JP2019100793A - Underground radar apparatus and method for manufacturing underground radar apparatus - Google Patents

Abstract

To provide an underground radar apparatus capable of reducing unnecessary components such as side lobes and ringing quickly with a simple structure and a method for manufacturing the underground radar apparatus.SOLUTION: Formation of a compensation filter 18 based on a signal characteristic of a reference signal SS passing through a reference propagation path RP which is a known path from the transmission unit 20 side to the reception unit 30 side can reflect characteristics inherent in the apparatus in which the respective units are assembled. To quickly and surely remove unnecessary components such as side lobes and ringing included in an actual reception signal S2 received by a reception part 30 perform a signal compensation quickly and surely by preparing a compensation filter 18 having such characteristics in advance and using it in actual operation for searching.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an underground radar apparatus that transmits and receives signals using radio waves, and relates to an underground radar apparatus and a method of manufacturing the underground radar apparatus that reduce unnecessary components generated when transmitting and receiving signals.

  For example, in order to remove unnecessary components, a method of adjusting the frequency characteristic of a signal, a method of averaging received signals using signals of a plurality of frequency characteristics, and the like are known (see Patent Documents 1 and 2). ).

  However, in the techniques disclosed in Patent Literatures 1 and 2, there is a possibility that the feasibility due to the signal generation method may be limited, or the search may take time to obtain a sufficient reduction effect.

JP, 2016-90298, A JP, 2016-90297, A

  The present invention has been made in view of the above-described points, and an object thereof is to provide an underground radar apparatus and a method of manufacturing the underground radar apparatus which can reduce unnecessary components such as side lobes and ringing quickly with a simple configuration. I assume.

  In order to achieve the above object, a ground radar apparatus according to the present invention comprises a transmitting unit for transmitting a transmission signal for search, a receiving unit for receiving a received signal, and a received signal and a reference signal received by the receiving unit. And a signal processing unit for performing signal processing for detection of the buried object, and the signal processing unit is for compensation made based on the signal characteristics of the reference signal passing through the reference propagation path from the transmitting unit side to the receiving unit side. The filter compensates for the actual received signal received by the receiver.

  In the ground radar apparatus described above, the compensation filter is created based on the signal characteristics of the reference signal that has passed through the reference propagation path from the transmitter to the receiver, so that the compensation filter has characteristics unique to the apparatus. Can be reflected. By preparing in advance a compensation filter having such characteristics and using it in actual operation for searching, removal of unnecessary components such as side lobes and ringing included in the actual reception signal received by the reception unit And reduction or compensation of the signal can be performed quickly and reliably. Further, in this case, the removal or compensation of the unnecessary components as described above is performed by the compensation filter after acquisition of the reception signal, that is, as post-processing. Therefore, it is not necessary to achieve high performance in each part of the device or to perform high-precision adjustment, or to set manufacturing limitations on each part of the device, so a simple configuration is required. Becomes possible.

  In a specific aspect of the present invention, the compensating filter is created by comparing the signal characteristics of the reference signal with the theoretical ideal signal characteristics. In this case, based on the comparison result, the compensation reflecting the characteristic unique to the apparatus can be performed on the actual reception signal received by the reception unit.

  In another aspect of the present invention, the compensating filter is created based on the ratio of the Fourier transform of an ideal waveform exhibiting theoretical ideal signal characteristics to the Fourier transform of a reference waveform for a reference signal. In this case, based on the ratio of the Fourier transform of the ideal waveform and the Fourier transform of the reference waveform, compensation of the actual reception signal received by the receiver can be performed quickly and properly.

  In yet another aspect of the present invention, the compensation filter is created using the known sufficiently ideal propagation path configured by connecting the end of the transmission unit and the end of the reception unit as a reference propagation path. . In this case, by setting the reference propagation path as the above-described known propagation path, it is possible to more reliably eliminate other factors other than the characteristic unique to the device in the creation of the compensation filter.

  In yet another aspect of the present invention, in making the compensation filter, the appropriate determination based on the side lobe attenuation envelope is made on the correlation signal waveform that is the reference waveform for the reference signal. In this case, it is possible to confirm the presence or absence of other factors other than the characteristic unique to the device.

  According to still another aspect of the present invention, there are provided a filter creation mode in which a reference propagation path is configured to acquire a reference signal, and a compensation filter is generated based on the acquired reference signal, and a normal operation mode in which normal transmission and reception operations are performed. It has a mode switching unit to switch. In this case, as in the case where, for example, there may be a change due to the external environment, the mode switching makes it possible to perform normal transmission and reception after creating the compensation filter as needed. It is possible to make a quick and accurate search by compensating for the actual reception signal received by the unit.

  In still another aspect of the present invention, the compensating filter is capable of selecting one of a plurality of filters. In this case, an optimal filter can be prepared according to the purpose.

  In still another aspect of the present invention, the signal processing unit removes side lobes or ringing that occurs based on the characteristics of each part of the device by the compensation filter. In this case, it is possible to appropriately extract the signal in which the side lobe or ringing has been removed depending on the device.

  In still another aspect of the present invention, the transmission signal from the transmission unit is a chirp signal. In this case, the search depth can be increased while securing the resolution, and the occurrence of side lobes can be suppressed during the search.

  In order to achieve the above object, according to a method of manufacturing a ground radar apparatus according to the present invention, a transmitter configured to transmit a transmission signal for search, a receiver configured to receive a received signal, and an actual received signal received by the receiver And a signal processing unit for performing signal processing for detection of the buried object based on the received signal received by the receiving unit and the reference signal, and having a compensating filter for compensating for Then, a compensation filter is created based on the signal characteristics of the reference signal that has passed through the reference propagation path.

  In the above ground radar apparatus manufacturing method, a compensation filter for the manufactured ground radar apparatus is created based on the signal characteristics of the reference signal passing through the reference propagation path from the transmitter side to the receiver side. , The compensation filter can be made to reflect the characteristics specific to the device. By preparing in advance a compensation filter having such characteristics and using it in actual operation for searching, removal of unnecessary components such as side lobes and ringing included in the actual reception signal received by the reception unit And reduction or compensation of the signal can be performed quickly and reliably. Further, in this case, the removal or compensation of the unnecessary components as described above is performed by the compensation filter after acquisition of the reception signal, that is, as post-processing. Therefore, it is not necessary to achieve high performance in each part of the device or to perform high-precision adjustment, or to set manufacturing limitations on each part of the device, so a simple configuration is required. Becomes possible. Therefore, the present manufacturing method is simple and reliable as to the preparation of the compensation filter.

