JP3198316B2 - Buried object detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buried object detecting method for detecting an object (buried object) buried in the ground or in a structure using electromagnetic waves, and more particularly, to a method for detecting a set of a transmitting antenna and a receiving antenna. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buried object detection method for notifying a measurer of the presence of a buried object in real time by using a buzzer, a sound, a lamp, or the like while moving along a surface or a structure surface.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram of a conventional buried object detecting apparatus. In this device, a transmitter 1 sends a pulse having a width of several nsec to a transmitting antenna 2. The transmitting antenna 2 converts the transmitted pulse signal into an electromagnetic wave and radiates it toward the ground. A part of the radiated electromagnetic wave is reflected by the ground surface 9, but a part propagates through the ground, and if there is a part having different electric characteristics, the part is reflected there. These reflected electromagnetic waves are received by the receiving antenna 3 and are converted into electric signals by the receiver 4. In the actual measurement, the antennas 2 and 3 and the distance detection unit 5 are moved in the directions indicated by the arrows in FIG. Then, the above-described transmission and reception processes are performed for each prescribed distance 1 (for example, 2 cm), and a plurality of reception signals are recorded. The antenna moving distance is calculated by the distance detecting unit 5 from the rotation angle of the moving wheel 6. The plurality of received signals are color-modulated for each magnitude of the amplitude value in the arithmetic unit 7 and then arranged two-dimensionally to form an underground section observation pattern. This underground section observation pattern is displayed on the display unit 8.

FIG. 9 shows an underground section observation pattern displayed.
FIG. 9A shows a reception signal received when the antenna is located above the buried tube 11. In FIG. 9A, time positions where the absolute value of the amplitude value of the received signal is equal to or greater than the specified value A are indicated by oblique lines, and other time positions are indicated by blanks. A pattern 12 in FIG. 9A corresponds to a group of reflected waves from the ground surface 9. Further, the pattern 13 is the stratum boundary surface 10.
(E.g., a reflected wave from an asphalt-soil interface). Since the electromagnetic wave radiated from the antenna spreads at a certain angle, the pattern of the reflected wave from the buried pipe 11 is shown in FIG.
It has a hyperbolic shape like the pattern 14 in FIG. The actual position of the buried pipe 11 is the position of the vertex of the hyperbola. Therefore, the buried pipe 11 can be detected by recognizing the hyperbolic shape in the underground section observation pattern.

Conventionally, in order to recognize this hyperbolic shape,
Recognition processing based on the synthetic aperture method has been mainly performed. The shape of the hyperbola depends on the propagation speed of the electromagnetic wave in the ground. Therefore, the hyperbolic shape is theoretically calculated assuming the propagation speed, and the theoretical curve is matched with the actually observed hyperbolic shape 14, so that the hyperbolic shape in the underground section observation pattern can be recognized. However, this method cannot detect the buried object in real time while moving the antenna, and when the surface on which the antenna is moved is not paved, the shape of the hyperbola is deformed due to the unevenness of the surface, and the matching is accurate. Could not.

Therefore, a method of detecting a buried object that can notify a measurer of the presence of the buried object in real time while moving the antenna and that can detect even a condition in which the shape of the hyperbola is deformed is disclosed in Japanese Patent Application No. Hei. No. 5-65939 has been proposed. That is, a reflected wave is received at a certain time interval, the differential value of the received signal is calculated, and the time value at which the differential value becomes 0 is focused on, and the amplitude value is set to “1”.
Normalized to “−1” and “0”, the standard value of two consecutively received signals is “1” or “−”.
Check the relationship between the coordinates that are "1", calculate the change in the propagation time between the coordinates determined to be related, add and store the result on the added value map, and embed the value. A method for recognizing the position of an object has been proposed. Hereinafter, this method is referred to as a real-time recognition method using a normalization / tracking addition process.

