Oceanographic meter

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention integrally measures the wave height, period, wave direction, etc., which are the parameters of sea waves, as well as the current conditions, tide level fluctuations, long-period waves (tsunami, secondary vibration, etc.), etc. related to the tidal currents of multiple layers. Regarding the meter, in particular, one sensor (transmitter / receiver) can simultaneously obtain multi-element wave and flow data necessary for measuring these marine events at the same station, and it is not actually possible depending on the existing ocean observation technology. Measurement of wave direction in coastal deep sea areas where the water depth is large compared to the magnitude of sea surface waves that have been considered possible, and tidal currents from the seabed along with waves without using special facilities and equipment on the sea surface or in the sea off the coast , It enables measurement of tide level fluctuations, etc., and realizes an oceanographic meter that can be applied to long-term steady observation.

【0002】

[Conventional technology]

Conventionally, as an instrument installed on the seabed or under the sea to measure waves on the surface of the sea, that is, waves on the surface of the sea, for example, there is an ultrasonic wave height meter. In this ultrasonic wave height meter, ultrasonic pulses transmitted from an ultrasonic transmitter / receiver, which is a measurement sensor installed on the sea floor or under the sea, toward the sea surface are reflected at the boundary layer between the sea surface and the air, and are again used as sea surface echo. It uses the principle of grasping the position of the sea surface by measuring the time required to return to the transmitter / receiver in the sea, and by repeating this operation at short intervals, the waveform of the sea surface that changes from moment to moment is obtained. It is a thing. The wave height and period can be obtained by statistically processing the obtained waveform.

【0003】

Further, as an instrument for measuring the wave attack direction, that is, the wave direction, for example, there is a stationary ultrasonic velocimeter type wave directional meter to which an ultrasonic velocimeter is applied. This acoustic doppler current meter type wave direction meter measures the horizontal flow velocity component of the movement of water particles in the sea caused by the waves on the sea surface with an ultrasonic flow velocity meter using a sensor for measuring orthogonal two components, and is installed in the same sensor at the same time. The water pressure measurement sensor measures the pressure fluctuation in water caused by the wave, and obtains a plurality of wave amounts necessary for estimating the wave direction or the direction spectrum of the wave.

【0004】

In addition, as a method of simultaneously measuring multi-element wave data for estimating the wave direction spectrum, for example, three or more ultrasonic wave height gauges are installed in the same area to simultaneously measure the wave motion of the sea surface. There is a method using a wave height meter array. This wave height meter array measures sea surface waveforms at multiple points at the same time by arranging three or more wave height meters, such as ultrasonic wave height meters, at the required intervals on the seafloor or under the sea, for example, in a triangular, star-shaped or linear shape. By doing so, a plurality of wave amounts required for estimating the wave direction or the wave direction spectrum are obtained.

【0005】

The method and model of automatically measuring the flow with an instrument installed on the seabed or underwater in the coastal sea area are roughly classified into a fixed installation type and a mooring installation type depending on the installation method. The fixed installation type includes an ultrasonic current meter and an electromagnetic current meter. The mooring installation type includes propeller type and rotor type flow direction / current meters. Most mooring-type flow direction / current meters and electromagnetic current meters on the market have a direct writing structure with a built-in measuring / recording device, so these are classified as handling classifications. In some cases, they are collectively classified as direct writing type or portable type. In addition to automatic measurement by installing an instrument on the seabed or in the sea, as a method of measuring the flow by ship, the specified water depth from the ship where the flow direction / current meter such as power generation type, ultrasonic type, electromagnetic type, Ekmammelz, etc. is anchored. A measurement method that is hung on a ship, a method that uses an electromagnetic current meter (GEK) or a drop-type galvanometer (XCP) that measures by towing a ship in transit, or a drifting buoy from a ship, aircraft, or shore. There is a method of discharging a drifting rod or dye, etc., and tracking the movement by a positioning machine, a ship, an artificial satellite, or the like.

【0006】

In addition, some models of the above-mentioned mooring installation type or hanging type current meter from the ship are on the sea surface via an electrical conversion circuit that replaces the direct writing type measurement recording device built in the main body. In some cases, a method of transmitting a measurement signal to a buoy device and wirelessly transmitting the measurement signal from the buoy to the shore to acquire measurement data is used. In addition, when these measuring instruments are installed on the seabed to measure only the bottom layer flow, the measuring instruments are attached to a framework-type pedestal that is directly installed on the seabed regardless of buoys or mooring lines. However, the measuring instrument installed on the seabed is limited to the direct writing type, and the measurement data is acquired by collecting the measuring instrument at regular intervals.

