KR20220164277A - Groundwater level measurement system using Distribution type Time Domain Reflectometry device - Google Patents

Abstract

Provided is a groundwater level measurement system, which comprises: a plurality of distribution-type time domain reflectometry (TDR) measuring devices, each of which diagnoses an allocated underground area; a management server which creates a 3D graphical representation of the areas monitored by the plurality of distribution-type TDR measuring devices, and calculates and manages a change in groundwater levels based on measurement data transmitted from the plurality of distribution-type TDR measuring devices and the positional information of the plurality of distribution-type TDR measuring devices; and a user terminal which receives diagnostic information of groundwater levels from the management server and displays the information in a 3D graphical format as a map. Therefore, the groundwater level measurement system provides convenience in inspection and management.

Description

Groundwater level measurement system using Distribution type Time Domain Reflectometry device}

The present invention relates to a measuring device, and more particularly, to a groundwater level measuring system using a distributed TDR measuring device.

Until now, the groundwater level gauge applied to civil structures is a probe-type sensor, and such a sensor measures the groundwater level by directly penetrating the measuring hole. Excessive measuring holes are constructed according to the importance of the measurement, and as a result, there is a disadvantage in that excessive manpower and cost are consumed, and the need for improvement measures through smart inspection technology is emerging.

In addition, the conventional groundwater level measurement method is a method in which an inspector measures the groundwater level by reading the length indicated on the lead wire with a beep sound generated when the sensor contacts water. There are some serious downsides to this.

1 is an exemplary diagram of a branch type TDR sensor.

In order to prevent levee collapse due to infiltration or leakage, it is most important to understand the unsaturation and behavior of the embankment body. However, there are limitations to the drilling presented in the river design standard, the point-type measuring instrument, and the physical survey method presented in Figure 1, and numerical analysis Even if the technique is applied, it is difficult to accurately analyze it due to the initial conditions of the actual embankment and the problems of inhomogeneity and anisotropy.

Methods such as electrical resistivity survey, natural potential method, and GPR survey are proposed as physical survey methods for infiltration behavior, but accurate detection of infiltration behavior is difficult due to the occurrence of errors such as uncertainty, period, refraction, etc. due to ground conditions or structural characteristics. pointed out as difficult.

In order to compensate for the disadvantages of these point-type sensors, research on a distributed Time Domain Reflectometry (TDR) sensor is being actively conducted.

KR 10-2013-0137420 A

The present invention has been proposed to solve the above technical problem, and groundwater level measurement capable of providing groundwater diagnosis information by 3D graphics of the underground space in charge of a plurality of distributed TDR (Time Domain Reflectometry) measuring devices provide the system.

According to an embodiment of the present invention for solving the above problem, a plurality of distributed Time Domain Reflectometry (TDR) measurement devices for diagnosing the underground space of each assigned area, and a plurality of distributed Time Domain Reflectometry (TDR) measurements The area covered by the device is made into a 3D graphic, but the underground water is based on the measurement data transmitted from the plurality of distributed Time Domain Reflectometry (TDR) measurement devices and the location information of the plurality of distributed Time Domain Reflectometry (TDR) measurement devices. There is provided a groundwater level measurement system including a management server that calculates and manages changes in water level, and a user terminal that receives diagnostic information on groundwater level from the management server and maps and displays it in a 3D graphic form.

In addition, a plurality of distributed time domain reflectometry (TDR) measurement devices included in the present invention each transmit a pulse signal to a TDR measurement line and receive a reflected pulse signal reflected through the TDR measurement line. A reference clock signal generation unit for generating a signal, a clock signal distribution unit for generating the pulse signal to be transmitted to the TDR measurement line using the reference clock signal, and a sampling pulse signal having a higher frequency than the reference clock signal It is characterized in that it includes a sampling pulse signal generator and a reflection signal sampling unit for sampling a reflected pulse signal reflected through the TDR measurement line in response to the sampling pulse signal.

