JP2001083242A - Method and apparatus for search - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a technique for searching for a buried object whereby effects of reflecting signals can be removed from a surface of a medium irrespec tive of a material of the medium in a searching apparatus which radiates wave signals of electromagnetic waves or sound waves into the medium while moving on the medium surface, receives reflecting signals from the object present in the medium, generates and stores original data having coordinates of a position on the medium surface and a reflecting time with respect to an intensity of receive signals, and investigates a position of the object present in the medium. SOLUTION: The apparatus is with a center value-operating means 32 for obtaining a center value of a receiving signal intensity for every predetermined reflecting time to a plurality of stored original data, a difference-operating means 34 for operating a difference between the stored two-dimensional data and the obtained center value for every predetermined reflecting time and obtaining two-dimensional search data, and an output process means 38 for outputting the searched result in a medium on the basis of the obtained two-dimensional search data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of radiating a wave signal of an electromagnetic wave or a sound wave into a medium while moving on a surface in the medium, receiving a reflection signal from an object existing in the medium, and receiving the signal. The present invention relates to an exploration method and apparatus for exploring the position of an object existing in a medium by performing signal processing on a received signal, and further relates to an analyzer provided in the exploration apparatus.

[0002]

2. Description of the Related Art As an exploration method of this kind, for example, when exploring an embedded object buried in a medium such as a structure such as a concrete wall or the ground from the surface of the medium, a transmitting antenna which emits a pulse signal by electromagnetic waves and an embedded antenna are used. A probe equipped with a receiving antenna for receiving the reflected wave of the pulse signal from the object receives the above-mentioned reflected pulse signal sequentially while scanning over the surface of the medium, and moves the distance x with respect to the intensity of the reflected signal.
-Dimensional data s with coordinates (x, t) and reflection time t
Two-dimensional data s (x, t) having coordinates (x, t) or three-dimensional data having coordinates (x, y, t) of position (x, y) and reflection time t with respect to reflected signal intensity s (x,
y, t) is generated as original data, and the original data is subjected to predetermined data processing or the like to display the position of the concealed pipe two-dimensionally or to expand the two-dimensional data to three-dimensionally to display three-dimensionally. There are ways to explore.

[0003]

In such an exploration method, when a buried object exists below the receiving antenna, the received signal includes a reflected signal from the buried object and a reflected signal from a surface in the medium. May be synthesized, and it may be difficult to determine the presence or absence and depth of a buried object. For this reason, in a conventional exploration device, a reflection signal from the medium surface when there is no buried object or a standard signal simulating the signal is set in advance, and the difference between the received signal and the set signal is obtained, thereby obtaining the buried object. Was getting a reflected signal from However, in such a configuration, it is difficult to prepare a reflection signal from the surface of the medium when there is no buried object, and further, as the medium, various types of concrete, asphalt, ground, etc. However, since the reflected signals on the surface are all different,
There is also a problem that the simulated waveform cannot cope. Also,
As a method for solving such a problem, Japanese Patent Laid-Open Publication No.
There is a method disclosed in Japanese Patent No. 9835. This method
At the end of the measurement, the average value of the received signal is calculated by the number of receptions to obtain an average value, the difference between the received signal and the average value is obtained and the data is used to search for a buried object,
For example, when the buried object is close to the surface of the medium and the intensity of the reflected signal of the buried object is high, the average value is pulled to the value of the reflected signal and does not match the reflected signal from the medium surface when there is no buried object. It has been difficult to obtain a reflection signal from only the buried object even if the calculation is performed.

Accordingly, the present invention has been made in view of the above circumstances,
It is an object of the present invention to obtain a technique for searching for a buried object that can remove the influence of a reflected signal from the surface regardless of the material of the medium.

[0005]

According to a first feature of the present invention for achieving this object, a moving medium surface is moved as described in claim 1 of the claims.
Emitting a wave signal by electromagnetic waves or sound waves into the medium,
A transmission / reception step of receiving a reflection signal from an object present in the medium, and a data generation step of generating and storing original data having coordinates of a position on the surface of the medium and a reflection time with respect to a received signal strength, and storing the data. Executing a search method for searching for a position of an object present in the medium, wherein, for each of the plurality of stored original data, for each of the predetermined reflection times, a median value for obtaining a median value of the received signal intensity. A calculating step, for each of the predetermined reflection times, calculating a difference between the stored original data and the obtained median, and a difference calculating step of obtaining search data, based on the obtained search data. And an output processing step of outputting a search result in the medium.

The data generating step is configured to generate original data having coordinates of a position on the surface of the medium with respect to the intensity of the received signal and a reflection time, and the position on the medium is, of course, a direct search device. It can be configured to transmit and receive at every predetermined moving distance while detecting the position of the search device by the number of rotations of the wheels, etc., to generate original data, and further, when the search device scans at a constant speed, The position may be determined from the elapsed time from the start of the search and the speed of the search device, and transmitted and received at predetermined time intervals to generate the original data.