[0006]

However, in such a real-time recognition method using the normalization / tracking addition processing, since the difference of the propagation time of the standardized data is added, the recognition of the buried object requires the standard. The condition must be such that the hyperbola clearly appears with a certain size or more on the normalized data map in which the normalized data is arranged two-dimensionally. That is, it is necessary that the propagation time of the data at the tail of the hyperbola and the propagation time of the data at the vertex have a certain difference. Therefore, in the case of a pipe having a shallow buried depth, for example, as shown in FIG.
4 is a reflected wave 12 from the ground surface and a reflected wave 13 from the stratum boundary surface
Therefore, there is a problem that the hyperbolic shape does not appear clearly enough to be recognizable at the time of standardization. FIG. 10B shows the normalized data map shown in FIG. 10A, and FIG. 10C shows the coordinates extracted as a result of the tracking addition process, where the added value exceeds a specified value. On the other hand, as can be seen from FIG. 10 (c), the reflected waves from the stratum boundary surface change due to a change in the electromagnetic wave propagation velocity caused by the gradient of the stratum boundary surface itself and a subtle change in soil properties. Since it appears with a gentle inclination in the observation pattern, it has a large addition value similar to the hyperbolic reflected wave from the buried pipe, and there is a problem that it is erroneously recognized.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for superimposing a reflected wave from a buried object and a reflected wave from the ground surface or the like. It is an object of the present invention to provide a method for detecting a buried object, which can recognize the buried object and can prevent erroneous recognition due to the influence of a reflected wave from a stratum boundary.

[0008]

In order to achieve such an object, a first invention (an invention according to claim 1) is that, after moving a predetermined distance ΔL from a start point, starting at a position after the ΔL movement. Every time when moving by a certain distance l, a difference waveform of the amplitude value at the same propagation time is obtained from the waveform of the reception signal at that position and the waveform of the reception signal at a position separated by a predetermined distance ΔL, and the difference of this difference waveform The data is “1” for the difference data indicating the maximum value of each wave in the positive direction, and “−1” for the difference data indicating the maximum value of each wave in the negative direction.
In addition, the other difference data is normalized to “0”, and a data map in which the results of the normalization are two-dimensionally arranged with the moving distance and the propagation time as axes is created. Relevance between each reference coordinate having a value of “1” and “−1” of the line data that is the first normalization result of the two matching results and the coordinates of the line data that is the next normalization result From the set of the reference coordinates and the related coordinates determined to be related, the difference of the propagation time between the reference coordinates and the related coordinates is obtained, and this difference value is added with the same coordinate system as the data map. Stored in the coordinates corresponding to the relevant coordinates in the value map as an added value with the stored value in the coordinates corresponding to the reference coordinates, and when the added value stored in the coordinates of the added value map exceeds a prescribed value, To report the existence of buried objects It is intended. Further, the second invention (the invention according to claim 2) is that, after moving a predetermined distance ΔL from the start point, every time the position after the ΔL movement moves by a fixed distance l, the waveform of the received signal at that position And a waveform of the received signal at a position separated by a predetermined distance ΔL, a difference waveform of the amplitude value at the same propagation time is obtained, and the difference data of the difference waveform is calculated for the difference data indicating the maximum value of each wave in the positive direction. "1" if the absolute value is larger than the specified value
When the absolute value of the difference data indicating the maximum value of each wave in the negative direction is larger than the specified value, the value becomes “−1”.
The other difference data is normalized to “0”, and a data map is created by two-dimensionally arranging the result of this normalization on the axis of the moving distance and the propagation time. Check the relevance between each reference coordinate having a value of "1" and "-1" of the line data which is the first normalization result among the two normalization results and the coordinates of the line data which is the next normalization result. The difference between the reference coordinates and the related coordinates is determined by the pair of the reference coordinates and the related coordinates determined to be related, and the difference value is used as an addition value map having the same coordinate system as the data map. Is stored as a value added to the coordinates corresponding to the reference coordinates in the coordinates corresponding to the reference coordinates, and when the value stored in the coordinates of the added value map exceeds a prescribed value, the embedded object is stored. To announce the existence of It is. Further, the third invention (the invention according to claim 3) is the first invention or the second invention,
The amount of notification of the presence of a buried object is increased in proportion to the magnitude of the added value exceeding a prescribed value stored in the coordinates of the added value map. In the fourth invention (the invention according to claim 4), in the first invention or the second invention, a maximum value is stored among the added values exceeding a specified value stored in the coordinates of the added value map. The depth of the buried object is determined from the propagation time of the coordinates.