【0007】

The fixed-installation type current meter uses the single-land time difference method using an ultrasonic sensor or the electromotive force method using an electromagnetic sensor to obtain the flow velocity of each component by the time average of each component using the fluctuating flow velocity of the two-way component or the three-way component as the measurement input. In addition, the unique flow direction and flow velocity such as tidal current can be obtained by vector-synthesizing the flow velocity values for each required component. Since the measurement by this fixed installation type current meter is for the purpose of long-term steady observation and it is required to secure stable measurement coordinates, the installation of the instrument requires a bottoming type pedestal, near the sea surface or at an arbitrary depth position. When measuring in, it will be constructed using facilities such as an observation tower.

【0008】

The mooring installation type current meter / current meter consists of a main body having a mechanism that freely rotates along the flow by a mooring arm and arrow blades, and a watertight housing that houses a measurement / recording device incorporated in the main body. To measure the flow velocity, the rotation due to the flow of the propeller or rotor installed outside the main body is transmitted to the inside of the watertight housing by a magnet coupling or the like, and the rotation speed is mechanically or electrically counting mechanism or a power generation mechanism proportional to the rotation speed. The flow direction is measured by detecting the direction in which the main body holds according to the flow from the magnetic needle in the watertight housing, and measuring and recording the flow direction.

【0009】

The portable flow direction / current meter is installed by suspending or hoisting the measuring instrument to a predetermined water depth by a mooring buoy and a mooring line installed on the sea surface or in the sea by a mooring anchor thrown into the seabed.

【0010】

Floating tide detectors are used as standard for measuring tide levels at tide stations equipped with facilities such as wells, water pipes, and spheres standardized by the Japan Coast Guard and the Japan Meteorological Agency, for short-term and temporary purposes. A hydraulic simple tide gauge or the like is used for the observation of.

【0011】

Floating type tide gauges (previously, Kelvin type, Richard type, etc. were used for tide gauge wells that have a predetermined function for tide level observation and function for temporal changes in sea level due to tides, but now Hus It is almost unified to the type tide gauge. In the old days, hydraulic type and Honda type tide gauges were also used.) Measured with reference to the tide reference plane. The measurement is performed by transmitting the movement of the buoy that moves up and down following the change in the water level of the tide well to the tide detection mechanism, and recording the time change curve of the water level on the recording paper via the mechanical magnification conversion mechanism. Further, as the measurement record, a method of digitally converting the measured value and transmitting / recording it is also used.

【0012】

It should be noted that the prior art related to a dedicated instrument for measuring the offshore tide level in the coastal sea area included in the present invention and long-period waves such as tsunamis and sub-vibrations has not been developed.

【0013】

[Problems to be Solved by the Invention]

However, the conventional ultrasonic wave height meter measures the waveform of the sea surface, and although the information on the wave height and the period can be obtained from the measured data, the information on the wave direction cannot be obtained. In other words, the ultrasonic wave height meter does not have a function as a wave meter, and even when the wave height meter and the wave direction meter (for example, an ultrasonic flow meter type wave direction meter) are used together, the measurement by the wave height meter is performed. While it is possible to measure from shallow waters to deep coastal waters (standard water depth 50 m) with a certain degree of accuracy, the measurement accuracy of the wave direction meter drops sharply as the installed water depth increases, so what is the measurement accuracy of the measuring instrument? Regardless, the applicable limit is restricted to sea areas shallower than about 20 m in depth (see equations (2) to (4)). Therefore, it is impossible to integrally measure the wave specifications (wave height, period, wave direction) in the sea area deeper than that.

【0014】

In addition, the measurement data of the acoustic doppler current meter type wave direction meter is a plurality of wave quantities, and although it provides the information necessary for estimating the wave direction or the direction spectrum of the wave, the sea surface waveform data cannot be obtained. Information on wave height and period is to estimate the wave specifications corresponding to the sea surface waveform by statistically processing the pressure fluctuation waveform measured by the water pressure measurement sensor according to the theory of minute amplitude waves, which is the theory of sea waves. .. However, as for the magnitude of the wave amount in water due to the waves on the sea surface, it is difficult to obtain the wave amount to analyze the phenomenon because the deeper the water depth position and the shorter the wave period, the larger the attenuation in the transmission process. It becomes.

【0015】

The magnitude of the amount of wave motion in water due to sea surface waves is expressed by the following equations (1) to (4) according to the theory of minute amplitude waves in the region where the water depth h is 1/2 or less of the wavelength of the traveling wave.

【0016】

Equation (1) represents the water level η of a sine wave traveling in the positive direction on the X-axis (hydrostatic surface) on the horizontal plane.

