JPS62220888A - Survey system for underground burided body - Google Patents

Abstract

PURPOSE:To improve horizontal and vertical resolutions by forming a hyperbolic distribution pattern based on the target reflection in a reflection echo, distributing the pattern into areas and subdividing it, and performing composite aperture processing. CONSTITUTION:A pulse radio wave is radiated into the ground and the hyperbolic distribution pattern is formed based on the target reflection in the reflection echo from a target. The condition of the ground is calculated from the intensity of the reflection echo and the hyperbolic distribution pattern is divided into areas according to a level value based on the calculated condition of the ground. The pattern diagram of the area-divided hyperbolic distribution pattern is subdivided and the composited opening processing is performed based on the subdivided hyperbolic distribution pattern.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to synthetic aperture processing of electromagnetic pulses obtained through the ground, and particularly relates to an underground object exploration method that can realize high horizontal resolution and high horizontal resolution. .

[Prior art] This type of conventional underground buried object exploration method is described in IEICE Technical Report-5A.
NE83-8 (11183-08) "Ground Penetrating Radar (Other 2) - Compression Type" (Published by Institute of Electronics and Communication Engineers), also published by IEICE Journal 3/'84 V
olB? .

As described in No. 3 P, 308-P, 311, pulse radio waves are emitted underground, the reflected echo from the underground is received, and based on the target object reflection in the received reflected echo. A method has been adopted in which a hyperbolic distribution pattern is formed using the pulse width of the reflected echo, and the azimuth and depth of the target are searched by synthetic aperture processing based on the hyperbolic distribution pattern based on the pulse width of the reflected echo.

In addition, conventional underground buried object exploration methods include an inverse filter method, in which the waveform of pulsed radio waves that enter the ground is deformed depending on the conditions of the underground soil (such as a large dielectric constant). A method has been adopted in which the waveform deformation is inverse Fourier-transformed using an inverse filter to form the same waveform as the generated pulsed radio wave, thereby avoiding deterioration in the vertical resolution and horizontal resolution of synthetic aperture processing.

This method will be explained based on FIG. 4. To the target at depth RO from the ground surface as shown in Figure 4(a).

emitting a monocycle pulse (shown in FIG. 4(C));
This emitted monocycle pulse is reflected by the target object to obtain a received echo, and when this received echo is displayed as a pattern on the X-y coordinate axis, it becomes a multicurved distribution (as shown in FIG. 4(b)).

However, the X axis is the distance, and the Y axis is the time axis. Here, the received signal waveform is deformed as shown in FIG. 4(d) with respect to the manual waveform shown in FIG. 4(c). This is caused by the transmission system passing through the antenna system H/W and the soil. By approximating these transmission systems and passing them through an inverse filter, we can see in Figure 4 (b). This method repairs waveform distortion such as ringing and uses the results to perform synthetic aperture processing.

[Problems to be solved by the invention] Since the conventional underground buried object exploration method is configured as described above, a hyperbolic distribution pattern is created based on synthetic aperture processing depending on the type of underground soil or the presence or absence of inclusions. However, the problem is that the resolution of the direction and depth of the target object obtained by using the method decreases.

Furthermore, when the underground buried object exploration method is carried out using the inverse filter method, it is difficult to generalize the received echoes because each received waveform has a different degree of waveform deformation. Furthermore, when the pulse width is narrowed in order to improve vertical resolution, this tendency becomes particularly noticeable, resulting in a problem in that horizontal and vertical resolution are reduced.

This invention was made in order to solve the above-mentioned problems, and provides an underground object exploration method that achieves high horizontal resolution and high vertical resolution and can accurately search the direction and depth of a target. The purpose is to obtain.

[Means for Solving the Problems] The underground buried object exploration method according to the present invention emits pulsed radio waves underground, and generates a hyperbolic distribution pattern based on target reflections in reflected echoes from the target object. The soil conditions are calculated from the intensity of the reflected echoes, the 12 hyperbolic distribution patterns are divided into regions based on the level values based on the calculated soil conditions, and the pattern diagram of the divided hyperbolic distribution patterns is drawn as a thin line. , and performs synthetic aperture processing based on this thinned hyperbolic distribution pattern.