According to the second feature configuration, in addition to the first feature configuration, a median value obtained in the median value calculating step is added to the first feature configuration. ,
The point is that a frequency filter processing step of performing frequency filter processing and substituting the median value is performed.

[0008] In the third feature configuration, in addition to the second feature configuration, when the frequency filter processing step is performed, a cutoff frequency may be reduced as described in claim 3 of the claims. The point is that a low-pass filter process that is at least twice the center frequency of the wave signal is performed.

According to a fourth aspect of the present invention, in addition to any one of the first to third aspects, the wave signal is radiated to emit the wave signal as described in claim 4 of the claims. The time until the start of receiving the reflected signal is defined as a reference time, and in the stored original data, the time corresponding to the reflection time is equal to or longer than the reference time, and the time corresponding to two cycles of the wave signal is added to the reference time. The median value calculating step and the difference calculating step are performed on the original data for the second time or less.

According to a fifth aspect of the present invention, there is provided an exploration apparatus which can be used in an exploration method according to the first aspect of the present invention. Transmitting and receiving means for radiating a wave signal due to an electromagnetic wave or a sound wave into the medium while receiving a reflection signal from an object present in the medium while moving on the surface of the medium, and the medium surface for a received signal strength. A data generating means for generating and storing original data having coordinates of the upper position and the reflection time as coordinates, and in a search device for searching for a position of an object existing in the medium, For each of the predetermined reflection times, a median value calculating means for calculating a median value of the received signal intensity, and for each of the predetermined reflection times, the stored original data and the obtained median value. The difference Calculated by the difference calculation means for obtaining the search data, based on the survey data to which the obtained lies in that an output processing means for outputting a search result in said medium.

The sixth characteristic configuration relates to a search device suitable for using the search method according to the second characteristic configuration, and as described in claim 6 of the claims section, the fifth characteristic configuration. In addition to the above, there is provided a frequency filter processing means for performing a frequency filter process on the median value obtained by the median value calculation means and replacing the median value with the median value.

The seventh feature configuration relates to a search device suitable for using the search method according to the third feature configuration, and as described in claim 7 of the claims, the sixth feature configuration. In addition to the above, the frequency filter means is a means for performing a low-pass filter processing in which a cutoff frequency is twice or more the center frequency of the wave signal.

The eighth feature configuration relates to a search apparatus suitable for using the search method according to the third feature configuration, as described in claim 8 of the claims section. In addition to any of the above features, the time until the wave signal is emitted and the reception of the reflection signal is started is set as a reference time, and in the original data, the reflection time t is equal to or longer than the reference time, and The median value calculating means and the difference calculating means operate on original data which is not more than a second time obtained by adding a time corresponding to two cycles of the wave signal to a reference time.

A ninth characteristic configuration according to the present invention for achieving this object relates to a search method and an analysis device that can be used in the search device according to the first and fifth characteristic configurations. 10. A transmitting and receiving means for radiating a wave signal by an electromagnetic wave or a sound wave into the medium while moving on the surface of the medium and receiving a reflected signal from an object existing in the medium as described in claim 9, Data generating means for generating and storing original data having coordinates of a position on the surface of the medium with respect to signal intensity and a reflection time, and provided in an exploration apparatus for analyzing the original data and existing in the medium. An analysis device for searching for a position of an object, for each of the plurality of stored original data, for each predetermined reflection time, a median value calculating means for calculating a median value of the received signal strength; and For each firing time, the difference between the stored original data and the median calculated in the median calculation step is calculated, and as the analysis result, the difference calculation means for calculating the search data and the calculated search data are used. Output processing means for outputting a search result in the medium based on the information.

[0015] The tenth characteristic configuration relates to a search method and an analysis device suitable for use of the search device according to the second and sixth characteristic configurations, and as described in claim 10 in the claims section. In addition to the ninth characteristic configuration, the present invention is characterized in that a frequency filter processing unit is provided for performing a frequency filter process on the median obtained by the median value calculation unit and replacing the median value with the median value.

An eleventh characteristic configuration relates to an exploration method and an analysis device suitable for use of the exploration device according to the third and seventh characteristic configurations, as described in claim 11 of the claims. In addition to the tenth characteristic configuration, the frequency filter means is a means for performing a low-pass filter process in which a cutoff frequency is equal to or more than twice a center frequency of the wave signal.