[Number 1]

<img file="JP2948472B2_D0001.tif" />Here, H is the wave height, K is the wave number; K = 2π / L, L is the wavelength of the wave, σ is each frequency; σ = 2π / T, T is the period of the wave, and t is the time.

【0017】

The pressure P at any point Z in the water due to the wave of Eq. (1) is given by Eq. (2) below.

[Number 2]

<img file="JP2948472B2_D0002.tif" />Here, W₀ Is the unit volume weight of water and h is the water depth.

【0018】

Further, the horizontal component U and the vertical component W of the water particle motion velocity due to the wave are given by the following equations (3) and (4).

[Number 3]

<img file="JP2948472B2_D0003.tif" />[Number 4]

<img file="JP2948472B2_D0004.tif" />As shown in Eqs. (2) and (3), the magnitude of the wave amount measured by the acoustic doppler current meter type wave direction meter attenuates depending on the measured water depth and the wave period. Therefore, there is a drawback that the applicable water depth, the wave height that can be analyzed, and the period are restricted.

【0019】

The wave direction measurement method using the wave height meter array has the disadvantage that the equipment configuration is large and the cost is high because three or more wave height meters are used. In addition, in order to estimate the wave direction spectrum or wave direction from the obtained data, it is necessary that the mutual distance between the installed wave height meters, the mutual angle, and the installation direction of the wave height meter array are accurately measured. Will be done. However, accurate surveying in the sea is technically difficult, and it costs a huge amount of money, especially when the water depth is large, and it is also technically difficult.

【0020】

A fixed-installation type or mooring-installation type flow direction / current meter is used to measure steady flow, but the models belonging to the latter usually have a direct writing type structure and are measuring every week to one month. It requires complicated work to install and collect and acquire measurement data. Further, when it is intended to acquire the data of the water depths of a plurality of layers at the same time, a plurality of measuring instruments corresponding to the number of measurement points are required regardless of the installation method.

【0021】

In addition, since the former is a measurement method that requires the installation and construction of facilities and structures on or near the sea surface as a necessary condition for implementation, it is necessary to select measurement points in relation to ship operations, fisheries, etc. It is restricted by the extremely low degree of freedom. In addition, in the case of the former, a great deal of technical and economic burden is required for the design and construction of the facility, and in the latter case, stable equipment installation and measurement performance are ensured when used for the purpose of measurement in stormy weather. It is not possible.

【0022】

According to the present invention, an ultrasonic wave transmitter / receiver installed on the seabed can detect backscattered waves from an arbitrary water depth (measurement point) from the seabed to the sea surface to obtain information on the flow, which is enormous cost. And defects with technical difficulties can be eliminated.

【0023】

The tide level is measured at the tide station, and the tide station is located in the harbor or near the estuary, and the tide wells and headraces, which are the basis of the tide facility, are based on about 24 hours. It is designed and constructed for the purpose of measuring changes in the tide level due to the tide (astronomical tide). Therefore, it is almost impossible to accurately measure the actual conditions of tides and abnormal tides (astronomical tides + storm surges and other meteorological tides + others) that occur off the coast, and the cycle varies from several minutes to several tens of minutes. It is not uncommon for long-period waves (edge waves, tsunamis, secondary vibrations, etc.) to not be detected even if they occur. In particular, the measurement of traveling waveforms and water level fluctuations offshore of long-period waves has not been developed, and the scale is only estimated based on the abnormal tide level, etc., as well as the run-up height to the shore and the inundation level. .. The estimated values of these events due to run-up height, etc. can differ several times even at the same point depending on the topography, features, and incident conditions of the event.

【0024】

The present invention makes it possible for the first time to constantly and integrally measure tides, abnormal tide levels, long-period waves (tsunami, secondary vibration, etc.), etc. at coastal offshore points, which was considered impossible by conventional technology. It is a thing. In addition to clarifying the properties of each of these events, this means that wave deformation (changes in wave height, wavelength, refraction, etc. due to changes in water depth in shallow waters), harbor calmness, beach deformation, and burial of river mouths. It provides basic information that is essential for the investigation and research of overtopping and overflowing phenomena on coastal embankments and breakwaters, elucidating marine phenomena that occur in coastal waters, harbors, fishing ports, coasts, coastal disaster prevention, and other oceans. Information based on the actual situation as basic data for planning / designing or functional surveys and construction management of sexual facilities / structures, prediction of occurrence of various events / phenomena or environmental changes, investigation of disaster causes, examination of countermeasures, etc. Will be able to be obtained. In addition, the basic information acquired by this invention can be used for the simulation (numerical calculation / hydraulic model experiment) that has been conventionally used in this kind of investigation, to improve the method, set appropriate initial conditions, and actually. It will provide necessary and useful materials for verification of the estimated results according to the rules.

