WO2012023668A1

WO2012023668A1 - Device and method for measuring vertical velocity distribution of river

Info

Publication number: WO2012023668A1
Application number: PCT/KR2010/008742
Authority: WO
Inventors: 김원; 이찬주; 김동구; 권성일
Original assignee: 한국건설기술연구원
Priority date: 2010-08-20
Filing date: 2010-12-08
Publication date: 2012-02-23
Also published as: KR101080711B1

Abstract

Disclosed are a device and a method for measuring a vertical velocity distribution of a river. The device for measuring a vertical velocity distribution of a river, in which velocity distributions at each water level in the river are measured by using single and multiple pulse repetition frequencies of ultrasonic waves, comprises a water depth measurement unit, a maximum velocity value calculation unit, an SPRF mode execution unit, a measurement mode conversion unit, and an MPRF mode execution unit. The water depth measurement unit measures the vertical depth of water in the river. The maximum velocity value calculation unit: calculates a maximum measurement distance, which is the distance of an ultrasonic signal until it reaches the surface of the water, wherein the ultrasonic signal is transmitted in a direction inclined as much as the preset angle from the direction in which the vertical depth is measured, and pulse repetition frequency (PRF) which is obtained using the measured water depth data; and calculates a maximum velocity value corresponding to said water depth data by using the pulse repetition frequency (PRF). The SPRF mode execution unit measures vertical velocity distributions of the river by using a single ultrasonic pulse signal to which the pulse repetition frequency (PRF) is applied, and sets the fastest velocity to a representative value of velocity. Further, the measurement mode conversion unit compares the maximum velocity value with the representative value of the velocity, does not convert a measurement mode if the maximum velocity value is larger than the representative value of the velocity, and converts into an MPRF mode if the maximum velocity value is smaller. When the mode is converted into the MPRF mode, the MPRF mode execution unit measures vertical velocity distributions of the river by using a plurality of ultrasonic pulse signals, to which a plurality of preset pulse repetition frequencies (PRFs) measurable up to the deepest level of the river are applied. Thus, the invention accurately measures the vertical velocity distributions of natural rivers and shortens the measurement time, since based on the maximum measurement distance and a maximum measurement velocity relative to the measured water depth: the velocity is obtained by a Doppler signal analysis method using a single pulse repetition frequency if the velocity is slower than said standard; and the velocity is obtained by a Doppler signal analysis method using multiple pulse repetition frequencies if the velocity is faster than said standard.

Description

River Vertical Flow Rate Measurement Apparatus and Method

The present invention relates to an apparatus and method for measuring a vertical flow velocity distribution in a stream, and more particularly, to an apparatus and a method for measuring a flow velocity distribution for each depth in a stream using single and multiple pulse repetition frequencies of ultrasonic waves.

At present, ultrasonic flowmeters for measuring vertical flow rate distributions have been developed and marketed in foreign countries, and each of them uses various methods in converting ultrasonic signals to flow rates.

One of them is a Doppler signal using a pulse repetition frequency, which is used in medical devices as a method of measuring blood flow velocity of a human body, and is used in areas such as measuring a relative speed of an airplane in flight using a radar ( Ultrasonic Doppler and Radar Doppler).

However, in the case of Doppler signal analysis using a single pulse repetition frequency, a case of measuring the velocity of the fluid in the laboratory has been reported, but there have been few reports of the measurement of the velocity in actual rivers.

In addition, even if the actual flow velocity of the river is measured by using the Doppler signal analysis method using a single pulse repetition frequency, there is a problem that it is difficult to accurately measure the flow velocity when the flow velocity is fast because of the depth of the river.

In addition, since the ultrasonic wave is inclined at the time of manufacturing the ultrasonic flowmeter using the pulse repetition frequency, it will be common to generate the ultrasonic transceiver part inclined in the ultrasonic flowmeter.

The ultrasonic tachometer as described above may be implemented as shown in FIG. 1, and FIG. 1 is a diagram illustrating an ultrasonic tachometer in which the ultrasonic transceiver is inclined.

However, when the ultrasonic flowmeter as shown in Figure 1 is buried in the bottom of the river, the ultrasonic transceiver is covered by the soil on the floor, there is a problem that it is difficult to accurately transmit and receive the ultrasonic wave.