In addition, the reflected signal sampling unit included in the present invention is characterized in that the reflected pulse signal is sampled in response to a differential signal corresponding to the sampling pulse signal.

In addition, the reflected signal sampling unit included in the present invention includes a sampling signal coupled matching unit that receives the sampling pulse signal and outputs a first output signal and a second output signal in a differential form corresponding to the sampling pulse signal, and the first output signal. and a sampler circuit for sampling the reflected pulse signal in response to the second output signal.

The groundwater level measurement system according to an embodiment of the present invention can provide convenience of inspection management by providing groundwater diagnosis information by 3D graphics of the underground space in charge of a plurality of distributed time domain reflectometry (TDR) measuring devices. there is.

1 is an exemplary diagram of a branch type TDR sensor;
2 is a block diagram of a groundwater level measurement system 10
3 is another block diagram of the groundwater level measuring system 10
4 is a first exemplary view of a monitoring screen provided by the groundwater level measuring system 10
4A is a second exemplary view of a monitoring screen provided by the groundwater level measuring system 10
4B is a third exemplary view of a monitoring screen provided by the groundwater level measurement system 10
4C is a fourth example of a monitoring screen provided by the groundwater level measuring system 10.
5 is a conceptual diagram of a distributed time domain reflectometry (TDR) sensor;
6 is a diagram showing the principle of a distributed time domain reflectometry (TDR) sensor;
7 is a block diagram of a distributed Time Domain Reflectometry (TDR) measuring device 1 according to an embodiment of the present invention.
8 is a circuit diagram of a Time Domain Reflectometry (TDR) measuring device 1 according to the first embodiment.
8a is a circuit diagram according to a second embodiment of a TDR (Time Domain Reflectometry) measuring device 1
9 is a block diagram of a distributed time domain reflectometry (TDR) measuring device 2 according to another embodiment of the present invention.
10 is an exemplary operation diagram of the sampling pulse signal generator 300A of FIG. 9
11 is a diagram showing a pulse signal and a reflected pulse signal output from the TDR measuring devices 1 and 2;

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings in order to describe in detail enough for those skilled in the art to easily implement the technical idea of the present invention.

2 is a block diagram of the groundwater level measurement system 10, FIG. 3 is another block diagram of the groundwater level measurement system 10, and FIG. 4 is a first example of a monitoring screen provided by the groundwater level measurement system 10. FIG. 4A is a second example of a monitoring screen provided by the groundwater level measurement system 10, FIG. 4B is a third example of a monitoring screen provided by the groundwater level measurement system 10, and FIG. 4C is a diagram. It is a fourth example of a monitoring screen provided by the groundwater level measurement system 10 .

2 to 4, the groundwater level measurement system 10 includes a plurality of distributed time domain reflectometry (TDR) measuring devices 1-1, 1-2, 1-3, and 1-4, and a management server. (2) and a user terminal (3).

The proposed groundwater level measurement system is a system that remotely controls groundwater level measuring devices installed in various areas including river embankments, and measures and collects temperature, humidity, wind volume, and rainfall from environmental sensors attached to the groundwater level measuring devices. is defined

This system is equipped with login and member sign-up functions to allow access only to authorized users, and allows sign-up through authentication through the mobile phone number of the member who wants to sign up. (Identity verification function)

A plurality of vertically buried distributed TDR (Time Domain Reflectometry) measuring devices (1-1, 1-2, 1-3, 1-4) diagnose the distribution of groundwater in each allocated underground space, and each TDR (Time Domain Reflectometry) It is assumed that the domain reflectometry (TDR) measurement device is configured with the TDR (Time Domain Reflectometry) measurement device of FIGS. 5 to 11 to be described later.

The management server 2 3D graphics the underground space in charge of a plurality of distribution type TDR (Time Domain Reflectometry) measuring devices (1-1, 1-2, 1-3, 1-4), Measurement data transmitted from type TDR (Time Domain Reflectometry) measuring devices (1-1, 1-2, 1-3, 1-4) and multiple distributed TDR (Time Domain Reflectometry) measuring devices (1-1, 1 -2, 1-3, 1-4) Calculate the location that needs inspection based on each satellite location information.

