JP2849765B2 - Underground radar reflected signal processing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention relates to a method and an apparatus for processing a reflection signal of an underground radar used for underground geological survey, detection of a buried object, and the like, and particularly to a detection target. The present invention relates to a method and an apparatus for processing a reflection signal of an underground radar capable of clearly detecting a target such as a certain geological situation or an underground object.

[Prior Art] As a well-known method, a state of underground is investigated, or a pulsed electromagnetic wave is radiated toward the ground as a method of nondestructively detecting an underground object, and the electromagnetic wave is present in the ground. Radar that observes and analyzes the return time and reflection intensity of reflected electromagnetic waves reflected from the boundary of changing objects and soil changes is being used as a radar for exploring the ground conditions outside underground construction machinery or as an underground exploration radar .

The transmitting antennas for radiating electromagnetic waves and the receiving antennas for receiving reflected waves of these radars have directivity in the direction of the electromagnetic waves, but the directivity is not always sharp, and the antenna structure has a different gain depending on the direction. Has a specific divergence angle determined by

Therefore, not all signal waves returning at the same time return from the same direction, and information on the direction seen from the antenna with respect to the ground at a certain spread angle is combined.

Therefore, for example, even if there is an underground object, the position and shape of the underground object are not clearly displayed on the image screen of the display device displaying the reflected wave, and the shape is enlarged to a certain range. Is displayed.

As a countermeasure, the reflection signal from the target is emphasized by adding a large number of reflection data at each measurement position to each other while moving the position of the antenna corresponding to the directional characteristic of the antenna. Devices have been made using the synthetic aperture method.

[Problem to be Solved by the Invention] According to the synthetic aperture method as described above, it is possible to clearly express a specific object in a complicated environment, but a large number of reflection data are added. Requires a lot of time even with a computer capable of high-speed processing.

However, there is a problem that it is difficult to adopt a computer which is expensive and capable of high-speed processing, and cannot be used for on-site work which requires work in real time. In other words, various unexpected situations occur at the site, even if you look at the searched image, you may not be able to judge whether it is a buried object or a noise signal,
Alternatively, it is often unclear whether the object is another unnecessary buried object. At this time, there is a case where it is desired to immediately investigate the unclear image part in detail. At this time,
Even if the measurement is performed again in the same way, or even if the synthetic aperture processing is performed on the measured image data, a large amount of time is required as described above. There was a problem that it was not possible to perform exploration efficiently.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to provide a method and an apparatus for processing a reflected signal of an underground radar capable of executing signal processing capable of clearly displaying a detection target in a short time.

Means for Solving the Problems In order to achieve the above object, in the method for processing a reflected signal of a radar according to the present invention, a predetermined position is moved from each measurement position toward the underground while moving the measurement position by a predetermined distance. Transmitting a signal, detecting a reflection signal of the transmission signal, performing a synthetic aperture process based on the reflection signal at a measurement position in a predetermined section, and detecting a target object by displaying the processing result. In the reflected signal processing method of the radar, after confirming the image of the reflected signal in the predetermined section, a processing range for restricting a range to be investigated in detail as a target of the synthetic aperture processing is set from the outside, and only within the set restriction range. The synthetic aperture processing is performed on the reflected signal, and the set restriction range is such that the time from when the transmitted signal is transmitted to when the reflected signal returns is a predetermined time. It is characterized in that the reception level value of the reflected signal is within a predetermined level range. Further, the set restriction range is such that the measurement position is within a predetermined position range.

In the underground radar reflected signal processing apparatus, a predetermined signal is transmitted from each measurement position toward the underground while moving the measurement position by a predetermined distance, and a reflection signal of the transmission signal is detected, and a predetermined signal is detected. In a reflection signal processing device of an underground radar that performs a synthetic aperture process based on the reflection signal at the measurement position of the section, an area of the reflection signal image in the predetermined section, which is to be examined in detail, is a range of the synthetic aperture process. Means for externally setting a processing range to be restricted as a target,
Synthetic aperture processing means for performing synthetic aperture processing only on signals within the set restriction range, and further, the set restriction range, the reflected signal returns after transmitting the transmission signal The time until arrival is within a predetermined time range, and the set regulation range is such that the reception level value of the reflected signal is within a predetermined level range.
The set restriction range is such that the measurement position is within a predetermined position range.

[Operation] According to the above method and its apparatus, the range of the reflected signal data to be subjected to the synthetic aperture processing is externally set and regulated. In particular, a target is set as the regulated range, that is, only within a certain return time. Limited to reflected signals, limited to signals only within a certain reception level range, and limited to the area to be explored, so that it is possible to perform calculations related to synthetic aperture processing in a short period of time over a range to be investigated in detail. It became so.

FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 4 show an embodiment of a method and an apparatus for processing a reflected signal of an underground radar according to the present invention. This will be described in detail with reference to FIG.

FIG. 1 is a diagram showing an embodiment of an underground object exploration apparatus to which the small radar used in the present invention is applied. Reference numeral 20 denotes an antenna section of the underground object exploration apparatus, and an antenna 1 is mounted on a bottom portion thereof. Also, traveling wheels 20a are mounted. Reference numeral 21 denotes a control display device of the underground object exploration device, and the antenna unit 20 and the control display device 21 are connected by a cable 6. Numeral 30 indicates an underground buried object which is the target of the exploration.

FIG. 2 is a diagram showing an embodiment of a circuit configuration of the underground radar according to the present invention, and FIG. 3 is a schematic circuit configuration diagram for explaining an operation in the present invention. FIG. 4 is a flowchart showing an outline flow for explaining the operation in the present invention, and FIG. 5 is an image example for explaining the operation in the present invention.

FIG. 2 shows the configuration of the main circuit of the underground radar.
Circuit elements used to operate the antenna unit are omitted. In the figure, reference numeral 20 denotes an antenna unit of the underground radar, reference numeral 21 denotes a control display device of the underground radar, and various signals and commands are transmitted between the antenna unit 20 of the underground radar and the control display device 21. They are connected by cables 6 for signal transmission.

Reference numeral 11a denotes a transmitting antenna, and 11b denotes a receiving antenna. The receiving antenna is provided as a pair on the housing of the antenna unit 20 of the underground radar toward the ground. Further, 1a indicates a radiated electromagnetic wave transmitted from the transmitting antenna 11a, 1b indicates a reflected electromagnetic wave, and the reflected electromagnetic wave 1b is received by the receiving antenna 11b.

The antenna unit 20 includes a trigger circuit 2, a pulsar 3, a sampler 4, a signal processing circuit 5, a travel sensor 12, and a position measuring device 13 in addition to the transmitting antenna 11a and the receiving antenna 11b. Further, the control display device 21 is connected to the signal processing circuit 5 of the antenna unit 20 through the cable 6 connected thereto.
Computer 7. The signal processing circuit 5 and the computer 7 each include auxiliary circuits such as an interface circuit for transmitting and receiving various detection signals and command signals via the cable 6.

In addition to the computer 7, the control display device 21
It comprises a storage device 8, an operation panel 10, a CRT display device 9a for displaying and outputting detection results and the like, and a printer 9b. FIG. 3 shows a CRT display device 9a and a printer 9b.
Are collectively shown as a display device 9. In addition, the operation panel 10 externally sets a range to be investigated in detail,
That is, it is provided with an operation switch or the like that regulates a range of a calculation target of the synthetic aperture processing. Range (that is, regional range)
Are provided individually or in combination.

The travel sensor 12 is a travel distance measurement sensor such as a rotary encoder mounted on a moving wheel of the antenna unit that measures the travel distance of the antenna unit, and the position measurement device 13 processes a signal from the travel sensor 12 to obtain position information. It consists of a position measurement circuit that is continuously created.

In the above configuration, the pulse signal generated at a fixed timing by the trigger circuit 2 is controlled by the pulser 3 so as to have an appropriate pulse oscillation frequency component and power, and transmitted to the transmission antenna 11a. The sending antenna 11a
The electromagnetic wave 1a radiated from is reflected by a medium boundary surface such as the ground or a buried object, and is received by the receiving antenna 11b as a reflected electromagnetic wave 1b.

The reflected electromagnetic wave 1b received by the receiving antenna 11b includes:
Since it contains a signal component that interferes with target detection transmitted directly from the transmitting antenna 11a to the receiving antenna 11b, the sampler 4 removes the interference signal by a predetermined time from the trigger pulse signal. The received signal is masked during to to obtain a signal containing appropriate reflection information. Further, the signal processing circuit 5 combines the reflected pulse signal with the trigger pulse signal from the trigger circuit 2 and the position information from the position measuring device 13, converts the signal into a predetermined signal form, and converts the signal into an internal interface circuit (not shown). ) Through the cable 6 together with the trigger pulse to an interface circuit (not shown) of the computer 7 for performing arithmetic processing.

The computer 7 determines the state of the measurement target from the time between the time when the reflected electromagnetic wave 1b is received and the time when the reflected wave is transmitted, the reception intensity of the reflected electromagnetic wave 1b, and the positional information of the antenna unit at the time. Calculated and CRT display device 9
Send to a for display. Further, the reflection data for performing the synthetic aperture processing later and the calculated information and the like are sent to the storage device 8 and stored, and are reproduced when necessary to perform the synthetic aperture calculation. Use as reference information. Further, the calculation information can be printed out on recording paper by the printer 9b.

Next, referring to FIG. 3 showing a schematic circuit configuration for explaining the operation in the present invention, FIG. 4 showing an example of a flowchart, and FIG. 5 showing an example of a waveform, an operation in the control display device 21 will be described. Will be described in detail.

In step O shown in FIG. 4, a search image by the standard processing is displayed on the display device 9 by the above-described function.

If the display image displayed on the display device 9 is unclear and the operator wants to clearly display an image in a certain range from the ground on the image (Step 1), the operator operates the operation panel 10 in Step 2. By operating the operation switch for the regulation range setting, for example, the setting dial, a depth range in which calculation processing is desired, a signal level range,
And setting the area range.

The above setting types may be used alone or in combination of a plurality of settings.

The image illustrated in FIG.
Bt scope displayed by the CRT display device 9a and processed by the CRT display device 9a, where Kt indicates the return reflection time range in which the synthetic aperture operation is to be performed, that is, the depth from the ground to be examined in detail, and Kd indicates the depth from the ground to be examined. It indicates the area range to be set, that is, the restriction range set on the measurement position data obtained from the position measurement device 13.

Therefore, the data of the reflected signal in the range surrounded by Kt and Kd is data used for executing the synthetic aperture operation.

The image illustrated in FIG. 5B is an A scope displayed by the computer, and to is a target transmitted directly from the transmitting antenna 11a to the receiving antenna 11b as described above. This is the time for masking the signal component c that interferes with detection.

Further, Kt indicates a return reflection time range in which the synthetic aperture calculation is to be performed, that is, a depth from the ground to be investigated in detail,
Ke indicates the level range of the reflection signal to be investigated in detail, and in this example, it is judged that the signal larger than Ke, that is, the difference between the boundary between the exploration target to be explored and the earth and sand is clearly different This is the setting in the case.

Therefore, the reflection signal b is larger than the set level Ke of the reflection signal, but is not included in the depth to be searched, and accordingly,
Since it is outside the regulation range, it does not become data when performing the synthetic aperture calculation, but the reflection signal a becomes data when performing the synthetic aperture calculation because it is within the regulation range.

Although the above-described setting of the reflection signal level has been described using the A scope, a portion having a predetermined density in the image on the B scope shown in FIG.

In the computer 7, for example, with respect to the setting of the depth, the time from the emission of the electromagnetic wave to the return of the reflected wave is converted into a distance and displayed. A time range required for the aperture calculation is calculated, and the regulated synthetic aperture (hereinafter referred to as a target synthetic aperture) calculation condition is automatically set in the calculation program. (Step 3) With respect to other setting conditions, predetermined processing is performed to automatically set the calculation conditions in the calculation program.

In the state where the above-mentioned previous stage is completed, in step 4,
The operator operates the operation switch of the operation panel 10 (not shown).
To start a search based on the target synthetic aperture method.

Alternatively, a switch operation for reading necessary data from the storage device 8 and performing arithmetic processing based on the synthetic aperture is performed.

In step 5, the computer 7 of the underground radar starts the arithmetic processing based on the target synthetic aperture method, and displays the processing result on the display device 9.

To perform the synthetic aperture processing in real time, in step 6, the operator moves the antenna unit 20 of the underground radar on the ground to be searched to continue the search, and the computer 7 performs the search based on the received reflection information data. The arithmetic processing based on the target synthetic aperture method is continuously performed, and the operation and the display device 9 are performed until the operator performs the operation of completing the search by operating switches (not shown) on the operation panel 10 (step 7).
Continue displaying to.

When performing an arithmetic operation based on the synthetic aperture based on the off-line data based on the reflection data stored in the storage device 8, the setting is made in Step 3 and the operation is started in Step 4, and when the operation is completed, Step 7 is performed. , The calculation is automatically stopped, the calculation result is displayed on the display device 9, and printed out as necessary.

In the above description, the setting range has been described with respect to the depth, the magnitude of the reflection signal level, and the exploration area range. However, other calculation conditions are limited and set in the computer, and the calculation processing based on the target synthetic aperture method is performed. It is also possible.

In the above description, the range of the arithmetic processing for performing the synthetic aperture processing is restricted by looking at the display image such as the A scope or the B scope by the normal image processing, but the search by the radar is started. Before performing the process, a regulation range of the arithmetic processing for performing the synthetic aperture processing may be set.

[Effects of the Invention] As described above, according to the present invention, the range of the reflected signal data to be subjected to the synthetic aperture processing is externally set and regulated,
In particular, a target is set as the regulation range, that is, only a reflection signal within a certain return time is limited, a signal is limited only within a certain reception level range, and an area to be explored is limited. Therefore, it becomes possible to perform the operation related to the synthetic aperture processing in a short time for the range to be investigated in detail, and it is possible to specify a specific range from an unclear display screen and clearly display it, so that even an unskilled operator can It is possible to easily and reliably determine an object to be searched, and to obtain an excellent effect that an efficient underground object search can be performed on site.

[Brief description of the drawings]

FIG. 1 is an example of an underground object exploration apparatus to which the underground radar used in the present invention is applied. FIG. 2 is an example of a schematic configuration of a circuit of an underground radar used in the present invention. FIG. 3 is a schematic circuit configuration diagram for explaining the operation in the present invention. FIG. 4 is a flowchart for explaining the operation in the present invention. FIG. 5 (A) is a photograph of an oscilloscope waveform instead of a drawing showing an example of a display screen on a display device. FIG. 5B is an image diagram for explaining the operation in the present invention. DESCRIPTION OF SYMBOLS 1 ... Antenna, 1a, 1b ... Electromagnetic wave, 2 ... Trigger circuit, 3 ... Pulser, 4 ... Sampler, 5 ... Signal processing circuit, 6 ... Cable, 7 ... Computer, 8 ... Storage device , 9 ... Display device, 9a ... CRT display device, 9b ...
Printer, 10 Operation panel, 11a Transmission antenna, 1
1b: receiving antenna, 12: traveling sensor, 13: position measuring device, 20: antenna unit, 20a: traveling wheel, 21 ...
Control display device, 30 ... Underground buried object.

Continuing on the front page (72) Inventor Yasuhiko Ichimura 1200 Manda, Hiratsuka-shi, Kanagawa Prefecture, Komatsu Ltd.Laboratory (72) Inventor Yasuo Kanemitsu 1200, Manda, Hiratsuka-shi, Kanagawa Komatsu Ltd. Laboratory (56) References JP JP-A-63-75585 (JP, A) JP-A-63-305277 (JP, A) JP-A-57-50671 (JP, A) JP-A-63-305272 (JP, A) JP-A-63-305274 (JP, A) , A) JP-A-63-305271 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01S 13/88

Claims (8)

(57) [Claims] 1. A predetermined signal is transmitted from each measurement position toward the underground while moving the measurement position by a predetermined distance, a reflection signal of the transmission signal is detected, and the reflection at the measurement position in a predetermined section is detected. Performing synthetic aperture processing based on the signal, and detecting the target by displaying the processing result, in the underground radar reflected signal processing method, after confirming the image of the reflected signal in the predetermined section, A processing range that restricts the range to be investigated as a target of synthetic aperture processing is set from the outside, and the synthetic aperture processing is performed on the reflected signal only within the set restriction range. Signal processing method. 2. The set restriction range is such that the time from transmission of the transmission signal to return of the reflection signal is within a predetermined time range.
The underground radar reflected signal processing method as described in the above. 3. The underground radar reflection signal processing method according to claim 1, wherein the set regulation range is such that a reception level value of the reflection signal is within a predetermined level range. 4. The underground radar reflection signal processing according to claim 1, wherein the set restriction range is such that the measurement position is within a predetermined position range. Method. 5. A method of transmitting a predetermined signal from each measurement position toward the underground while moving the measurement position by a predetermined distance, detecting a reflection signal of the transmission signal, and detecting the reflection at the measurement position in a predetermined section. In a reflection signal processing device for an underground radar that performs synthetic aperture processing based on a signal, a processing range that regulates a range to be investigated in detail as an object of the synthetic aperture processing in an image of a reflection signal in the predetermined section is externally set. And a synthetic aperture processing means for performing a synthetic aperture process only on signals within the set regulation range. 6. The set restriction range is such that the time from transmission of the transmission signal to return of the reflection signal is within a predetermined time range.
The underground radar reflection signal processing apparatus according to claim 1. 7. The underground radar reflection signal processing apparatus according to claim 5, wherein the set regulation range is such that a reception level value of the reflection signal is within a predetermined level range. 8. The underground radar reflection signal processing according to claim 5, wherein the set restriction range is such that the measurement position is within a predetermined position range. apparatus.