In addition, when the ultrasonic tachometer is installed on the bottom surface of the river to prevent the ultrasonic transceiver unit from being covered, there is a problem that the ultrasonic tachometer may be damaged by the float moving in the river.

The present invention has been made to solve such a conventional problem, and aims to measure the vertical flow rate distribution of natural streams using a Doppler signal analysis method using a single or multiple pulse repetition frequency.

Stream vertical flow rate measurement apparatus according to the present invention for solving the above problems includes a depth measurement unit, a maximum flow rate value calculation unit, an SPRF mode execution unit, a measurement mode switching unit, and an MPRF mode execution unit.

The depth measuring unit measures the vertical depth of the river, and the maximum flow rate value calculating unit measures the maximum measurement distance, which is the distance from the direction in which the vertical depth is measured to the surface of the ultrasonic signal transmitted in the inclined direction by a predetermined angle. The pulse repetition frequency (PRF) is calculated using the obtained depth data, and the maximum repetition velocity value corresponding to the depth data is calculated using the pulse repetition frequency (PRF), and the SPRF mode execution unit performs the pulse repetition frequency (PRF). Using a single ultrasonic pulse signal to which is applied, the vertical flow velocity distribution of the stream is measured, and the fastest flow velocity is set as a representative value of the flow velocity.

In addition, the measurement mode switching unit compares the maximum flow rate value with the representative value of the flow rate. If the maximum flow rate value is larger than the representative value of the flow rate, the measurement mode switching unit does not change the measurement mode. When switching to the MPRF mode, the vertical flow velocity distribution of the stream is measured by using a plurality of ultrasonic pulse signals to which a plurality of preset pulse repetition frequencies (PRFs) that can be measured up to the maximum depth of the stream are applied.

For this reason, based on the maximum measurement distance and the maximum measurement speed for the measurement depth, the flow rate is calculated using the Doppler signal analysis method using a single pulse repetition frequency when it is lower than the reference value, and when using the multi-pulse repetition frequency when the reference value is higher than the reference Since the flow velocity is obtained by the Doppler signal analysis method, the vertical flow velocity distribution of the natural river can be accurately measured and the measurement time can be shortened.

In addition, the SPRF mode execution unit measures the vertical flow rate distribution of the plurality of streams for a preset time, averages the measured plurality of vertical flow rate distributions at a preset time, and sets the fastest average flow rate as the representative value of the flow rate. have.

Also, the MPRF mode execution unit transmits a plurality of pulse signals for each pulse repetition frequency (PRF), receives a plurality of scattered pulse signals, extracts scattered signals at a depth corresponding to the depth data, and extracts the extracted signals. An aliased Doppler signal can be extracted from the stream to determine the vertical velocity distribution of the stream.

In addition, the MPRF mode executing unit may measure the vertical velocity distribution of the stream by applying the 'Chinese residual theorem' to a plurality of aliased Doppler frequencies.

By applying the 'Chinese remainder theorem', the correct Doppler frequency can be calculated from the aliased Doppler frequency, thereby measuring the correct flow rate.

In addition, the stream vertical flow rate distribution measuring apparatus according to the present invention is implemented in a predetermined form so as to secure a path through which ultrasonic waves are transmitted and received, and to flatten the upper surface of the stream soft flow rate measurement apparatus, so as not to affect the ultrasonic transmission and reception The apparatus may further include an ultrasonic path providing unit formed of a material.

In addition, an invention embodying the apparatus in the form of a method is disclosed.

According to the present invention, when the flow rate of the water depth to which the user wants to measure the flow rate in the stream is slow, the flow rate can be measured in the SPRF mode, and the flow rate can be measured in the MPRF mode when the flow rate is fast. The vertical flow rate distribution of natural streams can be measured, and the SPRF mode and the MPRF mode can be executed with one device, thereby reducing the measurement time.

1 is a view showing an ultrasonic flowmeter in which the ultrasonic transceiver is obliquely generated.

Figure 2 is a block diagram schematically showing an embodiment of the configuration of the stream vertical flow rate measurement apparatus according to the present invention.

Figure 3 is a view showing an embodiment for measuring the vertical flow rate distribution in the river using the stream vertical flow rate measurement apparatus.

