JP2010151603A - Underground radar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground radar not only detecting the position of a buried object but also discriminating whether the underground buried object is a metal object or a nonmetal object, when examining a buried state prior to an underground drilling work. <P>SOLUTION: This underground radar 1 includes an electromagnetic wave transmission part 4 for transmitting an electromagnetic wave toward the underground, and an electromagnetic wave reception part 5 for receiving a reflected electromagnetic wave based on the transmitted electromagnetic wave, and detects a buried object 9 buried underground based on an electromagnetic wave received by the electromagnetic wave reception part 5. The radar 1 has a constitution including a correlation processing part 22 for performing mutual correlation processing between a reception waveform 19 of the electromagnetic wave received by the electromagnetic wave reception part 5 and a transmission waveform 12 of the electromagnetic wave transmitted from the electromagnetic wave transmission part 4, and autocorrelation processing of the reception waveform 19; and a discrimination part 7 for calculating the ratio between a mutual correlation value and an autocorrelation value acquired by the correlation processing part 22, and discriminating whether the underground buried object 9 buried underground is a metal object or a nonmetal object based on the calculated ratio. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ground penetrating radar for detecting a buried object in the ground, and more particularly to a ground penetrating radar that can identify whether a buried object is a metal object or a non-metal object.

  In railway track improvement work, road construction, etc., for example, excavation work such as soil or concrete may be performed. Prior to such excavation work, the safety of the work may be ensured by investigating the state of burial of existing equipment such as gas pipes, water pipes, and power cables in the excavation work area. Such burial status investigation is generally performed by operating a ground radar in an excavation work area.

As this type of subsurface radar, for example, as described in Patent Document 1, a transmitter that generates a radar transmission wave, a transmission antenna that transmits the transmission wave, and a reflected wave from an underground object are used. There is a configuration that has a receiving antenna for receiving and detects the position of an embedded object by performing predetermined arithmetic processing on received wave data.
Japanese Patent No. 3039509

  However, since this type of conventional underground radar only detects the position of the buried object, as described above, the underground situation is investigated prior to excavation work, and the position of the buried object is known. However, it was impossible to identify whether the buried object was a metal object or a non-metal object (for example, identification of a metal tube or a vinyl chloride tube). Therefore, to ensure that excavation works smoothly regardless of whether the buried object is a metal object or a non-metal object, it is necessary to prepare machines and construction tools for excavation work that can handle both. There is a case where unnecessary preparation may be required, and preparation is expensive.

  The inventor calculates the cross-correlation value between the transmission waveform of the electromagnetic wave transmitted toward the ground and the reception waveform of the electromagnetic wave reflected based on the transmitted electromagnetic wave, and the autocorrelation value of the reception waveform. Based on the ratio between the autocorrelation value and the cross-correlation value, it was found that the buried object buried in the ground can be identified as a metal object or a non-metal object.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a ground penetrating radar that can identify whether a buried object is a metal object or a non-metal object.

In order to achieve the above object, an underground radar according to the present invention includes an electromagnetic wave transmission unit that transmits an electromagnetic wave toward the ground, and an electromagnetic wave reception unit that receives an electromagnetic wave reflected based on the transmitted electromagnetic wave. An underground radar for detecting an embedded object buried in the ground based on the electromagnetic wave received by the electromagnetic wave receiving unit, and the received waveform of the electromagnetic wave received by the electromagnetic wave receiving unit and the electromagnetic wave transmitting unit A correlation processing unit that performs a cross-correlation process with the transmission waveform of the electromagnetic wave and an auto-correlation process of the reception waveform, and calculates a ratio between the cross-correlation value and the auto-correlation value obtained by the correlation processing unit, An identification unit for identifying whether the buried object buried in the ground is a metal object or a non-metal object based on the ratio.

  With such a configuration, the electromagnetic wave sending unit sends the electromagnetic wave toward the ground, and the electromagnetic wave receiving unit receives the electromagnetic wave reflected based on the sent electromagnetic wave and is buried in the ground. The correlation processing unit performs cross-correlation processing between the reception waveform of the electromagnetic wave received by the electromagnetic wave reception unit and the transmission waveform of the electromagnetic wave transmitted from the electromagnetic wave transmission unit, and autocorrelation processing of the reception waveform. The identification unit calculates the ratio between the cross-correlation value and the autocorrelation value obtained by the correlation processing unit, and whether the buried object buried in the ground based on the calculated ratio is a metal object or not. Identify whether it is a metal object. As a result, when investigating the burial status prior to underground excavation work, not only the position of the buried object is detected, but also whether the underground buried object is a metal object or a non-metal object is identified. .