The user terminal 3 receives groundwater information of the underground space from the management server 2 and maps it in a 3D graphic form and displays it. In this embodiment, a user terminal is a generic term for a device that a user can carry and use, such as a mobile phone, a smart phone, a smart pad, and the like, and a work computer.

That is, since the user terminal 3 pre-registered in the management server 2 maps and displays the groundwater diagnosis information of the underground space provided from the management server 2 in a 3D graphic form, the field inspector can view the groundwater level etc. You can proceed with the inspection while conveniently grasping.

In addition, if the wireless communication device is linked to the TDR measuring device, information is obtained from the communication base station, the location is displayed, and the distance of the abnormal part can be accurately grasped with the sensor line connected from the TDR measuring device, so that the manager can know the actual location of the problem. can tell you That is, the location information of the TDR measurement device is determined by a method in which the server knows the satellite location information of the TDR measurement device in advance, a method in which the TDR measurement device transmits the satellite location information, and a method in which the TDR measurement device transmits signals from a communication device to multiple base stations. The method of checking and understanding in , etc. may be applied.

In addition, as shown in FIG. 3, the measurement device may use only USB communication, only a wireless communication device, or both depending on the user's intention. In addition, by configuring a measuring device and a wireless communication device as one set, a plurality of devices can be managed by a remote management server.

In addition, since the measuring device has an ID selection function, multiple devices can be connected in parallel through RS485 communication and managed by communicating with the management server through one wireless communication device.

Referring to FIGS. 4 to 4C , the groundwater level measuring system 10 manages the address and location where the groundwater measuring device is installed to show the installed location and grasp the current state, and can easily determine the installation location when registering the device. can be specified.

In addition, operation history and error occurrence status of the installed groundwater measuring device may be left as a log to check operation and error occurrence.

In addition, it provides a function to check the latest sensor information of the installed groundwater measuring device and control it on the web screen, and provides a screen optimized for PC environment and mobile environment such as mobile phone as a responsive website.

5 is a conceptual diagram of a distributed time domain reflectometry (TDR) sensor, and FIG. 6 is a diagram showing the principle of a distributed time domain reflectometry (TDR) sensor.

Referring to FIGS. 5 and 6, TDR (Time Domain Reflectometry) is a radar principle that emits electromagnetic waves or electrical signals and measures the location and type of the cause of reflection using a waveform reflected by an object. It is a skill.

It is a method of analyzing the time domain response of the system, and the state of the system (underground well) can be analyzed by applying a pulse or step signal to the system to be measured (TDR measurement line) and measuring the reflected signal. there is.

Time Domain Reflectometry (TDR) and Time Domain Transmission (TDT) are time domain analyzers that analyze the response of how a pulse signal propagates through an interconnect. That is, the time domain reflectometry measurement applies a measurement principle for evaluating frequency-dependent electrical and dielectric properties of various materials and materials.

A portable and miniaturized distributed time domain reflectometry (TDR) measuring device capable of sampling a repetitive square wave used as an output pulse signal and an underground facility diagnostic visualization system using the same will be described.

7 is a block diagram of a distributed Time Domain Reflectometry (TDR) measuring device 1 according to an embodiment of the present invention.

The TDR (Time Domain Reflectometry) measuring device 1 according to the present embodiment includes only a simple configuration for clearly explaining the technical idea to be proposed.

Referring to FIG. 7 , the TDR (Time Domain Reflectometry) measuring device 1 includes a reference clock signal generator 100, a clock signal distributor 200, a sampling pulse signal generator 300, and a reflection signal sampling unit 400. ), a logic controller 500, a line driver 600, an amplification unit 700, and an analog-to-digital converter 800.

The TDR (Time Domain Reflectometry) measuring device 1 transmits a pulse signal to the TDR measuring line and receives the reflected pulse signal reflected through the TDR measuring line to detect an abnormality (groundwater level) in the well. to be. The TDR measurement line can be directly installed in the soil to detect groundwater level and changes in soil quality (moisture content), and can also be placed along pipelines or underground facilities that transport fluids.