4 is a graph showing the limits of the measurement depth and velocity according to the pulse repetition frequency (PRF) calculated using Equation 1 and Equation 2 when the measurement line of the ultrasonic signal forms an angle of 45 ° with the vertical direction. drawing.

5 is a diagram illustrating a process of measuring a vertical flow rate distribution using a pulse repetition frequency (PRF) in the SPRF mode execution unit.

6 is a circuit diagram showing each configuration of a stream vertical flow rate distribution measuring apparatus.

7 is a side view of a stream vertical flow rate measurement apparatus embedded in the river bottom.

8 is a perspective view of a stream vertical flow rate measurement apparatus embedded in the river bottom.

FIG. 9 is a flowchart schematically illustrating an embodiment of a method for measuring vertical flow rate distribution using the apparatus for measuring the vertical flow rate distribution in FIG. 2.

10 is a flow chart showing in detail the steps of measuring the vertical flow rate distribution and setting representative values of the flow rate in the SPRF mode.

11 shows the flow rate vertical distribution in MPRF mode. Flow chart detailing the steps for measuring.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In order to more clearly understand the present invention, the same reference numerals are used for the same components in different drawings.

Figure 2 is a view showing an embodiment for measuring the vertical flow rate distribution in the river using the stream vertical flow rate measurement apparatus 100 according to the present invention.

The vertical flow rate distribution measuring apparatus 100 is installed at the bottom of the river, and measures the vertical flow rate distribution of the stream at the point where the vertical flow rate distribution measuring apparatus 100 is installed.

The vertical flow rate distribution means a flow rate according to the depths of the water from the vicinity where the vertical flow rate distribution measuring apparatus 100 is installed to the vicinity of the surface of the water, and the vertical flow rate distribution measuring apparatus 100 of the present invention, as shown in FIG. Depth can be measured for each depth layer of 1 cm or less.

In this case, the vertical flow rate distribution measuring apparatus 100 transmits / receives ultrasonic waves obliquely in a direction opposite to the flow (main flow) flowing from the upstream to the downstream of the stream, as shown in FIG. It can be measured.

3 is a block diagram schematically showing an embodiment of the configuration of the device 100 for measuring the vertical flow velocity distribution of the stream of FIG. 2.

The stream vertical flow rate distribution measuring apparatus 100 for measuring the flow rate distribution for each depth in the river using single and multiple ultrasonic pulse repetition frequencies is executed by the depth measuring unit 110, the maximum flow rate value calculating unit 120, and the SPRF mode. The unit 130, the ultrasonic transceiver 140, the measurement mode switching unit 150, MPRF mode execution unit 160, and the flow rate data storage unit 170.

The depth measuring unit 110 generally measures the vertical depth of the river by measuring the vertical distance from the measuring device 100 to the water surface using a depth sensor used for measuring the depth of the fluid.

Hereinafter, the vertical depth value of the measured stream is referred to as depth data, and the depth data may include a depth measurement time.

The maximum flow rate value calculation unit 120 converts the depth data measured by the depth measurement unit 110 to the maximum measurement distance by reflecting the angle between the vertical direction and the measurement line in FIG. 2 (a). For example, if the measured depth is 1m and the angle between the vertical direction and the measurement line is 45 °, the maximum measurement distance may be 1m × (1 / cos 45 °), which may be 1.414m.

The maximum flow rate value calculator 120 calculates the pulse repetition frequency PRF by substituting the calculated maximum measurement distance into the maximum measurement distance Rmax of Equation 1, and calculates the calculated pulse repetition frequency PRF. And the frequency of the transmission signal is substituted into the pulse repetition frequency PRF of the equation (2) and the frequency fo of the transmission signal to calculate the maximum flow rate value corresponding to the depth data.

Equation 1 is

In this case, the SPRF mode execution unit 130, which will be described later, may repeatedly derive a limitation of the measurement distance due to repeatedly transmitting / receiving a pulse signal.

That is, since the reception of the n th pulse signal must be terminated before the n + 1 th pulse signal is transmitted, the maximum measurement distance is determined by the pulse repetition period.

In Equation 1, Rmax is the maximum measurement distance, Tr is the pulse repetition period, c is the sound velocity, PRF is the pulse repetition frequency.

In addition, Equation 2 is

to be.