【0025】

The present invention has been made in view of the above-mentioned drawbacks of the prior art. First, as a satisfaction of the wave direction measurement function which cannot be achieved by the conventional wave height meter, the drawbacks of the conventional wave direction meter or the wave direction measurement method are eliminated. A function to measure sea level fluctuations due to waves using the underwater propagation time measurement method of ultrasonic pulses, and a function to measure flow velocity fluctuations of water particle motion at multiple points at the required water depth position by applying the Doppler effect of ultrasonic waves. Invented a wave meter equipped in an integrated manner, and applied these functions to estimate multiple event specifications such as waves, current conditions, and tide level fluctuations using a single multi-function sensor on the mechanism. By simultaneously acquiring data on wave motion and flow, it is possible to expand the measurement function and improve the quality of measurement data and install sensors, which enables unified and steady observation of all marine events (waves, current conditions, tide level fluctuations, etc.). The purpose is to provide a wave meter that can eliminate the above technical and economic drawbacks.

【0026】

[Means for solving problems]

The present invention is a means for transmitting ultrasonic pulses in three or more directions toward the sea surface from a sensor installed on the sea floor or in the sea, and a sea surface echo of the ultrasonic pulses transmitted in the vertical direction among the ultrasonic pulses. From the operation of obtaining the time required from transmission to reception by receiving the sea level, the sea level fluctuation measuring means for measuring the time fluctuation (sea level waveform) data of the sea level, and the transmission beam axis of the ultrasonic pulse from the vertical to the required angle. From the operation of receiving the backward scattered wave of the ultrasonic pulse transmitted at an angle and finding the flow velocity in the predetermined scattering layer by Doppler frequency analysis, the time of the water particle velocity in the beam axis direction of the transmitted ultrasonic pulse generated by the wave and flow. Frequency spectrum, cross spectrum and sea surface wave calculated using the time fluctuation data of the sea surface water level and the time fluctuation data of the water particle velocity at multiple points, which are centrally measured by the flow velocity fluctuation measuring means for measuring the fluctuation data. A calculation means for calculating wave parameters such as wave direction spectrum, wave height, period, and wave direction using the wave motion transmission function in the water depth direction calculated from wave theory, and water particles at multiple points in multiple layers. Calculation means such as wave flow (flow direction / flow velocity) obtained by vector-synthesizing the flow velocity of the three-direction components (horizontal orthogonal two components / vertical component) of each layer calculated using the time fluctuation data of the velocity and the horizontal orthogonal two components. Further, it is configured to be provided with calculation means such as a tide level and a long-period wave obtained by averaging the time fluctuation data of the sea level.

【0027】

[Example]

Next, an example of the oceanographic meter according to the present invention will be described using a Doppler wave meter.

【0028】

As shown in FIG. 1, this Doppler wave meter is installed in the sea, a wave transmitting / receiving unit 1 as a means for transmitting ultrasonic pulses, a sea level fluctuation measuring circuit 2A as a means for measuring sea level fluctuation, and a flow velocity. It is composed of a flow velocity fluctuation measurement circuit 2B as a fluctuation measurement means, a measurement unit 2 including a signal processing circuit 2C, and a calculation unit 3 as a direction spectrum calculation means for performing direction spectrum calculation and wave parameter calculation.

【0029】

The transmission / reception unit 1 and the measurement unit 2 are connected by a multi-core shielded cable. The transmission / reception unit 1 is composed of a transmitter / receiver 10, a transmission / reception circuit 11 for sea level water level measurement, a transmission / reception circuit 12 for flow velocity measurement, and a switching circuit 13.

【0030】

As shown in FIG. 2, the transmitter / receiver 10 has a substantially cylindrical shape and is formed of a watertight housing made of stainless steel, and is composed of a base 101, a circuit housing portion 102, and an oscillator mounting portion 103. ing. The upper surface of the oscillator mounting portion 103 is formed in a substantially rounded shape, and the oscillator 10a for sea level water level measurement is mounted in the Z-axis direction in which the ultrasonic radiation direction is vertical with respect to the horizontal plane.

【0031】

Further, the oscillators 10b, 10c, and 10d for measuring the flow velocity are equally divided at an angle of β (120 in this embodiment).⁰ Three crossing) are arranged, and the radiation angle is the required angle of the zenith angle α (about 30 in this embodiment).⁰ ) Is fixed. The circuit storage section 102 inside the watertight housing of the transmitter / receiver 10 houses a sea level water level measurement transmission / reception circuit 11, a flow velocity measurement transmission / reception circuit 12, a switching circuit 13, and the like as shown in FIG.