  According to a second aspect of the present invention, the electromagnetic wave transmission unit includes a transmission wave amplifier unit that amplifies an output of an electromagnetic wave to be transmitted toward the ground, and a correlation processing unit. It is preferable to have a configuration having a distribution unit for distribution.

  Furthermore, as in claim 3, the electromagnetic wave transmission unit may be configured to send the electromagnetic wave multiple times toward the ground.

  Furthermore, as in claim 4, an average processing unit for calculating the average value by adding all the data of each received waveform received at different times based on the electromagnetic wave transmitted multiple times toward the ground You may make it the structure which has.

  Further, as in claim 5, a threshold value is set in advance, and the threshold value is compared with the calculated ratio to identify whether the buried object buried in the ground is a metal object or a non-metal object. You may make it the structure which has the identification part to perform.

  According to the first aspect of the present invention, the electromagnetic wave transmitting unit transmits the electromagnetic wave toward the ground, and the electromagnetic wave receiving unit receives the electromagnetic wave reflected based on the transmitted electromagnetic wave, and is embedded in the ground. The correlation processing unit detects a buried object, and performs a cross-correlation process between the reception waveform of the electromagnetic wave received by the electromagnetic wave reception unit and the transmission waveform of the electromagnetic wave transmitted from the electromagnetic wave transmission unit, and self of the reception waveform Correlation processing is performed, the ratio between the cross-correlation value and autocorrelation value obtained by the correlation processing unit is calculated by the identification unit, and the embedded object embedded in the ground based on the calculated ratio is a metal object Therefore, the position of the embedded object can be detected and whether the embedded object is a metal object or a non-metal object can be identified. Therefore, for example, prior to excavation work in the ground, if it is identified that the buried object is a non-metallic object, it is not necessary to prepare only machines and tools that correspond to the case where the non-metallic object is buried. It is possible to prepare for construction without incurring significant costs.

  According to the second aspect of the invention, the transmission unit amplifies the output of the electromagnetic wave transmitted to the ground by the distribution unit, and the correlation processing unit Can be distributed. Therefore, the correlation processing unit can easily obtain a transmission waveform.

  Furthermore, according to the invention which concerns on Claim 3, an electromagnetic wave can be sent out several times toward the ground by the said electromagnetic wave transmission part. Therefore, the electromagnetic wave receiving unit can receive the electromagnetic wave reflected based on the transmitted electromagnetic wave a plurality of times at different times, and reduce reception errors.

  Furthermore, according to the invention according to claim 4, all the received waveform data received at different times based on the electromagnetic waves transmitted a plurality of times toward the ground are all added by the averaging processor. Let the average value be calculated. Thereby, for example, irregular noise components from the electronic circuit of the ground penetrating radar, random noise components caused by irregular reflected waves from the ground surface, and the like, The signal component of the reflected wave of the electromagnetic wave from the buried object can be strengthened. Therefore, the S / N ratio of the received waveform can be improved, and for example, the visibility when the detection result is displayed as an image can be improved.

  According to the invention according to claim 5, whether the buried object buried in the ground is a metal object or a non-metal object by comparing a preset threshold value with the calculated ratio. Can be identified. Therefore, it is possible to easily identify whether the buried object buried in the ground is a metal object or a non-metal object.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing an embodiment of a ground penetrating radar according to the present invention.
In FIG. 1, a ground penetrating radar 1 according to this embodiment includes a wheel portion 2 and a ground penetrating radar main body 3. The ground penetrating radar main body 3 includes an electromagnetic wave transmitting portion 4, an electromagnetic wave receiving portion 5, and a signal processing portion. 6, an identification unit 7, and a display unit 8.

  The wheel unit 2 enables the underground radar main body 3 to be easily transported to a place where the buried state of the buried object 9 such as a metal pipe or a vinyl chloride pipe is detected, for example, as shown in FIG. For example, it is attached below the underground radar main body 3.

  As shown in FIG. 1, the electromagnetic wave transmission unit 4 transmits an electromagnetic wave toward the ground. The transmission wave amplifier 10 amplifies the output of the electromagnetic wave to be transmitted, and transmits the amplified electromagnetic wave toward the ground. And a transmitting antenna unit 11 for performing the above operation. Here, the transmission waveform 12 of the transmitted electromagnetic wave is a waveform whose amplitude (voltage) changes with time, as shown in FIG.