Equation 2 can be derived from the sampling theorem. That is, since the pulse repetition period becomes the sampling period of the Doppler signal, the amount of Doppler frequency shift that is 1/2 of the pulse repetition frequency (PRF) by the sampling theorem is measured. This can lead to a limitation of the maximum measurement speed.

In Equation 2, Vmax is the maximum measurement speed, c is the sound speed, PRF is the pulse repetition frequency, fo is the frequency of the transmission signal.

Referring to FIG. 4, when the pulse repetition frequency (PRF) is 1000 Hz, the depth in the vertical direction from the ultrasound transceiver 140 may be within a range of about 75 cm, and the speed may measure only a flow rate of about 40 cm / s or less. It can be seen.

The SPRF mode execution unit 130 measures the vertical flow velocity distribution of the stream using a single ultrasonic pulse signal, and sets a representative value of the flow velocity.

That is, the SPRF mode refers to a flow rate distribution measurement mode using a single pulse repetition frequency (SPRF).

At this time, the ultrasonic transceiver 140 transmits a pulse signal to which the pulse repetition frequency (PRF) calculated from Equation 1 is applied by the maximum flow rate value calculator 120, which is a single ultrasonic pulse signal, in a direction opposite to the stream flow. , A pulse signal scattered from the suspended solids 20 can be received.

In addition, the SPRF mode execution unit 130, among the scattered signals received by the ultrasound transceiver 140, a time difference according to a specific time difference (pulse repetition frequency (PRF)) at a specific distance (sleep) from the ultrasound transceiver 140. ) And extract the received signals.

FIG. 5 is a diagram illustrating a process of measuring a vertical flow rate distribution using a pulse repetition frequency (PRF) in the SPRF mode execution unit 130, with reference to FIG. 2.

FIG. 5 (a) shows that when an ultrasonic pulse signal is transmitted from the ultrasonic transceiver unit 140 along the measurement line as shown in FIG. 2 (a), the signal is scattered from the float 20. (b) is an ultrasonic wave among the signals scattered and received by the float 20 from the ultrasonic pulse signal transmitted by the ultrasonic transceiver unit 140 according to the pulse repetition frequency (PRF) as shown in FIG. It shows a signal extracted with a time difference according to the pulse repetition frequency (PRF) at a specific distance from the transceiver 140.

In addition, since the horizontal position (relative time after transmission) of the vertical dotted line (arrow dotted line) in FIG. 5B means the distance (depth) from the vertical flow rate distribution measuring apparatus 100, if the position of the vertical dotted line is If it is on the right side, it means the depth of water far from the vertical flow rate distribution measuring apparatus 100, and if the position of the vertical dotted line is on the left side, it means the depth of water near the vertical flow rate distribution measuring apparatus 100.

That is, the relative time axis after transmission is equal to the distance (depth) from the vertical flow rate distribution measuring apparatus 100.

In addition, the SPRF mode execution unit 130 may calculate the Doppler frequency as shown in FIG. 5C from the extracted signals with a time difference according to the pulse repetition frequency (PRF), and measure the flow rate from the Doppler frequency. .

The Doppler frequency refers to the Doppler frequency due to the float moving at that depth (selected relative time).

Referring to (c) of FIG. 5, the signals having the same period are generated by extracting signals having the same relative time from the extracted signals as shown in FIG. 5 (b), and the signal having the specific period is the Doppler signal. Becomes

From the frequency of the generated Doppler signal, it is possible to measure an accurate flow rate for each depth. In detail, the vertical flow velocity distribution is obtained by dividing the entire depth of the river from the ultrasonic transceiver unit 140 to the surface by 1 cm interval and the corresponding times. Can be measured.

By repeating the above-described process for transmitting the ultrasonic signal and measuring the vertical flow rate distribution for a predetermined time, and averaging the results of measuring the plurality of vertical flow rate distributions in the predetermined time, the average value of the flow rate for each 1 cm depth Can be obtained, and the average value of the flow velocity at the position where the fastest flow velocity appears in the vertical flow velocity distribution (generally, the position near the surface of the river) can be set as the representative value of the flow velocity.

The measurement mode switching unit 150 compares the maximum flow rate value calculated by the maximum flow rate value calculating unit 120 with the representative value of the flow rate measured by the SPRF mode execution unit 130, so that the maximum flow rate value is larger than the representative value of the flow rate. If large, the vertical flow rate distribution average value measured by the SPRF mode execution unit 130 may be set as the flow rate data without switching the measurement mode.