It is a block diagram for explaining a ground radar device concerning a 1st embodiment. (A) is a side view which shows notionally about the mode of the search by the underground radar apparatus, (B) is a graph which shows the mode of the waveform detected in operation | movement of (A). (A) is a conceptual diagram showing a state in which the buried object is in the ground, and (B) and (C) show a state of the display when the ideal exploration is performed in the state of (A). It is a conceptual diagram which shows, (D) is a conceptual diagram which shows the appearance of the display in the real search in the state of (A). It is a figure for demonstrating the mode about the signal waveform in the real case and a theoretical case. It is a block diagram for demonstrating the processing content in the filter for compensation. It is a block diagram for demonstrating an example of the manufacturing method of the underground radar apparatus. It is a flowchart for demonstrating the process in the manufacturing process of the underground radar apparatus. It is a block diagram for demonstrating the underground radar apparatus which concerns on 2nd Embodiment. It is a flowchart for demonstrating the operation | movement of the underground radar apparatus. It is a block diagram for demonstrating the process in the manufacturing process of the underground radar apparatus which concerns on 3rd Embodiment. (A)-(D) are figures for demonstrating an example about the aptitude determination of the received signal waveform in the manufacturing process of the underground radar apparatus. It is a flowchart for demonstrating the process in the manufacturing process of the underground radar apparatus. It is a block diagram for demonstrating the underground radar apparatus which concerns on 4th Embodiment. (A) and (B) is a figure for demonstrating the difference in the characteristic between several theoretical ideal signals. It is a flowchart for demonstrating the operation | movement of the underground radar apparatus.

First Embodiment
Hereinafter, an example of the ground penetrating radar device according to the first embodiment will be described with reference to FIG. 1 and the like. FIG. 1 is a block diagram for explaining the configuration of the underground radar device 100 according to the present embodiment. 2 (A) is a side view conceptually showing the state of exploration by the ground penetrating radar device 100, and FIG. 2 (B) is a view corresponding to FIG. 2 (A). It is a graph which shows the mode of the waveform detected according to a position (depth) in operation | movement of 2 (A).

  As shown in FIG. 2A, the underground radar device 100 transmits the transmission signal S1 from the ground surface ST to the ground SO, and the transmission signal S1 transmitted by itself is a buried object embedded in the ground SO. The position of the object to be searched OB is reflected by a certain object to be searched OB and the reflected component due to the reflection is received as a received signal S2 and the received time (the length of time corresponds to the depth), the magnitude of intensity, etc. Measure (depth). Further, here, for signal reception in the ground penetrating radar device 100, a so-called A scope waveform as shown in FIG. 2B, for example, is acquired. That is, the search result is shown based on the pattern of the received signal S2 shown in FIG. 2B as an example, that is, the pattern of the response wave.

  Hereinafter, referring back to FIG. 1 and the like, the functions and characteristics of the underground radar device 100 will be described by more specifically describing the elements constituting the underground radar device 100 for performing the above-described search. Do.

  As shown in FIG. 1 or FIG. 2 (A), the underground radar apparatus 100 according to the present embodiment is for underground exploration, and includes a signal processor 10, a transmitter 20, and a receiver 30. And a display unit 40.

  The signal processing unit 10 is a main control device that performs various signal processing of the ground penetrating radar device 100, and includes a transmission control unit 11, a transmission chirp signal generation unit 11a, and a correlation processing chirp signal generation unit 11b. An amplifier 12, a correlation processing unit 15, an amplifier 16, an A / D converter 17, and a compensation filter 18 which is a filter processing unit are provided.

  The transmission unit 20 is a device for transmitting (or transmitting) a transmission signal S1 for search toward the ground based on a command from the signal processing unit 10, and includes an amplifier 21 and a transmission antenna 22. Prepare.

  The receiving unit 30 is a device for receiving a reception signal S2 including a response wave which is a reflection component of the transmission signal S1 transmitted from the transmission unit 20 to the ground, and includes a receiving antenna 31 and an amplifier 32. Prepare.

  The display unit 40 displays the search result based on the received signal that has undergone various processes in the signal processing unit 10.

  In the following, in the signal processing unit 10, the part in charge of each processing of various signal generation will be described more specifically.

  The transmission chirp signal generation unit 11a generates a chirp signal used as a transmission signal S1 to be transmitted to the ground, and sends the generated chirp signal to the transmission unit 20. The chirp signal is formed, for example, with high frequency components of 50 MHz to 800 MHz and a certain bandwidth. Thereby, the search depth can be made deeper while securing the resolution. Further, as will be described later in detail, by adopting the configuration as in this embodiment, it is possible to suppress the occurrence of side lobes and the like when searching.

  The chirp signal generating unit 11 b for correlation processing generates a chirp signal used as a reference signal R 1 for correlation processing of the received signal received from the buried object in the ground and sends it to the correlation processing unit 15.

  In the signal processing unit 10, the transmission control unit 11 is a timing control unit that sends timing control signals to the two chirp signal generation units 11a and 11b. The timing control signal from the transmission control unit 11 is a chirp signal for correlation processing generated from the chirp signal generation unit 11b with respect to the transmission chirp signal (transmission signal S1) generated from the chirp signal generation unit 11a. The reference signal R1) is generated while being shifted little by little at the nanosecond (ns) level. As described above, the correlation processing unit 15 can perform correlation processing on the received signal S2 from the receiving unit 30 with the reference signal R1.

  In addition to the above, in the illustrated example, an amplifier 12 is provided between the chirp signal generation unit 11 b and the correlation processing unit 15 as an amplifier for amplifying the reference signal R 1.

  Next, in the signal processing unit 10, the part in charge of each processing after receiving the signal will be described more specifically.

  In the signal processing unit 10, the correlation processing unit 15 includes, for example, a correlator 15a and a convolution processing unit 15b, and performs correlation processing between the reception signal S2 and the reference signal R1. That is, in the correlator 15a, the reception signal S2 from the reception unit 30 is input, and the reference signal R1 from the chirp signal generation unit 11b is input, and the convolution processing unit 15b appropriately performs convolution processing on the input information. Are correlated to generate a correlation signal. Here, it is assumed that the correlation processing unit 15 generates a correlation signal of a waveform (see, for example, the upper stage in FIG. 4) corresponding to each correlation processing.

  Besides the above, in the illustrated example, an amplifier 16 is provided on the output side of the correlation processing unit 15 as an amplifier for amplifying the generated correlation signal.

  The A / D converter 17 also receives an analog correlation signal output from the correlation processing unit 15, A / D converts it, and sends it to the compensating filter 18.

  The compensation filter 18 performs filter processing for compensating the reception signal S2 received by the receiving unit 30 (that is, a filter processing unit). In particular, the compensating filter 18 is connected to the receiving unit 30 from the transmission unit 20 side. By creating based on the signal characteristics of the reference signal passing through the reference propagation path to the side, the distortion due to the characteristic unique to each ground radar device 100, that is, the circuit characteristic is reflected. If the circuit characteristics are not ideal with distortion, the side lobes deteriorate much more than the theoretical value. On the other hand, in the present embodiment, the compensation filter 18 having the characteristics as described above is prepared in advance, and is used in an actual operation for searching, thereby the actual reception received by the receiving unit 30 Removal and reduction of unnecessary components such as side lobes and ringing included in the signal S2, that is, compensation of the signal can be performed quickly and reliably. A detailed example of a method of producing the compensation filter 18, ie, a method of mounting will be described later with reference to FIG.