The twelfth characteristic configuration relates to a search method and an analysis device suitable for use of the search device according to the fourth and eighth characteristic configurations, as described in claim 12 of the claims. In addition to any one of the ninth to eleventh features, the time until the wave signal is emitted and the reception of the reflection signal is started is set as a reference time, and in the original data, the reflection time t is , The median value calculating means and the difference calculating means operate on original data which is equal to or longer than the reference time and equal to or shorter than a second time obtained by adding a time corresponding to two cycles of the wave signal to the reference time. is there.

The operation and effect of these features will be described below.

According to the first characteristic configuration, the reflection signal from the surface of the medium in the case where there is no buried object (object existing in the medium) is obtained by executing the above-mentioned median calculation step to obtain a predetermined reflection time t. Since it is calculated as the median value c (t) of the received signal strength s every time, the reflected signal from the medium surface when there is no buried object is not affected by the strong reflected signal of the buried object like the average value. It can be obtained with high accuracy. In addition, in the difference calculation step, the search data can be satisfactorily obtained as a reflection signal from only the buried object, and the search data obtained in the difference calculation step can be output as a search result, for example, as image data. Particularly, when the existence ratio of the buried object in the search direction is 50% or less, a good search result is obtained. In such a data generation step, two-dimensional data s (x, t) having coordinates as coordinates (x, t) using a moving distance x and a reflection time t with respect to the reflection signal intensity are used. , T) can be configured to be generated and stored as original data, and the position (x, y) and the reflection time t are represented by coordinates (x, y,
The three-dimensional data s (x, y, t) as t) may be generated and stored as original data.

According to the second or third characteristic configuration, by performing the frequency filtering process, the reflection signal from the surface of the medium when there is no buried object can be converted into the predetermined reflection time t by the predetermined reflection time t. Is determined as the median c (t) from the received signal intensity of the nearby reflection time t including the reflection time t, and the distribution of the median c (t) in the direction of the reflection time t-axis becomes smooth, Better results can be obtained. Furthermore, since the frequency less than twice the center frequency of a wave signal is a signal component, and the frequency more than twice is considered a noise component, the cutoff frequency should be twice or more the center frequency of the above wave signal. Is preferable, and a median c (t) having a smoother distribution can be obtained.

According to the fourth characteristic configuration, the calculation by the median value calculation step and the difference calculation step is generated from a reference time when the reception of the reflection signal is started to a time twice as long as the wavelength of the wave signal. Since it is performed only for the original data
The processing time can be reduced without substantially reducing the effect.

According to the fifth characteristic configuration, the reflection signal from the surface of the medium when there is no buried object is converted into the median value c () of the received signal intensity s by the median value calculation means at every predetermined reflection time t. Since it is obtained as t), the reflection signal from the medium surface when there is no buried object can be obtained with high accuracy without being affected by the strong reflection signal of the buried object like the average value. In addition, the exploration data can be satisfactorily obtained as a reflection signal from only the buried object by the difference operation means, and the exploration data obtained by the difference operation means is output as the search result, for example, as image data by the output processing means can do. In particular, it is possible to configure a search device that can obtain a good search result when the presence ratio of the buried object in the search direction is 50% or less. Such data generating means generates two-dimensional data s (x, t) having coordinates as coordinates (x, t) using a moving distance x and a reflection time t with respect to the reflected signal intensity. , T) is generated and stored as original data, but a three-dimensional coordinate system in which the position (x, y) and the reflection time t are represented by coordinates (x, y, t) with respect to the reflection signal intensity is provided. Data s
(X, y, t) may be configured to be generated and stored as original data. Furthermore, with this feature configuration,
Since the search method according to the present invention having the above-mentioned first characteristic configuration can be used, the operation and effect of the above-mentioned first characteristic configuration can be exhibited.

According to the sixth or seventh characteristic constitution, the reflection signal from the medium surface when there is no buried object is converted by the frequency filter processing means into the predetermined reflection time t for each of the predetermined reflection time t. Is determined as the median c (t) from the received signal strength of the nearby reflection time t including
The distribution of the median value c (t) in the direction of the reflection time t-axis becomes smooth, and better results can be obtained. Furthermore, since the frequency less than twice the center frequency of a wave signal is a signal component, and the frequency more than twice is considered a noise component, the cutoff frequency should be twice or more the center frequency of the above wave signal. Is preferable, and a median c (t) having a smoother distribution can be obtained. Furthermore, with this characteristic configuration, the exploration method according to the present invention having the above-described second and third characteristic configurations can be used, so that the operational effects of the second and third characteristic configurations can be exhibited. It is.

According to the eighth characteristic configuration, the calculations in the median value calculation means and the difference calculation means are generated from a reference time when the reception of the reflection signal is started to a time twice as long as the wavelength of the wave signal. Since the processing is performed only on the original data that has been processed, the processing time can be reduced without substantially reducing the effect. Further, with this characteristic configuration, since the search method according to the present invention having the above-described fourth characteristic configuration can be used, the operation and effect of the above-mentioned fourth characteristic configuration can be exhibited.