[0009]

Therefore, according to the present invention, in the first invention, after moving a predetermined distance ΔL from the start point, every time the position after the ΔL movement is moved by a fixed distance 1 as a starting point, the waveform of the received signal at that position is obtained. And a waveform of the received signal at a position separated by a predetermined distance ΔL, a difference waveform of the amplitude value at the same propagation time is obtained. The difference data of the difference waveform is “1” for the difference data indicating the maximum value of each wave in the positive direction.
The difference data indicating the maximum value of each wave in the negative direction is normalized to “−1”, and the other difference data is normalized to “0”. Then, a data map is created in which the results of the normalization are arranged two-dimensionally with the moving distance and the propagation time as axes, and the first normalization result of two adjacent normalization results of the created data map is created. The relationship between the reference coordinates of the line data having the values of “1” and “−1” and the coordinates of the line data that is the next standardization result is checked, and it is determined that there is a relationship. The difference between the propagation time of the reference coordinate and the related coordinate is determined by the set of the reference coordinate and the related coordinate, and the difference value is calculated as the coordinate corresponding to the related coordinate of the added value map having the same coordinate system as the data map. It is stored as an added value with the stored value in the coordinates corresponding to the reference coordinates, and when the added value stored in the coordinates of the added value map exceeds a prescribed value, the presence of the buried object is notified. In the second invention, a difference waveform is obtained in the same manner as in the first invention. The difference data of the difference waveform is “1” when the absolute value of the difference data indicating the maximum value of each wave in the positive direction is larger than the specified value, and the difference data indicates the maximum value of each wave in the negative direction. If the absolute value of the data is larger than the specified value, it is normalized to "-1", and the other difference data is normalized to "0". Then, in the same manner as in the first invention, the tracking addition processing is performed, and when the added value stored in the coordinates of the added value map exceeds a prescribed value, the presence of the buried object is notified. Further, in the third invention, in the first invention or the second invention, the amount of notification of the presence of a buried object, for example, in proportion to the magnitude of the addition value exceeding a prescribed value stored in the coordinates of the addition value map, for example, The volume of the buzzer increases. Further, in the fourth invention, in the first invention or the second invention, a propagation time T of a coordinate storing a local maximum value among addition values exceeding a prescribed value stored in the coordinates of the addition value map, For example, D = (T / 2) · [C /
(Ε) ^1/2 ], the depth D of the buried object is obtained. Here, C is the propagation speed of the electromagnetic wave in free space, and ε is the relative permittivity underground.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. FIG. 1 shows a processing procedure of a method for detecting a buried object according to the present invention. In this embodiment, a pipe buried underground is described as an example of a buried object. Further, in the method for detecting an object to be buried according to the present embodiment, the waveforms of two received signals received at two antenna positions separated by a certain distance are compared to calculate a difference. Is set. It is often appropriate that ΔL is about 10 cm to 20 cm, but is not limited to this. Hereinafter, the processing content of each step shown in FIG. 1 will be described.

[STEP 1] In FIG.
Sends a pulse with a width of several nsec to the transmitting antenna 2. The transmitting antenna 2 converts the transmitted pulse signal into an electromagnetic wave and radiates it toward the ground. A part of the radiated electromagnetic wave is reflected by the ground surface 9, but a part propagates in the ground and has a different electric property, that is, a stratum boundary surface 10 or a buried pipe 11.
And so on. These reflected electromagnetic waves are received by the receiving antenna 3 and converted into electric signals by the receiver 4 in accordance with the timing transmitted from the distance measuring unit 5 at every fixed moving distance l. The received signal converted into the electric signal is stored.

[STEP 2] The waveform of the received signal received in STEP 1 is compared with the waveform of the received signal received at an antenna position separated by ΔL in STEP 3 to be described later. There is no signal waveform. Therefore, until the antenna movement distance L becomes equal to or more than ΔL (L ≧ ΔL), STEP1 is repeated according to NO in STEP2.

[STEP 3] If it moves from the start point by ΔL, that is, if L = ΔL, ST
In accordance with the repetition processing of EP3 to STEP8, every time the position after the movement of ΔL is moved by a fixed distance 1 starting from the position, the waveform of the received signal at that position and the antenna position separated by ΔL (the antenna movement distance from the start point) Is L-ΔL)
, And the difference between the amplitude values of the two waveforms at the same position on the time axis is calculated. FIG. 2 shows an example of a waveform of a received signal received at a certain antenna position L.
FIG. 2A shows an example of a waveform of a received signal received at a position separated by ΔL from the antenna position L. FIG. However, these are digitized signals.
In the figure, 15 and 16 indicate reflected waves from the ground surface 9, 1
7 and 18 correspond to the reflected waves from the buried pipe 11, and 19 and 20 correspond to the reflected waves from the stratum boundary 10, respectively. The reflected waves 17 and 18 from the buried pipe 11 correspond to the reflected waves 15 from the ground surface 9. , 16 and reflected wave 1 from stratum boundary 10
9 and 20 are superimposed. By calculating the difference between the amplitude values at the same position on the time axis of the two waveforms, FIG.
As shown in (1), only the portion 21 corresponding to the reflected wave from the buried pipe 11 can be extracted.