【0032】

The transmitter / receiver 10 is installed on the seabed or the like, but since the seabed or the installation frame of the equipment is not always horizontal, the inclination for measuring the installation direction and the tilt angle is not shown inside. It has a built-in measuring instrument including a meter and an azimuth meter. The measurement signal measured by this is a trigger pulse Tr that performs time division control as shown in FIG.₁ It is transmitted to the measuring unit 2 as a frequency signal superimposed on.

【0033】

Note that FIG. 1 shows a case where four vibrators for measuring the flow velocity shown in FIG. 3 are arranged in two orthogonal components in the X direction and the Y direction for measurement. On the other hand, in the example of FIG. 2, 120⁰ Three crossing oscillators for flow velocity measurement with a zenith angle of about 30⁰ However, in principle, it is sufficient to measure the flow velocity in two or more directions using two or more oscillators. In addition, it is sufficient if the horizontal flow velocity component is detected for the mounting zenith angle of the oscillator 30⁰ Not limited to.

【0034】

In addition, the trigger pulse Tr₁ Is sent from the control circuit (CTL) 27, which is composed of a microcomputer or the like, to the transmission / reception unit 1 as shown in FIG. Assuming that the pulse interval is 125 ms for each of the sea level fluctuation measurement signal H for wave height and the flow velocity fluctuation measurement signals A, B, and C in this order as in the embodiment, the measurement repetition time is 0.5 s. Therefore, the oscillators 10a to 10d shown in FIG. 2 are switched and driven by the signal according to the switching timing. The sea level fluctuation measurement signal H and the flow velocity fluctuation measurement signals A, B, and C are identified by the pulse width in this embodiment.

【0035】

Further, the measurement positions of the flow velocity fluctuation measurement signals A, B, and C are arbitrarily set as shown by Zc in FIG. Normally, the measurement is performed at a distance of about 10 m from the sea surface, but the measurement position can be arbitrarily set according to this embodiment. Therefore, for example, the flow velocity fluctuation measurement signals A, B, and C can be set in a plurality of layers below the sea surface, for example. Calculations can be performed for the upper layer, middle layer, and lower layer. Further, it is possible to perform more accurate measurement by performing automatic control such as measuring near the surface layer when the wave height is small and deepening the measurement layer when the wave height is large depending on the wave condition.

【0036】

The transmission / reception circuit 12 for flow velocity measurement includes a clock generation circuit 21 in the flow velocity fluctuation measurement circuit 2B, a frequency divider circuit (Div) 22 for dividing the clock generated by the clock generation circuit, an oscillation circuit (Osc) 23, and a gate circuit. Trigger pulse Tr from (Gate) 24, auto power control circuit (APC) 25, power amplifier 26₂ In response to this, an oscillation signal of several hundred kHz (500 KHz in this embodiment) is created, and a tone burst wave is generated in synchronization with the trigger pulse. This signal excites the flow velocity measuring oscillators 10b to 10d and sends an ultrasonic pulse into the water. Further, the received Doppler signal is amplified by the flow velocity measurement transmission / reception circuit 12 and transmitted to the measurement unit 2.

【0037】

On the other hand, the transmission / reception circuit 11 for sea level water level measurement is a trigger pulse Tr from the sea level fluctuation measurement circuit 2A.₃ In response to this, an oscillation signal of several hundred KHz (200 KHz in the example) is created, the oscillator 10a for sea level water level measurement shown in FIG. 2 is excited, and an ultrasonic pulse is sent toward the sea surface.

【0038】

The received sea level water level signal is amplified by the sea level water level measurement transmission / reception circuit 11 and transmitted to the sea level fluctuation measurement circuit 2A and output to the A / D converter 33. A water pressure signal is superimposed on the sea level water level signal, frequency-converted, and transmitted. This water pressure signal is measured by a water pressure sensor as an underwater pressure fluctuation measuring means provided in the transmitter / receiver 10 for the time fluctuation data of the underwater pressure due to the sea surface wave.

【0039】

As described above, the transmission / reception unit 1 transmits the received sea level water level signal and the water particle scattering reception signal to the measurement unit 2 in a time-divided manner. Further, the installation direction and tilt angle of the transmission / reception unit 1 are also transmitted to the measurement unit 2 as a frequency signal superimposed on the measured trigger pulse signal.