According to the ninth aspect, the median value calculating means converts the reflected signal from the medium surface when there is no buried object into the median value c () of the received signal strength s at every predetermined reflection time t. Since it is obtained as t), the reflection signal from the medium surface when there is no buried object can be obtained with high accuracy without being affected by the strong reflection signal of the buried object like the average value. In addition, the exploration data can be satisfactorily obtained as a reflection signal from only the buried object by the difference operation means, and the exploration data obtained by the difference operation means is output as the exploration result, for example, as image data by the output processing means. can do. In particular, it is possible to configure an analyzer that can obtain a good search result when the presence ratio of the buried object in the search direction is 50% or less. Such data generating means generates two-dimensional data s (x, t) having coordinates as coordinates (x, t) using a moving distance x and a reflection time t with respect to the reflected signal intensity. , T) is generated and stored as original data, but a three-dimensional coordinate system in which the position (x, y) and the reflection time t are represented by coordinates (x, y, t) with respect to the reflection signal intensity is provided. Data s
(X, y, t) may be configured to be generated and stored as original data. Furthermore, with this feature configuration,
Since the exploration method according to the present invention having the above-described first characteristic configuration and the exploration apparatus according to the fifth characteristic configuration can be used, the operational effects of the above-described first and fifth characteristic configurations can be exhibited. It is.

According to the tenth or eleventh feature,
By the frequency filter processing means, the reflected signal from the medium surface when there is no buried object, for each of the predetermined reflection time t,
The median c (t) is determined from the received signal intensity of the nearby reflection time t including the predetermined reflection time t, and the distribution of the median c (t) in the reflection time t-axis direction is smooth. And a better result can be obtained. Furthermore, since the frequency less than twice the center frequency of a wave signal is a signal component, and the frequency more than twice is considered a noise component, the cutoff frequency should be twice or more the center frequency of the above wave signal. Is preferable, and a median c (t) having a smoother distribution can be obtained. Further, with this characteristic configuration, the search method according to the present invention of the second and third characteristic configurations and the search device according to the sixth and seventh characteristic configurations can be used. The function and effect of the three characteristic configurations can be exhibited.

According to a twelfth characteristic configuration, the calculation by the median value calculating means and the difference calculating means is performed by calculating the wavelength of the wave signal from a reference time at which reception of the reflected signal is started.
Since the processing is performed only for the original data generated up to twice the time, the processing time can be reduced without substantially reducing the effect. Furthermore, with this characteristic configuration, the search method according to the present invention having the fourth characteristic configuration and the search device according to the present invention having the eighth characteristic configuration can be used. The function and effect of the configuration can be exhibited.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, an embodiment of the exploration apparatus according to the present invention includes a transceiver 10 as a transmission / reception unit and a data analysis device 20 for processing a signal obtained by the transceiver 10 as main devices. It is constituted as prepared. In the present application, the analysis process in the data analysis device 20 has the feature.

As shown in FIG. 1, a buried object 2 such as a concrete concealed pipe is buried in a concrete wall 1 which is a medium, and an exploration device 3 having a transceiver 10 and a data analysis device 20 is used as a surface of the concrete 1. While moving, the location of the buried object 2 is buried. The moving direction is the x direction. The buried object 2 shown in FIG. 1 schematically illustrates an object to be searched.

The transceiver 10 is, for example, 100 MHz to 1
A single-pulse signal illustrated in FIG. 2B and FIG. 2A at 1 GHz is generated in the transmission circuit 13 and emitted from the transmission antenna 11 into the concrete wall 1 as an electromagnetic wave signal. For example, when moving on the surface of the buried object 2 as illustrated in FIG. 2A, the incident wave 4 incident on the concrete wall 1 in the electromagnetic wave radiated from the transmitting antenna 11 is reflected and scattered on the surface of the buried object 2. Then, after the reflected wave 5 therein is received by the receiving antenna 12, the receiving circuit 14 performs the operation shown in FIG.
The signal is demodulated and amplified as a reception signal as exemplified in (2) (in this figure, a single line corresponds to a plurality of reception signal groups received at fixed positions with a time difference). Further, the reception circuit 14 performs amplitude correction, waveform smoothing, and noise removal processing as necessary. The time difference (the substantial reflection time) t radiated from the transmitting antenna 11 and received by the receiving antenna 12 is the distance from the surface of the concrete wall 1 to the buried object 2 and the relative permittivity ε of the concrete wall 1 or electromagnetic wave. Is uniquely determined from the propagation speed of
In the case shown in FIG. 1, the transmitting antenna 11 and the receiving antenna 12 are arranged at regular intervals so as to face the ground surface.
The x-direction movement is performed so as to cross the embedded object 2.