[STEP 4] The difference data obtained in STEP 3 is normalized to "1", "-1", and "0". The difference data of the difference waveform is set to "1" for the difference data indicating the maximum value of each wave in the positive direction, to "-1" for the difference data indicating the maximum value of each wave in the negative direction, and otherwise. Are normalized to “0”. On this occasion,
In order to eliminate the influence of noise, when the absolute value of the difference data is smaller than the specified value B, the difference data is set to “0” at all time positions. That is, the difference data of the difference waveform is set to “1” when the absolute value of the difference data indicating the maximum value of each wave in the positive direction is larger than the specified value B, and the maximum value of each wave in the negative direction is set to If the absolute value of the indicated difference data is larger than the specified value B, the difference data is normalized to “−1”, and the other difference data is normalized to “0”. The result of the standardization in this way is shown in FIG.
(B).

[STEP 5] A data map is created in which the standardization results obtained in STEP 4 are arranged two-dimensionally. For example, FIG. 3C shows a data map for the standardized signal of FIG. 3B. In FIG. 3C, the hatched portion in the cell corresponds to “1”, and the dotted portion corresponds to “−1”. In FIG. 4, for example,
8 shows a data map obtained from ten consecutive reception signals. However, in this example, ΔL is set to three times the reception interval 1 of the reflected wave. The vertical axis represents the propagation time, and each cell corresponds to a sampling point of the signal. The numbers on the horizontal axis indicate the order in which the difference waveforms were calculated. Hereinafter, each vertical line in FIG. 4 is referred to as n-line data corresponding to the number n (-).

Paying attention to the standard values "1" and "-1" contained in each line data, the following line drawing tracking addition processing is performed. A description will be given by taking the coordinates 22 whose standard value is “1” as an example. FIG. 5 is an enlarged view of the vicinity of the coordinates 22 in FIG. 4 for explaining the tracking processing. As shown in FIG. 5, attention is focused on a range of a certain specified value SA (hereinafter referred to as a search range) centered on the coordinates 23 of the line data at the same propagation time position as the coordinates 22. If there is a coordinate having the same standard value "1" as the coordinate 22 in the search range SA, it is determined that both are related. This process is performed for all the coordinates where the standard values of the line data are “1” and “−1”.
As a result, in FIG. 4, it is determined that the coordinates 25 and 26 are related in addition to the coordinates 22 and 24. It is determined that there is no relevant coordinate for the coordinate 27. The above processing is referred to as tracking processing.

[STEP 6] The following processing is performed on each set of coordinates determined to be relevant by the tracking processing in STEP 5. Here, a description will be given of a set of coordinates (reference coordinates) 22 and coordinates (related coordinates) 24. Difference value of the propagation time T ₂₄ of the propagation time T ₂₂ and coordinates 24 of the coordinates 22 (T ₂₂ -
T ₂₄ ) is calculated (T ₂₂ −T ₂₄ = 1 nsec in the present embodiment). Next, an addition value map (see FIG. 6) having the same coordinate system as in FIG. 4 is created. Here, for example, coordinates 2 in FIG.
2 and FIG. 6 are defined to be in the same coordinate system. The calculated difference value is stored in the coordinates 240 of the addition value map (FIG. 6) corresponding to the coordinates (related coordinates) 24 in FIG. Further, the sum of the value (0 in this embodiment) already stored at the coordinate 220 (the coordinate corresponding to the reference coordinate 22) and the value stored at the coordinate 240 is calculated, and the result is stored in the coordinate 240 again. Store. The values shown in the cells in FIG. 6 are stored values (addition values). This process is performed for all sets of coordinates determined to be relevant.