【0040】

Next, the water particle scattering wave receiving signal is transmitted to the measuring unit 2 via the switching circuit 13 and the flow velocity measurement transmitting / receiving circuit 12. This transmitted water particle scattering received signal enters the mixer (Mix) 30 via the time variable gain circuit (TVG) 28 and the auto gain circuit (AGC) 29. The time variable gain circuit (TVG) 28 is a circuit that corrects the intensity of the reflected signal reflected from the transmitter / receiver 10.

【0041】

The mixer (Mix) 30 multiplies the signal oscillated from the flow velocity measurement transmission / reception circuit 12 (500 KHz in this embodiment) and the signal oscillated from the control circuit (CTL) 27 (for example, 480 KHz). Of the sum and difference signal components obtained in this way, only the difference component is extracted through the bandpass filter (BPF) 31.

【0042】

As a result, if there is no Doppler component corresponding to the flow velocity, the reference frequency is 20 KHz, but since it is actually affected by the Doppler component, a signal of 20 KHz ± Δf can be obtained. This change is input to the A / D converter 33 of the signal processing circuit 2c.

【0043】

That is, the signal component of 500 KHz is detected as the deviation from the reference signal of 20 KHz, which is a low frequency component.

【0044】

Assuming that this deviation Δf is, for example, about 5 KHz, the water particle velocity Vr is Vr = C / 2 × Δf / f.₀ , Where C is the speed of sound, f₀ Is expressed at 500KHz, so there is a 1% deviation. When it deviates by + 1%, it means that the flow velocity is in the foreground, and when it deviates by -1%, it means that it deviates in the direction of moving away. The signals of the sea level fluctuation component output from the water particle velocity fluctuation and sea level fluctuation measurement circuit 2A obtained in this way are calculated for sea level fluctuation and flow velocity fluctuation in the circuit inside the measurement unit, and are calculated for direction spectrum and wave parameters. It is digitally transmitted by GPIB36 to the arithmetic unit 3 that performs arithmetic processing such as direction spectrum, wave height, period, and wave direction.

【0045】

In addition, the signal processing circuit 2c is composed of an I / O circuit 34, a CPU 35 as a control circuit, and a GPIB 36 as an interface. As shown in FIG. 1, bidirectional communication is performed between the control circuit 27 and the like and the I / O circuit 34, and control signals are also output to other circuits.

【0046】

Next, the operation of the present invention having the above-described configuration will be described.

【0047】

As shown in FIG. 1, the trigger pulse signal Tr that controls transmission in a time-division manner from the control circuit 27 of the measurement unit 2₁ Is sent to the transmission / reception unit 1, and the oscillators 10a to 10d shown in FIG. 2 are switched and driven by the switching timing by the signal.

【0048】

The transmission / reception circuit 12 for flow velocity measurement is a trigger pulse Tr from the flow velocity fluctuation measurement circuit 2B.₂ In response to this, an oscillation signal of several hundred kHz (500 KHz in this embodiment) is created, and a tone burst wave is generated in synchronization with the trigger pulse. This signal excites the flow velocity measuring oscillators 10b to 10d and sends an ultrasonic pulse into the water. The received Doppler signal is amplified by the flow velocity measurement transmission / reception circuit 12 and transmitted to the measurement unit 2.

【0049】

On the other hand, the transmission / reception circuit 11 for sea level water level measurement is a trigger pulse Tr from the sea level fluctuation measurement circuit 2A.₃ In response to this, an oscillation signal of several hundred KHz (200 KHz in the example) is created, the oscillator 10a for sea level water level measurement shown in FIG. 2 is excited, and an ultrasonic pulse is sent toward the sea surface. The received sea level water level signal is amplified by the sea level water level measurement transmission / reception circuit 11 and transmitted to the sea level fluctuation measurement circuit 2A and output to the A / D converter 33. A water pressure signal is superimposed on the sea level water level signal, frequency-converted, and transmitted.

【0050】

As described above, the transmission / reception unit 1 transmits the received sea level water level signal and the water particle scattering reception signal to the measurement unit 2 in a time-divided manner. Further, the installation direction and tilt angle of the transmission / reception unit 1 are also transmitted to the measurement unit 2 as a frequency signal superimposed on the measured trigger pulse signal.

【0051】

The water particle scattering received signal enters the mixer (Mix) 30 via the time variable gain circuit (TVG) 28 and the auto gain circuit (AGC) 29.

【0052】

The mixer (Mix) 30 multiplies the signal oscillated from the flow velocity measurement transmission / reception circuit 12 (500 KHz in this embodiment) and the signal oscillated from the control circuit (CTL) 27 (for example, 480 KHz). Of the obtained sum and difference signal components, only the difference component is extracted through the bandpass filter (BPF) 31.

【0053】

The component of the difference obtained by this is detected as a deviation with respect to the reference signal of 20 KHz, and this deviation is sampled by the A / D converter 33.

【0054】

The signals of the sea level fluctuation component output from the water particle velocity fluctuation and sea level fluctuation measurement circuit 2A obtained in this way are calculated for sea level fluctuation and flow velocity fluctuation in the circuit inside the measurement unit, and are calculated for direction spectrum and wave parameters. It is digitally transmitted by GPIB36 to the arithmetic unit 3 that performs arithmetic processing such as direction spectrum, wave height, period, and wave direction.

【0055】

By the way, in the Doppler current wave meter according to the present embodiment, a sensor for measuring the horizontal flow velocity component of the water particle motion in the sea generated by the wave on the sea surface is used as a sensor for measuring the orthogonal two component like the conventional acoustic doppler current level meter type wave direction meter. Measured with an acoustic doppler current meter, and at the same time, a water pressure measuring sensor equipped with the same sensor measures the pressure fluctuation in water caused by waves, and obtains multiple wave amounts required to estimate the wave direction or wave direction spectrum. On the other hand, since the sea surface water level signal and the water particle scattering wave receiving signal are performed in a time-divided manner, it is necessary to correct the phase relationships of the sea surface fluctuation measurement signal H and the flow velocity fluctuation measurement signals A, B, and C, respectively. ..

【0056】

Usually, the extended maximum likelihood method (EMLM) is used for this directional spectrum analysis. That is, the flow velocity component observed by the Doppler wave meter is not the water particle velocity at a specific point in water, but the average water particle velocity in a volume having a certain width. Therefore, as shown in FIG. 1, the integral is integrated at a distance of Δr in the r-axis direction and averaged, and an approximate transfer function is used for the directional spectrum analysis. This is shown in Eq. (5).

[Number 5]

<img file="JP2948472B2_D0005.tif" />Using the above equation, the estimation equation of the EMLM directional spectrum is given by the equation shown in Eq. (6).

[Number 6]

<img file="JP2948472B2_D0006.tif" />Here, H is a matrix composed of the transfer functions of each wave amount given by the equation (5), H.^{* t}Is the complex conjugate of H, φ^-1Is the cross spectrum φ between each wave amount_mnThe inverse matrix of the matrix φ composed of (f), k is a constant for normalizing the energy of the directional spectrum.

【0057】

As described above, all the transmission / reception control signals of the measuring unit 2 (for example, the A / D conversion timing signal for obtaining the water particle velocity at the required water depth) are controlled by the CPU 35. In addition, the CPU35 digitally processes all water particle velocities and sea level fluctuations calculated by the measurement unit 2. The calculation result is transmitted to the calculation unit 3 by GPIB36, and calculation processing such as the direction spectrum, wave height, period, and wave direction is performed. Using the water particle velocity and sea level fluctuation data transmitted from the measurement unit 2, the calculation unit 3 performs various calculations such as the direction spectrum and wave parameters by EMLM.

【0058】

By using the Doppler wave meter according to the present invention, it has a function of measuring flow (three-way component flow velocity, flow direction of tidal current, flow velocity, etc.) and a function of measuring tide level fluctuation, long-period wave (tsunami, sub-vibration, etc.). It can be used as a device.

【0059】

Flow measurement function This Doppler wave meter can measure the flow below sea level for multiple layers (three or more layers). The flow is the time average (usually about 3 minutes) of the water particle velocity measured by the transmitter / receiver in the three directions 10b, 10c, and 10d shown in Fig. 2 (hereinafter, the axial direction is indicated by A, B, and C). ), And it is possible to perform arithmetic and measurement for a plurality of layers below the sea surface (for example, upper layer, middle layer, and lower layer).

【0060】

This arithmetic expression is shown by Eq. (7).

[Number 7]

<img file="JP2948472B2_D0007.tif" />The above matrix is expressed by Eq. (8).

[Number 8]

<img file="JP2948472B2_D0008.tif" />Where Vx: the horizontal east-west component of the flow velocity. East facing positive. Vy: Horizontal north-south component of flow velocity. North facing positive. Vz: Vertical component of flow velocity. Positive upwards. V_A , V_B , V_C : Flow velocity component in each beam axis ABC direction cos (xi), cos (yi), cos (zi) (i = A, B, C): Direction cosine of the A, B, C beam axes with respect to x, y, z, respectively. By using the above calculation formula, it is possible to measure the flow (flow velocity) of a plurality of layers below the sea surface (for example, upper layer, middle layer, lower layer). In addition, the flow direction and flow velocity of the tidal current and the like can be obtained by vector-synthesizing the above two horizontal components (Vx, Vy).

【0061】

In the embodiment shown in FIG. 2 of this Doppler wave meter, the beam inclination angle, that is, the zenith angle is about 30.⁰ At 120⁰ In the embodiment consisting of intersecting beam axes, the beam axis directions A, B, and C are respectively direction 0.⁰ ,120⁰ ,240⁰ Then, it becomes as shown in Eq. (10).

[Number 10]

<img file="JP2948472B2_D0009.tif" />Will be. From this, the calculation formula for obtaining each component of the flow velocity is the formula (11).

[Number 11]

<img file="JP2948472B2_D0010.tif" />【0062】

Measurement function for tide level fluctuations, etc. This Doppler wave meter measures the sea level by measuring the pulse propagation time until the ultrasonic pulse emitted from the transmitter / receiver installed on the sea floor is reflected on the sea surface and received again by the transmitter / receiver. be able to. In addition, the water level fluctuation η for calculating the wave parameters and direction spectrum uses only the fluctuation of the sea level as shown in Eq. (1), but the measurement principle is Shanghai surface water level H._l Is also obtained, and this can be time-averaged and smoothed, for example, the measured value of each hourly value can be measured, and this measured value can be used as a value for detecting tide level fluctuations. Further, by processing the time averaging / smoothing process with a required bandpass filter, various long-period waves (tsunami, sub-vibration, etc.) can be measured.

【0063】

Sea level H_l (Tide level H_l ) And the pulse propagation time are shown in Eq. (9).

[Number 9]

<img file="JP2948472B2_D0011.tif" />Here H_l : Sea level (m) C: Speed of sound t: Pulse propagation time (s) Is.

【0064】

[Effect of the invention]

As described above, according to the present invention, one sensor (integrated wave transmission / reception unit) can set wave parameters such as wave direction spectrum, wave height / period / wave direction, etc. in the deep sea area of coastal waters, which was difficult in the past. ), It is possible to realize a wave meter consisting of a measurement / calculation unit composed of a relatively simple circuit, and according to the present invention, the movement of water particles in water due to waves on the sea surface among the wave amounts. There is an effect that the fluctuation of the flow velocity can be obtained near the sea surface where the attenuation of the phenomenon is small by using the measurement method applying the Doppler effect. As a result, with the conventional ultrasonic wave direction meter, it is possible to measure the wave direction with a water depth of about 20 m as the limit, even in a coastal deep water area with a water depth of 50 m as a standard. Further, according to the present invention, it is possible to measure the flow of a plurality of layers below the sea surface (for example, upper layer, middle layer, lower layer). Further, according to the present invention, the sea level is time-averaged and smoothed or band-passed using the sea level to measure the tide level off the coast (conventional measurements were limited to berthing points) and various long cycles. Can measure waves (tsunami, secondary vibration, etc.). In this way, being able to measure multiple coastal marine events at the same station at the same time is essentially an essential condition for measuring and analyzing phenomena that are inextricably linked to each other, but in reality. This technology has been regarded as impossible in the past, and the present invention clarified the actual condition of coastal sea conditions for the first time, including planning and design of marine facilities and structures, coastal disaster prevention, and investigation of the causes of disasters. As basic data for environmental surveys, it makes it possible to constantly acquire and provide effective and appropriate observation data for elucidation and statistical analysis of previously unknown and unsolved coastal marine phenomena.

[Simple explanation of drawings]

[Figure 1]

FIG. 1 is a circuit diagram of a sea elephant meter (Doppler wave meter) according to the present invention.

[Figure 2]

FIG. 2 (a) is a plan view of the transmitter / receiver shown in FIG. 1, and FIG. 2 (b) is a cross-sectional view of the AOA in FIG. 2 (a).

[Fig. 3]

FIG. 3 is a plan view showing another embodiment of the transmitter / receiver shown in FIG.

[Fig. 4]

FIG. 4 shows the trigger pulse Tr shown in FIG.₁ It is a figure which shows.

[Fig. 5]

FIG. 5 is an explanatory diagram showing the generation of a complex signal by an analog circuit.

[Explanation of symbols]

1 Transmission / reception section 2 Measuring unit 2A sea level fluctuation measurement circuit 2B Flow velocity fluctuation measurement circuit 2C signal processing circuit 3 Calculation unit 10 Transmitter / receiver 11 Transmission / reception circuit for sea level measurement 12 Transmission / reception circuit for flow velocity measurement 13 Switching circuit