Alternatively, the vertical flow rate distribution may be re-measured and set as the flow rate data. The ultrasonic transceiver unit 140 as described above may use the pulse repetition frequency (PRF) calculated by Equation 1 in the maximum flow rate value calculator 120. The ultrasonic signals may be transmitted, signals received from a specific distance are extracted from the scattered signals to be received, a Doppler signal may be generated from the extracted signals, and a vertical velocity distribution may be measured from the Doppler frequency.

In addition, the measurement mode switching unit 150 switches to the MPRF mode when the maximum flow rate value is smaller than the representative value of the flow rate.

In other words, if the representative value of the flow rate is larger than the maximum flow rate value (the Doppler frequency exceeding the maximum measurement rate), an accurate Doppler frequency cannot be calculated due to aliasing due to undersampling. Switching to the mode using the pulse repetition frequency (MPRF mode).

In addition, referring to FIG. 4, the shallow flow rate and the slow flow rate can be measured by the flow rate measurement method using the SPRF mode. However, since the flow rate is high, the flow rate can not be measured. It may be desirable to switch to MPRF mode and measure the flow rate.

When the MPRF mode execution unit 160 switches to the MPRF mode, the MPRF mode execution unit 160 measures the vertical flow velocity distribution of the stream by using the multiple ultrasonic pulse signals.

In other words, the MPRF mode refers to a flow rate distribution measurement mode using a multiple pulse repetition frequency (MPRF).

At this time, the ultrasonic receiver 140 transmits a plurality of pulse signals to which a plurality of preset pulse repetition frequencies (PRF) are applied, which are multiple ultrasonic pulse signals, and are scattered from the float 20 in the water. A plurality of pulse repetition frequencies (PRFs) for the pulse repetition frequency (PRF) can be received, wherein the plurality of preset pulse repetition frequencies (PRF) is low pulse repetition frequency (PRF) (e.g. 200 Hz, 320 Hz, 440 Hz, etc.).

The MPRF mode execution unit 160 extracts the received signals with a specific time difference from the ultrasound transceiver 140 at a specific distance (sleep) from the plurality of scattered signals received by the ultrasound receiver 140.

In addition, the MPRF mode execution unit 160 measures a flow rate by obtaining a plurality of aliased Doppler frequencies from signals having the same relative time in the extracted signals for each pulse repetition frequency (PRF).

The aliased Doppler frequency is the Doppler frequency due to the moving float. Each of the plurality of low pulse repetition frequencies (PRF) as described above is a low pulse repetition frequency (PRF) that can be measured up to the maximum depth of the fluid to be measured, so that all depths can be measured, but relatively high flow rates are measured. Since aliasing occurs beyond the maximum measurement rate, the aliased Doppler frequencies can be extracted.

That is, the aliased Doppler frequency extracts signals having the same relative time from the signals having a specific time difference extracted from the above, and generates a signal having a specific period from these signals, and calculates the frequency of the generated signal. can do.

Since the correct flow rate for the corresponding depth cannot be calculated from the aliased Doppler frequency, the MPRF mode execution unit 160 applies the 'China remaining theorem' to the multiple aliased Doppler frequencies, so that the correct flow rate can be calculated. Can be measured.

The Chinese Theorem Theorem gives the answer to the problem of finding a common solution of simultaneous linear joint equations, with the aliased measurement (aliased Doppler frequency) remaining and the corresponding pulse. By applying the repetition frequency (PRF) to the rest of the Chinese theorem, a correct Doppler frequency can be calculated and converted into a flow rate to determine the correct flow rate for the corresponding depth.

If the above-described function of the MPRF mode execution unit 160 is applied to Equations 1 and 2,

MPRF mode uses a low pulse repetition frequency (PRF),

Equation 1

silver

Equation 3

Become,

In addition, because a plurality of low pulse repetition frequency (PRF) is used,

Equation 2

Is

Equation 4

Becomes

That is, through the modified equations (3) and (4), when measuring the flow velocity of the river in the MPRF mode, it can be seen that there is no restriction on the measurement distance (depth) or the measurement speed (flow velocity).

The flow rate data storage unit 170 may store data about the flow rate measured by the SPRF mode execution unit 130 and the MPRF mode execution unit 160 in association with the depth data.

Stored flow rate data can be used to manage streams, for example, by calculating the time to neutralize contaminants, by estimating the rate of inflow of water accumulated in the dam during the rainy season, or by setting up discharges in rivers. It can be installed in (洑) to measure the flow of the river and can be used to grasp the amount of water resources.

6 is a circuit diagram showing the respective components of the stream vertical flow rate distribution measuring apparatus 100. The digital control unit 30 has the remaining components (depth measurement unit 110, the maximum flow rate value calculation unit except for the ultrasonic transceiver unit 140). 120, the SPRF mode execution unit 130, the measurement mode switching unit 150, the MPRF mode execution unit 160, and the flow rate data storage unit 170 may be included.

The stream vertical flow rate distribution measuring apparatus 100 as described above is installed on a stream structure having a flat bottom, such as a river bottom or a beam blocking the river, or a bottom surface of the river and an upper surface of the stream vertical flow rate measuring apparatus 100. It may be embedded to form a plane.

FIG. 7 is a side view of the stream vertical flow rate measurement apparatus 100 embedded in the river bottom, and FIG. 8 is a perspective view of the stream vertical flow rate measurement apparatus 100 embedded in the river bottom.

At this time, the stream vertical flow rate distribution measuring apparatus 100 may further include an ultrasonic path providing unit 10, the ultrasonic path providing unit 10 may be implemented with a material that does not affect the ultrasonic transmission and reception, ultrasonic It may have a form that can secure the path to be transmitted and received, and may also be implemented in various forms according to the bottom surface of the river.

For example, as shown in FIG. 7 and FIG. 8, the upper surface of the ultrasonic path providing unit 10 may be implemented in a predetermined form such that the upper surface of the stream vertical flow rate distribution measuring apparatus 100 is flattened. By reducing the risk of damage to the measuring device 100, it is possible to reduce the disturbance to the flow of the river.

Depth measurement unit 110, the maximum flow rate value calculation unit 120, the SPRF mode execution unit 130, the ultrasonic transceiver unit 140, the measurement mode switching unit 150, MPRF mode execution unit 160 as described above Due to the configuration of the flow rate data storage unit 170, the user may measure the flow rate in the SPRF mode when the flow rate of the depth to which the user wants to measure the flow rate in the stream is slow, and in the MPRF mode when the flow rate is fast. As a result, the vertical flow velocity distribution of the natural stream can be accurately measured without limiting the depth and flow rate, and the measurement time can be shortened because the SPRF mode and the MPRF mode can be executed by one device.

FIG. 9 is a flowchart schematically illustrating an example of a method for measuring a vertical flow rate distribution using the stream vertical flow rate measurement apparatus 100 of FIG. 2.

The stream vertical flow rate distribution measuring apparatus 100 measures the total depth of the stream, which is the vertical distance from the measuring apparatus 100 to the water surface, using a general depth sensor (S100), and the depth data of the measured depth, The maximum flow rate value is calculated using the equations (1) and (2) previously set (S200).

That is, the depth data is expressed by Equation 1

Pulse repetition frequency (PRF) is calculated by substituting Rmax of

By substituting for, the maximum flow velocity value corresponding to the depth data can be calculated.

Next, the stream vertical flow rate distribution measuring apparatus 100 is an SPRF mode using a single ultrasonic pulse signal, The vertical flow rate distribution is measured and a representative value of the flow rate is set (S300).

FIG. 10 is a flowchart illustrating in detail the steps of measuring the vertical flow rate distribution and setting the representative value of the flow rate in the SPRF mode. Referring to FIG. 9, step S300 will be described.

The ultrasonic transmitting / receiving unit 140 of the stream vertical flow rate distribution measuring apparatus 100 transmits a pulse signal by applying the pulse repetition frequency (PRF) calculated in step S200, which is a single ultrasonic pulse signal, from the suspended solid 20 in the water. When receiving the scattered pulse signal (S310), the stream vertical flow rate distribution measuring apparatus 100 may extract the received signals at a specific distance from the measuring device 100 at a specific distance (S320).

When the Doppler signal is generated from the extracted signals with the same relative time (S330), and the Doppler signal is generated from the signals with the same relative time (S340), the frequency of the generated Doppler signal is converted into a flow rate at the corresponding relative time. The flow velocity of the corresponding depth can be measured (S350).

At this time, when a Doppler signal is generated for each relative time at a plurality of relative times corresponding to an interval at a depth of 1 cm of the stream, the vertical velocity distribution of the stream may be measured by converting the frequency of the generated Doppler signal into a flow rate (S360). ).

Next, the above-described steps S310 to S360 are repeated for a preset time, and the plurality of vertical flow rate distributions are measured, and the measured results are averaged at a preset time, and the average value of the vertical flow rate distribution, which is an average value of flow rates for each 1 cm depth, is measured. After calculating (S370), the position at which the fastest flow rate appears in the average value of the vertical flow rate distribution (generally, the flow rate average value of the position near the surface of the river) is set as the representative value of the flow rate (S380).

Referring back to FIG. 9, the stream vertical flow rate distribution measuring apparatus 100 determines whether to switch to the MPRF mode by comparing the maximum flow rate value calculated as described above and the representative value of the flow rate (S400), and the maximum flow rate value is If greater than the representative value of the flow rate (S410), the flow rate data storage unit in the stream vertical flow rate distribution measuring apparatus 100 by setting the average value of the vertical flow rate distribution calculated in the SPRF mode to generate the representative value of the flow rate as the flow rate data In operation 170, the storage is stored at 170.

In this case, instead of setting the average value of the vertical flow rate measurement measured in step S300 as the flow rate data, step S310 to step S350 of FIG. 9 is an ultrasonic signal to which the pulse repetition frequency (PRF) calculated from Equation 1 is applied in step S200. In addition, the vertical flow velocity distribution of the measured stream may be set as the velocity data and stored in the velocity data storage unit 170.

If the maximum flow rate value and the representative value of the flow rate are compared, and the maximum flow rate value is smaller than the representative value of the flow rate (S410), the stream vertical flow rate distribution measuring apparatus 100 is switched to the MPRF mode, and the multiple ultrasonic pulse signals The flow rate corresponding to the depth data is measured in the MPRF mode using (S600).

FIG. 11 is a flowchart illustrating the steps of measuring the flow rate vertical distribution in the MPRF mode in detail. Referring to FIG. 11, step S600 will be described.

The ultrasonic transmitting / receiving unit 140 of the stream vertical flow rate distribution measuring apparatus 100 transmits a plurality of pulse signals to which a plurality of predetermined (three or more) low pulse repetition frequencies (PRFs), which are multiple ultrasonic pulse signals, are applied and are underwater. When receiving a plurality of pulse signals scattered from the float (20) (S610), the stream vertical velocity distribution measuring apparatus 100 receives the signals received at a specific distance from the measuring device 100 at a specific distance from each pulse repetition frequency (PR620) is extracted for each (S620).

Then, signals having the same relative time are extracted again from the extracted signals (S630), and a Doppler signal aliased from the extracted signals having the same relative time is generated for each pulse repetition frequency (PRF) (S640). .

By applying the 'Chinese residual theorem' to the frequencies of a plurality of aliased Doppler signals, an accurate Doppler frequency can be calculated for each pulse repetition frequency (PRF) (S650), and the flow rate is calculated using the calculated Doppler frequency. In operation S660, an accurate flow velocity at a depth corresponding to the corresponding relative time may be measured.

Then, by changing the relative time to correspond to the depth position of the 1cm interval and repeating step S630 to step S660, it is possible to measure the vertical flow rate distribution of the stream (S670).

Referring back to FIG. 9, the stream vertical flow rate distribution measuring apparatus 100 stores the flow rate data, which is a vertical flow rate distribution of the stream measured in the MPRF mode, in the flow rate data storage unit 170 in the stream vertical flow rate distribution measuring apparatus 100. (S500).

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

Claims

Depth measurement unit for measuring the vertical depth of the river;

Pulse repetition after obtaining the maximum measurement distance, which is the distance from the direction in which the vertical depth is measured to the ultrasonic wave transmitted in a direction inclined by a predetermined angle, to reach the surface using the depth data measured by the depth measuring unit A maximum flow rate value calculator for calculating a frequency PRF and calculating a maximum flow rate value corresponding to the depth data using the pulse repetition frequency PRF;

An SPRF mode execution unit for measuring a vertical flow rate distribution of the stream using a single ultrasonic pulse signal to which the pulse repetition frequency (PRF) is applied, and setting the fastest flow rate as a representative value of the flow rate;

A measurement mode switching unit which compares the maximum flow rate value with the representative value of the flow rate and does not change the measurement mode when the maximum flow rate value is larger than the representative value of the flow rate, and switches to the MPRF mode when the flow rate is small;

An MPRF mode execution unit configured to measure a vertical flow velocity distribution of the stream by using a plurality of ultrasonic pulse signals to which a plurality of preset pulse repetition frequencies (PRFs) that can be measured up to a maximum depth of a river are measured when the MPRF mode is switched; Stream vertical flow rate measurement apparatus using a pulse repetition frequency comprising a.
The method of claim 1,

The SPRF mode execution unit,

Measuring a vertical flow rate distribution of the plurality of streams for a preset time, averaging the measured plurality of vertical flow rate distributions to the preset time, and then setting the fastest average flow rate as a representative value of the flow rate; Stream vertical flow rate measurement device using a pulse repetition frequency.
The method of claim 1,

The MPRF mode execution unit,

Transmitting the plurality of pulse signals for each pulse repetition frequency (PRF), receiving a plurality of scattered pulse signals, extracting scattered signals at a depth corresponding to the depth data, and eliminating from the extracted signals. A stream vertical velocity distribution measurement apparatus using a pulse repetition frequency, characterized in that the vertical velocity distribution of the stream is measured by extracting an aliased Doppler signal.
The method of claim 3, wherein

The MPRF mode execution unit,

Stream vertical flow rate measurement apparatus using a pulse repetition frequency characterized in that for measuring the vertical flow rate distribution of the stream by applying the 'China remaining theorem' to the frequency of the aliased (plural) Doppler signals.
The method of claim 1,

An ultrasonic path providing unit configured to secure a path through which ultrasonic waves are transmitted / received, and to have an upper surface of the stream soft flow rate distribution measuring device flattened, and not to affect ultrasonic transmission / reception; Stream vertical flow rate measurement apparatus using a pulse repetition frequency characterized in that it further comprises.
(a) measuring the vertical depth of the river;

(b) Using the depth data measured in step (a), the maximum measurement distance, which is the distance from the direction in which the vertical depth is measured to the surface of the ultrasound signal transmitted in a direction inclined by a predetermined angle, reaches the surface of the water; Calculating a pulse repetition frequency (PRF) and calculating a maximum flow rate value corresponding to the depth data using the pulse repetition frequency (PRF);

(c) measuring a vertical flow rate distribution of the stream using a single ultrasonic pulse signal to which the pulse repetition frequency (PRF) is applied, and setting the fastest flow rate as a representative value of the flow rate;

(d) comparing the maximum flow rate value with the representative value of the flow rate, and switching the measurement mode when the maximum flow rate value is larger than the representative value of the flow rate, and switching to the MPRF mode when the flow rate is small; And

(f) measuring the vertical flow velocity distribution of the stream by using a plurality of ultrasonic pulse signals to which a plurality of preset pulse repetition frequencies (PRFs), which can be measured up to the maximum depth of the stream, are converted into the MPRF mode; Stream vertical flow rate measurement method using a pulse repetition frequency comprising a.
The method of claim 6,

In the step (c),

After measuring the vertical flow rate distribution of the plurality of streams for a preset time, averaging the measured plurality of vertical flow rate distributions to the preset time, and setting the fastest average flow rate as a representative value of the flow rate. Stream vertical flow rate measurement method using the pulse repetition frequency.
The method of claim 6,

In the step (f),

Transmitting the plurality of pulse signals for each pulse repetition frequency (PRF), receiving a plurality of scattered pulse signals, extracting signals scattered at a depth corresponding to the depth data, and extracting the extracted signals from the extracted signals A stream vertical velocity distribution measurement method using a pulse repetition frequency, characterized in that the vertical velocity distribution of the stream is measured by extracting an aliased Doppler signal.
The method of claim 8,

In the step (f),

The stream vertical velocity distribution measurement method using the pulse repetition frequency characterized in that for measuring the vertical flow rate distribution of the stream by applying the 'China remaining theorem' to the aliased plurality of Doppler frequencies.