[STEP 7] When the added value stored at any of the coordinates in the added value map of FIG. 6 exceeds a specified value SH, a buzzer is sounded at a volume proportional to the magnitude of the added value, for example. The presence of the buried pipe 11 is notified. FIG. 7 shows the relationship between the antenna position with respect to the buried pipe 11 and the volume of the buzzer in this case. Since the difference between the amplitude values often becomes 0 near the antenna position that has passed through the buried pipe 11 by ΔL / 2, the tracking is generally interrupted when the added value becomes the maximum. The horizontal position at which the added value becomes maximum is almost the same as the buried pipe 1 unless ΔL is too large.
1 directly above.

[STEP 8] If the measurement is not completed, the reflected electromagnetic wave is received again at the time of the antenna movement distance (L + 1) (STEP 9), and the process returns to STEP 3. As described above, the above STEPS 3 to 8 are repeatedly performed by moving the antenna. As a result, the added value becomes maximum at the coordinates 280 and 290 of the added value map of FIG. 6 corresponding to the coordinates 28 and 29 of the data map of FIG. In this embodiment, when the specified value SH = 1, the added value stored at the coordinates 280 of the line data exceeds the specified value, and the buzzer sounds at this position.

[STEP 10] When the measurement is completed, ST
The process proceeds to STEP 10 in response to YES in EP8, and the burial depth is calculated. In this case, the following equation (1) is used from the propagation time T of the coordinate 280 storing the local maximum value among the added values exceeding the specified value SH stored in the coordinates of the added value map shown in FIG. To determine the depth D of the buried pipe 11. However,
In the following equation (1), C is the propagation speed of the electromagnetic wave in free space, and ε is the relative permittivity underground. D = (T / 2) · [C / (ε) ^1/2 ] (1)

[0021]

As is apparent from the above description, according to the present invention, in the first invention, after moving a predetermined distance ΔL from the start point, every time the vehicle travels a predetermined distance l from the position after the ΔL movement as a starting point. Then, a difference waveform of the amplitude value at the same propagation time is obtained from the waveform of the reception signal at that position and the waveform of the reception signal at a position separated by a predetermined distance ΔL, and normalization / tracking addition is performed on this difference waveform. Processing is performed, that is, normalization and tracking addition processing is performed by extracting only the waveform corresponding to the reflected wave from the buried object,
It is possible to recognize a buried object even with data in which the reflected wave from the buried object and the reflected wave from the ground surface, etc., which were difficult to recognize with the conventional real-time recognition method, It is also possible to prevent erroneous recognition due to the influence of the reflected wave from the boundary surface. The second
According to the present invention, the difference data of the difference waveform is set to “1” when the absolute value of the difference data indicating the maximum value of each wave in the positive direction is larger than a specified value, and the maximum value of each wave in the negative direction is set to “1”. When the absolute value of the indicated difference data is larger than a specified value, the difference data is standardized to “−1”, and for the other difference data, it is standardized to “0”. In addition to the effect of the first invention, the influence of noise is removed. It has the effect that it can be done. Further, in the third invention, the amount of notification of the presence of the buried object increases in proportion to the magnitude of the addition value exceeding the specified value stored in the coordinates of the addition value map, and the notification amount of the buried object is determined by the notification amount. The position in the horizontal direction can be captured. Further, in the fourth invention, the depth D of the buried object is obtained from the propagation time T of the coordinates storing the local maximum value among the added values exceeding the specified value stored in the coordinates of the added value map, The vertical position of the object can be known as a specific numerical value.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure of an embedded object detection method according to the present invention.

FIG. 2 is a diagram exemplifying a difference waveform obtained by calculating a difference between amplitude values of two received signals and a waveform of these received signals at the same position on the time axis.

FIG. 3 is a diagram illustrating normalization of difference data in the difference waveform.

FIG. 4 is a diagram illustrating a data map in which differential data (normalized data) of each normalized differential waveform is two-dimensionally arranged and represented.

FIG. 5 is a diagram for explaining the relevance of coordinates whose standard values are “1” and “−1” in two consecutive standardized data.

FIG. 6 is a diagram exemplifying an addition value map that stores a result of calculating a change on the propagation time axis between coordinates determined to be related as an addition value;

FIG. 7 is a diagram illustrating a relationship between an antenna position with respect to a buried pipe and a sound volume of a buzzer.

FIG. 8 is a block diagram of a conventional buried object detection device.

FIG. 9 is a diagram showing an example of an underground cross-section observation pattern displayed on a display unit of the buried object detection device.