  In the present embodiment, as shown in FIG. 1, the electromagnetic wave transmission unit 4 uses a wave source having a wide frequency component such as a Gaussian wave, an impulse wave, a chirp wave, or an FM-CW wave in advance. A plurality of wave source selection units 13 that can select and output a wave source signal by switching a wave source of electromagnetic waves to be transmitted by a switch, and restrict a frequency component of the selected wave source to generate a wave source signal in a specific frequency range. A plurality of filters for attenuating the output are prepared in advance, and the frequency characteristic changing means 15 is configured by a filter selection unit 14 capable of selecting a filter by switching a switch and outputting a signal of a predetermined transmission waveform 12 through the filter. It has. Further, the electromagnetic wave transmission unit 4 includes a distribution unit 16 that distributes and outputs the signal of the transmission waveform 12 input from the filter selection unit 14 to the transmission wave amplifier 10 and a correlation processing unit 22 described later. The electromagnetic wave transmission unit 4 can select the wave source and filter of the electromagnetic wave to be transmitted, change the frequency characteristics of the transmission waveform 12, and transmit the electromagnetic wave of the predetermined transmission waveform 12 toward the ground.

  In addition, although the wave source selection unit 13 and the filter selection unit 14 have been described with respect to the configuration in which the wave source and the filter are selected by a switch, the present invention is not limited to this. For example, the wave source selection unit 13 uses a modulator with one wave source. The wave source may be selected by changing the parameters of the wave source, and the filter selection unit 14 uses a single packaged filter to select the filter by changing the constants and arrangement parameters of the constituent elements of the filter. It may be configured.

  Furthermore, in this embodiment, the electromagnetic wave transmission part 4 is comprised so that electromagnetic waves may be sent in multiple times toward the underground. For this reason, since the electromagnetic waves reflected based on the transmitted electromagnetic waves can be received a plurality of times at different times, reception errors can be reduced. Further, it is possible to easily obtain a plurality of data for processing the signals of the received waveforms received at different times by the average processing unit 6 described later.

  The electromagnetic wave receiving unit 5 receives an electromagnetic wave reflected based on the transmitted electromagnetic wave and amplifies the output. As shown in FIG. 1, a receiving antenna unit 17 that receives the reflected electromagnetic wave, And a reception wave amplifier 18 for amplifying the output of the electromagnetic wave. The received waveform 19 of the electromagnetic wave received here is a waveform in which the amplitude (voltage) of the received wave changes with time, as shown in FIGS.

  The signal processing unit 6 processes a signal output from the reception wave amplifier 18. As illustrated in FIG. 1, the signal processing unit 6 removes harmonic noise from the reception waveform 19 and the waveform processing unit 20. The A / D converter 21 converts the analog signal into a digital signal. Note that the waveform processing unit 20 is configured by a low-pass filter, for example.

  Here, in the present embodiment, the signal processing unit 6 includes a correlation processing unit 22 that processes an input signal from the reception wave amplifier 18 as shown in FIG. The correlation processing unit 22 performs a cross-correlation process between the reception waveform 19 of the electromagnetic wave received by the electromagnetic wave reception unit 5 and the transmission waveform 12 of the electromagnetic wave transmitted (distributed) from the distribution unit 16 of the electromagnetic wave transmission unit 4 and the reception waveform. 19 auto-correlation processing is performed, and the obtained cross-correlation value and auto-correlation value data are output to the identification unit 7 described later. Further, the signal of the reception waveform 19 from the reception wave amplifier 18 is transmitted to the waveform processing unit 20. In the autocorrelation process, for example, the received waveform 19 of the first wave is stored in advance in a memory not shown, and then the received waveform 19 of the second and subsequent waves and the received waveform 19 of the first wave stored in the memory are stored. This is done by performing correlation processing with. Also, the autocorrelation and cross-correlation processing results are confirmed on the display unit 8 to be described later as autocorrelation waveforms 23 (see FIGS. 5 and 6) and cross-correlation waveforms 24 (see FIGS. 5 and 6). You can also.

  In the present embodiment, the signal processing unit 6 further includes an average processing unit 25 as shown in FIG. This average processing unit 25 calculates the average value by adding all the data of each reception waveform 19 received at different times based on the electromagnetic waves sent out a plurality of times. Is output to the identification unit 7 described later. As described above, since the electromagnetic wave transmission unit 4 is configured to transmit the electromagnetic wave multiple times toward the ground, the electromagnetic wave reflected based on the transmitted electromagnetic wave is received multiple times at different times. Thus, each received waveform 19 can be obtained. Note that the electromagnetic wave transmission unit 4 may be configured to transmit the electromagnetic wave once. In this case, the average processing unit 25 creates a plurality of time-shifted waveform data for the received waveform 19 and adds all of them. To calculate the average value.

Furthermore, in this embodiment, the underground radar main body 3 includes an identification unit 7 as shown in FIG. The identification unit 7 identifies whether the buried object 9 embedded in the ground is a metal object or a non-metal object, and uses the cross-correlation value and the autocorrelation value obtained by the correlation processing unit 22. Based on the ratio between the cross-correlation value and the auto-correlation value as a correlation ratio, for example, the correlation ratio is expressed by the following formula: correlation ratio = 100− (cross-correlation value / auto-correlation value) × 100
By defining the unit of the correlation ratio as a percentage and comparing the threshold value for the correlation ratio set in the identification unit 7 in advance with the calculated correlation ratio (%), Identify non-metallic objects. Then, the identification result is output to the display unit 8 described later and can be confirmed. The identification unit 7 is also used to control the entire apparatus such as the signal processing unit 6 and is configured by a device such as a CPU or an FPGA (Field Programmable Gate Array).

  The display unit 8 displays the above-described identification result, and in addition, based on the data of the averaged received waveform 19 obtained from the average processing unit 25, for example, a detection result with good visibility can be displayed as an image. it can. As described above, the autocorrelation waveform 23 and the cross-correlation waveform 24 can also be displayed.

  Next, in the underground radar 1 configured as described above, for example, the underground is made of concrete (thickness t = 5 cm, relative permittivity Er = 6) as an upper layer (ground surface) as shown in FIG. 2) with a soil (relative permittivity Er = 36) as a lower layer, and a cylindrical resin tube or columnar metal tube each having a diameter of 10 cm is embedded in a soil layer at a depth of 2 m from the ground surface. The operation and procedure for identifying whether the buried object 9 is a metal object or a non-metal object based on the results of preliminary experiments by operating the ground penetrating radar in each of the two cases will be described.

  First, as shown in FIG. 7A, the ground radar 1 is installed in the detection area, and the frequency characteristics of the electromagnetic wave to be transmitted are operated by operating the switches of the wave source selection unit 13 and the filter selection unit 14, for example, a Gaussian waveform. Of the transmission waveform 12 is transmitted to the distribution unit 16, the signal of the transmission waveform 12 is output to the transmission wave amplifier 10 by the distribution unit 16, and the output of the signal of the transmission waveform 12 is amplified by the transmission wave amplifier 10. An electromagnetic wave is transmitted from the transmission antenna unit 11 toward the ground.

  Next, an electromagnetic wave reflected based on the transmitted electromagnetic wave is received by the receiving antenna unit 17, the output of the received electromagnetic wave is amplified by the reception wave amplifier 18, and the cylindrical resin tube or the cylindrical metal tube is A signal of the first received waveform 19 is obtained. Then, the obtained data of the received waveform 19 of the first wave is stored in the memory (not shown).

  Then, the transmission waveform 12 after the second wave is transmitted from the distribution unit 16 to the transmission wave amplifier 10 and the correlation processing unit 22, and the output of the signal of the transmission waveform 12 is amplified by the transmission wave amplifier 10. 11 sends out electromagnetic waves toward the ground. The electromagnetic wave reflected based on the transmitted electromagnetic wave is received by the reception antenna unit 17, the output of the received electromagnetic wave is amplified by the reception wave amplifier 18, and the signal of the reception waveform 19 after the second wave is correlated with the correlation processing unit. 22 for output.

  Further, the correlation processing unit 22 performs a cross-correlation process between the received waveform 19 after the second wave and the transmission waveform 12 of the second and subsequent electromagnetic waves distributed from the distributing unit 16, and simultaneously receives the received two waves. For each received waveform 19 after the first, autocorrelation processing with the received waveform 19 stored in advance in a memory (not shown) is performed. Then, the obtained cross correlation value and autocorrelation value data are output to the discriminating unit 7, and the signal of the reception waveform 19 after the second wave from the reception wave amplifier 18 is transmitted to the waveform processing unit 20.

  Further, the waveform processing unit 20 removes the harmonic noise of the received waveform 19 after the second wave by, for example, a low-pass filter, and the A / D conversion unit 21 converts the analog signal from the waveform processing unit 20 into a digital signal. Then, a digital signal is output to the average processing unit 25. Then, for each received waveform 19 after the second wave received at different times, all the data after noise removal is added to calculate an average value, and the data is displayed on the display unit 8 via the identification unit 7. Transmit and display the detection result with good visibility. In addition, the waveform is displayed on the display unit 8 as an autocorrelation waveform 23 and a crosscorrelation waveform 24 as autocorrelation and crosscorrelation processing results.

  Here, based on the cross-correlation value and autocorrelation value obtained from the correlation processing unit 22, the above-described correlation ratio is calculated by the identification unit 7. The correlation ratio was about 37% when the buried object 9 was the cylindrical resin tube, and about 5% when the buried object 9 was the cylindrical metal tube. Thus, it can be seen that the correlation ratio obtained when the buried object 9 is a cylindrical resin pipe is larger than the correlation ratio obtained when the buried object 9 is a cylindrical metal pipe. Note that reliable data can be obtained by calculating the correlation ratio based on the received waveforms 19 after the second wave. For example, the correlation ratio may be calculated based only on the second received waveform 19.

  Preliminary experiments were carried out by changing the conditions (embedding depth, shape, structure, material) of the buried object 9 in the same procedure. As a result, it has been found that even when the embedment depth of the embedment 9 is 1 m and 1.5 m, a correlation ratio substantially equivalent to the above is obtained. Further, in the case where the embedded object 9 is not a cylindrical metal tube but a hollow metal tube having an outer diameter of 10 cm and an inner diameter of 8 cm or a square metal having a side of 10 cm, the correlation is almost the same as that in the case where the cylindrical metal tube is embedded. It turns out to get a ratio. Furthermore, even when the embedded object 9 is not a cylindrical resin pipe but a spherical cavity with a diameter of 10 cm, spherical water with a diameter of 10 cm, or square material (wood) with a side of 10 cm, the cylindrical resin pipe is embedded. It was found that the correlation ratio was almost the same as when

  Therefore, regardless of the conditions (embedding depth, shape, structure, material) of the buried object 9, the correlation ratio obtained when the buried object 9 is a non-metallic object (resin, air, water, wood, etc.) In the preliminary experiment in which the conditions of the above are changed, the correlation ratio obtained in the case of a metal object is about 30 to 37% (in the preliminary experiment in which the conditions of the buried object are changed, about 5 to 8%). %) Is clearly larger. In this way, the correlation unit 7 calculates the correlation ratio. For example, a threshold value for identifying whether the embedded object 9 is a metal object or a non-metal object is determined in advance based on the preliminary experiment result. 7, the threshold value is compared with the calculated correlation ratio in the subsequent operation to identify whether the embedded object 9 is a metal object or a non-metal object, and the identification result is displayed on the display unit 8. To display.

  Moreover, in the same procedure, the buried object 9 is treated under the conditions of the ground (relative permittivity of concrete and soil) for a cylindrical metal tube with a diameter of 10 cm, a square material (wood) with a side of 10 cm, and spherical water with a diameter of 10 cm. Preliminary experiments were carried out by changing the thickness of the concrete layer. As a result, the relative permittivity (Er = 36) of the soil layer is not changed, and even when the relative permittivity Er of the concrete layer is 2.0, 3.0, and 4.0, as shown in FIG. It was found that correlation ratios substantially equivalent to those described above were obtained. Furthermore, when the relative permittivity Er of the soil layer is set to 10 and 20 without changing the relative permittivity of the concrete layer, or the relative permittivity of the concrete layer and the soil layer is not changed, the thickness of the concrete layer is 50 cm, It was also found that the correlation ratios approximately equivalent to those described above were obtained for the cases of 100 cm and 150 cm, respectively.

  Therefore, regardless of the underground conditions (concrete dielectric constant of concrete and soil, the thickness of the concrete layer, etc.), the correlation ratio obtained when the buried object 9 is a non-metallic object (preliminary changes in the above-mentioned underground conditions) In the case of a simple experiment, about 24 to 46%) is clearly larger than the correlation ratio obtained in the case of a metal object (about 2 to 6% in the preliminary experiment in which the above ground conditions are changed). It becomes.

  Furthermore, in the above description, as shown in FIG. 7 (a), the underground layer is a two-layered structure of a concrete layer and a soil layer, and the buried object 9 is embedded in the soil layer. As described above, the present invention is not limited to this. As shown in FIG. 7B, the underground is only a soil layer, and the buried object 9 is embedded in the soil layer. As shown in the figure, the underground is a two-layer structure of a concrete layer and a soil layer, but also when the buried object is buried in the concrete layer, the buried object is obtained in the case of the non-metallic object as described above. It has been confirmed that the correlation ratio is obviously larger than the correlation ratio obtained in the case of the metal object.

  Furthermore, in the above description, the identification procedure when the depth of the buried object is 1 m, 1.5 m, and 2 m has been described. However, the present invention is not limited to this, and the output level is increased by increasing the output level of electromagnetic waves. The buried object can be identified up to a depth corresponding to.

  From the above, the underground conditions (relative permittivity, concrete layer thickness, underground layer conditions) of the area where the buried object is to be detected and the buried object conditions (burial depth, shape, structure, Regardless of the material, it is possible to identify whether the embedded object is a metal object or a non-metal object based on the correlation ratio.

  In addition, although the case where the wheel part 2 was attached to the underground radar main body 3 was demonstrated, you may make it the structure which drags and conveys the underground radar main body 3 without providing this, without providing the wheel part 2. Moreover, although the case where the transmitting antenna unit 11 and the receiving antenna unit 17 are installed at a distance from the ground surface is shown in FIG. 1, the present invention is not limited to this, and the ground surface, the transmitting antenna unit 11 and the receiving antenna unit 17 interfere with each other. It may be installed as close to the ground surface as possible.

It is a block diagram which shows one Embodiment of the ground penetrating radar by this invention. It is explanatory drawing which shows an example of the transmission waveform of the electromagnetic waves sent out toward the ground. It is explanatory drawing which shows an example of the received waveform from a nonmetallic embedded object. It is explanatory drawing which shows an example of the received waveform from a metal embedment. It is explanatory drawing which shows an example of the waveform of a cross correlation and autocorrelation in case an embedded object is a nonmetal. It is explanatory drawing which shows an example of the waveform of the cross correlation and autocorrelation in case an embedded object is a metal. It is explanatory drawing which shows the state of underground and the burial position of a buried object, (a) is the situation figure in which the underground is formed by two layers of concrete and soil, and the buried object is buried in the soil layer. ) Is a situation diagram in which the underground is formed and buried in soil, and (c) is a situation diagram in which the underground is formed of two layers of concrete and soil, and the buried object is buried in the concrete layer. It is a table | surface which shows the preliminary experiment result at the time of changing the dielectric constant of a concrete layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Subsurface radar 4 ... Electromagnetic wave transmission part 5 ... Electromagnetic wave reception part 6 ... Signal processing part 7 ... Identification part 9 ... Embedded object 12 ... Transmission waveform 19 ... Reception waveform 22 ... Correlation processing part 25 ... Average processing part

Claims (5)

An electromagnetic wave transmitting unit that transmits an electromagnetic wave toward the ground, and an electromagnetic wave receiving unit that receives an electromagnetic wave reflected based on the transmitted electromagnetic wave, and the underground based on the electromagnetic wave received by the electromagnetic wave receiving unit In the ground penetrating radar that detects buried objects buried in
A correlation processing unit that performs a cross-correlation process between a reception waveform of the electromagnetic wave received by the electromagnetic wave reception unit and a transmission waveform of the electromagnetic wave transmitted from the electromagnetic wave transmission unit, and an autocorrelation process of the reception waveform;
The ratio between the cross-correlation value and the autocorrelation value obtained by the correlation processing unit is calculated, and whether the embedded object buried in the ground is a metal object or a non-metal object based on the calculated ratio. An identifying part for identifying;
A ground penetrating radar characterized by comprising:   The electromagnetic wave transmission unit includes a distribution unit that distributes a signal of a transmission waveform of the transmitted electromagnetic wave to a transmission wave amplifier unit that amplifies an output of the electromagnetic wave transmitted toward the ground and the correlation processing unit. The ground penetrating radar according to claim 1.   The underground radar according to claim 1 or 2, wherein the electromagnetic wave transmission unit is configured to transmit the electromagnetic wave a plurality of times toward the ground.   4. An average processing unit for calculating an average value by adding all received waveform data received at different times based on electromagnetic waves transmitted a plurality of times toward the ground. The ground penetrating radar according to any one of the above.   The identification unit sets a threshold value in advance, compares the threshold value with the calculated ratio, and identifies whether the embedded object embedded in the ground is a metal object or a non-metal object The ground penetrating radar according to claim 1.

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