JPS61773A - Apparatus for detecting embedded object - Google Patents

Abstract

PURPOSE:To achieve the imaging of the position of an embedded object at a high speed with high accuracy by shortening the processing time of a position detector, by operating the curve corresponding to the inclination of the locus curve of the embedded object obtained with the scanning of a radio wave emitter and a reflected wave detector and increasing the memory content to said curve to display the result thereof. CONSTITUTION:The signal from an oscillator 10 is guided to an antenna 12 through a circulator 11 to emit a radio wave. The reflected wave from the embedded object 2 under the ground 1 is detected by the antenna 12 to be inputted to an operator 15 through the circulator 11, an amplifier 13 and a sampling apparatus 14. The output of the scanning position detector 16 of the antenna 12 is inputted to the operator 15. CPU15 calculates the tangential line of the locus curve of the embedded object to calculate the inclination thereof and calculates reflected light paths to calculate the position of the object as the intersecting point of one or more of reflected light paths. By performing this calculation at plural points, the memory content at the position where the object is present is increased. Said memory content is modulated in its intensity and displayed on a display device 17 and the position of the object is discriminated from the image thereof.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a device for detecting an object buried or installed underground or in water using a single radar system using electromagnetic waves. The present invention relates to a buried object detection device suitable for accurately imaging.

[Background of the invention]

Conventionally, radar devices have been known as detection devices for gas pipes and water pipes buried underground, for example (for example, see the paper "Underground Radar System" in Journal of the Institute of Electronics and Communication Engineers, Vol. 66, No. 6). ). This system transmits pulsed electromagnetic waves underground, detects reflected waves from buried objects, processes them, and visualizes them.

In order to improve the image quality, the antenna, which transmits and receives radio waves, scans the earth's surface and detects reflected waves at each scanning position.

At this time, the distance of the buried object obtained from the time from radio wave transmission to reception is expressed by the following formula.

y2=(x-xn)2+g2(1) where y;
Depth of detected buried object, ′ x; Antenna scanning position, (x!l r >'l )? Location coordinates of buried objects.

As can be seen from equation (1), the object at the position (Xm + ys) is visualized as if it existed in a wide range on the hyperbola (x, y). Because of this, the I4 cage decreases as the object is detected, causing the problem that the position of the buried object cannot be determined accurately. Two methods for solving this problem include the use of the synthetic aperture method (``Ground Exploration Radar'' presented at the 9th Moat Sensing Symposium (December 1982)).

In this method, reflected wave information at a large number of antenna scanning positions is stored and visualized by back calculation processing using equation (1). In this method, information from a wide range of antenna scanning is calculated backwards, so the calculation time is large, and it is impossible to detect a buried object while scanning.

[Purpose of the invention]

The present invention aims to shorten the sintering time of a position detection device in a radar-only system, thereby detecting the location of buried objects with high precision.
Furthermore, the purpose is to provide a device that can visualize images at high speed.

[Summary of the invention]

The present invention will be explained in detail below. The present invention is characterized in that it focuses on the inclination of the image formed by equation (1).

In other words, the property of the curve represented by equation α) having a convergence effect on light, etc. is utilized. Conceptually speaking, when a ray parallel to the y-axis hits a reflecting mirror with the shape shown by equation (1), most of the ray is focused at the position (X+, 1.5y+). use things. In reality, at a scanning position of a certain antenna, the slope of equation (1) is found from the data in the vicinity, and the optical path along which the rays parallel to the y-axis are reflected is determined by geometrical optics calculations. When this calculation is performed, the amount of light rays increases where the object is, and it can be clearly distinguished from other places. Since the computation of the present invention is a linear computation of the optical path at a certain location, the computation time is short and, to put it in the extreme, it has the advantage of being able to identify a buried object even from data at two points.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 is a diagram showing the configuration of the present invention. 2 is the ground surface, and 2 is the buried object. 2, a signal from an oscillator 10 is guided to an antenna 12 through a circulator 11, and radio waves are radiated. 20 reflected radio waves are detected at 12,
11 to an amplifier 13 for amplification. 14 is a sampling device, which receives a signal from the IO and samples the output of 13, which is a reflected signal. The reflected signal shifted to a lower frequency by 14 is input to a computing machine. The outputs of the 12 scanning position detectors 16 are also input to 15, and these are used to calculate the position of the object 2, and the results are displayed on the display 17. As can be seen from this configuration diagram, the essential part of the present invention is the calculation contents of the 15 calculation machines. The contents of the 15 calculations will be explained below. Figure 2 shows
This is a conceptual explanation of the calculation contents of No. 15. The X-axis corresponds to the ground surface, and the y-axis direction corresponds to the burial depth direction. As can be seen from the diagram that 20 corresponds to equation (1), even if there is an object at the true buried position 21, it becomes the song MK of 20 according to the scanning of the antenna. In the present invention, at a certain antenna position X=X, the M line parallel to the y-axis is extended to 20 to obtain the reflected optical path 23. By determining at least two of these lines, the position of the object is calculated as the intersection point of these lines.The following will be explained using mathematical formulas.