[Operation] The thinning of the hyperbolic distribution pattern based on the received reflected echoes in the present invention is performed by determining whether the received reflected echoes are from a plurality of targets at different depths underground or from the same target. The hyperbolic m-diagram of the hyperbolic distribution pattern formed by the first and second waves of echoes is converted into an m-line, and the first
Wave and second wave based diagrams are identified to improve the results of synthetic aperture processing with respect to horizontal resolution and 6-axis resolution.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. Figure 1 is a flowchart of the operating procedure of this embodiment, Figure 2 (a) is a diagram of how two targets are buried, Figure 2 (b) is a hyperbolic distribution pattern in the case of Figure 2 (a), Figure 2 (C) is a reflected echo waveform diagram for the case of Figure 2 (a), Figure 2 (d) is the hyperbolic distribution pattern of the second wave in the reflected echo of Figure 2 (C), and Figure 3 ( a) is a diagram of the x-y coordinate array of received data, Figure 3 (b) is a diagram of the level setting mode, Figure 53 (c) is a diagram of the image diagram of the reflected echo by the 53th Lebel, and Figure 3 (C) is An image diagram of the reflected echo by the second level, FIG. 3(d) is an image diagram of the reflected echo by the second level, and FIG. ◆(a) is a diagram of the scanning direction of the antenna.
FIG. 4(b) is an x-y coordinate diagram of a target reflected echo, FIG. 4(c) is a basic waveform diagram of an electromagnetic pulse, and FIG. 4(d) is a waveform diagram of a received reflected echo.

In each of the above figures, the underground buried object exploration method according to this embodiment emits a monocycle pulse D underground, and
A hyperbolic distribution pattern is formed based on the target reflection in the reflected echo RO from the ground, soil conditions are calculated from the intensity of the reflected echo RO, and the hyperbolic distribution pattern is defined as a region using the level value according to the calculated soil condition. The divided hyperbolic distribution patterns are recognized and processed by referring to the marks and hyperbolic distribution patterns formed according to the soil conditions.
Thin the pattern diagram of the above hyperbolic distribution pattern,
The configuration is such that synthetic aperture processing is performed based on this thinned hyperbolic distribution pattern.

Next, the operation of the underground object exploration method according to this embodiment based on the above configuration will be explained. First, in the state shown in Fig. 2(a), a monocycle pulse D is emitted to targets A and H that exist at different depths underground, and a reflected echo R from target A is emitted.
A hyperbolic distribution pattern is formed as the first peak P^1, second peak PA7, etc. in the received waveform of O, and a hyperbolic distribution pattern is formed as the first peak Pal,... in the received waveform of the reflected echo RO from target B. A distribution pattern is formed, resulting in an image in which the hyperbolic distribution pattern at the second peak of target A and the hyperbolic Iσ pattern at the first peak of target B overlap (see FIG. 2(b)). In other words, the hyperbolic distribution patterns based on the reflected echoes RO from targets at different depths have different shapes, and based on this difference in shape, two hyperbolic distribution patterns that are recognized to be at the same depth in the received data are distinguished, and the following procedure is used. identify

Receive the reflected echoes RO of the targets A and H, and store the reflected echoes Ro as distribution data (hyperbolic distribution pattern) in a two-dimensional array (x+, Y+) on the x-y coordinates (step 1); Here, the two-dimensional array distribution data x+ (or n) indicates position information in the horizontal direction, and yJ (or xj) indicates depth information in the vertical direction. The values of the distribution data of the L two-dimensional array are subjected to region differentiation processing based on the dark value (see FIG. 3(b)) (step 2).

Furthermore, the hyperbolic distribution pattern, which is the distribution data of the two-dimensional array divided into regions, is subjected to image processing called thinning processing for the region exceeding the threshold L, and the hyperbolic distribution pattern of the reflected echoes RO from targets A and B is extracted. (Step 3).

Next, the extracted hyperbolic distribution pattern is recognized (matched) by referring to a standard hyperbolic distribution pattern (assumed to have been created in advance) that corresponds to the soil conditions.
processed (performed as one process during synthetic aperture processing) (step 4). Furthermore, synthetic aperture processing is performed based on the thinned hyperbolic distribution pattern recognized in the above recognition processing to output an image representing the azimuth and depth of the targets A and H (step 4).