The TDR (Time Domain Reflectometry) measuring device 1 may be composed of 4 channels suitable for inspection. The number of channels may be configured to be expandable from at least one to more.

That is, one or more channels are connected to one TDR (Time Domain Reflectometry) measuring device 1, and as an embodiment of the present invention, it is configured to connect 4-channel TDR sensing lines (TDR measurement lines), and is configured to connect a BNC connector and a coaxial cable. combine as

Summarizing the function and configuration of the proposed TDR (Time Domain Reflectometry) measuring device (1), the TDR (Time Domain Reflectometry) measuring device (1) is a vertical pipe that transports fluid, the temperature and leakage (water content ratio) of the well ) It is defined as a sensing system for detecting change, and is configured to measure at least one or more channels, preferably 4 channels of sensing lines (TDR measurement lines).

That is, when a fluid leak or a change in groundwater level occurs, the magnitude of the reflected pulse signal changes due to the change in permittivity around the TDR measurement line. You can determine what happened.

The TDR (Time Domain Reflectometry) measuring device 1 can measure the water content (%) within 200m (up to 1km) with a distance resolution of 6.7cm, and measures the temperature (℃) using an additionally provided temperature sensing line. can be measured

In addition, the TDR (Time Domain Reflectometry) measuring device 1 has a 485 communication port for communication with the management server, RS232 to USB communication is possible, and the measured result is displayed on a PC (or smartphone) viewer program (serial plotter) It is configured so that it can be displayed as

In addition, the Time Domain Reflectometry (TDR) measuring device 1 may use an SD card (memory card) so that a manager can directly receive data.

The output waveform of the pulse signal output from the TDR (Time Domain Reflectometry) measuring device 1 is based on a 25KHz rectangular pulse (2ns rise time) with a duty ratio of 50%, and the signal is repetitively measured using an A/D converter. By capturing the waveform of , defects within 200m (up to 1km) can be measured with a resolution of 10cm. (Detection distance and resolution change depending on the wavelength and frequency of the pulse used)

The effective clock cycle of the clock of the TDR measuring device according to the embodiment is 250 MHz (4 ns) and the phase angle (0, 60, 120, 180, 240, 300) magnification ratio is up to k = 6, and the effective sampling frequency is 1.5 GHz, At this time, the temporal resolution is 4ns/6=0.67ns, and the distance resolution is 6.7cm. A 0.67ns time resolution is maintained in the system so that the rising edge can be traced with a rise time of approximately 2ns while the amplitude resolution remains at 10-bit level.

The TDR (Time Domain Reflectometry) measuring device 1 changes the boundary layer with an accuracy of ±10 cm and can monitor the positional change of the boundary layer with a resolution of approximately 6.7 cm. In particular, when measuring a coaxial cable with 67% of the speed of light, measuring the location of a defect with a resolution of 10 cm requires 1 ns time. The time resolution is 1 ns. In addition, in the case of a 200 m transmission line, the travel time (T_travel) in one direction is about 1,000 ns. The theoretical limit of the measurement signal (50% square wave) frequency should be 1/4T_travel = 1/4000ns (250KHz) or more, and the period of the measurement signal should be larger than 4 times the signal travel time in one direction (line) of the signal. . In this embodiment, it is 8 times the signal travel time in one direction.

In addition, 25 KHz is selected as the basic repetition frequency of the TDR signal (pulse signal) as a compromise between acquisition time, time resolution and transmission line length. The "loop time" in the circuit totals 4000ns, and the maximum trigger signal frequency can be limited to 1/4000ns = 25KHz. At this time, with a basic frequency of 25 KHz, it can be designed with a time resolution of 0.67 ns and a distance resolution of 6.7 cm as a compromise between the amplitude resolution and the required acquisition time. The sampling period of the analog-to-digital converter (A/D) is 4,000 ns and coincides with the period of the output (step wave pulse signal). For reference, the fundamental frequency Hz and the shape and duty ratio of the output waveform of the pulse signal may be set in various ways according to embodiments.