Let the antenna position be X. If the coordinates of the intersection 24 of 22 and 23 are (X, Y), the values of X and Y can be detected. 16, and Y can be determined from the relationship between the time from radio wave emission to reflected wave detection and the underground radio wave propagation speed. Refer to Figure 3.

First, the slope of the tangent 25 at the intersection 24 of 20 and 22 is determined. Therefore, x = X - ΔX, x = = X + JX
Find the i-direction of y of f. These are y+a and Y+b, respectively.
Then, the slope of 25 can be approximated by (ab)/2ΔX.

From this, θ in FIG. 3 is related by tanθ=(ba)/2ΔX(2). Therefore, finding equation 23, we get
The slope is tan (*/2-2θ) and (X.

It is determined from the condition that passes Y). This is in the form y = x / tan 2θ0K (3), so if x = X and y = Y, y = ((x - X )
Aan2θ+Y ) X 2/3 (4
). Also, as is well known, tan 2
θ= 2 tan 2θ/ (1-tan2θ) (5)
It is. Based on these, the equation of the straight line 23 at the antenna position X is determined. Therefore, (X.

When this straight line is on the memory corresponding to (y), (x
, y) is performed at multiple points where X is different, thereby increasing the memory content at the position where the object exists. Reference numeral 17 displays the contents of this memory after intensity modulation, and the object position can be identified from the image 17.

FIG. 4 is a flowchart showing the contents of 15 calculations. In 1501, find the antenna position X, and further,
At this position, Y is determined from the time from radio wave emission to reflected wave detection and the velocity of underground radio waves determined in advance (1502). This X.

Calculate tanθ from Y and ΔX using equation (2) (
1503). At this stage, equation (4) has been determined, so by specifying is performed for a preset range of X (1506). This operation continues until the end (1507).

As a result of the above calculations, the memory contents at the location where the buried object is present rapidly increase, thereby making it possible to identify the buried location of the object.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to visualize a buried object even from data with a small antenna scanning position. In other words, the image is not reproduced after all data is collected, as is the case in the past.

Therefore, it is possible to visualize buried objects while scanning the antenna, which has a great practical advantage9.

[Brief explanation of drawings]

Figure 1 is a basic configuration diagram of the present invention, and Figures 2 and 3 are essential parts of the present invention. FIG. 4, which is an explanatory diagram of the calculation contents of the JitJT machine, is a flowchart of the processing. l... Ground surface, 2... Buried object, 10... Oscillator, 11... Circulator, 12... Antenna, 1
3...Amplifier, 14...Zampli/gu device, 15.
...Arithmetic machine, 16...Antenna scanning position detector, 17
...Display device, 20... Trajectory of buried object obtained during antenna scanning, 21... Buried position, 22... Straight line parallel to the y-axis of antenna position lfX, 23... Reflected optical path,
24...the intersection of 20 and 22, the ligature at 25...24, the 11th me 2 at 26...24? -Rutaku 3 b

Claims (1)

[Claims] 1. In a device that emits radio waves at each of multiple positions and processes the reflected waves from the buried object to visualize the buried object, the image of the buried object obtained by scanning the radio wave emitter and the reflected wave detector. A buried object detection device that calculates a straight line according to the slope of a trajectory curve, increases memory contents corresponding to this straight line, and displays the result.