Note that the line thinning in the above embodiment can be performed with a pulse width of less than or equal to the pulse width of the received reflected second knee Ro.

That is, the above-mentioned thinning is inappropriate because if the data Ijl in the depth direction is too narrow, the hyperbolic distribution pattern for each depth determined by the setting of soil conditions will deviate, making it unrecognizable. Therefore, when thinning the received pulse rlJ, the same decomposition as when using a frequency four times the transmitting pulse frequency can be obtained.

In addition, in the recognition process in the synthetic aperture process, if the 2nd recognition is not above, the width of the L line thinning is
It is also possible to adopt a configuration in which recognition is performed by changing the value from % of the pulse width to a value that is successively decreased until just before an image no longer appears.

[Shot 1! Effect 1 of II As shown in 2 below, the underground buried object exploration method according to the present invention has the following effects:
Pulse radio waves are emitted into the ground, a hyperbolic distribution pattern is formed based on the target object reflections in the reflected echoes received from the target object, and the soil conditions are calculated from the intensity of the reflected echoes. The Kitami hyperbolic distribution pattern is divided into regions based on the level value according to the soil conditions, the pattern diagram of the divided hyperbolic distribution pattern is thinned, and the thinned lines are synthesized based on the thinned hyperbolic distribution pattern. By adopting this configuration during aperture processing, it is possible to identify whether the echoes are reflected from multiple targets at different depths underground or from the same target, resulting in high vertical resolution and high vertical resolution. The effect is that resolution is achieved and the direction and depth of the target can be accurately searched.

[Brief explanation of drawings]

Figure 1 is a flowchart of the operating procedure of this embodiment;
Figure (a) is a diagram of the buried state of two targets, Figure 2 (b) is the hyperbolic distribution pattern in the case of Figure 2 (a), Figure 2 (C)
are the reflected echo waveform diagrams for the case of Figure 2(a) and Figure 2(d).
) is the second wave hyperbolic distribution pattern in the reflected echo of FIG. 2(C), FIG. 3(a) is the x-y coordinate array diagram of the received data, FIG. 3(b) is the level setting diagram, Figure 3 (
C) is an image diagram of the reflected echo by Lebel, and Figure 3 (d)
) is an image diagram of the reflected echo at the second level, and Figure 4 (a
) is a diagram of the scanning direction of the antenna, Figure 4(b) is an x-y coordinate diagram of the target object reflected echo, Figure 4(C) is a basic waveform diagram of the electromagnetic pulse, and Figure 4(d) is the received waveform. FIG. 3 is a waveform diagram of reflected echoes. In the figure, (D) is a monocycle pulse, A and B are buried objects, (Ro) is a reflected echo, (Pl) is the first peak, (
Pl) is the second peak. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Masu Oiwa Joint tube 1 Figure 3 (a) (b) Ward τ (C) (d)

Claims (3)

[Claims] (1) In the underground object exploration method, which emit pulsed radio waves underground and perform synthetic aperture processing on the reflected echoes from the target object to investigate the direction and depth of the target object, the reflected echoes received A hyperbolic distribution pattern is formed based on the target reflection, the soil conditions are calculated from the intensity of the reflected echo, the hyperbolic distribution pattern is divided into regions based on the level value according to the calculated soil conditions, and the hyperbolic distribution pattern is divided into regions. An underground buried object exploration method characterized in that a pattern diagram of a hyperbolic distribution pattern is thinned, and synthetic aperture processing is performed based on the thinned hyperbolic distribution pattern. (2) The underground buried object exploration method according to claim 1, characterized in that the thinning of the hyperbolic distribution pattern is made to be 1/4 or less of the pulse width of the received reflected echo. (3) In the synthetic aperture processing, if the recognition during this processing is not sufficient, the width of the thinning is successively reduced from 1/4 of the pulse width of the received reflected echo until just before no image appears. 3. An underground buried object exploration method according to claim 1 or 2, characterized in that the underground object exploration method is configured to recognize the buried object by changing it to .