As shown in FIG. 1, the transceiver 10 is provided with signal intensity modulating means 15 for modulating the gain of the amplifying section of the receiving circuit 14 in accordance with the time difference t. A configuration in which the loss of the pulse signal propagating through the wall 1 is increased and the received signal intensity is attenuated by amplitude correction to obtain a received signal intensity distribution that does not attenuate rapidly with the increase in the time difference t, that is, the reflection time t. Have been. With this configuration, it is possible to secure the signal strength necessary for the subsequent signal processing.

Next, the data analyzer 20 to which a received signal is sent will be described with reference to FIGS. The data analysis device 20 includes a data processing unit 21 including a microcomputer, a semiconductor memory, and the like, and an input unit 2 such as a mouse and a keyboard for inputting an operation instruction from the outside.
2 and a display unit 23 such as a CRT monitor or a liquid crystal display for displaying image data and output results at each processing stage. Further, an external auxiliary storage unit 24 such as a magnetic disk for storing data and output results at each processing stage is provided.

The data processing section 21 has a two-dimensional data generating means 31 for organizing and processing the received signal input from the receiving circuit 14 in relation to the movement distance x on the medium surface and the time t. . This two-dimensional data generation means 3
Numeral 1 is for generating original data to be used in the subsequent processing. The received signal processed by the receiving circuit 14 is sampled for every fixed moving distance, A / D converted, and the fixed moving distance is obtained. For each received signal strength data, two-dimensional data s (x, t) having the position x and the reflection time t of the reflection signal as coordinates (x, t) is generated as the original data. .

Further, the data processing unit 21 applies two-dimensional data s (x, t) generated by the two-dimensional data generating means 31 and temporarily stored in the memory 21a to the data processing unit 21.
For each predetermined reflection time t, the median c of the received signal strength s
A central value calculating means 32 for calculating (t), and a low frequency band whose cutoff frequency is at least twice the center frequency of the radiated pulse signal with respect to the central value c (t) calculated by the median value calculating means 32. Frequency filter processing means 33 for performing frequency filter processing for performing pass filter processing and replacing the median value c (t) with the stored two-dimensional data s (x, t) for each predetermined reflection time t A difference calculation means 34 for calculating a difference from the value c (t) to obtain two-dimensional search data s1 (x, t) is provided. The two-dimensional search data s1 (x, t), and output two-dimensional search data s1 (x,
and a display unit 23 for displaying a gradation of t) on a display screen.

[Embodiment 1] Next, an embodiment of the search method according to the present invention will be described with reference to a flowchart of a typical data processing procedure in the data processing unit 21 shown in FIG. This will be described while showing the processing results of the search. By the way, in the embedding condition shown in FIG. 4, an embedded object 2 of a pipe having a cover of 50 mm and a diameter of 25 mm is embedded in a concrete wall 1.

[Two-Dimensional Data Generation Step (ST1)] In this step, the exploration apparatus 3 scans the surface of the concrete wall 1 shown in FIG. This is a step of collecting, processing this, generating two-dimensional data s (x, t) to be used in the subsequent processing, and temporarily storing it in the memory 21a. In this step, a cross-sectional image of the concrete wall 1 including the object is obtained from the digitized received signal strength by using the antennas 11 and 12.
The coordinates (x, x) of the moving distance x on the surface of the medium and the reflection time t of the reflected wave 5 from the buried object 2 (actually, the time from the oscillation of a predetermined incident signal until the reflected signal reaches the receiving antenna).
t), the received signal is displayed as luminance in a plurality of gradations according to the intensity of the received signal, and the positive value of the signal intensity is set to white (high luminance), A negative value of the signal strength is taken as black (low luminance), and a signal strength of 0 is taken as an intermediate gradation. Specifically, this gray scale is expressed by an 8-bit (256) gray scale, where a gray scale 128 is an amplitude value 0 of the reflected signal intensity, a gray scale of 129 or more, the positive value of which is 1
The amplitude value is a negative value at gradations of 27 or less. More specifically, the digitized reception signal is represented by a quantization bit width when the A / D conversion processing is performed, and a travel distance x on the medium surface and a reflection time t of the reflected wave 5 from the buried object 2. The determined coordinates (x, t) are encoded as an address signal and stored in a predetermined area of the memory 21a in the data processing unit as two-dimensional data s (x, t) of a plurality of gradations. The two-dimensional data s thus stored in the memory 21a
(X, t) is the output of the two-dimensional data generation means 31
Delivered to subsequent steps. As will be described later, FIG. 6 shows an example in which the two-dimensional data s (x, t) generated and stored as described above is displayed on the display unit 23 by the output processing unit 38.
Displayed in (a). Here, in this data, a reflection signal from the buried object 2 and a reflection signal from the surface of the concrete wall 1 are synthesized signals.
This is for obtaining a signal obtained by removing a signal reflected from the surface of the concrete wall 1 from this signal.

[Median Value Computing Step (ST2)] Next, a median value computing step is performed. In this step, after the scanning device 3 completes one scan for collecting data while moving, it is generated in that scan. This is a step of processing the two-dimensional data s (x, t) stored in the memory 21a. In this step, a plurality of two-dimensional data s
(X, t) is taken out, the median value c (t) of the received signal strength s for each predetermined reflection time t is determined, and is passed to the next step.

[Difference calculation step (ST3)] Next, the two-dimensional data s (x, t) generated in the two-dimensional data generation step
And a median value c (t) obtained in the median value calculation step, and a difference calculation step of obtaining two-dimensional search data s1 (x, t) is performed. By this process, two-dimensional data s
From (x, t), two-dimensional exploration data s1 (x, t) can be obtained by subtracting data of median c (t) close to the signal reflected from the surface of concrete wall 1.

[Output Processing (ST4)] By outputting such processed data, the buried pipe can be clearly searched.

Next, 2 obtained by performing each of the above-described steps was obtained.
Dimensional data s (x, t) and two-dimensional search data s1
(X, t) and, as a comparative example, data s obtained by subtracting an average value from two-dimensional data s (x, t) by a conventional method.
a is shown in FIGS. 7 and 8. Note that FIG. 7 shows the moving distance x =
0 mm, that is, data when there is no buried object 2, and FIG.
Is data when the moving distance x = 145 mm, that is, when the buried object 2 is present. As shown in FIG. 7, the two-dimensional data s
Since (0, t) is mostly a reflection signal from the surface of the concrete wall 1, it shows a large amplitude near a short reflection time. However, the two-dimensional exploration data s1 (0, t) obtained by the present method has an amplitude of about 0, and contains almost no reflected signal from the surface of the concrete wall 1. Since the data sa (0, t) obtained by subtracting the average value of the conventional method uses the average value, the average value is pulled by the reflection signal from the buried object and is equal to the reflection signal from the concrete wall 1 surface. Since the data sa (0, t) is not affected, the amplitude does not become 0 near the depth where the buried object 2 exists even though the buried object 2 does not exist. Therefore, in the data at the position where the buried object 2 is located as shown in FIG. 8, the two-dimensional exploration data s1 (14
In (5, t), the reflected signal from the buried object 2 can be obtained accurately and sufficiently. On the other hand, in the data sa (145, t) obtained by the conventional method,
Due to the influence of the above average value being pulled by the reflected signal from the buried object, the reflected signal from the buried object 2 cannot be obtained accurately.

Further, FIG. 6A shows the two-dimensional data s (x, t) displayed as a two-dimensional image as a two-dimensional image, and the two-dimensional search data s1 (x, t) obtained by the present method is shown in FIG.
FIG. 6B shows a two-dimensional image displayed as a gray scale.
Further, the data sa obtained by the above-mentioned conventional method is used.
FIG. 6 shows a gradation display of (x, t) as a two-dimensional image.
It is shown in (c). As shown in FIG. 6A, in the two-dimensional data s (x, t), the buried pipe 2 and the concrete wall 1
The reflected signal from the surface is in a synthesized state. On the other hand, the display result of the two-dimensional exploration data s1 (x, t) according to the present method shown in FIG. It can be seen that the reflected signal from the target was successfully removed. Further, in the display image of the data sa (x, t) obtained by the conventional method shown in FIG.
A black band appears near the depth of the object, and the intensity of the reflected signal from the buried object 2 is also weakly displayed. The two-dimensional exploration data obtained by this method is effective for accurately exploring the buried object. You can see that there is.

[Embodiment 2] Next, another embodiment of the search method according to the present invention will be described with reference to the flow chart of a typical data processing procedure in the data processing section 21 shown in FIG.
A description will be given while showing the processing results of the search for the burial condition shown in FIG. By the way, in the embedding condition shown in FIG. 9, an embedded object 2 of a pipe having a cover of 100 mm and a diameter of 80 mm is embedded in a concrete wall 1. In the data processing procedure shown in FIG. 10, the steps other than the frequency filter processing step are the same as those of the above-described embodiment except that the embedded state of the embedded object 2 and the scanning distance in the two-dimensional data generation step are 285 mm. The description is omitted because it is the same as.

[Frequency Filter Processing Step (ST3)] The frequency filter processing step is performed on the median c (t) obtained in the median calculation step. This step is a step of filtering and replacing the median c (t) determined in the median calculation step.