  In the transmitting unit 20, the amplifier 21 is an amplifier for amplifying the chirp signal generated by the transmitting chirp signal generating unit 11a, and the transmitting antenna 22 is a chirp signal amplified by the amplifier 21; It transmits toward the apparatus exterior as transmission signal S1.

  Further, in the receiving unit 30, the receiving antenna 31 receives various signals from the outside. As a result, the chirp signal as a reflection component of the transmission signal S1 transmitted from the transmission unit 20 to the outside is also acquired as a part of the reception signal S2, whereby detection of a buried object in the underground radar device 100 is performed. Signal processing is possible. The amplifier 32 is an amplifier for amplifying the reception signal S2 acquired from the reception antenna 31. The received signal S2 passed through the amplifier 32 is sent to the correlation processing unit 15.

  As a result of the correlation processing and the like in the signal processing unit 10 as described above, for example, a so-called A scope waveform as shown in FIG. 2B is acquired. Here, as described above, FIG. 2 (B) corresponds to FIG. 2 (A). Specifically describing this, for example, among the waveforms shown in the pattern of FIG. 2B, the reflection portion P1 is a waveform of a component corresponding to the reflection on the ground surface ST of FIG. The reflection portion P2 is a waveform of a component corresponding to reflection on a plurality of exploration objects OB embedded in the ground SO. The reflected portions P1 and P2 are extracted as waveforms by correlation processing or the like in the signal processing unit 10. The ground penetrating radar device 100 receives the reflected components such as the reflected portions P1 and P2 at predetermined timing with respect to the transmission signal, and receives the reflected portion P2 while removing the reflected portion P1 which is the reflected component on the ground surface ST. By measuring the passage of time, it is possible to grasp the distance to the target exploration object (embedded object) OB, that is, the depth of the exploration object OB. Therefore, in the extraction of the waveform as shown in FIG. 2B, it is desirable to remove noise and the like and extract data on the response wave in an ideal state as much as possible.

  3 (A) to 3 (D) show an example of an image display that visualizes the A-scope waveforms as shown in FIG. 2 (B) while searching them in the ground penetrating radar apparatus 100. It is a figure for explaining conceptually. First, FIG. 3A is a conceptual diagram showing an example of a state in which the search object OB embedded in the underground OS is present. That is, here, as an example similar to that shown in FIG. 2A, it is assumed that a spherical (or cylindrical) search object OB is buried at a certain depth from the ground surface ST. In this case, if the result of the search by the ground penetrating radar device 100 is ideal, the results are as shown in FIGS. 3 (B) and 3 (C). That is, a curved partial image GDi is detected corresponding to the spherical (or cylindrical) search object OB shown in FIG. 3 (B). That is, as the image of the inspection result, only the partial image GDi is detected as shown in FIG. 3C, and from this result, the search is performed to the position as shown in FIG. 3B or 3A. It can be understood that the object OB is buried. However, since various unnecessary components are also detected in practice, for example, as shown in FIG. 3D, in addition to the curved partial image GDi to be detected, a linear or layered partial image NZi Will be detected together. In addition, the partial image GDi may not be a sharp figure, and may be blurred and have low definition. In addition, it is possible to perform the above-mentioned image display in the display part 40. FIG.

  Here, in general, as in the case of the present application, in the case of an underground radar device that performs a search by transmitting radio waves to the ground and receiving a reflected component, first, a reflected component on the underground surface exists, and This is taken as a large component (reflected part P1 of FIG. 2 (B)). In this case, if unnecessary components (noises) such as side lobes and ringing included in the reflection component on the underground surface are also detected, the reflection components of the buried object as the search object near the ground surface will be detected. It will be in the state of being mixed with unnecessary components. In particular, if the reflection signal of the object to be probed near the ground surface is weak in amplitude, it may be buried by unwanted components. Further, for example, even when a plurality of embedded objects are in proximity, the unnecessary components included in the respective components may be detected together, which may hinder the appropriate separation of the components to be extracted. In such a case, only an image as illustrated in FIG. 3D may be obtained.

  As one of the causes of side lobes and ringing which are unnecessary components as described above, an amplifier (ie, an amplifier), a signal generator, a correlator, or the like provided in the device to configure the ground penetrating radar device 100. In each part, distortion due to circuit characteristics such as inherent characteristics or variations in performance among individual differences is considered to be present. That is, at each location, there is a difference between the theoretical value (ie, the ideal value) and the value that is actually obtained. Furthermore, since the paths of the received signal and the reference signal are different, the occurrence of the above difference also differs depending on the path. For this reason, correlation processing in an ideal state can not necessarily be performed.

  On the other hand, in the ground radar apparatus 100 according to the present embodiment, the filter processing for compensating the received signal after the filter 18 for compensating the received signal in consideration of the gap between the ideal and the reality as described above is taken as a filter 18 for compensation By performing the above, it is possible to easily and quickly reduce unnecessary components that occur when transmitting and receiving signals.

  FIG. 4 is a diagram for conceptually explaining an example of signal waveforms in the real case and the theoretical case. The upper part (or the upper column) of the boxed one in the figure shows an example of the correlation signal waveform WR actually extracted. The correlation signal waveform WR has a value of time t on the horizontal axis and intensity (amplitude) vr (t) on the vertical axis, and the A scope waveform shown in FIG. 2B corresponds to each reflection component. Is a collection of correlated signal waveforms. In this embodiment, an object is to remove unnecessary components by applying Fourier transform or the like to information obtained as the A scope waveform, and to perform separation and extraction in a good state with respect to those corresponding to each correlation signal waveform WR. Do. However, in the following, in order to simplify the description, the process will be described as processing for the correlation signal waveform WR extracted as one unit.

  In the case of what is acquired in reality as described above, the extracted correlation signal waveform WR includes an unnecessary component and includes side lobes and ringing. By using the existing Fourier transform method for this waveform, for example, as shown as a graph FR in the figure, a value with the frequency f on the horizontal axis and the intensity (amplitude) | Vr (f) on the vertical axis can be obtained . That is, from the thing regarding a time domain about a correlation signal, what was converted into the amplitude and phase information by a frequency domain is obtained. Furthermore, in this regard, when the group delay is obtained from the phase information, as shown as a graph GR in the figure, a value with the frequency f on the horizontal axis and the group delay GD (Vr (f)) on the vertical axis is obtained. In this case, the group delay is generally not constant.

  On the other hand, the lower part (or the lower column) in the figure shows an example of a theoretical or ideal correlation signal waveform (hereinafter also referred to as a theoretical ideal correlation signal waveform) WI. . The ideal correlation signal waveform WI is a waveform when each part constituting the ground penetrating radar device 100 operates ideally. That is, the correlation signal waveform on an ideal basis is calculated according to the design of the underground radar device 100, and the characteristics of the transmission signal (here, the chirp signal) to be used, and the standards and specifications of each part such as the amplifier to be adopted. If various design values are determined, it is a waveform that can be derived only by calculation based on those design values. As to the correlation signal waveform WI on an ideal, typically, as illustrated in the drawing, only the main lobe can be included without including side lobes and ringing. The ideal correlation signal waveform WI has a value of time t on the horizontal axis and intensity (amplitude) vi (t) on the vertical axis. Also, in this case, regarding the Fourier transform of the correlation signal waveform WI on an ideal, as shown as a graph FI in the figure, a value with the frequency f on the horizontal axis and the intensity (amplitude) Vi (f) on the vertical axis is obtained. It will be. Further, in this regard, when the group delay is obtained from the phase information, as shown as a graph GI in the figure, a value with the frequency f on the horizontal axis and the group delay GD (Vi (f)) on the vertical axis is obtained. In this case, in short, the group delay shown in the graph GI is constant. That is, in the ideal graph FI and graph GI states as described above, the phase is not distorted at any frequency. If this is replaced with the search by the ground penetrating radar device 100, the time until it is emitted to and returned from one buried object becomes the same for all the signals having different frequencies.

  However, as illustrated in the upper part of the figure, in reality, the above-described one is not ideal, and as illustrated in the graph FR and the graph GR, a delay in phase or the like occurs depending on the frequency. For example, although there is no big difference with the ideal state on the relatively low frequency side, on the high frequency side, there may be a situation where a delay occurs due to the influence of the characteristics of the capacitor that constitutes the amplifier. It can be considered as an example.

  Based on the above, in the present embodiment, the gap between the ideal and the reality as described above is filled after the time, that is, according to the characteristics generated in each device so that the actual data approaches the data on the ideal. A compensation filter 18 having a compensation function for performing adjustment is provided.

  FIG. 5 is a block diagram for explaining the processing contents in the compensating filter 18. As conceptually illustrated in FIG. 5, the compensation filter 18 performs Fourier transform processing in the Fourier transform processing unit 18 a that performs Fourier transform processing on the correlation signal output from the correlation processing unit 15, and Fourier transform processing in the Fourier transform processing unit 18 a An arithmetic processing unit 18b which multiplies the subsequent signal by a filter coefficient FC stored in advance in the compensation filter 18, and an inverse Fourier transform processing unit which performs inverse Fourier transform processing on the signal subjected to the arithmetic processing by the arithmetic processing unit 18b And 18c.

  Note that, in one example here, the correlation signal as the actual processing target is discrete, that is, digitized. That is, the Fourier transform in the above aspect is based on fast Fourier transform performed numerically, and the calculation in the arithmetic processing unit 18 b and the filter coefficient FC used at that time are also digitized. For this reason, as described above, for example, the A / D converter 17 is provided at the front stage of the compensation filter 18.

  Note that the filter coefficient FC is not necessarily a simple configuration in which frequency components in a certain range are removed as in a normal band pass filter, and depending on the characteristics of the individual ground penetrating radar devices, There may be a complicated configuration in which components in one frequency band are reduced while components in another frequency band are amplified. By the adjustment with the filter coefficient FC, the side lobe and ringing components caused by the amplifier and the like constituting the ground radar device 100 are canceled out, and signal extraction can be performed in a good state. That is, the filter coefficient FC to be applied is in accordance with the characteristic unique to each ground penetrating radar device 100, and appropriate compensation is performed.

  The operation of the compensating filter 18 having the above-described configuration will be briefly summarized below. First, when a correlation signal is input from the A / D converter 17 with respect to a reception signal actually received, this is subjected to Fourier transform (fast Fourier transform) in the Fourier transform processing unit 18a. Next, the arithmetic processing unit 18b performs arithmetic processing by multiplying the filter coefficients FC, and the inverse Fourier transform processing unit 18c performs inverse Fourier transform (fast inverse Fourier transform) to generate a correlation signal in the waveform in the time domain. Will be returned. As described above, the correlation signal waveform output from the compensating filter 18 is a good one in which unnecessary components resulting from the internal configuration of the underground radar device 100 are reduced. That is, distortion due to the circuit characteristics is removed from the search A scope waveform obtained by the search, and it is possible to obtain A scope data as a search result composed of a waveform having ideal side lobe characteristics.

  Hereinafter, with reference to FIG. 6, an example of the manufacturing method of the ground-penetrating radar device having the compensation filter for enabling the above-mentioned filter processing will be described.

  FIG. 6 is a diagram corresponding to FIG. 1, and particularly shows one aspect of the preparation of the compensation filter 18 (calculation of the filter coefficient FC) as one step of the process of manufacturing the ground penetrating radar device 100 shown in FIG. It is a thing. Here, as compared with the case of FIG. 1 (finished product), instead of the transmitting antenna 22 and the receiving antenna 31, the portions corresponding to these, ie, the end Ta of the transmitting unit 20 and the end Tb of the receiving unit 30 are connected To provide a coaxial cable CC whose characteristics are known. Furthermore, a filter creation processing unit FP is provided at a location (see FIG. 1) to be the compensating filter 18. The filter creation processing unit FP is connected to an input unit (input unit of the ideal correlation signal waveform) IN having data on the theoretical ideal correlation signal waveform. Also,

The display unit 40 is appropriately attached after the filter creation processing unit FP becomes the compensation filter 18.

  In the case of the state shown in FIG. 6, the transmission signal S1 passed through the transmission side amplifier 21 is not transmitted to the outside, goes to the reception side amplifier 32 via the coaxial cable CC, and is thereafter treated as the reception signal S2. become. Here, a signal following such a path is referred to as a reference signal SS. In addition, a path through which the reference signal SS passes (or a path along which a component related to the reference signal SS passes), that is, the reference signal SS generated by the chirp signal generation unit 11a for transmission includes the amplifier 21, the coaxial cable CC, and the amplifier 32. Then, the correlation processing unit 15 performs correlation processing with the reference signal R1 generated by the chirp signal generation unit 11b, and further sets the path passing through the amplifier 16 and the A / D converter 17 as a reference propagation path RP. In this case, the reference propagation route RP propagates only the elements constituting the ground penetrating radar device 100 and the coaxial cable CC, that is, a known propagation route which does not include in the route an element whose characteristics such as the ground surface or the buried object are unknown. It is. Therefore, the unnecessary component generated through the reference propagation route RP is caused only by the internal configuration of the ground penetrating radar device 100. In other words, the reference signal SS that has passed through the reference propagation path RP is a signal that indicates the degree of deviation from the theoretical ideal signal based on the internal configuration of the underground radar device 100. Therefore, the reference signal SS passed through the reference propagation path RP is measured in the filter creation processing unit FP, and further, in the filter creation processing unit FP, the signal characteristics of the reference signal SS passed through the reference propagation path RP and the theoretical ideal signal characteristics To make the filter 18 for compensation on the basis of the comparison result, that is, calculating the respective numerical data to be the filter coefficient FC, thereby making it possible to remove the unnecessary component as described above. it can.

For comparison between the signal characteristics of the reference signal SS and the theoretical ideal signal characteristics, typically, the Fourier transform of the ideal waveform showing the theoretical ideal signal characteristics and the Fourier transform of the reference waveform for the reference signal It is conceivable to create based on the ratio. That is, the ratio between the value Vi (f) for the Fourier transform of the ideal waveform as exemplified by the graph GI in the lower part of FIG. 4 and the value Vr (f) for the Fourier transform of the signal waveform for the reference signal SS
ΔV (f) = Vi (f) / Vr (f) (1)
It is conceivable to determine the filter coefficient FC from the value as indicated by. That is, by adopting the above equation (1), the compensation filter 18 serving as a filter that cancels the deviation from the theoretical ideal signal with respect to the received signal S2 received by the receiving unit 30 of the underground radar device 100 Can create

  Hereinafter, with reference to the flowchart of FIG. 7, a series of processes in the manufacturing process of the above-described ground penetrating radar device 100 will be described. First, as a premise, each unit is connected so as to form a reference propagation route RP between transmission and reception. That is, the coaxial cable CC is provided at the portions to be the transmitting antenna 22 and the receiving antenna 31, that is, at the ends Ta and Tb (step S101). Then, the signal processing unit 10 generates the reference signal SS and records the received signal waveform in the state of the correlation waveform (correlation signal waveform) in the filter creation processing unit FP (step S102). Next, the signal processing unit 10 Fourier-transforms the recorded received signal waveform (correlation signal waveform) in the filter creation processing unit FP (step S103), and the theoretical ideal from the input unit IN of the ideal correlation signal waveform Data on the correlation signal waveform is read out (step S104). Here, it is assumed that the ideal correlation signal waveform is extracted in a Fourier transformed state. Next, the signal processing unit 10 compares the Fourier transform of each of the correlation signal waveforms obtained in step S103 and step S104, and calculates the difference between the amplitude and the phase in both signals (step S105). The difference information corresponding to the above equation (1) is converted into a filter coefficient (step S106). That is, the compensation filter coefficient FC is calculated. Finally, the compensation filter coefficient FC is recorded in the filter creation processing unit FP (step S107), and thereafter, the filter creation processing unit FP functions as the compensation filter 18.

  As described above, in the ground penetrating radar device 100 according to the present embodiment or the method for manufacturing the same, the signal characteristics of the reference signal SS passed through the reference propagation route RP, which is a known route from the transmitting unit 20 to the receiving unit 30. By making the compensation filter 18 on the basis of this, it is possible to reflect characteristics specific to the device in which each unit is assembled. By preparing in advance the compensation filter 18 having such features and using it in the actual operation for searching, unnecessary such as side lobes and ringing included in the actual received signal S2 received by the receiving unit 30 The removal and reduction of components, ie the compensation of the signal, can be performed quickly and reliably. Further, in this case, the processing for removing or compensating for the unnecessary component as described above is performed by the compensation filter 18 after the reception signal S2 is acquired by the reception unit 30, that is, as a post-processing. Therefore, it is not always necessary to improve the performance of each part of the underground radar apparatus 100 or to perform adjustment with high accuracy, or to set manufacturing restrictions on each part of the underground radar apparatus 100. . Therefore, the underground radar device 100 can be configured simply. In addition, although the occurrence of side lobes can not be avoided in principle in the chirp underground radar apparatus using a signal having a certain bandwidth, the occurrence of side lobes and the like can be sufficiently suppressed in this embodiment.

  The above is an example, and various modifications can be considered. For example, although the filter coefficients for the frequency domain are determined based on the Fourier transform in the above, it is also conceivable to determine the filter coefficients based on the group delay. That is, by creating a filter coefficient that makes the group delay constant with respect to the frequency, it is possible to manufacture an underground radar device having the same function as that described above.

  In addition, the calculation of the filter coefficient is also determined by the ratio of the value Vr (f) of the Fourier transform of the signal waveform of the reference signal SS as the denominator in Equation (1), but the invention is not limited thereto. It is conceivable to determine the filter coefficient based on the comparison of various ratios, differences (differences), etc. of the filter.

Second Embodiment
Hereinafter, with reference to FIG.8 and FIG.9, an example is demonstrated about the underground radar apparatus which concerns on 2nd Embodiment.

  In the ground radar apparatus 100 according to the first embodiment, the compensation filter 18 is prepared in advance at the manufacturing stage. On the other hand, the ground radar device 200 according to the present embodiment illustrated in FIG. 8 is different from that of the first embodiment in that the compensation filter 18 can be created each time the search operation is performed. There is.

  Hereinafter, with reference to FIG. 8, an example of the ground penetrating radar device 200 according to the present embodiment will be specifically described. In addition, the underground radar apparatus 200 which concerns on this embodiment is a modification of the underground radar apparatus 100 which concerns on 1st Embodiment, and FIG. 8 is a figure corresponding to FIG. 1 or FIG. Therefore, about the thing which attaches | subjects the same code | symbol, the thing of the function similar to the case of FIG. 1 etc. abbreviate | omits detailed description.

  As shown in FIG. 8, the underground radar device 200 includes a signal processing unit 210, a transmission unit 220, a reception unit 230, a display unit 40, and a coaxial cable CC.

  Similar to the signal processing unit 10 of FIG. 1, the signal processing unit 210 includes a transmission control unit 11, a transmission chirp signal generation unit 11a, a correlation processing chirp signal generation unit 11b, an amplifier 12, a correlation processing unit 15, and an amplifier. 16, an A / D converter 17 and a compensating filter 18.

  In addition to the above, the signal processing unit 210 includes a filter generation processing unit FP and an input unit (input unit of an ideal correlation signal waveform) IN having data on the theoretical ideal correlation signal waveform. The filter creation processing unit FP is connected to the input portion IN of the ideal correlation signal waveform. In addition, the signal processing unit 210 includes a mode switching unit 250. The mode switching unit 250 is a mechanism for switching between a filter creation mode for creating a compensation filter and a normal operation mode for performing a normal transmission / reception operation. In the signal processing unit 210, the filter creation processing unit FP and the compensation filter 18 are disposed in parallel in the subsequent stage of the A / D converter 17, and the mode switching unit 250 is connected to the A / D converter 17. Switch the destination as appropriate.

  The transmission unit 220 includes an amplifier 21 and a transmission antenna 22 as in the transmission unit 20 of FIG. 1. Furthermore, in addition to these, the transmission unit 220 has a first switch unit SW1 which can switch alternatively the connection from the amplifier 21 to the transmission antenna 22 and the connection from the amplifier 21 to the coaxial cable CC.

  The receiving unit 230 includes a receiving antenna 31 and an amplifier 32 as in the receiving unit 30 of FIG. 1. Furthermore, in addition to these, the receiving unit 230 has a second switch unit SW2 that can alternatively switch between the connection from the receiving antenna 31 to the amplifier 32 and the connection from the coaxial cable CC to the amplifier 32.

  The first switch unit SW1 and the second switch unit SW2 are respectively connected to the mode switching unit 250, and the mode switching unit 250 appropriately switches the first switch unit SW1 and the second switch unit SW2.

  In the configuration as described above, in the filter creation mode, the mode switching unit 250 connects the A / D converter 17 to the filter creation processing unit FP, and coaxial cables for both the first and second switch units SW1 and SW2 Connect to CC side. On the other hand, in the normal operation mode, the mode switching unit 250 connects the A / D converter 17 to the compensation filter 18, and connects the first switch unit SW1 to the transmission antenna 22, and receives the second switch unit SW2. Connect to the antenna 31. As described above, in the filter preparation mode, the mode is the same as that shown in FIG. 6, and in the normal operation mode, the mode is the same as that shown in FIG.

  Hereinafter, with reference to the flowchart of FIG. 9, a series of processes in the above-described ground-penetrating radar device 200 will be described. First, the signal processing unit 210 operates the mode switching unit 250 to set the filter creation mode, connects the A / D converter 17 to the filter creation processing unit FP, and then transmits the reference propagation path RP between transmission and reception. Connect each part to configure. That is, in the mode switching unit 250, the first and second switch units SW1 and SW2 are both connected to the side of the coaxial cable CC to configure the reference propagation path RP (step S201). Next, the signal processing unit 210 generates a reference signal SS, and records the received signal waveform in the state of a correlation waveform (correlation signal waveform) in the filter generation processing unit FP (step S202). Next, the signal processing unit 210 Fourier-transforms the received signal waveform (correlation signal waveform) recorded in the filter creation processing unit FP (step S203), and the theoretical ideal from the input unit IN of the ideal correlation signal waveform. Data on the correlation signal waveform is read out (step S204). Next, the signal processing unit 210 compares the Fourier transforms of the correlation signal waveforms obtained in step S203 and step S204, and calculates the difference between the amplitude and the phase of the two signals (step S205). The difference information corresponding to the equation (1) is converted into a filter coefficient (step S206). That is, the compensation filter coefficient is calculated. Next, the signal processing unit 210 records the compensation filter coefficient calculated in the filter creation processing unit FP in the compensation filter 18 (step S207). Thus, the compensating filter 18 functions as a filter that enables desired compensation. That is, it is possible to switch to the normal operation mode in which normal transmission / reception operation is performed. Therefore, when the recording in step S207 is completed, the signal processing unit 210 operates the mode switching unit 250 to connect the A / D converter 17 to the compensation filter 18 in order to set the normal operation mode. Between transmission and reception, the transmission unit 220 is connected from the amplifier 21 to the transmission antenna 22, and the reception unit 230 is connected to the reception antenna 31 and the amplifier 32 (step S208). When the switching process in step S208 is completed, the signal processing unit 210 causes the transmission signal S1 to be transmitted to start the normal transmission / reception operation, that is, perform the main operation (searching) by the ground penetrating radar device 200 (step S209). This operation (searching) is continued until there is a command to end the operation (Step S210: No).

  As described above, also in the ground penetrating radar device 200 according to the present embodiment, the compensation is performed based on the signal characteristics of the reference signal SS that has passed through the reference propagation route RP, which is a known route from the transmitting unit 20 to the receiving unit 30. Filter 18 is created in advance and used in an actual operation for searching, thereby removing or reducing unnecessary components such as side lobes and ringing included in the actual received signal S2 received by the receiving unit 30, that is, a signal Compensation can be done quickly and reliably. Further, in the case of the present embodiment, a filter creation mode in which the reference propagation path RP is configured to acquire a reference signal, and the compensation filter 18 is generated based on the acquired reference signal, and a normal operation mode in which normal transmission and reception operations are performed By including the mode switching unit 250 that switches the mode, it is possible to create the compensation filter as needed. Therefore, for example, as in the case where there may be a change due to the external environment, it is possible to perform normal transmission and reception after creating the compensation filter each time as needed, ie, actually received by the receiving unit The compensation of the received signal can be performed for quick and accurate search.

Third Embodiment
Hereinafter, with reference to FIGS. 10-12, an example is demonstrated about the manufacturing method of the underground radar apparatus which concerns on 3rd Embodiment.

  In the ground penetrating radar device 100 according to the first embodiment, when the compensation filter 18 is formed, the coaxial cable CC whose characteristic is known is provided at the location corresponding to the antennas 22 and 31 and the transmission signal S1 is not transmitted to the outside And the reference signal SS. On the other hand, the method of manufacturing the ground-penetrating radar device according to the present embodiment illustrated in FIG. 10 is different from that of the first embodiment in that the compensation filter is created in a state of performing transmission and reception with the antennas 22 and 31. It is different from the case. That is, in the present embodiment, the route which is temporarily transmitted from the antenna 22 to the outside and returned to the antenna 31 is used as the reference propagation route RP.

  Hereinafter, with reference to FIG. 10, an example of a method of manufacturing the ground penetrating radar device according to the present embodiment will be specifically described. The method of manufacturing the underground radar device according to the present embodiment is a modification of the method of manufacturing the underground radar device according to the first embodiment, and FIG. 10 is a view corresponding to FIG. Therefore, about the thing which attaches | subjects the same code | symbol, the thing of the function similar to the case of FIG. 1 etc. abbreviate | omits detailed description. In addition, the ground radar apparatus manufactured by the method of manufacturing the ground radar apparatus according to the present embodiment is not shown in FIG. 1 except for data (how to obtain data) in the compensation filter in the manufacturing process. Since the configuration is the same as that of the device 100, illustration and description will be omitted.

  First, as shown in FIG. 10, also in the present embodiment, as in the case of FIG. 6, the compensation filter is created by performing measurement in the filter creation processing unit FP. However, the difference is that in the filter generation processing unit FP, a reference signal appropriateness determination unit JD for performing the appropriateness determination of the reference signal is provided. Furthermore, in the present embodiment, unlike the case of FIG. 6, with the transmission antenna 22 and the reception antenna 31 provided, the transmission destination of the transmission signal S1 from the transmission antenna 22, that is, the underground side in actual operation, The point of difference is that an ideal reflecting wall WL is provided whose characteristics are known. In the present embodiment, only the component reflected by the wall WL is received by the receiving antenna 31 and treated as the reference signal SS, whereby the compensation filter is created in the filter creation processing unit FP. In particular, in the present embodiment, in the filter creation processing unit FP, the reference signal appropriateness determination unit JD determines the appropriateness of the reference signal SS. As a result, when it is determined that a component other than the component reflected by the wall WL is included, the processing for creating the compensation filter is not performed, and the environment in which the reference signal SS is received is changed again. It makes it possible to create various compensation filters.

  Unlike the case where the reference signal SS is transmitted without being transmitted to the outside as in the first embodiment, in the case of the present embodiment, an unintended component is included in the reference signal SS in the reception at the receiving antenna 31. There is a possibility of On the other hand, in the present embodiment, as described above, such a situation is avoided by performing the appropriateness determination on the reference signal SS by the reference signal appropriateness determination unit JD.

  11 (A) to 11 (D) are diagrams for conceptually explaining an example of the aptitude determination of the received signal waveform in the manufacturing process of the underground radar device in the present implementation system. Hereinafter, with reference to FIGS. 11A to 11D, a specific example of the determination method in the reference signal appropriateness determination unit JD will be described. Here, the appropriate determination is performed based on the side lobe attenuation envelope with respect to the correlation signal waveform that is the reference waveform for the reference signal SS.

  First, as shown in FIG. 11A, for the transmission signal S1 transmitted from the transmission antenna 22 of the transmission unit 20, the wall WL is ideal, and only the component reflected by the wall WL is the reference signal SS. When the signal is received by the receiving antenna 31, as a result of the correlation process, for example, a correlation signal waveform CW as shown in FIG. 11B should be acquired. In this case, since the receiving unit 30 receives a signal for only one reflection component on the wall WL, as shown in FIG. 11B, the main lobe has the strongest intensity with respect to the correlation signal waveform CW. As shown, the side lobes have gradually smaller peaks as they move away from the main lobe. As a distinctive feature of the correlation signal waveform CW, as indicated by a broken line in the drawing, a side lobe attenuation envelope AE can be drawn which attenuates along the side lobe with one main lobe as the highest intensity.

  On the other hand, unlike the case shown in FIGS. 11A and 11B, when not only the component reflected by the wall WL but also other components are included in the reference signal SS, the influence is also exerted on the correlation signal waveform. It is thought to appear. For example, as shown in a typical example in FIG. 11C corresponding to FIG. 11A, if there is an unintended object UO at the back side of the wall WL, in that case, at the wall WL Apart from the reflection component, a reflection component due to the presence of the object UO should also be detected. Specifically, as shown in an example in FIG. 11D, in the correlation signal waveform CW, in addition to the main lobe related to the reflection component at the wall WL, there is a portion showing a strong intensity considered to be another main lobe. It can be thought that it will not be a simple attenuation. In this case, unlike the case shown in FIG. 11 (B), there is a place XX where the side lobe attenuation envelope AE which attenuates along the side lobes with one main lobe as the highest intensity is present. . Therefore, it is possible to determine whether or not the reference signal SS is appropriate by appropriately preparing an algorithm for drawing the side lobe attenuation envelope AE as described above as the reference signal appropriateness determination unit JD.

  Hereinafter, with reference to the flowchart of FIG. 12, a series of processes in the manufacturing process of the above-described ground-penetrating radar device will be described. First, as a premise, each unit is connected so as to form a reference propagation route RP between transmission and reception. That is, by setting the wall WL to the end of the transmitting antenna 22 and the receiving antenna 31, an ideal reflection environment is set (step S301). Then, the signal processing unit 10 generates the transmission signal S1 to be the reference signal SS, and records the reception signal waveform in the filter generation processing unit FP in the state of the correlation waveform (correlation signal waveform) (step S302). ). Next, the signal processing unit 10 determines whether the recorded correlation signal waveform is appropriate or not in the reference signal appropriateness determination unit JD of the filter creation processing unit FP (step S303). In step S303, when it is determined not to be appropriate (step S303: No), the operation from step S301 is repeated again. That is, after resetting the wall WL, the correlation signal waveform is recorded again. On the other hand, when it is determined in step S303 that the received signal waveform is appropriate (step S303: Yes), the recorded received signal waveform (correlation signal waveform) is subjected to Fourier transform (step S304), and the input portion of the ideal correlation signal waveform Data on the theoretical ideal correlation signal waveform from IN is read out (step S305). Next, the signal processing unit 10 compares the Fourier transform of each correlation signal waveform obtained in step S304 and step S305, and calculates the difference between the amplitude and phase of both signals (step S306), and the information of the difference, ie, The difference information corresponding to equation (1) is converted into filter coefficients (step S307). That is, the compensation filter coefficient is calculated. Finally, the compensation filter coefficient is recorded in the filter creation processing unit FP (step S308), and thereafter, the filter creation processing unit FP functions as a compensation filter.

  As described above, also in the method of manufacturing the underground radar device according to the present embodiment, based on the signal characteristics of the reference signal SS passing through the reference propagation route RP, which is a known route from the transmitting unit 20 to the receiving unit 30. The compensation filter is created in advance and used in the actual operation for searching, thereby removing or reducing unnecessary components such as side lobes and ringing included in the actual received signal S2 received by the receiving unit 30, that is, Signal compensation can be done quickly and reliably. Further, in the case of the present embodiment, in the creation of the compensation filter, the reference signal appropriateness determination unit JD makes an appropriate determination based on the side lobe attenuation envelope with respect to the correlation signal waveform that is the reference waveform for the reference signal. The presence or absence of other factors other than the characteristic unique to the device, that is, whether or not an unintended component from the outside is included in the reference signal can be confirmed. Further, in this case, since it is possible to create the compensation filter in a state where the transmitting antenna 22 of the transmitting unit 20 and the receiving antenna 31 of the receiving unit 30 are attached, for example, unnecessary components due to the transmitting antenna 22 or It is possible to deal with cases where removal or reduction is required.

  In addition, although detailed description is abbreviate | omitted, it is good also as an aspect which uses creation of the filter for compensation by the coaxial cable further applied in 1st Embodiment etc. in the above in combination.

Fourth Embodiment
Hereinafter, with reference to FIGS. 13-15, an example is demonstrated about the underground radar apparatus which concerns on 4th Embodiment.

  The ground radar apparatus 100 according to the first embodiment is equipped with one compensation filter. On the other hand, the ground radar device 400 according to the present embodiment illustrated in FIG. 13 has a plurality of (two in the illustrated example) compensation filters mounted on the compensation filter 418, which makes it possible to select a filter. Is different from the case of the first embodiment in that

  Hereinafter, with reference to FIG. 13, an example of the ground penetrating radar device 400 according to the present embodiment will be specifically described. In addition, the underground radar apparatus 400 which concerns on this embodiment is a modification of the underground radar apparatus 400 which concerns on 1st Embodiment, and FIG. 13 is a figure corresponding to FIG. Therefore, about the thing which attaches | subjects the same code | symbol, the thing of the function similar to the case of FIG. 1 abbreviate | omits detailed description.

  As shown in FIG. 13, the underground radar device 400 includes a signal processing unit 410, a transmission unit 20, a reception unit 30, and a display unit 40.

  Similar to the signal processing unit 10 shown in FIG. 1, the signal processing unit 410 includes a transmission control unit 11, a transmission chirp signal generation unit 11a, a correlation processing chirp signal generation unit 11b, an amplifier 12, a correlation processing unit 15, and an amplifier. In addition to 16 and A / D converter 17, compensation filter 418 containing two filters and filter selection part FS are provided.

  In the signal processing unit 410, the compensation filter 418 includes a first filter 418a and a second filter 418b having filter coefficients different from each other.

  In the signal processing unit 410, the filter selection unit FS is a filter of one of the two filters 418a and 418b constituting the compensation filter 418 in accordance with an external input instruction from the user of the ground penetrating radar device 400. Is a mechanism for selecting

  Hereinafter, with reference to FIGS. 14A and 14B, a specific example of the first filter 418a and the second filter 418b constituting the compensating filter 418 will be described. FIGS. 14A and 14B are diagrams for explaining the difference in characteristics among a plurality of theoretical ideal signals.

  Here, with regard to the creation of the compensation filter, the theoretical ideal signal as a basis for creation and the characteristics thereof are determined according to the design of the underground radar device 100, but, for example, the embedding situation of the survey target object to be measured In some cases, the ideal correlation signal waveform may be different from the most suitable ideal signal. That is, it may be considered that it is preferable to prepare an ideal correlation signal waveform of different properties according to the embedding situation. Specifically, as exemplified in FIG. 14A for more reliable detection, it is conceivable that the correlation signal waveform W1 having no side lobes and only the main lobe is used as the ideal correlation signal waveform. . On the other hand, when it is desired to further increase the resolution in detection, as illustrated in FIG. 14B, it is ideal to make the correlation signal waveform W2 having a smaller main lobe in a narrower range while having some small side lobes. It may be desirable to have a correlation signal waveform. As apparent from comparison between FIG. 14A and FIG. 14B, the width (for example, half width) of the main lobe located at the center of the correlation signal waveform W2 is at the center of the correlation signal waveform W1. It is narrower than the width of the robe. For example, in the case where it is predicted that a plurality of search objects are closely embedded, extraction of a correlation signal waveform having a shape as shown in FIG. It can be expected to distinguish and detect the search object of In the present embodiment, a plurality of ideal correlation signal waveforms represented by FIGS. 14 (A) and 14 (B) are prepared in advance, and in the method of producing the compensation filter described in each of the above embodiments. By calculating the filter coefficients that bring the actual correlation signal waveform closer to each ideal correlation signal waveform, for example, a plurality of filters such as the first filter 418a and the second filter 418b are stored in the compensating filter 418, and the filter By appropriately selecting and applying one of them in the selection unit FS, the optimum analysis processing is performed according to the aspect of the search.

  Hereinafter, with reference to the flowchart of FIG. 15, the filter selection process in the above-described ground-penetrating radar device 400 will be described. First, when a selection command for selecting a desired waveform characteristic is issued according to an external input instruction from the user of the ground penetrating radar device 400 (step S401), the filter selection unit FS Information on filter coefficients for the first filter 418a and the second filter 418b is read out (step S402), and the information corresponding to the selection command is applied (step S403). As described above, filter selection processing is performed.

  As described above, also in the method of manufacturing the underground radar device according to the present embodiment, removal and reduction of unnecessary components such as side lobes and ringing, that is, signal compensation can be performed quickly and reliably. Further, in the case of the present embodiment, the compensating filter 418 can select one of the plurality of filters 418a and 418b. In this case, an optimal filter can be prepared according to the purpose.

[Others]
The present invention is not limited to the above embodiment, and can be implemented in various modes without departing from the scope of the invention.

  First, in the above description, the transmission signal S1 from the transmission unit 20 is a high frequency component and a chirp signal having a certain bandwidth. However, various modes can be considered for the bandwidth. Furthermore, the present invention may be applied in a mode in which not only a chirped signal but also a pulsed signal is used as a signal.

  In the above, four amplifiers 12, 16, 21 and 32 are arranged in the amplifier, but their performance and the like may be variously changed according to the purpose, etc. The present invention can also be applied to an embodiment in which there is no part, or in a case where it is arranged in another place. Furthermore, various arrangements other than the above examples can be considered for components other than the amplifier.

  In addition, various Fourier transform methods can be selected depending on the purpose and the like. Also, various filter processes may be added separately from the above.

  DESCRIPTION OF SYMBOLS 10 ... Signal processing part, 11 ... Transmission control part, 11a ... Chirp signal generation part, 11a, 11b ... Chirp signal generation part, 11b ... Chirp signal generation part, 12, 16, 21, 32 ... Amplifier, 15 ... Correlation processing part , 15a: correlator, 15b: processor, 17: converter, 18: filter for compensation, 18a: Fourier transform processor, 18b: arithmetic processor, 18c: inverse Fourier transform processor, 20: transmitter, 21: Amplifier 22 22 Transmission antenna 30 Reception unit 31 Reception antenna 32 Amplifier 40 Display unit 100 Ground radar apparatus 200 Ground radar apparatus 210 Signal processing unit 220 Transmission section , 230: reception unit, 250: mode switching unit, 400: ground penetrating radar device, 410: signal processing unit, 418: compensation filter, 418a: first filter, 41 b ... second filter, AE ... side lobe attenuation envelope, CC ... coaxial cable, CW ... correlation signal waveform, f ... frequency, FC ... filter coefficient, FC ... compensation filter coefficient, FI, FR ... graph, FP ... filter creation Processing unit, FS ... filter selection unit, GDi ... partial image, GI, GR ... graph, IN ... input unit, JD ... reference signal appropriateness determination unit, NZi ... partial image, OB ... search object, OS ... underground, P1 , P2: reflection portion, R1: reference signal, RP: reference propagation path, S1: transmission signal, S2: reception signal, SO: ground, SS: reference signal, ST: ground surface, SW1: first switch unit, SW2: Second switch section, t: time, Ta, Tb: end, UO: object, W1, W2, WI, WR: correlation signal waveform, WL: wall, XX: location

Claims (10)

A transmitter for transmitting a transmission signal for exploration;
A receiving unit that receives a received signal;
And a signal processing unit that performs signal processing for detecting a buried object based on the reception signal received by the reception unit and the reference signal,
The signal processing unit compensates for the actual reception signal received by the receiving unit, using a compensation filter created based on the signal characteristics of the reference signal that has passed through the reference propagation path from the transmitting unit to the receiving unit. , Underground radar equipment.   The underground radar apparatus according to claim 1, wherein the compensation filter is created by comparing a signal characteristic of the reference signal with a theoretical ideal signal characteristic.   The underground radar according to claim 2, wherein the compensation filter is created based on a ratio of a Fourier transform of an ideal waveform showing theoretical ideal signal characteristics and a Fourier transform of a reference waveform on the reference signal. apparatus.   The filter for compensation according to any one of claims 1 to 3, wherein a known propagation path configured by connecting an end of the transmission unit and an end of the reception unit is created as the reference propagation path. Underground radar device described in the paragraph.   The underground according to any one of claims 1 to 3, wherein in the creation of the compensation filter, a proper determination based on a side lobe attenuation envelope is made on a correlation signal waveform which is a reference waveform for the reference signal. Radar equipment.   A mode switching unit configured to switch between a filter creation mode in which the reference propagation path is configured to acquire the reference signal, and the compensation filter is generated based on the acquired reference signal, and a normal operation mode in which normal transmission and reception operations are performed The underground radar apparatus as described in any one of Claims 1-5.   The underground radar apparatus according to any one of claims 1 to 6, wherein the compensation filter is capable of selecting one of a plurality of filters.   The ground radar apparatus according to any one of claims 1 to 7, wherein the signal processing unit removes side lobes or ringing generated based on the characteristics of each part of the apparatus by the compensation filter.   The underground radar apparatus according to any one of claims 1 to 8, wherein the transmission signal from the transmission unit is a chirp signal. A reception signal received by the reception unit, including a transmission unit for transmitting a transmission signal for search, a reception unit for receiving the reception signal, and a compensation filter for compensating for the actual reception signal received by the reception unit A signal processing unit for performing signal processing for detection of a buried object based on a reference signal, and
A method of manufacturing an underground radar device, wherein the compensation filter is created based on the signal characteristics of a reference signal that has passed through a reference propagation path.

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