That is, after sampling the reflected pulse signal in synchronization with 1.5 GHz in the internal circuit of the TDR (Time Domain Reflectometry) measuring device 1, the signal is output through an analog-to-digital converter (A/D). At this time, the analog-to-digital converter ( A/D) samples the signal in response to an internal signal equal to the period of the TDR signal (pulse signal) and then outputs an output signal.

That is, the analog-to-digital converter (A/D) samples and outputs the sequentially received reflected pulse signal once in response to an internal signal equal to the period of the TDR signal (pulse signal) during one pulsing period, and then outputs the internal signal sequentially. While delaying by , the reflected pulse signal received next time is sampled again during one pulsing section and output.

That is, when the first reflected pulse signal and the second reflected pulse signal are sequentially received, the analog-to-digital converter (A/D) samples and outputs the first reflected pulse signal once during the pulsing period, and then outputs the second reflected pulse signal During the pulsing section of , it is sampled and output again. At this time, the sampling timing of the second reflected pulse signal is delayed by a predetermined time compared to that of the first reflected pulse signal. In this embodiment, the analog-to-digital converter (A/D) samples and outputs 1000 reflected pulse signals sequentially received, combines them, and displays them as an inspection result signal.

The detailed configuration and main operation of the TDR (Time Domain Reflectometry) measuring device 1 proposed above are as follows.

The reference clock signal generator 100 generates a 250 MHz reference clock signal by doubling the 125 MHz external clock signal.

The clock signal distribution unit 200 distributes the 250 MHz reference clock signal at a predetermined ratio to generate a 25 KHz pulse signal for transmission to the TDR measurement line. A pulse signal of 25 KHz is transmitted to the TDR measurement line through the line driver 600.

The sampling pulse signal generating unit 300 generates a sampling pulse signal SYNC having a higher frequency than the reference clock signal by dividing the 250 MHz reference clock signal into a plurality of phases.

In this embodiment, the sampling pulse signal generator 300 receives a 250 MHz reference clock signal based on phases of 0 degree, 60 degree, 120 degree, 180 degree, 240 degree, and 300 degree, respectively, and receives a 1.5 GHz sampling pulse. output a signal

The reflected signal sampling unit 400 samples the transmitted reflected pulse signal reflected through the TDR measurement line in response to the 1.5 GHz sampling pulse signal.

The signal sampled and output from the reflected signal sampling unit 400 is transmitted to the logic controller 500 through the amplifier 700 and the analog-to-digital converter 800.

The logic control unit 500 processes the signal output from the analog-to-digital converter 800 and transfers it to the management server or to the user terminal, and controls to display the measured result when a liquid crystal display is provided.

8 is a circuit diagram of a Time Domain Reflectometry (TDR) measuring device 1 according to the first embodiment, and FIG. 8A is a circuit diagram of a Time Domain Reflectometry (TDR) measuring device 1 according to the second embodiment.

Referring to FIGS. 7, 8 and 8A simultaneously, the clock signal distribution unit 200 distributes the 250 MHz reference clock signal at a predetermined ratio to generate a 25 KHz pulse signal (T_PULSE) for transmission to the TDR measurement line, , The line driver 600 is composed of a circuit for driving a pulse signal (T_PULSE) of 25 KHz to the TDR measurement line.

The reflection signal sampling unit 400 samples the reflection pulse signal R_PULSE in response to differential signals R_DIFF and F_DIFF corresponding to the sampling pulse signal SYNC.

That is, the reflected signal sampling unit 400 is synchronized with the rising section of the first differential signal R_DIFF corresponding to the sampling pulse signal SYNC and the falling section of the second differential signal F_DIFF, and is reflected from the TDR measurement line. After sampling the transmitted reflected pulse signal (R_PULSE), the sampling output signal (R_SYNC) is output.

The reflected signal sampling unit 400 includes a sampling signal coupled matcher 410 and a sampler circuit 420.

The sampling signal coupled matcher 410 receives the sampling pulse signal SYNC, and receives a first differential output signal (first differential signal R_DIFF) corresponding to the sampling pulse signal SYNC and a second output signal ( A second differential signal (F_DIFF)) is output. Since the sampling signal coupled matching device 410 of FIG. 8 and the sampling signal coupled matching device 410A of FIG. 8A perform the same function, hereinafter, a circuit diagram according to the first embodiment of FIG. 8 will be mainly described.

The sampler circuit 420 samples the reflected pulse signal R_PULSE in response to the first output signal (first differential signal R_DIFF) and the second output signal (second differential signal F_DIFF) to sample the sampling output signal R_SYNC. ) as output.

For reference, a rising period of the first output signal (first differential signal R_DIFF) output from the sampling signal coupled matcher 410 and a falling period of the second output signal (second differential signal F_DIFF) Since precise matching is achieved, reliability of operation of the sampler circuit 420 is secured.

In this embodiment, the sampler circuit 420 includes a first resistor R57 connected between the first differential signal R_DIFF input node and the ground voltage terminal VSS, the second differential signal F_DIFF input node and the ground voltage terminal A second resistor R72 connected between (VSS), a first diode whose anode is connected to the first differential signal (R_DIFF) input node and whose cathode is connected to the sampling output signal (R_SYNC) output node (D1), the anode (Anode) is connected to the first differential signal (R_DIFF) input node and the cathode (Cathode) is connected to the reflected pulse signal (R_PULSE) input node of the second diode (D2), the anode (Anode) is sampling A third diode D3 connected to the output node of the output signal R_SYNC, the cathode connected to the input node of the second differential signal F_DIFF, and the anode connected to the input node of the reflected pulse signal R_PULSE. and a fourth diode (D4) whose cathode is connected to the input node of the second differential signal (F_DIFF), and a capacitor (C95) connected between the output node of the sampling output signal (R_SYNC) and the ground voltage terminal (VSS). do.

The sampling output signal (R_SYNC) sampled and output from the reflected signal sampling unit 400 is transferred to the logic controller 500 through the amplifier 700 and the analog-to-digital converter 800.

The analog-to-digital converter 800 samples the sampling output signal R_SYNC in response to an internal signal equal to the cycle of the TDR signal (pulse signal T_PULSE) and then outputs an output signal.

That is, the analog-to-digital converter (A/D) samples and outputs the sequentially received sampling output signal (R_SYNC) once in response to an internal signal equal to the period of the TDR signal (pulse signal (T_PULSE)) during one pulsing period. Then, while sequentially delaying the internal signal, the sampling output signal (R_SYNC) received next is sampled again during one pulsing period and output.

That is, when the first sampling output signal R_SYNC and the second sampling output signal R_SYNC are sequentially received, the analog-to-digital converter 800 samples and outputs the first sampling output signal R_SYNC once during the pulsing period. After that, it is sampled and outputted once again during the pulsing period of the second sampling output signal R_SYNC. At this time, the sampling timing of the second sampling output signal R_SYNC is delayed by a predetermined time compared to that of the first sampling output signal R_SYNC. In this embodiment, the analog-to-digital converter 800 samples and outputs 1000 sequentially received sampling output signals R_SYNC, and the logic control unit 500 analyzes the waveform based on this to detect water leakage (abnormality) and water leakage location. Determine

FIG. 9 is a block diagram of a distributed time domain reflectometry (TDR) measuring device 2 according to another embodiment of the present invention, and FIG. 10 is an exemplary operation diagram of the sampling pulse signal generator 300A of FIG. 9 .

The TDR (Time Domain Reflectometry) measuring device 2 according to another embodiment has the same basic operation as the TDR (Time Domain Reflectometry) measuring device 1 according to one embodiment, and the sampling pulse signal generator 300A The detailed configuration was composed using an analog circuit. Therefore, descriptions of overlapping functions are omitted.