Median value calculation step (ST2) before this step
The data of the median c (t) and the data of the reflected signal from the surface of the concrete wall 1 without the buried object 2 are shown in FIG. It can be seen that unnatural irregularities are present at a reflection time of about 3 to 4 ns. Since the pulse width of the wave signal transmitted from the antenna 11 is 0.6 ns, one cycle is 1.2 ns and the center frequency is about 80 ns.
It turns out that it becomes 0 MHz. The spectral distribution obtained by Fourier-transforming the signal waveform of the median c (t) obtained in the above-described median calculation step, and the reflection signal from the surface of the concrete wall 1 without the buried object 2, the so-called moving distance x is 0 FIG. 12 shows a spectrum distribution obtained by performing a Fourier transform on the data of the reflected signal at the time of. Here, since the peak frequency at which the signal intensity is the strongest generally matches the center frequency, it can be seen that the center frequency is about 800 MHz. Further, since the frequency twice or more of the center frequency is considered to be noise, the signal obtained by performing the inverse Fourier transform after setting the cutoff frequency to 2 GHz and setting all the frequencies 2 GHz or more of the spectrum distribution of the median c (t) to 0. The waveform is replaced with data of the median c (t), and the data and the buried object 2
FIG. 13 shows the data of the reflection signal from the surface of the concrete wall 1 having no surface. As a result, the median c (t) before the frequency filtering process shown in FIG.
Although there were unnatural irregularities in about ns, by performing this frequency filtering process, as shown in FIG. 13, the unnatural irregularities disappeared, and the concrete wall 1 having no more buried objects 2 was removed from the surface. Data of the median c (t) close to the data of the reflected signal of

As a comparative example, two-dimensional data s (x,
The data of the average value of t) and the data of the reflection signal from the surface of the concrete wall 1 without the buried object 2 are shown in FIG. As a result, it is found that the median data is closer to the data of the reflection signal from the surface of the concrete wall 1 without the buried object 2 than the data of the average value, As simulated data of the reflected signal of
It can be seen that it is preferable to use the median c (t).

[Another Embodiment] <1> In the above embodiment, the search device 3 is
Are moved in the x-axis direction as shown in FIG. 3 and scanned by the two-dimensional data generation means as two-dimensional data s (x,
Although the configuration for generating t) is shown, the position (x, y) on the surface of the medium 1 of the search device 3 and the reflection time t with respect to the received signal strength s are determined by using the two-dimensional data generating means as three-dimensional data generating means. 3D data s with coordinates (x, y, t)
(X, y, t) may be generated as original data.

<2> In the above-described embodiment, the two-dimensional data s (x, t) is configured to be generated based on the received signal for each predetermined moving distance of the search device 3. In the case of scanning, the two-dimensional data s (x, t) is generated every predetermined time by transmitting and receiving every predetermined movement time, obtaining the position from the elapsed time from the start of the search and the speed of the search device. You can also.

<3> Two-dimensional data s (x, t)
In, the influence of the reflection signal from the surface of the medium, the time until the start of the reception of the reflection signal to emit the wave signal is the reference time, the value of the reflection time t, the Since the two-dimensional data s (x, t) is within the range of not less than the reference time and not more than the second time obtained by adding the time corresponding to the two periods of the wave signal to the reference time, the data from the medium surface In order to eliminate the influence of the reflection signal, it is possible to perform the above-described median value calculation step and difference calculation step only on the two-dimensional data s (x, t) within the above-mentioned reflection time range. Time can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an exploration apparatus.

FIG. 2 is an explanatory diagram of waveforms of a transmission signal and a reception signal.

FIG. 3 is a functional block diagram of the data analyzer.

FIG. 4 is an explanatory diagram showing a burial state of a place where the exploration data used in the data processing procedure of the present invention is collected.

FIG. 5 is a flowchart showing a data processing procedure of the present invention.

FIG. 6 is a diagram showing a search image obtained by the present method and a search image obtained by a conventional method.

FIG. 7 is a diagram showing a reception signal obtained at a position where there is no buried object, a processing result by the present method, and a processing result by a conventional method;

FIG. 8 is a diagram showing a reception signal obtained at a position where an object is buried, a processing result by the present method, and a processing result by a conventional method;

FIG. 9 is an explanatory diagram showing a buried state of a place where the exploration data used in the data processing procedure of the present invention is collected.

FIG. 10 is a flowchart showing a data processing procedure of the present invention.

FIG. 11 is a diagram showing a received signal obtained at a position where there is no buried object and median data used in the present method.

FIG. 12 is a spectrum distribution diagram of a received signal obtained at a position where there is no buried object and median data used in the present method.

FIG. 13 is a diagram showing a received signal obtained at a position where there is no buried object and frequency-filtered median data used in the present method;

FIG. 14 is a diagram showing a received signal obtained at a position where there is no buried object and average value data used in a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concrete wall (medium) 2 Buried object 3 Exploration device 4 Incident wave 5 Reflected wave 31 Two-dimensional data generation means 32 Median value calculation means 33 Frequency filter processing means 34 Difference calculation means

Continued on front page F-term (reference) 5J070 AB01 AC01 AC03 AD02 AE07 AE11 AF02 AH13 AH19 AH25 AH31 AH33 AH35 AH39 AH50 AJ08 AJ14 AK28 BG10 BG11 5J083 AA02 AB12 AC18 AD01 AD06 AE06 AF04 BA01 BE11 BE38 BE41 BE41

Claims (12)

[Claims] 1. A transmitting / receiving step of radiating a wave signal due to an electromagnetic wave or a sound wave into the medium while moving on a surface of the medium and receiving a reflected signal from an object present in the medium, and A data generating step of sequentially generating and storing original data having coordinates of a position on the surface of the medium and a reflection time and storing the data, and searching for a position of an object existing in the medium, A median value calculating step of obtaining a median value of the received signal strength for each of the predetermined reflection times for the plurality of pieces of the obtained original data, and for each of the predetermined reflection times, the stored raw data and the obtained A search method for executing a difference calculation step of calculating a difference from the obtained median to obtain search data, and an output processing step of outputting a search result in the medium based on the obtained search data. 2. The exploration method according to claim 1, wherein a frequency filtering process is performed on the median value obtained in the median value calculating process, and a frequency filtering process for replacing the median value is performed. 3. The method according to claim 1, wherein the cutoff frequency is equal to two times the center frequency of the wave signal.
The search method according to claim 2, wherein the low-pass filter processing is performed at least twice. 4. A time until the wave signal is emitted and the reception of the reflection signal is started is set as a reference time, and in the stored original data, the reflection time is equal to or longer than the reference time and the reference time 2 of the wave signal
The search method according to any one of claims 1 to 3, wherein the median value calculation step and the difference calculation step are performed on original data that is equal to or less than a second time obtained by adding a time corresponding to a cycle. 5. A transmitting and receiving means for radiating a wave signal due to an electromagnetic wave or a sound wave into the medium while moving on the surface of the medium and receiving a reflected signal from an object existing in the medium, and A data generating means for generating and storing original data having coordinates of a position on the surface of the medium and a reflection time, and a search device for searching for a position of an object present in the medium, For a plurality of original data, for each of the predetermined reflection times, a median calculating means for calculating a median of the received signal strength, and for each of the predetermined reflection times, the stored original data and the obtained A search apparatus comprising: a difference calculation unit that calculates a difference from a median to obtain search data; and an output processing unit that outputs a search result in the medium based on the obtained search data. 6. The exploration apparatus according to claim 5, further comprising frequency filter processing means for performing a frequency filter process on the median value obtained by the median value calculation means and replacing the median value with the median value. 7. The exploration apparatus according to claim 6, wherein said frequency filter means is a means for performing a low-pass filter processing in which a cutoff frequency is at least twice a center frequency of said wave signal. 8. A time until the wave signal is emitted and the reception of the reflection signal is started is set as a reference time. In the original data, the reflection time t is equal to or longer than the reference time, and The exploration according to any one of claims 5 to 7, wherein the median calculation means and the difference calculation means operate on original data that is equal to or less than a second time obtained by adding a time corresponding to two periods of the wave signal. apparatus. 9. A transmitting / receiving means for radiating a wave signal due to an electromagnetic wave or a sound wave into the medium while moving on the surface of the medium and receiving a reflected signal from an object existing in the medium, and Data generating means for generating and storing original data having coordinates of the position on the surface of the medium and the reflection time, provided in a search device, analyzing the original data, and determining the position of an object present in the medium. An analysis device for searching, for each of the plurality of stored original data, for each predetermined reflection time, a median value calculating means for calculating a median value of the received signal strength, and for each of the predetermined reflection times. Calculating the difference between the stored original data and the median calculated in the median calculation step,
An analysis apparatus comprising: a difference calculation unit for obtaining search data as the analysis result; and an output processing unit for outputting a search result in the medium based on the obtained search data. 10. The analyzing apparatus according to claim 9, further comprising frequency filter processing means for performing frequency filter processing on the median value obtained by said median value calculation means and replacing the median value with the median value. 11. The analyzer according to claim 10, wherein said frequency filter means is a means for performing a low-pass filter processing in which a cutoff frequency is twice or more a center frequency of said wave signal. 12. A reference time is defined as a time from the emission of the wave signal to the start of reception of the reflection signal, wherein the reflection time t in the original data is equal to or longer than the reference time, and The analysis according to any one of claims 9 to 11, wherein the median value calculation means and the difference calculation means operate on original data that is equal to or less than a second time obtained by adding a time corresponding to two periods of the wave signal. apparatus.