connected to the receiving circuit 23. The wave output is given from the matching transformer 22 to the receiving circuit 23 as a received signal 22a having a waveform which is transmitted through the ground 202 which uses the first swept continuous FM signal as a transmission path.

The receiving circuit 23 pre-amplifies the received signal 22 a to the extent that it can be transmitted to the control processing / display unit 301, and the received signal 23 a is converted into the electrical / optical conversion circuit 24.
Give to. The battery 21 is a power source independently provided for operating each circuit arranged in the receiving unit 602 including the receiving circuit 23, and is, for example, an alkaline manganese dry battery.

The electric / optical conversion circuit 24 is a circuit for converting the reception signal 23a by an electric signal into an optical signal, for example, a circuit for obtaining a target optical signal by a laser diode, and converting the reception signal 23a into light. Converted optical signal 24a
To the receiving lead 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 26 of the control processing / display unit 301 arranged remotely. Where the optical signal 24
Let τ ₃ be the transmission time required to transmit a for the length L ₃ of the receiving conductor 701.

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 24 and the receiving circuit 23 is housed and arranged, and Inside the cylindrical body 601b of the receiver 602
The power source battery, that is, the battery 21 is housed and arranged.

The outer cover 25 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 25a 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 25 is the same as the structure in which the transmitting antenna 403 and the like are housed inside the outer cover 12, for example.

The optical / electrical conversion circuit 26 is a circuit for converting the optical signal 24a 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 26a as a signal is given to the post-stage amplifier circuit 27.

The post-stage amplifier circuit 27 outputs the received signal 26a as
An amplifying circuit that amplifies to a required voltage required for frequency conversion in the third converting circuit 28 described later, for example, an amplifying circuit using a transistor, and supplies the amplified received signal 27a to the third converting circuit 28.

Here, in the first embodiment, the received signal 2
The first converted signal generated by the first local signal generation circuit 1 is the second converted received signal 30a obtained from
Of the constant frequency signal 1a as a correlation signal is performed 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 beat frequency f _b from the power spectrum. By knowing the change in the transmission time τ ₂ of the electromagnetic wave 501 corresponding to the transmission signal in the underground 202 corresponding to the transmission path, the situation of the transmission path, that is, the underground 202
It is intended to determine the geological condition of.

For this reason, the second converted reception signal 30a, which will be described later, obtained by frequency conversion of the reception signal 27a is provided as one multiplication input of the multiplication circuit 31. However, only the beat detection is performed. For example, received signal 27a
The objective can be achieved simply by giving a signal obtained by frequency conversion as a multiplication input.

However, in this case, in the beat component, the total amount of the transmission time τ ₁ , the transmission time τ _2, and the transmission time τ ₃ is τ ₁₁ τ ₁₁ = τ ₁ + τ ₂ + τ ₃ , The variable frequency signal related to the first swept continuous FM signal 4a is the above-mentioned second conversion circuit 4, preamplification circuit 6,
The optical conversion circuit 7, the optical / electrical conversion circuit 8, the transmission circuit 9, the reception circuit 23, the electric / optical conversion circuit 24, the optical / electrical conversion circuit 26, the post-amplification circuit 27, and the third conversion circuit 28 described later. The total sum of the delay times delayed by each circuit and the time amount τ ₁₂ , that is, the total delay time τ ₁₃ τ ₁₃ = τ ₁₁ + τ ₁₂ is included.

Therefore, in the transmission line, that is, in the underground 202
Since the change rate of the change of the beat component due to the change of the transmission time τ ₂ in the inside is detected by the change rate with respect to the total delay time τ ₁₃ , the change rate to be detected will eventually decrease. That is why.

Therefore, it is possible to cancel the delay by correlating the signal obtained by delaying the first sweep type continuous FM signal 4a and the received signal 27a with a multiplication circuit. Then, this delay is ideally the transmission time in the transmission path from the above-mentioned total delay time τ ₁₃ , that is, the underground 202
Becomes to delay the transmission time tau ₂ only time amount _{τ 14 τ 14 = τ 13 -τ} 2 minus first swept continuous FM signal 4a at the inner, in the present invention, the correlation process at a fixed frequency In order to be able to carry out, by supplying the second swept continuous FM signal 5a to the delay circuit 29 and the delayed swept continuous FM signal 29a delayed by the delay time amount τ _s to the third conversion circuit 28, , The same effect as that obtained by delaying the first sweep type continuous FM signal 4a is obtained.

This delay time amount τ _s is at least the time amount τ ₁₅ τ _s = τ ₁ + τ ₃ = τ ₁₅ obtained by adding the transmission time τ ₁ and the transmission time τ ₃ , and preferably the above time period. Delay the time up to the quantity τ ₁₄ . 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 29 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 7, the transmission conductor 401, and the optical / electric conversion circuit 8. 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 29, 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 third conversion circuit 28 carries out a frequency conversion by the received signal 27a and the delayed swept continuous FM signal 29a to obtain the sum frequency of the frequency of the received signal 27a and the delayed swept continuous FM signal 29a. The first converted reception signal 28a is created and is given to the fourth conversion circuit 30.

Here, the received signal 27a is a signal obtained by transmitting the transmission signal based on the first swept-type continuous FM signal 7a to the underground 202, which is the transmission line, so it may vary depending on the transmission condition on the transmission line. Even if given a frequency change,
A frequency that is approximately the same as that of the first swept continuous FM signal 7a,
That is, the signal has a frequency of about 1 to 81 MHz, and the delayed sweep type continuous FM signal 29a is 281 to 36.
Since the signal has a frequency of 1 MHz, the first converted reception signal 28a appears as a signal having a frequency of about 280 MHz.

The fourth conversion circuit 30 performs frequency conversion between the second constant frequency signal 3a and the first converted reception signal 28a, and the frequency of the second constant frequency signal 3a and the first converted reception signal 28a. Second with a frequency that is different from the frequency of
The converted reception signal 30a is generated and given to the multiplication circuit 31.

Here, the second constant frequency signal 3a is 27
Since the first converted reception signal 28a has a frequency of 0 MHz and the first converted reception signal 28a has a frequency of about 280 MHz, the second converted reception signal 30a has the same frequency as the first constant frequency signal 1a. It will appear as a signal having a frequency similar to 10 MHz.

The multiplication circuit 31 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. This is a circuit for outputting a signal of an amplitude value obtained as a multiplication signal, and is obtained by multiplying the second converted reception signal 30a corresponding to the correlated signal and the first constant frequency signal 1a corresponding to the correlation signal. The multiplied signal 31a to be applied is supplied to the low-pass filtering circuit 32.

The low-pass filter circuit 32 receives the correlation signal, that is,
A frequency higher than the highest frequency predicted as the beat detection output by the first constant frequency signal 1a and the correlated signal, that is, the second converted reception signal 30a, that is, a frequency of 1 kHz or less is used as the passing frequency. A filtering circuit for filtering, which is a multiplication correlation signal 32a obtained by filtering.
To the processor 33.

The processing processor 33 is, for example, a processor that performs a Fourier transform by a microcomputer, and performs a Fourier transform based on the digital value data obtained by sampling the multiplied correlation signal 32a to obtain the multiplied correlation signal 32a. 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 34 as the calculated value signal 33a.

The winch 801 moves up and down the transmission path, that is, the transmitting portion and the receiving portion for exploration arranged in the ground 202, and by moving the outer cover 12 and the outer cover 25, In order to perform this movement, a cable 802 (not shown) connected to the outer cover 12 and the outer cover 25 or the transmission conductor 401 and the reception conductor 701 is wound up or down, and at the same time, the cable 802 or the transmission conductor 701 is wound. The positions of the transmitting portion and the receiving portion, that is, the transmitting antenna 403 and the receiving antenna 601 are detected based on the detected amount of movement of the 401 and the receiving conductor 701.
A depth signal 801a representing the depth of the is supplied to the processor 33.

The display 34 displays the depth value data based on the depth signal 801a from the processor 33 and the calculated value data corresponding to the substantial change amount of the transmission time τ ₂ based on the calculated value signal 33a. 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 33 will be described below.

Here, in order to easily and easily understand the arithmetic processing, the first conversion circuit 2, the second conversion circuit 4, the preamplification circuit 6, the electric / optical conversion circuit 7, the optical / electrical conversion circuit 8, and the transmission circuit. 9
Each signal delay time in each circuit of the receiving circuit 23, the electrical / optical conversion circuit 24, the optical / electrical conversion circuit 26, the post-stage amplification circuit 27, and each of the third conversion circuit 28 and the fourth conversion circuit 30 described later. Ignoring the total amount of time τ ₁₂ of, the delay time from the first constant frequency signal 1a to the second converted reception signal 30a is calculated as the transmission time τ ₁ , the transmission time τ _2, and the transmission time τ.
₃ considered as the amount of time tau ₁₁ the sum of the fixed delay circuit 29
It is assumed that the delay time τ _s of is set to the time amount τ ₁₅ that is the sum of the transmission time τ ₁ and the transmission time τ ₃ .

Therefore,

[Equation 1] Suppose

Then, the first constant frequency signal 1a as the correlation signal is e ₁ , the second constant frequency signal 3a is e ₂ , the third constant frequency signal 2a is e ₃ , and the second sweep type continuous FM.
Signal corresponding to a transmission signal for sending a signal 5a e _4, the control processor / display unit 301, i.e., the first swept continuous F
M signal 4a is e ₅ , a signal output from the transmission unit 402,
That is, the transmission output signal output from the transmission circuit 9 is e
₆ , the signal output from the receiving unit 602, that is, the received signal 23a output from the receiving circuit 23 is e ₇ , the received signal 27a corresponding to the received signal received by the control processing / display unit 301 is e ₈ , and the delayed sweep Type continuous FM signal 29a
₉ , the first converted reception signal 28a is represented by e ₁₀ , and the second converted reception signal 30a is represented by e ₁₁ , each signal can be represented by the following equation.

Ω ₄₀ is the first sweep type continuous FM signal 4
a, that is, the angular frequency of e ₅ , ω ₅₀ is the second swept continuous FM signal 5 a, that is, the angular frequency of e ₄ , and ω ₁ is the first constant frequency signal 1 a, that is, the corner of e ₁ . Frequency, ω
₂ is a second fixed frequency signals 3a, that is, represents the angular frequency of e _2, also, BPF [] denote the output of the bandpass filter circuit.

[0083]

[Equation 2] Here, the relationship between ω ₁ , ω ₂ , ω ₄₀ , and ω ₅₀ is

[Equation 3] Since it is set to

[Equation 4] From equation (1)

[Equation 5] From formula (1), formula (2), and formula (3)

[Equation 6]

Here, the multiplication correlation signal 31a is represented by E ₁ , and the function for low-pass filtering by the low-pass filtering circuit 32 is LPF [
]]

[Equation 7] Here, the second term in [] in the equation (4) disappears by the filtering of the low-pass filtering circuit 32, so that the multiplication correlation signal 32a output from the low-pass filtering circuit 32 is eventually

[Equation 8] Can be expressed as

Ω ₄₀ of the first swept continuous FM signal 4a is
A swept continuous FM signal having a variable frequency f ₄₀ such as the frequency change of FIG. 10 is shown in FIG.
If are the waveforms such signals, wherein the (4) omega ₄₀
Can be expressed as:

[0086]

[Equation 9] However, 0 ≦ t ≦ T.

Here, paying attention to the phase term of the equation (5),

[Equation 10] Then, the frequency signal E ₁ output as the multiplication correlation signal 32a is

[Equation 11] Becomes

From equations (6) and (7),

[Equation 12] Is obtained.

Here,

[Equation 13] , Which does not include the time t, represents a fixed amount of phase shift, and can be ignored.

Therefore, the beat frequency component f _b of the frequency signal E ₁ , that is, the condition of the transmission path, that is, the underground 20
The beat frequency component that changes according to the change in the transmission time τ ₂ that occurs with the change in the geological condition of ₂ is calculated from the equation (9).

[Equation 14] The beat frequency component of the equation (10) is included in the frequency signal E ₁ of the multiplication correlation signal 32a.

The expansion of each equation described above is based on the digital signal data obtained by A / D converting the frequency signal E1 output as the multiplication correlation signal 32a, that is, the signal of equation (8) by the processor 33. This means that the beat frequency f _b can be obtained by calculating the power spectrum, that is, the frequency power distribution by Fourier transform.

Here, the Fourier transform is

[Equation 15] And the power spectrum

[Equation 16] Then,

[Equation 17] Therefore, if the relation of this equation (11) is expressed in a graph, for example, it becomes as shown in FIG. The beat frequency f _b corresponding to the geological condition at the depth of the underground 202 where the transmitting antenna 403 and the receiving antenna 601 are located, that is, the frequency of the beat signal Alternatively, it is possible to obtain a value representing the phase change.

By the way, in the above calculation, the delay time value τ _s in the fixed delay circuit 29 is

[Equation 18] And also

[Formula 19] Therefore, the change of the beat frequency f _b can be viewed as the change rate with respect to the frequency corresponding to τ ₂ .

On the other hand, when the fixed delay circuit 29 is not provided, the value of τ ₂ is

[Equation 20] Therefore, the change in the beat frequency f _b will be viewed as a rate of change with respect to the frequency corresponding to τ ₁₁ .

Therefore, as described above, when τ _s is delayed, compared with the case where it is not delayed,

[Equation 21] Therefore, the change in the condition of the transmission path, that is, the change in the transmission time τ ₂ due to the change in the geological condition of the underground 202 is investigated by increasing the accuracy of the ratio of equation (12). It will be possible.

[Second Embodiment] A second 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 the parts having the same reference numerals explained in FIGS.

The transmitting part and the receiving part are constructed in exactly the same way as in FIG. 2 in the first embodiment, that is, the parts in FIG. 5 are connected to and in FIG. It is configured as one.

The component different from that of the first embodiment is that the correlation processing portion in the first embodiment has a multiplication configuration of orthogonal two-phase multiplication correlation, that is, a two-phase correlation signal having a phase difference of 90 °. This is a modification, and a 90 ° phase shift signal 35a obtained by shifting the first constant frequency signal 1a by 90 ° in the 90 ° phase shift circuit 35 to the configuration of the first embodiment of FIG. 1 is used as a correlation signal, The converted received signal 30a is used as a correlated signal, and the multiplication signal 36a multiplied by the multiplication circuit 36 is used as a low-pass filtering circuit 37.
The configuration is additionally provided to obtain the 90 ° multiplication correlation signal 37a filtered by.

Since the 90 ° multiplication correlation signal 37a becomes a signal E ₂ having a 90 ° phase difference with respect to the signal E ₁ of the equation (5), the signal E ₂ and the multiplication correlation signal 32a by the 90 ° multiplication correlation signal 37a are obtained. Signal E ₁ by the processor 3
3 is used to cause the Fourier transform in the processor 33 to be performed in the form of Fourier transform by orthogonal function expansion.

[Third Embodiment] A third embodiment will be described below with reference to FIGS. 6 and 7. Parts in FIGS. 6 and 7 that have the same reference numerals as those in FIGS. 1 to 5 have the same functions as those in FIGS. 1 to 5 that have the same reference numerals.

Then, the transmitting portion is configured to be exactly the same as the transmitting portion on the left side in the configuration of FIG. 2 in the first embodiment, that is, the portion of FIG. 6 is connected to that of FIG. Further, the receiving portion is configured as shown in FIG. 7, that is, the portions of and in FIG. 6 are connected to and of FIG.

Further, the constituent parts different from the structure of the first embodiment are that the delay circuit 29 arranged in the control processing / display unit 301 in the first embodiment is eliminated and a part of the frequency conversion part is provided. 7, that is, the position where the third conversion circuit 28 is moved to the side of the receiving unit 602 in FIG. 7 and the second sweep type continuous FM signal 5a is delayed by the moving line. Delayed sweep type continuous FM delayed by 182
This is a portion where the signal 29a 'is changed so as to be applied to the third conversion circuit 28.

The components of the configuration of FIGS. 6 and 7 different from the configuration of FIG. 1 will be specifically described below. The third conversion circuit 28 is arranged integrally with the reception unit 602 and is operated by the power supply battery 21, and the reception circuit 23 gives the reception signal 23a to the third conversion circuit 28.

The delayed sweep type continuous FM signal 29a 'given for performing the frequency conversion is the second sweep type continuous FM signal 5a.
a is converted into light by the electric / optical conversion circuit 181, and an optical signal 181 is obtained.
After being set to "a", it is delayed by the delay lead wire 182 and is arranged integrally with the receiving unit 602.
It is obtained by giving it to the amplifier circuit 184.

In the portion for obtaining the delay time amount τ _s , the electric / optical conversion circuit 181 and the optical / electrical conversion circuit 183 are configured by the same ones as the electric / optical conversion circuit 7 and the optical / electrical conversion circuit 8, and The delay conductor 182 is made of the same material as the transmitter conductor 401 and has the same standard and the same length L ₁ , so that the transmission time τ ₁ of the optical signal 7 a in the transmitter conductor 401 is the same.

Further, the amplifier circuit 184 uses the optical signal 181a.
Signal 183a converted by the optical / electrical conversion circuit 183
To an amplitude value suitable as an input for performing frequency conversion in the third conversion circuit 28.

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 preamplifier circuit 6, the electric / optical conversion circuit 7, the optical / electrical conversion circuit 8, the transmission circuit 9, and the reception circuit 23 are preferably set.

Therefore, in the third embodiment, in the frequency conversion operation of the third conversion circuit 28, the delay amount τ ₁ and the second delay amount τ _{1 of} the first swept continuous FM signal 4a delayed by the transmission wire 401 are compared. Since the sweep type continuous FM signal 5a has the same delay amount as the delay amount τ ₁ delayed by the delay line 182, it is caused by the delay of the first sweep type continuous FM signal 4a included in the first converted reception signal 28a. The amount of delay is
This means that the first swept-type continuous FM signal 4a has a delay amount corresponding to the transmission time τ ₂ required to transmit the underground 202 corresponding to the transmission path.

The first converted received signal 28a is converted into light by the electric / optical conversion circuit 24 ', and converted into light.
The optical signal 24 is given to the receiving conductor 701 ′ and transmitted to the side that performs the correlation process, that is, the control processing / display unit 301 side.
The photoelectric conversion circuit 26 'converts a' into the first conversion reception signal 26a 'which is an electric signal and is given to the post-stage amplification circuit 27'. The post-stage amplification circuit 27 ′ applies the first converted reception signal 27 a ′ to the fourth conversion circuit 30 by amplifying the first converted reception signal 26 a ′ to the amplitude value necessary for the frequency conversion operation in the fourth conversion circuit 30. I have to.

Here, the first conversion circuit 28 obtains the first
The converted reception signal 28a of FIG. 2 is delayed until it is given to the fourth conversion circuit 30 via the electric / optical conversion circuit 24 ', the receiving conductor 701', the optical / electrical conversion circuit 26 ', and the post-stage amplification circuit 27'. It is subject to a fixed delay due to the amount, but first
Since the converted received signal 28a of the above is a constant frequency signal, this fixed delay amount is a mere DC component in the Fourier transform operation by the processor 33 of the multiplication correlation signal 32a represented by the signal E ₁ of the equation (5). Therefore, the amount of delay is completely irrelevant to the beat frequency f _b obtained as a result of the correlation processing.

Therefore, the beat frequency f _b corresponding to the transmission time τ ₂ by the remaining underground 202 in which the transmission time τ ₁ by the transmission conductor 401 is canceled by the transmission time τ ₁ by the delay conductor 182 is directly obtained. You will get it. Further, the length of the receiving conductor 701 'can be set to an arbitrary length irrespective of the search performance.

In the configuration of the third embodiment, the entire frequency conversion portion on the receiving side, that is, the frequency conversion portion by the third conversion circuit 28 and the fourth conversion circuit 30 is received by the receiving section 602.
And the second constant frequency signal 3a is guided to the receiving unit 602 side by using a configuration similar to that of the above-mentioned second sweep type continuous FM signal 5a being guided to the receiving unit 602 side. Can be configured.

The delay amount due to the length of the conducting wire for guiding the second constant frequency signal 3a to the receiving section 602 side depends on the receiving conducting wire 701 'because the second constant frequency signal 3a has a constant frequency. Similar to the delay amount, the delay amount is completely unrelated to the beat frequency fb obtained as a result of the correlation processing.

[Fourth Embodiment] The fourth embodiment will be described below with reference to FIG. Parts in FIG. 8 having the same reference numerals as those in FIGS. 1 to 7 have the same functions as the parts having the same reference numerals described in FIGS.

The transmitting part and the receiving part are constructed in exactly the same manner as in the third embodiment, that is, the part in FIG. 8 is connected to the part in FIG. It is something.

Further, in the structure of the fourth embodiment, the constituent parts different from those of the third embodiment are those in which the correlation processing part is changed to the two-phase correlation processing, and the concretely different constituent parts are the second embodiment. Since the difference between the configuration of the first embodiment and the configuration of the second embodiment described in the above section is exactly the same, the description of the specific operation is omitted here.

The first conversion circuit 2 in each embodiment
Second conversion circuit 4, third conversion circuit 28, fourth conversion circuit 30
Each of the conversion circuits is a circuit formed by combining a mixing circuit that mixes and amplifies two input frequencies and a filtering circuit that filters an output frequency, or a multiplication circuit that multiplies two input frequencies, for example, a double circuit. A multiplying circuit using a balance mixer and a filtering circuit with an amplifying element for filtering the output frequency, for example, the first conversion circuit 2 and the third conversion circuit 2
8 is a high-pass filter circuit, the second conversion circuit 4 is a low-pass filter circuit, and the fourth conversion circuit 30 is a circuit in combination with a band-pass filter circuit.

[Summary of Configuration of Each Embodiment] To summarize the configuration of each of the above embodiments, in each configuration of the first embodiment and the third embodiment, two locations of the transmission line, for example, the search holes 203. 20
4, the transmission part, for example, the transmission part 402 / transmission antenna 403 is arranged, and the reception part, for example, the reception antenna 601 / reception part 602 is arranged on the other side, and the sweep type continuous FM signal from the transmission part, that is, , A signal based on the received signal 23a obtained in the reception part by transmitting the first swept-type continuous FM signal 4a is used as a correlated signal, and this correlated signal is subjected to correlation processing by a predetermined correlation signal, for example, by the multiplication circuit 31. A correlation detection type transmission line search device, for example, the borehole radar 1 that obtains a required search signal, for example, the calculated value signal 33a, based on the signal obtained by performing the multiplication correlation.
At 00,

Correlation means for performing correlation processing using a constant frequency signal, for example, the first constant frequency signal 1a as the above-mentioned predetermined correlation signal, and the above correlation signal, that is, the first constant frequency signal 1a or this correlation signal. Based on the constant frequency signal, for example, the second constant frequency signal 3a by the second swept continuous FM signal 5a having a variable frequency range higher than the variable frequency range of the first swept continuous FM signal. Frequency conversion means for obtaining the above-mentioned first swept continuous FM signal 4a by performing conversion, and the above-mentioned correlation signal by performing frequency conversion of the above-mentioned received signal 23a opposite to the above-mentioned frequency conversion, that is, This constitutes the first configuration in which the first constant frequency signal 1a and the inverse frequency conversion means for obtaining the correlated signal having the same frequency as the first constant frequency signal 1a are provided.

In each of the configurations of the second and fourth embodiments,
The correlation processing in the first configuration is the two-phase correlation processing,
For example, in a correlation detection type transmission path exploration device that performs multiplication correlation by the multiplication circuits 31 and 36, for example, the borehole radar 100, a constant frequency signal, for example, a first constant frequency is used instead of the correlation means in the first configuration. The signal 1a and the constant frequency signal 1a are, for example, 90 °
The phase shift circuit 35 has a second configuration in which a correlation means for performing the above-described two-phase correlation processing with the phase shift signal 35a obtained by 90 ° phase shift as a predetermined correlation signal is configured. Is.

In each of the configurations of the first, second, third, and fourth embodiments, the portion of the frequency conversion means in the first or second configuration is replaced by the correlation signal described above. For example, as the constant frequency signal based on the first constant frequency signal 1a, for example, the second constant frequency signal 3a, the frequency of the above correlation signal, for example, higher than 10 MHz, and the above first sweep type The maximum frequency of the continuous FM signal, for example, a constant frequency higher than 81 MHz, for example, a signal of 280 MHz, that is, a high constant frequency signal is used, and the second swept continuous FM signal 5 described above is used.
The frequency of the high constant frequency signal as a, that is, 2
Variable frequency range higher than 80 MHz, eg 281
A third configuration including frequency conversion means using a signal having ˜361 MHz;

The portion of the frequency conversion means in the third structure is the above-mentioned first sweep type continuous FM signal 4a.
One variable frequency generation circuit, for example, a wide variable frequency range that cannot be stably generated in a VCO circuit having a PLL configuration, that is, a wide variable frequency range, for example, 1 to 81.
A signal having a frequency of 1 MHz is used, and the above correlation signal, for example, the first constant frequency signal 1a is used as the wide variable frequency range, that is, a frequency within 1 to 81 MHz, for example,
A signal having 0 MHz is used, and as the second swept continuous FM signal 5a, a variable frequency range that can be stably generated by one variable frequency generation circuit, for example, a VCO circuit having a PLL synthesizer configuration, for example, The fourth configuration is provided with a frequency conversion unit that uses a signal having 281 to 361 MHz.

Further, in each of the configurations of the first and second embodiments, in the above-mentioned first to fourth configurations, the first sweep type continuous FM signal 4a obtained on the side performing the above correlation processing is obtained. Is converted into an optical signal by a light guide line, that is, a transmission side light guide line, for example, the above-mentioned transmission portion by the transmission lead 401, for example,
Transmitting wire means for giving to the transmitting unit 402 and the transmitting antenna 403, and a light guide line by converting the received signal 23a into an optical signal, that is, a receiving side light guide wire, for example, a receiving wire 701.
By means of the above-mentioned correlation processing, for example, the receiving conductor means given to the control processing / display unit 301 side, and at least the second sweep type continuous FM signal 5a for performing the above frequency conversion, Side light guide wire, that is, transmission lead wire 4
The transmission time of the first swept-type continuous FM signal 4a in the area 01 and the above-mentioned receiving side light guide line, that is, the receiving lead wire 70
A fifth configuration for providing a delay means for delaying a time amount corresponding to a time amount obtained by adding the transmission time of the reception signal 23a in the portion 1;

In the fifth configuration, the above delay is
At least the length of the above-mentioned transmission-side light guide line, for example, the length L ₁ of the transmission conductor 401 and the above-mentioned length of the reception-side light guide line, for example, the length L ₃ of the reception conductor 701 are added. The sixth configuration is provided with the above-mentioned delay means obtained by a light guide line having a length corresponding to, for example, a length of L ₁ + L ₃ .

Furthermore, in each of the configurations of the third and fourth embodiments, in the above-described first to fourth configurations, a part of the above-mentioned frequency conversion means, for example, the frequency conversion by the third conversion circuit 28 is performed. Part or all, for example, the third conversion circuit 2
8 and the fourth conversion circuit 30 provide a frequency conversion part arranging means for arranging the frequency conversion part on the reception part side, for example, the reception part 602, and in the seventh structure, the delay described above is provided. The eighth delay means is provided to obtain at least the length of the transmission-side light guide line, for example, a light guide line having a length corresponding to the length L ₁ of the transmission conductor 401, for example, the length L ₁ . It means that the structure of is configured.

[Modified Implementation] The present invention includes the following modified implementation. (1) The first swept continuous FM signal 4a is changed to a swept continuous FM signal by stepwise continuous frequency modulation shown in FIG.

(2) The first sweep type continuous FM signal 4a is
As indicated by the thick solid line in FIG. 12, the linear variable frequency f _{40 in} FIG. 10 is changed during the short time Ta in the period TA.
Same signal, or the stepped variable frequency f in FIG.
The same signal as that of ₄₀ is changed to the arranged signal and configured. Further, as shown by the thick dotted line in FIG. 12, the period in which frequency modulation is not performed is changed to a signal that is held at a constant frequency, for example, frequency f ₀ .

(3) All or part of the delay circuit 29 in the first and second embodiments is constructed 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) 2 in the second and fourth embodiments
As for the phase correlation signal, when the first constant frequency signal 1a which is one of the correlation signals is a sin wave, the 90 ° phase shift signal 35a which is the other correlation signal is a cos wave. The multiplication correlation signal 37a is expressed by the formula (1
Since the phase angle based on the beat frequency component fb in 0) is represented by the X-axis value and the Y-axis value when represented by the polar coordinates, the multiplication correlation signal 32a and the 90 ° multiplication correlation signal 37a are represented on the polar coordinates. The calculation signal obtained by calculating the phase angle of is output as the target search signal.

(5) The well-known two-phase sample and hold circuits 101 and 102 as shown in FIG. 13 are used for the two-phase correlation components of the multiplication circuits 31 and 36 and the low-pass filtering circuits 32 and 37.
And the sample hold signals 101a and 102a are changed to the A / D conversion circuit 105.1.
The digital signal obtained by giving the value to 06 is obtained as the X-axis value / Y-axis value in the configuration of (4) above. That is, as shown in FIG. 14, the first constant frequency signal 1a, which is a two-phase correlation signal, and the 90 ° phase shift signal 35a are 90 degrees in phase.
The sampling time point signals 103a and 104a for performing the sample hold with the deviation are made into pulse signals by pulsing the zero-cross points of the signals by the pulse conversion circuits 103 and 104 as shown in FIG. The A / D conversion values ex · ey of the sample hold signals 101a · 102a obtained by sample-holding the converted reception signal 30a to be the correlated signal by the sample time point signals 103a · 104a are used as X-axis values / Y-axis values of polar coordinates. It is configured to perform a calculation for obtaining the phase angle.

(6) The processing processor and the display unit are configured by a personal computer with a printer, and the processing results can be printed and saved.

(7) Transmission conductor 401, reception conductor 70
1. In the rotation center portion of the rotary drum of the winch 801 for winding up and down the light guide wires constituting the 1 / delay conducting wire 182, these light guide wires are connected to the rotating side and the fixed side by relay connection. An optical rotary coupler, for example, an optical fiber rotary joint is provided at the relay connection portion.

(8) The transmission line is made of a dielectric material such as fresh water, for example, a river or dam, and the transmission signal is an electromagnetic wave, so that the change in water amount or the degree of pollution can be detected. To configure.

(9) The transmission path is a continuum of electrically distributed constants, such as a communication cable, and the transmission signal is an electric signal so that distortion of the transmission signal can be predicted.

(10) In the first to fourth embodiments, an amplifying circuit is added at a required position in order to make each signal have a signal amplitude necessary for operation, or a sufficient signal amplitude is obtained. The amplifier circuit is deleted from the configuration.

(11) Sweep-type continuous FM signal swept so as to shift from a high frequency to a low frequency, that is, the variable frequency f ₄₀ of FIGS. 10, 11 and 12 is set to the frequency f ₀ at time _0. + Δf, which is a signal that sweeps toward frequency f ₀ with the passage of time.

[0137]

According to the present invention, firstly, since the received signal is converted into a signal having a constant frequency in the portion where the search signal is obtained from the received signal, the received signal can be filtered with an extremely narrow bandwidth. In this way, the S / N ratio of the received signal can be significantly improved, and the received signal converted into the constant frequency is subjected to the correlation processing by the correlation signal of the constant frequency signal. Therefore, the harmonic signal component based on the multiplication operation can be reduced, and unnecessary interference given to other components can be drastically reduced.

Secondly, since the portion for obtaining the two-phase correlation signals used for the two-phase multiplication correlation can be shifted by only the constant frequency signal, inaccuracies due to the distortion of the correlation signal due to the phase shift and the like can be avoided. Since it can be removed, the cause of the error in the correlation operation can be reduced and the search information in the search signal can be made highly accurate.

Third, the sweep type continuous F used for the transmission signal.
Since the M signal is obtained by performing the two frequency conversions of once obtaining the M signal at a frequency higher by one digit and then returning it to the lower frequency band, generally, in the high frequency band, a relatively wide frequency range is set to one variable frequency. Since it can be stably generated in the generation circuit, the transmission signal used for the search can be a signal having an extremely wide variable frequency in a low frequency band, and therefore the search can be finely performed over a wide range of frequencies.

Fourthly, since each signal transmitted between the correlation processing portion and the transmitting portion and the receiving portion is converted into light and is transmitted through the light guide line, the variable sweeping continuous FM signal is changed. The group delay associated with frequency components can be accurately and easily delayed, and
The delay amount can be adjusted only by the length of the light guide line.

Fifth, since the main part of the frequency conversion part can be provided on the receiving part side, by using a commercially available light guide line which bundles a plurality of lines, it is possible to cancel the delay amount by a simple length. In addition to the above, there is a feature that the frequency conversion part on the receiving side interferes with the frequency conversion part on the transmitting side to eliminate an error that occurs and a highly accurate search signal can be obtained.

[Brief description of drawings]

1 to 8 show an embodiment of the present invention, and FIG.
14 to 14 show a conventional technique, and the contents of each figure are as follows.

[Fig. 1] Whole block configuration Ground layout partial view

[Fig. 2] Partial diagram of the overall block configuration

[Fig. 3] Signal waveform diagram of main part

FIG. 4 is a signal waveform diagram of essential parts.

FIG. 5 is a block diagram of a main part of a portion arranged on the ground.

FIG. 6 is a block diagram of a main part of a portion arranged on the ground.

FIG. 7 is a block diagram of a main part of an underground arrangement portion.

FIG. 8 is a block diagram of a main part of a portion arranged on the ground.

FIG. 9 is an overall block configuration diagram.

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

FIG. 11 is a signal waveform diagram of essential parts.

FIG. 12 is a signal waveform diagram of essential parts.

FIG. 13 is a block diagram of the main part

FIG. 14 is a signal waveform diagram of essential parts.

[Explanation of symbols]

1 First local signal generation circuit 1a First constant frequency signal 2 First conversion circuit 2a Third constant frequency signal 3 Second local signal generation circuit 3a Second constant frequency signal 4 Second conversion circuit 4a First sweep type continuous FM signal 5 Variable frequency generator 5a Second sweep type continuous FM signal 6 Preamplifier circuit 6a amplified signal 7 Electric / optical conversion circuit 7a Optical signal 8 Optical / electrical conversion circuit 8a First sweep type continuous FM signal 9 Transmitter circuit 9a Transmission output signal 10 Matching transformer 11 batteries 12 Outer cover 12a gland packing 22 Matching transformer 22a Received signal 23 Receiver circuit 23a received signal 24 Electric / optical conversion circuit 24 'electric / optical conversion circuit 24a optical signal 24a 'optical signal 25 Outer cover 26 Optical / electrical conversion circuit 26 'photoelectric conversion circuit 26a Received signal 26a 'First converted received signal 27 Rear amplification circuit 27 'post-stage amplifier circuit 27a Received signal 27a 'First converted received signal 28 Third Conversion Circuit 28a First converted received signal 29 Delay circuit 29a Delayed sweep type continuous FM signal 29a 'Delayed sweep type continuous FM signal 30 Fourth conversion circuit 30a Second converted received signal 31 multiplication circuit 31a Multiplication signal 32 low pass filter 32a Multiplication correlation signal 33 Processor 33a Calculated value signal 34 Display 35 90 ° phase shift circuit 35a 90 ° phase shift signal 36 Multiplier circuit 36a Multiplication signal 37 Low-pass filtering circuit 37a Multiplication correlation signal 38 Power supply for operation 100 borehole radar 101 Sample and hold circuit 101a sample hold signal 102 Sample and hold circuit 102a sample hold signal 103 pulse circuit 103a sample time point signal 104 pulse circuit 104a sample time point signal 105 A / D converter 106 A / D converter 181 Electric / optical conversion circuit 181a optical signal 182 Lead wire for delay 183 Photo-electric conversion circuit 183a delayed signal 184 amplifier circuit 201 above ground 202 underground 203 exploration hole 204 exploration hole 301 Control processing / display unit 401 transmission lead wire 402 transmitter 403 transmission antenna 403a cylindrical body 403b cylindrical body 501 electromagnetic wave 601 reception antenna 601a cylindrical body 601b cylindrical body 602 receiver 701 receiving wire 701 'Receiving wire 801 winch 801a depth signal

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-288834 (JP, A) JP-A-4-130294 (JP, A) JP-A-4-80684 (JP, A) JP-A-4- 152286 (JP, A) JP-A-6-324162 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01V 3/30 G01S 7/292 G01S 13/32

Claims (8)

(57) [Claims] 1. A transmission part is arranged at one of two positions of a transmission line and a reception part is arranged at the other part thereof, and a sweeping continuous FM signal (hereinafter referred to as a first sweeping continuous FM) is transmitted from the transmission part.
Signal) and a signal based on the received signal obtained in the receiving portion as a correlated signal, and a required search signal based on a signal obtained by performing correlation processing on the correlated signal with a predetermined correlation signal. A correlation detection type transmission path exploring apparatus for obtaining, wherein: a correlating unit that performs the correlation process using a constant frequency signal as the predetermined correlation signal; and the correlation signal or a constant frequency signal based on the correlation signal, the first sweep Second swept continuous F having a variable frequency range higher than the variable frequency range of the continuous FM signal
Frequency conversion means for obtaining the first swept continuous FM signal by performing frequency conversion with the M signal; and frequency equivalent to the correlation signal by performing frequency conversion of the received signal opposite to the frequency conversion. And an inverse frequency conversion means for obtaining the correlated signal having the above-mentioned correlation detection type transmission path searching apparatus. 2. A transmission part is arranged at one of two positions of a transmission line and a reception part is arranged at the other part thereof, and a sweeping continuous FM signal (hereinafter referred to as a first sweeping continuous FM signal) is transmitted from the transmission part.
Signal), and a signal based on the received signal obtained in the receiving portion is set as a correlated signal, and a required signal is obtained based on a signal obtained by performing two-phase correlation processing on the correlated signal by a predetermined correlation signal. A correlation detection type transmission line exploration device for obtaining an exploration signal, wherein the constant frequency signal and a phase shift signal obtained by phase-shifting the constant frequency signal by 90 ° are used as the predetermined correlation signal.
Correlation means for performing phase correlation processing, and a second sweep type having a variable frequency range higher than the variable frequency range of the first sweep type continuous FM signal as the correlation signal or a constant frequency signal based on the correlation signal. Frequency conversion means for obtaining the first swept continuous FM signal by performing frequency conversion with the continuous FM signal, and frequency conversion means for performing reverse frequency conversion on the received signal, which is the same as the correlation signal. And a reverse frequency conversion means for obtaining the correlated signal having a frequency. 3. The correlation detection type transmission line exploration device according to claim 1, wherein the constant frequency signal based on the correlation signal is higher than the frequency of the correlation signal, and the first sweep is performed. A signal having a constant frequency higher than the highest frequency of the continuous FM signal (hereinafter referred to as a high constant frequency signal) is used,
A correlation detection type transmission line exploration apparatus comprising the frequency conversion means that uses a signal having a variable frequency range higher than the frequency of the high constant frequency signal as the second swept continuous FM signal. 4. The correlation detection type transmission line exploring device according to claim 3, wherein the first sweeping continuous FM signal has a wide variable frequency range that cannot be stably generated by one variable frequency generating circuit. (Hereinafter, referred to as a wide variable frequency range), a signal having a frequency within the wide variable frequency range is used as the correlation signal, and one variable is used as the second swept continuous FM signal. A correlation detection type transmission line exploration device comprising the frequency conversion means that uses a signal having a variable frequency range that can be stably generated by a frequency generation circuit. 5. The correlation detection type transmission line exploration device according to claim 1, wherein the first swept continuous FM signal obtained on the side performing the correlation processing is converted into an optical signal and guided. Transmission lead means for giving to the transmission part by a light ray (hereinafter, referred to as transmission side light guide line), and a side for converting the received signal into an optical signal and performing the correlation processing by a light guide line (hereinafter, referred to as reception side light guide line) And a second sweep-type continuous FM for performing the frequency conversion.
Corresponding to at least the amount of time, which is the sum of the transmission time of the first swept-type continuous FM signal in the portion of the transmission-side light guide line and the transmission time of the reception signal in the portion of the reception-side light guide line, for the signal A correlation detection type transmission line exploration device, comprising: delay means for delaying the amount of time to be performed. 6. The correlation detection type transmission line exploration device according to claim 5, wherein the delay corresponds to a length corresponding to at least a sum of the length of the transmitting side light guide line and the length of the receiving side light guide line. Detection type transmission line exploration device comprising the delay means obtained by a light guide line having a height. 7. The correlation detection type transmission line exploration device according to claim 1, wherein a part or all of the frequency conversion means is arranged on the reception part side, and the frequency conversion part arrangement means is provided. The second swept continuous FM for converting
A correlation detection type transmission path exploration apparatus comprising: a delay unit that delays a signal by at least an amount of time corresponding to a transmission time of the first sweep type continuous FM signal in a portion of the transmission side light guide line. 8. The correlation detection type transmission line exploration apparatus according to claim 7, further comprising: the delay unit that obtains the delay by a light guide line having a length corresponding to at least the length of the transmission side light guide line. Correlation detection type transmission line exploration device.