9 and 10, the TDR (Time Domain Reflectometry) measuring device 2 includes a reference clock signal generator 100, a clock signal distributor 200, a sampling pulse signal generator 300A, and a reflection signal sampling unit. It is composed of a unit 400, a logic controller 500, a line driver 600, an amplification unit 700, and an analog-to-digital converter 800.

The TDR (Time Domain Reflectometry) measuring device 2 is an inspection device capable of detecting a water level change in a well by transmitting a pulse signal to a TDR measuring line and receiving a reflected pulse signal reflected through the TDR measuring line. The TDR measurement line can be directly installed in the soil to detect groundwater level and changes in soil quality (moisture content), and can also be placed along a vertical pipe or underground facility that transports fluid.

As shown in FIG. 10, the sampling pulse signal generator 300A includes a programmable delay generator, and when the input signal goes from a low level (LOW) to a high level (HIGH), the output voltage U _C is the supply voltage approximates exponentially to A digital-to-analog converter (DAC) is used to set the comparator level, so the output signal is delayed according to this level.

That is, the sampling pulse signal generating unit 300A may generate a sampling pulse signal SYNC having a higher frequency than the reference clock signal by delaying the 250 MHz reference clock signal.

11 is a diagram showing a pulse signal and a reflected pulse signal output from the TDR measurement device 1.

Referring to FIG. 11, when a leak of fluid or a change in groundwater level occurs, the size of the reflected pulse signal R_PULSE changes due to the change in permittivity around the TDR measurement line, so the waveform change of the reflected pulse signal R_PULSE and By analyzing the time, it is possible to determine at what point the anomaly occurred.

The groundwater level measurement system according to an embodiment of the present invention can provide convenience of inspection management by providing groundwater diagnosis information by 3D graphics of the underground space in charge of a plurality of distributed time domain reflectometry (TDR) measuring devices. there is.

As such, those skilled in the art to which the present invention pertains will be able to understand that the present invention may be embodied in other specific forms without changing its technical spirit or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The scope of the present invention is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

100: reference clock signal generator
200: clock signal distribution unit
300, 300A: sampling pulse signal generator
400: reflection signal sampling unit
500: logic control unit
600: line driver
700: amplification unit
800: analog-to-digital converter

Claims (4)

A plurality of distributed TDR (Time Domain Reflectometry) measuring devices for diagnosing the underground space of each allocated area;
The area covered by the plurality of distributed Time Domain Reflectometry (TDR) measurement devices is 3D graphicized, and the measurement data transmitted from the plurality of distributed Time Domain Reflectometry (TDR) measurement devices and the plurality of distributed TDRs ( Time Domain Reflectometry) A management server that calculates and manages each change in groundwater level based on the location information of the measuring device; and
a user terminal receiving diagnosis information on the groundwater level from the management server and displaying the map in a 3D graphic form;
Groundwater level measurement system comprising a.
According to claim 1,
Each of the plurality of distributed time domain reflectometry (TDR) measurement devices,
In transmitting a pulse signal to a TDR measurement line and receiving a reflected pulse signal reflected through the TDR measurement line,
a reference clock signal generator for generating a reference clock signal;
a clock signal distribution unit generating the pulse signal to be transmitted to the TDR measurement line using the reference clock signal;
a sampling pulse signal generating unit generating a sampling pulse signal having a higher frequency than the reference clock signal; and
and a reflection signal sampling unit for sampling a reflection pulse signal reflected through the TDR measurement line in response to the sampling pulse signal.
According to claim 2,
The reflected signal sampling unit,
The groundwater level measurement system, characterized in that for sampling the reflected pulse signal in response to the differential signal corresponding to the sampling pulse signal.
According to claim 2,
The reflected signal sampling unit,
a sampling signal coupled matching unit that receives the sampling pulse signal and outputs a first output signal and a second output signal of a differential type corresponding to the sampling pulse signal; and
and a sampler circuit for sampling the reflected pulse signal in response to the first output signal and the second output signal.

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