FIG. 10 is a diagram showing an example of an underground cross-section observation pattern in which it is difficult to detect a buried object by the conventional real-time recognition method using normalization / tracking addition processing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transmitter, 2 ... Transmission antenna, 3 ... Reception antenna, 4
... Receiver, 5 ... Distance detector, 6 ... Movement wheel, 7 ... Calculator, 8 ... Display, 9 ... Ground surface, 10 ... Stratum boundary surface, 11
... buried pipe, 15, 16 ... pattern corresponding to reflected wave group from the ground surface in the waveform of the received signal, 17, 18 ... pattern corresponding to reflected wave group from the buried pipe in the waveform of the received signal,
19, 20: pattern corresponding to the reflected wave group from the stratum boundary in the waveform of the received signal, 21: portion corresponding to the reflected wave from the buried object in the differential waveform, 22-29: data map of normalized data Upper coordinates, 220 to 290... Coordinates on the added value map.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Masuda 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-6-258428 (JP, A) JP-A-Hei 4-184185 (JP, A) JP-A-4-69585 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01V 3/12 G01B 15/00 G01S 13/88

Claims (4)

(57) [Claims] 1. A buried object detection method for transmitting an electromagnetic wave from a transmission antenna while moving, receiving an electromagnetic wave reflected and returned by a reception antenna, and detecting the buried object based on the received signal. After moving a predetermined distance ΔL from the point, every time the position after the ΔL movement moves a predetermined distance l from the starting point, the same propagation is performed from the waveform of the received signal at that position and the waveform of the received signal at the position separated by the predetermined distance ΔL. A difference waveform of the amplitude value at time is obtained, and the difference data of the difference waveform is set to “1” for the difference data indicating the maximum value of each wave in the positive direction, and the maximum value of each wave in the negative direction is indicated. "-1" for the difference data,
The other difference data is normalized to “0”, and the result of this normalization is set to 2 with the moving distance and the propagation time as axes.
A data map arranged in a dimension is created, and line data “1”, which is the first normalization result of two adjacent normalization results of the created data map,
The relevance between each reference coordinate having a value of “−1” and the coordinates of the line data that is the next standardization result is checked, and a set of the reference coordinates and the relevant coordinates determined to be related by this is checked. The difference between the propagation times of the reference coordinates and the related coordinates is determined, and the difference value is stored in the coordinates corresponding to the related coordinates of the addition value map having the same coordinate system as the data map. A method for detecting the presence of a buried object when the added value stored in the coordinates of the added value map exceeds a prescribed value. 2. A buried object detection method for transmitting an electromagnetic wave from a transmission antenna while moving, receiving an electromagnetic wave reflected and returned by a reception antenna, and detecting the buried object based on the received signal. After moving a predetermined distance ΔL from the point, every time the position after the ΔL movement moves a predetermined distance l from the starting point, the same propagation is performed from the waveform of the received signal at that position and the waveform of the received signal at the position separated by the predetermined distance ΔL. A difference waveform of the amplitude value at time is obtained, and the difference data of the difference waveform is set to “1” when the absolute value of the difference data indicating the local maximum value of each wave in the positive direction is larger than a specified value. If the absolute value of the difference data indicating the maximum value of each wave in the negative direction is greater than the specified value, the difference data is normalized to "-1", and the other difference data is normalized to "0". Move 2 and the release and the propagation time as an axis
A data map arranged in a dimension is created, and line data “1”, which is the first normalization result of two adjacent normalization results of the created data map,
The relevance between each reference coordinate having a value of “−1” and the coordinates of the line data that is the next standardization result is checked, and a set of the reference coordinates and the relevant coordinates determined to be related by this is checked. The difference between the propagation times of the reference coordinates and the related coordinates is determined, and the difference value is stored in the coordinates corresponding to the related coordinates of the addition value map having the same coordinate system as the data map. A method for detecting the presence of a buried object when the added value stored in the coordinates of the added value map exceeds a prescribed value. 3. The method according to claim 1, wherein the notification amount of the presence of the buried object is increased in proportion to the magnitude of the added value exceeding a prescribed value stored in the coordinates of the added value map. A method for detecting a buried object, characterized in that: 4. The depth of a buried object according to claim 1 or 2, wherein the depth of the buried object is determined from the propagation time of the coordinate storing the local maximum value among the added values exceeding the prescribed value stored in the coordinate of the added value map. A method for detecting a buried object, characterized in that: