JP6732249B2 - Tide meter - Google Patents

Description

The present invention relates to a tidal current meter that measures the velocity of a tidal current at a predetermined depth in water such as the sea, lake, and river.

A tidal current meter that transmits an ultrasonic beam in water and measures the velocity of the tidal current at that depth based on the Doppler shift frequency of the reflected wave reflected from a scatterer in a water body at a predetermined depth is known. (For example, Patent Document 1). A tidal current meter, for example, when throwing a net into a water from a ship, confirms that there are no two or three tidal currents that change significantly depending on the depth of the water. Used to measure speed. This is because if the nets are thrown in where there are two or three tidal tides, the nets will not be fully deployed and the catch will decrease.

A conventional tidal current meter, for example, transmits four ultrasonic beams from the transducer in the front-rear direction and the left-right direction of the ship when the water surface is viewed from above, and measures the measurement target in each direction in which the ultrasonic beams are transmitted. A transducer receives a reflected wave returning from a scatterer (such as plankton) in a water mass located at a certain depth. The tidal current meter calculates the velocity of the tidal current at the depth to be measured based on the Doppler shift frequency of each reflected wave received in each direction. As described above, in the conventional tidal current meter, the velocity of the tidal current is calculated based on the reflected waves of the ultrasonic beams transmitted in different directions.

JP-A-3-12557

By the way, the bottom of the water such as the seabed, the bottom of the lake, and the bottom of the river is not flat, but has undulations. As a result, in each direction in which the ultrasonic beam is transmitted, when an attempt is made to receive a reflected wave returning from a scatterer in a water body located at the depth to be measured, the ultrasonic beam transmitted in some directions However, it may trap a shallow water bottom. If the velocity of the tidal current is calculated using the reflected wave of the ultrasonic beam that has captured the shallow water bottom, there is a possibility that a large error will occur in the calculated velocity of the tidal current.

On the other hand, in Patent Document 1, the depth (water depth) of the water bottom in each direction in which the ultrasonic beam is transmitted is measured in advance, and the velocity of the tidal current at a depth shallower than the shallowest depth of the water bottom is measured. However, this has a problem that the velocity of the tidal current at the desired depth cannot be calculated.

The present invention has been made to solve the above problems, and provides a tidal current meter capable of presenting the velocity of a tidal current to a user with a small error while enabling the velocity of the tidal current at a desired depth to be calculated. To aim.

In order to achieve this object, the tidal current meter according to claim 1 is mounted on a ship and measures the speed of tidal current around the ship at a depth to be measured, and transmits ultrasonic waves into the water. Then, the transducer that can receive the reflected wave and the ultrasonic wave are transmitted by the transducer in a plurality of directions, and the reflected wave of the ultrasonic wave is received by the transducer in each direction in which the ultrasonic wave is transmitted. Based on the received signal based on the reflected wave received in each direction by the control of the transmission/reception control unit, the transmission/reception control unit to control the Doppler shift frequency of the reflected wave from the depth in each direction. Based on the deriving means for deriving each, the Doppler shift frequency of the reflected wave in each direction derived by the deriving means, a calculating means for calculating the velocity of the tidal current at the depth, and the calculating means An output unit that outputs the velocity of the tidal current, a determination unit that determines the reception intensity of the reflected wave in each of the directions received by the vibrator, and a maximum intensity among the reception intensities determined by the determination unit And a minimum intensity is larger than a first predetermined value, the invalidation means for invalidating the calculation of the velocity of the tidal current by the calculation means based on the reflected wave whose reception intensity is determined. ..

A tidal current meter according to a second aspect is the tidal current meter according to the first aspect, wherein the invalidating means has a difference between the maximum intensity and the minimum intensity among the respective reception intensities judged by the judging means. When it is larger than the value, the calculation of the speed of the tidal current by the calculation means based on the reflected wave whose reception intensity is determined is not executed, thereby invalidating the calculation of the speed of the tidal current by the calculation means. To do.

The tidal current meter according to claim 3 is the tidal current meter according to claim 1, wherein the nullification means has a difference between the maximum strength and the minimum strength among the respective reception strengths judged by the judgment means. If the received intensity is larger than the value, the output of the speed of the tidal current calculated by the calculating means based on the reflected wave determined by the output means is not executed, so that the tidal current by the calculating means is not executed. The calculation of the speed of is invalid.

The tidal current meter according to claim 4 is the tidal current meter according to any one of claims 1 to 3, wherein the invalidating means of the output means invalidates the calculation of the velocity of the tidal current by the calculating means. In this case, the information indicating that the calculation of the velocity of the tidal current is invalid is output.

A tidal current meter according to a fifth aspect is the tidal current meter according to the first aspect, wherein the invalidating means has a difference between the maximum intensity and the minimum intensity among the respective reception intensities judged by the judging means. If the received power is greater than the value, the speed of the tidal current calculated by the calculating means based on the reflected wave whose reception intensity is judged is combined with the information indicating that the tidal current speed is invalid by the output means. Output.

The tidal current meter according to claim 6 is the tidal current meter according to any one of claims 1 to 5, wherein the invalidating means further includes a second predetermined value among the reception intensities determined by the determining means. Even if there is a large one, the calculation of the speed of the tidal current by the calculation means based on the reflected wave whose reception intensity is determined is invalidated.

The tidal current meter according to claim 7 is the tidal current meter according to any one of claims 1 to 6, wherein the invalidating means further has a third minimum intensity among the reception intensities determined by the determining means. Even when it is smaller than the predetermined value, the calculation of the velocity of the tidal current by the calculation means based on the reflected wave whose reception intensity is judged is invalid.

The tidal current meter according to claim 8 is the tidal current meter according to any one of claims 1 to 7, wherein the transmission/reception control means invalidates the calculation of the tidal current velocity by the calculation means by the invalidation means. In the case where the ultrasonic waves are transmitted, the plurality of directions for transmitting and receiving the ultrasonic waves are changed.

According to the tidal current meter of claim 1, when the velocity of the tidal current around the ship at the depth to be measured is measured, the transducer transmits ultrasonic waves in a plurality of directions, and each ultrasonic wave is transmitted. The transmission/reception control means controls so that the reflected wave from the scatterer or the like in the direction is received by the transducer. Then, the deriving unit derives the Doppler shift frequency of the reflected wave from the depth to be measured in each direction based on the received signal based on the reflected wave received in each direction. Based on the Doppler shift frequency of the reflected wave in each direction, the velocity of the tidal current at the depth to be measured is calculated by the calculation unit and output by the output unit. Here, the reception intensity of the reflected wave in each direction received by the vibrator is determined by the determination means. When the difference between the maximum intensity and the minimum intensity among the respective reception intensities judged by the judging means is larger than the first predetermined value, the tidal current of the tidal current by the calculating means based on the reflected wave whose reception strength is judged. The speed calculation is invalidated by the invalidation unit. As a result, even if ultrasonic waves in some directions among ultrasonic waves transmitted in multiple directions are captured by the shallow water bottom and reflected, and the reflected wave is received by the transducer, its reception intensity is measured. Since the received intensity of the reflected wave from the scatterer existing at the target depth becomes extremely large, the invalidation means invalidates the calculation of the tidal current velocity in such a case. Therefore, it is possible to calculate the speed of the tidal current at a desired depth and to present the user with the speed of the tidal current having a small error.

According to the tidal current meter of claim 2, in addition to the effect of the tidal current meter of claim 1, the following effect is achieved. That is, when the difference between the maximum intensity and the minimum intensity among the respective reception intensities judged by the judging means is larger than the first predetermined value, the speed of the tidal current by the calculating means based on the reflected wave whose reception strength is judged. Since the calculation of is not executed by the invalidation unit, the calculation of the speed of the tidal current by the calculation unit is invalidated. As a result, when there is a possibility that a large error is included in the calculated tidal current speed, the tidal current speed is not calculated, so only the tidal current speed with less error can be presented to the user, and unnecessary calculation is possible. There is an effect that it is possible to suppress the processing related to.

According to the tidal current meter of claim 3, in addition to the effect of the tidal current meter of claim 1, the following effect is achieved. That is, when the difference between the maximum intensity and the minimum intensity among the reception intensities determined by the determination means is larger than the first predetermined value, the reception intensity is calculated by the calculation means on the basis of the determined reflected wave. The output of the tidal current speed output means is made non-executed by the invalidation means, and the calculation of the tidal current speed by the calculation means is invalidated. As a result, when there is a possibility that the calculated tidal current velocity includes a large error, the calculated tidal current velocity is not output, so that only the tidal current velocity with less error can be presented to the user. There is.

According to the tidal current meter of claim 4, in addition to the effect of the tidal current meter of any of claims 1 to 3, the following effect is achieved. That is, when the invalidation means invalidates the calculation of the tidal current velocity by the calculation means, the output means outputs information indicating that the tidal current velocity calculation has been invalidated. This has the effect of making it possible for the user to grasp the fact that the calculation of the velocity of the tidal current is invalid.

According to the tidal current meter of claim 5, in addition to the effect of the tidal current meter of claim 1, the following effect is achieved. That is, when the difference between the maximum intensity and the minimum intensity among the reception intensities determined by the determination means is larger than the first predetermined value, the reception intensity is calculated by the calculation means on the basis of the determined reflected wave. Together with the speed of the tidal current, the invalidating means outputs information indicating that the speed of the tidal current is invalid from the output means. This indicates to the user that the velocity of the tidal current is invalid for the velocity of the tidal current that may include a large error, so present it to the user so that the velocity of the tidal current with less error can be known. There is an effect that you can.

According to the tidal current meter of claim 6, in addition to the effect of the tidal current meter of any of claims 1 to 5, the following effect is achieved. That is, even if the received intensity of each reflected wave determined by the determination means is larger than the second predetermined value, the velocity of the tidal current calculated by the calculated means based on the reflected wave whose received intensity is determined. The calculation is invalidated by the invalidation means. This makes it possible to determine the presence of reflected waves that may have been reflected from the bottom of the water in at least a part of the directions of the ultrasonic waves transmitted in a plurality of directions. Therefore, even if the difference between the maximum intensity and the minimum intensity of the received intensity of the reflected wave in each direction is smaller than the first predetermined value, the velocity of the tidal current based on the reflected wave that may have been reflected from the bottom of the water The calculation can be invalidated. Therefore, there is an effect that the velocity of the tidal current at a desired depth can be calculated and the velocity of the tidal current with a small error can be presented to the user.

According to the tidal current meter of claim 7, in addition to the effect of the tidal current meter of any of claims 1 to 6, the following effect is achieved. That is, even when the minimum intensity is smaller than the third predetermined value among the reception intensities of the reflected waves determined by the determination means, the tidal current velocity calculated by the calculation means based on the reflected waves whose reception intensity is determined. The calculation is invalidated by the invalidation means. As a result, the reception intensity of the reflected waves of the ultrasonic waves is weak in at least some directions among the ultrasonic waves transmitted in a plurality of directions, and as a result, even if the tidal current velocity cannot be calculated accurately, the invalidation means This invalidates the calculation of the tidal velocity. Therefore, there is an effect that the velocity of the tidal current having a small error can be more reliably presented to the user.

According to the tidal current meter of claim 8, in addition to the effect of the tidal current meter of any of claims 1 to 7, the following effect is achieved. That is, when the calculation of the velocity of the tidal current by the calculation means is invalidated by the invalidation means, the transmission/reception control means changes the plurality of directions for transmitting/receiving ultrasonic waves. As a result, it is possible to increase the possibility of transmitting and receiving ultrasonic waves in a direction in which the tidal current velocity can be calculated accurately, and thus there is an effect that the tidal current velocity with a small error can be presented to the user as quickly as possible.

It is a schematic diagram showing roughly the composition of the tidal current meter which is a 1st embodiment of the present invention. It is a schematic diagram which shows the state at the time of measuring the speed of the tidal current in water from the side surface with the ship equipped with the tidal current meter. FIG. 3 is a schematic diagram of a perspective view of a state in which the velocity of tidal current is measured by a ship equipped with a tidal current meter. It is sectional drawing which showed the cross section of the wave transmission/reception unit typically. It is the block diagram which showed the electric constitution of the tidal current meter. It is a flow chart which shows the tidal current measurement processing performed by the control device. It is a flow chart which shows the tidal current measurement processing performed by the control device of the tidal current meter which is a 2nd embodiment. It is a flow chart which shows the tidal current measurement processing performed by the control device of the tidal current meter which is a 3rd embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. First, an outline of the tidal current meter 12 according to the first embodiment, which is an embodiment of the present invention, will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic diagram schematically showing the configuration of the tidal current meter 12, and FIG. 2 shows a side view of a state in which the velocity of the underwater tidal current is measured by a ship 11 equipped with the tidal current meter 12. FIG. 3 is a schematic diagram, and FIG. 3 is a schematic diagram perspectively showing a state in the case of performing the same measurement.

The tidal current meter 12 is mounted on the ship 11 as shown in FIGS. 1 to 3, and measures the speed (speed and direction) of the tidal current around the ship 11 at a depth in water set by the user. .. The tidal current meter 12 can measure not only the tidal current in the sea but also the speed of the water flow in water in a lake, a pond, a river, or the like. The tidal current meter 12 is characterized in that the tidal current velocity at a desired depth can be calculated and the tidal current velocity with a small error can be presented to the user. The details will be described below.

The tidal current meter 12 includes a main body 13, operation buttons 14 provided on the main body 13, a display device 15 integrally formed on the main body 13, and a transducer 31 (see FIG. 4) for transmitting and receiving the ultrasonic beam TB. The wave unit 16 and an elevating device 17 for elevating the wave transmitting/receiving unit 16 are included. The main body 13 is arranged in the steering room of the ship 11, and the wave transmission/reception unit 16 and the lifting device 17 are arranged in the bottom of the ship 11.

The operation button 14 is a button that can be operated by the user, and is operated when the user makes various settings for the tidal current meter 12. For example, the depth at which the tidal current is measured (hereinafter referred to as “analysis depth”) is set by the user using the operation button 14. A plurality of analysis depths can be set. When a plurality of analysis depths are set, the tidal current velocity is measured at each analysis depth.

The wave transmission/reception unit 16 is vertically moved by the elevating/lowering device 17 so that the wave transmission/reception unit 16 can be retracted into and out of the water from the bottom of the ship 11. When measuring the velocity of the tidal current at the set analysis depth, the tidal current meter 12 drives the elevating device 17 to cause the wave transmission/reception unit 16 to project from the bottom of the ship 11, and to transmit a thin beam ultrasonic wave from the wave transmission/reception unit 16. The beam TB is transmitted (emitted). The tidal current meter 12 receives the reflected wave of the ultrasonic beam TB reflected from the scatterer G such as plankton in the transmission direction of the ultrasonic beam TB by the transmission/reception unit 16.

The wave transmission/reception unit 16 is configured by an all-round sonar, and the azimuth angle δ (scan angle, see FIG. 3) and the depression angle θ (tilt angle, see FIG. 2) of the ultrasonic beam TB transmitted and received by the wave transmission/reception unit 16. ) And can be changed.

Here, the azimuth angle δ (scan angle) is an angle representing the transmission/reception direction of the ultrasonic beam TB when the water surface on which the ship 11 floats is viewed from above. In the present embodiment, when the water surface is viewed from above, the time of transmitting and receiving the ultrasonic beam TB in the forward direction of the ship 11 (the direction in which the ship 11 is moving forward and the bow direction) is 0 degree, and the transmission and reception of the ultrasonic beam TB is performed. The magnitude of the azimuth angle δ is defined so that the azimuth angle δ increases as the direction changes clockwise of the ship 11.

In addition, the depression angle θ (tilt angle) is an angle formed by the transmitting/receiving direction of the ultrasonic beam TB and the water surface (horizontal surface) on which the ship 11 floats. The depression angle θ is defined as 0 degree, and the depression angle θ increases so that the transmission/reception direction of the ultrasonic beam TB increases from the horizontal surface to the direction perpendicular to the horizontal surface.

When measuring the velocity of the tidal current, the tidal current meter 12 drives the transmitting/receiving unit 16 to transmit the ultrasonic beam TB in four orthogonal directions, and the ultrasonic beam TB transmitted in each direction from the scatterer G is transmitted. The reflected wave is received by the transmission/reception unit 16. For example, the tidal current meter 12 sets the depression angle θ of the ultrasonic beam TB to a predetermined angle (for example, 60°) and sequentially sets the azimuth angle δ to 0°, 90°, 180°, 270°, The ultrasonic beam TB is transmitted in each direction (4 directions).

Then, the tidal current meter 12 transmits the reflected wave of the ultrasonic beam TB reflected from the scatterer G or the like in the water mass to the transmission/reception unit 16 in the ultrasonic beam TB transmitted in each direction in each direction. To receive. The tidal current meter 12 derives the Doppler shift frequency of the reflected wave reflected from the analysis depth in each of the received reflected waves, and calculates the velocity of the tidal current at the analysis depth based on the derived Doppler shift frequency.

The tidal current meter 12 calculates the speed of the tidal current based on the Doppler shift frequency of the ultrasonic beam TB transmitted/received in a plurality of directions (four directions in the present embodiment), so that the tidal current speed and the direction (vector) are calculated. I can figure it out. In the present embodiment, the ultrasonic beam TB is transmitted and received in four directions to calculate the tidal velocity, but the ultrasonic beam TB transmitted and received to calculate the tidal velocity may be transmitted in two or more directions. Good.

In this way, when the speed of the tidal current at the analysis depth set by the operation button 12 is calculated, the calculated speed is used as other information (for example, the analysis depth, the speed of the ship 11, the water depth under the ship 11). , Water temperature, etc.) and is displayed to the user.

Although the details will be described later, the azimuth angle δ of the ultrasonic beam TB in the transmission/reception direction is not necessarily fixed to 0°, 90°, 180°, 270°. Based on the received intensity of the reflected wave of the received ultrasonic beam TB in each direction, there is a possibility that the reflected wave from the analysis depth in at least some directions is not the scatterer G but the shallow water bottom. When it is determined, or when it is determined that the scatterer G existing at the analysis depth in at least a part of the directions may not be supplemented, the reflected wave is used to increase the velocity of the tidal current to be calculated. When there is a possibility that an error is included, the azimuth angle δ of the ultrasonic beam TB in the four directions to be transmitted is maintained at a different angle (for example, 45°) while maintaining the intervals (orthogonal relationship) in the four directions. , 135°, 225°, 315°). As a result, it is possible to transmit and receive the ultrasonic beam TB in a direction in which the tidal current velocity can be accurately calculated, so that the tidal current velocity with less error can be presented to the user as quickly as possible.

Further, in the present embodiment, when the velocity of the tidal current is measured, the depression angle θ of the ultrasonic beam TB is set to a predetermined angle. However, at this time, the depression angle θ may be set to a fixed angle or the velocity of the tidal current may be set. The depression angle θ of the ultrasonic beam TB may be set according to the depth to be measured (analysis depth). For example, when the analysis depth is shallow, the depression angle θ of the ultrasonic beam TB may be set small, and when the analysis depth is deep, the depression angle θ of the ultrasonic beam TB may be set large.

In this way, by setting the depression angle θ of the ultrasonic beam TB according to the analysis depth, when measuring the tidal velocity at a deep position, the ultrasonic beam TB can reach a deep position while the ultrasonic beam TB can reach a deep position. When measuring the velocity of the tidal current, by setting the depression angle θ of the ultrasonic beam TB small, it is possible to lengthen the time (distance) until the ultrasonic beam TB reaches the depth to be measured. Therefore, the frequency analysis width necessary for measuring the pulse width and the Doppler shift frequency of the ultrasonic beam TB can be set long, so that it is possible to prevent the frequency resolution from deteriorating even when measuring the velocity of the tidal current in the shallow field. it can. Further, the velocity resolution itself can be improved by setting the depression angle θ of the ultrasonic beam TB small. As a result, it is possible to accurately measure the speed of the tidal current not only at a deep place but also at a shallow place.

Next, a detailed configuration of the wave transmission/reception unit 16 will be described with reference to FIG. FIG. 4 is a sectional view schematically showing a section of the wave transmitting/receiving unit 16. The wave transmission/reception unit 16 includes a bottomed cylindrical lower case 21 having an upper end opened and a lower end hemispherical, a lidded cylindrical upper case 22 having an opened lower end and a disk-shaped upper end, and an upper case. It is configured by a disk-shaped lid 23 that closes the lower end opening of 22 and the upper end opening of the lower case 21. An upper storage space 24 is formed by the upper surface of the lid 23 and the upper case 22, and a lower storage space 25 is formed by the lower surface of the lid 23 and the lower case 21.

A through hole 26 is formed in the center of the lid body 23. A scan motor 27 formed of a stepping motor is fixed to the central portion of the lid 23, and an output shaft 27a of the scan motor 27 is rotatably inserted into the through hole 26 from the lower surface of the scan motor 27. It extends right below. The tip (lower end) of the output shaft 27a reaches the upper part of the lower storage space 25.

A disc-shaped support plate 28 is provided at the tip of the output shaft 27a, and the central portion of the upper surface of the support plate 28 is connected to the tip of the output shaft 27a. A support frame 29 having a substantially inverted U shape is provided on the lower surface of the support plate 28, and a horizontally extending rotary shaft 30 is rotatably provided between lower ends of the support frame 29.

A vibrator 31 that transmits a thin beam ultrasonic beam TB in one direction and can receive a reflected wave of the transmitted ultrasonic beam TB is fixed to the center of the rotating shaft 30. A substantially semicircular tilt gear 32 is fixed to a position adjacent to the vibrator 31 on the rotary shaft 30, and the rotary shaft 30, the vibrator 31 and the tilt gear 32 are configured to rotate integrally with each other. Has been done.

A tilt motor 33 formed of a stepping motor is fixed to the upper end of the support frame 29. The tilt motor 33 includes an output shaft 33a extending toward the tilt gear 32 side. A small gear 33b is provided at the tip of the output shaft 33a, and the small gear 33b meshes with the tilt gear 32.

When the scan motor 27 is driven, the output shaft 27a rotates, and accordingly, the support plate 28, the support frame 29, and the rotation shaft 30 integrally rotate about the output shaft 27a as an axis. The oscillator 31 fixed to the shaft also rotates about the output shaft 27a.

Accordingly, the transmission direction of the ultrasonic beam TB by the vibrator 31 can be changed clockwise or counterclockwise when the water surface on which the ship 11 floats is viewed from above. That is, by driving the scan motor 27, the azimuth angle δ (scan angle) of the ultrasonic beam TB transmitted by the transducer 31 is changed.

On the other hand, when the tilt motor 33 is driven, the output shaft 33a rotates, the small gear 33b rotates accordingly, and the tilt gear 32 meshing with the small gear 33b rotates, so that the tilt gear 32 is fixed. The rotating shaft 30 thus rotated rotates in accordance with the rotation of the tilt gear 32, and the vibrator 31 fixed to the rotating shaft 30 rotates about the rotating shaft 30.

As a result, the depression angle θ (tilt angle), which is the angle formed by the direction in which the oscillator 31 faces (the transmitting direction of the ultrasonic beam TB transmitted from the oscillator 31) and the water surface (horizontal plane) on which the ship 11 floats, is the tilt motor. It is changed by driving 33.

Next, the electrical configuration of the tidal current meter 12 will be described with reference to FIG. FIG. 5 is a block diagram showing the electrical configuration of the tidal current meter 12. The main body 13 (see FIG. 1) of the tidal current meter 12 has a control device 50. The control device 50 controls the operation of the tidal current meter 12. As shown in FIG. 5, the control device 50 includes a CPU (Central Processing Unit) 51, a ROM (Read Only Memory) 52, and a RAM (Random Access Memory) 53, which are connected via a bus line 55. Connected to the input/output port 54.

To the input/output port 54, the operation buttons 14, the display device 15, and the elevating device 17 that constitute the tidal current meter 12 are connected. Further, the scan motor 27 and the tilt motor 33 (see FIG. 4) that form the wave transmission/reception unit 16 are connected to the input/output port 54 via the motor driver 61, and the transducer 31 (see FIG. 4) transmits/receives data. It is connected to the input/output port 54 via the circuit 62.

The CPU 51 is an arithmetic unit that executes various calculations for controlling the operation of the tidal current meter 12 according to the program data 52a stored in the ROM 52, and executes, for example, the tidal current measurement processing shown in FIG. Details of the tidal current measurement processing will be described later with reference to FIG.

The ROM 52 is a non-rewritable non-volatile memory for storing the program data 52a executed by the CPU 51 and also for storing fixed value data and the like. A rewritable non-volatile memory (for example, a flash memory) may be used instead of the non-rewritable ROM.

The RAM 53 is a rewritable volatile memory and temporarily stores various data when the CPU 51 executes the program. The RAM 53 stores at least analysis depth data 53a, maximum value data 53b, minimum data 53c, and tidal current data 53d.

The analysis depth data 53a is data relating to the analysis depth set by the user. In this embodiment, a plurality of analysis depths can be set for the analysis depth data 53a. For example, when the user sets the analysis depth to 20 m, 40 m, 60 m, and 80 m, data indicating that the set analysis depth is 20 m, 40 m, 60 m, and 80 m is stored in the RAM 53 as the analysis depth data 53a. .. The CPU 51 executes a process of measuring the velocity of the tidal current with respect to the analysis depth indicated by the analysis depth data 53a.

Immediately after the power of the tidal current meter 12 is turned on, data indicating a predetermined analysis depth (for example, data indicating analysis depths of 10 m, 20 m, 30 m, and 40 m) is stored in the RAM 53 as an initial value of the analysis depth data 53 a. .. Therefore, when the analysis depth is not set by the user, the tidal current velocity is measured at the analysis depth indicated by this initial value.

When the power of the tidal current meter 12 is turned off, the value of the analysis depth data 53a is stored in a flash memory or the like provided separately, and when the power of the tidal current meter 12 is turned on, it is stored in the flash memory or the like. The calculated value may be stored in the RAM 53 as the analysis depth data 53a. As a result, even when the power is once turned off, the analysis depth previously set by the user is directly set in the analysis depth data 53a, so that the analysis depth once set by the user need not be set again. You can

The maximum value data 53b is each reflection reflected from the scatterer G existing at the analysis depth set by the analysis depth data 53a for each ultrasonic beam TB transmitted in a plurality of directions (four directions in this embodiment). It is data indicating the magnitude of the received intensity of the reflected wave having the highest received intensity among the waves. The minimum value data 53c is data indicating the magnitude of the received intensity of the reflected wave having the smallest received intensity among the reflected waves.

When the CPU 51 executes the tidal current measuring process, the ultrasonic beam TB is transmitted in four directions and the reflected wave of the ultrasonic beam TB is received in each direction in order to measure the velocity of the tidal current. For each of the received reflected waves, the reception intensity of the reflected wave reflected from the scatterer G existing at the analysis depth set by the analysis depth data 53a is determined. The magnitude of the reception intensity of the reflected wave having the highest reception intensity is stored in the RAM 53 as the maximum value data 53b, and the magnitude of the reception intensity of the reflected wave having the lowest reception intensity is the minimum value data 53c. Is stored in the RAM 53 as

The maximum value data 53b and the minimum value data 53c are used to determine whether or not the water bottom existing near the analysis depth is supplemented in at least a part of the directions of the ultrasonic beam TB transmitted in the four directions. Used. The reception intensity of the reflected wave of the ultrasonic beam TB reflected from the bottom of the water is extremely higher than the reception intensity of the reflection of the ultrasonic beam TB reflected from the scatterer G. Therefore, when it is determined that the difference between the maximum value data 53b and the minimum value data 53c is larger than a predetermined value (first threshold value), in some directions of the ultrasonic beam TB transmitted in four directions. , It is judged that the water bottom existing near the analysis depth is supplemented. In this case, even if the velocity of the tidal current is calculated using the reflected waves in these four directions, a large error is included in the calculated velocity of the tidal current. Therefore, in the present embodiment, in these four directions. The calculation of the tidal current velocity based on the reflected wave is not executed.

Even when it is determined that the maximum value data 53b is larger than the predetermined value (second threshold value), in at least a part of the directions of the ultrasonic beams TB transmitted in the four directions, the water bottom existing near the analysis depth is Since it was supplemented, it is determined that the reception intensity of the reflected wave has increased. The second threshold value is a value for determining whether or not the reception intensity of the reflected wave is the reception intensity from the bottom of the water (bottom intensity). Thereby, for example, when the water bottom is supplemented in all directions, the water bottom which is not detected by the difference between the maximum value data 53b and the minimum value data 53c and which is present in the vicinity of the analysis depth in at least some directions is supplemented. The case can be detected by comparing the maximum value data 53b with the second threshold value. Also in this case, even if the velocity of the tidal current is calculated using the reflected waves of these four directions, the velocity of the tidal current cannot be calculated correctly. Therefore, in the present embodiment, the velocity of the tidal current based on the reflected waves of these four directions. Is not executed.

The minimum value data 53c is also used to determine whether or not the received intensity of the reflected wave is extremely weak in at least a part of the directions of the ultrasonic beam TB transmitted in the four directions. To be That is, when the minimum value data 53c is smaller than the predetermined value (third threshold value), it is determined that the reception intensity of the reflected wave is extremely weak in at least some directions. In this case, it is difficult to derive a Doppler shift frequency with a small error, and as a result, there is a high possibility that a large error will be included in the speed of the tidal current to be calculated. The calculation of the tidal current velocity based on is not executed.

When a plurality of analysis depths are set for the analysis depth data 53a, the magnitude of the reception intensity of the reflected wave having the highest reception intensity among the reflected waves reflected from the deepest analysis depth is set. The data shown is set as the maximum value data 53b, and the data showing the magnitude of the received intensity of the reflected wave having the smallest received intensity is set as the minimum value data 53b. The reason will be described later.

The tidal current data 53d is data indicating the calculated tidal current velocity. When the ultrasonic beam TB is transmitted/received in four directions by the CPU 51 and the tidal current velocity is calculated based on the Doppler shift frequency of the reflected wave from the analysis depth in each direction, data indicating the calculated tidal velocity is obtained. It is stored in the RAM 53 as the tidal current data 53d. The CPU 51 displays the measured tidal current velocity on the display device 81 based on the tidal current data 53d stored in the RAM 53. If the velocity of the tidal current is not calculated based on the values of the maximum value data 53b and the minimum value data 53c because a large error is included, the tidal current data 53d is not overwritten, and at the preceding tidal current measurement timing, it is large. The data indicating the velocity of the tidal current, which is determined to include no error and is effectively calculated, is directly stored in the tidal current data 53d. Therefore, the data indicating the effectively calculated flow velocity is continuously displayed on the display device 81.

Next, with reference to FIG. 6, details of the tidal current measurement processing executed by the control device 50 will be described. FIG. 6 is a flowchart showing the tidal current measuring process. The tidal current measurement process is started by the CPU 51 when the power is turned on or when the tidal current velocity measurement is started. The tidal current measurement process is continuously executed until the power is turned off or until the tidal current velocity measurement is completed by the user operating the operation button 14 or the like.

In the power flow measurement process, first, the lifting device 17 is driven to lower the wave transmission/reception unit 16 (S11). As a result, the transmission/reception unit 16 is projected into the water from the bottom of the ship 11, and the ultrasonic beam TB can be transmitted and received by the transducer 31.

Next, it is determined whether or not it is the time to measure the power flow (S12). Specifically, in the process of S12, it is determined whether or not a predetermined time (for example, 1 second) has elapsed since it was previously determined that the power flow measurement timing was reached in the process of S12, and it is determined that the predetermined time has elapsed. When it is determined that the power flow measurement timing has come (S12: Yes). Further, when the process of S12 is executed for the first time after the power flow measurement process is executed, it is determined that the process of S12 has reached the power flow measurement timing (S12: Yes). In other cases, the process of S12 is determined to have not reached the power flow measurement timing (S12: No), and the process of S12 is repeatedly executed until it is determined that the power flow measurement timing has been reached (S12: Yes). It Thereby, the tidal current is measured (measured) at predetermined time intervals.

When it is determined by the process of S12 that the power flow measurement timing has come (S12: YES), first, the transmission direction of the ultrasonic beam TB to be transmitted to measure the power flow is set (S13). Specifically, the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ in four directions for transmitting the ultrasonic beam TB are set, and the depression angle θ of the ultrasonic beam TB is set. In the processing of S13, for example, the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ of the ultrasonic beam TB are set to 0°, 90°, 180°, and 270°, respectively, and the depression angle θ is set to 60°. ..

In the process of S13, when the process of S13 is executed for the first time after the power flow measurement process is executed (that is, when the power flow measurement timing comes for the first time), the azimuth angles δ ₁ , δ ₂ , δ ₃ , δ ₄ is set to 0°, 90°, 180°, and 270°, respectively, and thereafter, every time the process of S13 is executed, it is determined that a large error is not included in the power flow measurement timing immediately before that, and it is effective. The azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ of the ultrasonic beam TB for which the velocity of the tidal current can be calculated may be set as they are.

Although the details will be described later, in the tidal current measurement processing, when the reflected wave of the ultrasonic beam TB transmitted in four directions is used to calculate the velocity of the tidal current and it is determined that a large error is included, the ultrasonic wave is detected. The azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ of the beam TB are changed (see S26), and the ultrasonic beam TB is transmitted and received again in four directions. The azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ of the ultrasonic beam TB for which it was determined that a large error was not included in the immediately preceding tide measurement timing and the velocity of the tide could be calculated effectively were processed in S13. By setting as it is, it is possible to increase the possibility of calculating the velocity of the tidal current that does not include a large error even at the current tidal current measurement timing.

However, in this case, it is determined that even if the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ of the ultrasonic beam TB are changed at the immediately preceding tidal current measurement timing, a large error is included in the calculated tidal velocity. When it is done, it can happen. In such a case, in the process of S13, the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ of the ultrasonic beam TB finally set at the immediately preceding tidal current measurement timing may be set as they are, The initial values of the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ may be set to 0°, 90°, 180°, and 270°, respectively.

Further, in the processing of S13, the depression angle θ need not always be fixed and set to 60°, and as described above, the depression angle θ of the ultrasonic beam TB is set according to the analysis depth indicated by the analysis vibration data 53a. You may do it. For example, when the deepest analysis depth among a plurality of set analysis depths is at a shallow position, the depression angle θ of the ultrasonic beam TB is set small, and when the deepest analysis depth is at a deep position, the depression angle of the ultrasonic beam TB is set. You may set large (theta). As a result, as described above, it is possible to accurately measure the velocity of the tidal current not only in a deep place but also in a shallow place.

Next, the tilt motor 33 is driven via the motor driver 61 so that the ultrasonic beam TB is transmitted and received at the depression angle θ set by the process of S13 (S14). As a result, the transducer 31 is rotated about the rotation axis 30 (see FIG. 4), and the depression angle θ of the ultrasonic beam TB transmitted and received from the transducer 31 can be set to the depression angle θ set by the process of S13. it can.

Next, while driving the scan motor 28 via the motor driver 61, the transducer 31 sequentially transmits/receives ultrasonic beams TB in four directions via the transmission/reception circuit 62 (S15). Specifically, in the process of S15, first, the scan motor 28 is driven to rotate the transducer 31 about the output shaft 27a (see FIG. 4), and the ultrasonic beam TB transmitted and received from the transducer 31 is transmitted. The azimuth angle δ is δ ₁ . Then, the ultrasonic beam TB is transmitted from the transducer 31 in the direction of the depression angle θ and the azimuth angle δ ₁ , and the reflected wave of the ultrasonic beam TB transmitted in that direction is received by the transducer 31. The received signal based on the received reflected wave is temporarily stored in the RAM 53.

Next, in the process of S15, the scan motor 28 is driven to set the azimuth angle δ of the ultrasonic beam TB transmitted and received from the transducer 31 to δ ₂ . Then, similarly to the case where the azimuth angle δ is δ ₁ , the ultrasonic beam TB is transmitted from the transducer 31 in the direction of the depression angle θ and the azimuth angle δ ₂ , and the reflected wave of the ultrasonic beam TB transmitted in that direction is generated. The received signal based on the received reflected wave received by the oscillator 31 is temporarily stored in the RAM 53.

Further, in the processing of S15, the scan motor 28 is driven to set the azimuth angle δ of the ultrasonic beam TB to δ ₃ , and the ultrasonic beam TB is transmitted and received by the transducer 31 in the directions of the depression angle θ and the azimuth angle δ ₃ . The received signal based on the received reflected wave is temporarily stored in the RAM 53. Finally, in the processing of S14, the scan motor 28 is driven to set the azimuth angle δ of the ultrasonic beam TB to δ ₄ , and the ultrasonic beam TB is transmitted and received by the transducer 31 in the directions of the depression angle θ and the azimuth angle δ _4. The received signal based on the received reflected wave is temporarily stored in the RAM 53.

When the process of S15 ends, next, the frequency analysis of the reflected wave from the analysis depth indicated by the analysis depth data 53a is executed for each direction in which the ultrasonic beam TB is transmitted/received, and the Doppler shift frequency in the reflected wave is calculated. It derives (S16). When there are a plurality of analysis depths indicated by the analysis depth data 53a, the frequency analysis of the reflected wave from the corresponding analysis depth is executed for each direction in which the ultrasonic beam TB is transmitted/received for each analysis depth, and the Doppler shift is performed. Derive the frequency.

Next, for each direction in which the ultrasonic beam TB is transmitted/received, the averaging process is executed on the Doppler shift frequency of the reflected wave from the analysis depth indicated by the analysis depth data 53a, which is derived by the process of S16 ( S17). When there are a plurality of analysis depths indicated by the analysis depth data 53a, the averaging process is executed for each Doppler shift frequency derived for each direction in which the ultrasonic beam TB is transmitted and received. By performing the averaging process, fluctuations of the Doppler shift frequency due to noise can be suppressed.

Next, for each of the ultrasonic beams TB transmitted in the four directions, the reflected wave with the highest reception intensity among the reflected waves reflected from the deepest analysis depth among the analysis depths indicated by the analysis depth data 53a is selected. The maximum value search to be performed is executed (S18). The received intensity of the searched reflected wave having the highest received intensity is stored in the RAM 53 as maximum value data 53b.

In addition, for each ultrasonic beam TB transmitted in four directions, the reflected wave with the smallest reception intensity among the reflected waves reflected from the deepest analysis depth among the analysis depths indicated by the analysis depth data 53a is selected. The minimum value search to be performed is executed (S19). The received intensity of the reflected wave having the smallest received intensity searched for is stored in the RAM 53 as the minimum value data 53c.

The difference between the maximum value of the reception intensity of the reflected waves in the four directions indicated by the maximum value data 53b and the minimum value of the reception intensity of the reflected waves in the four directions indicated by the minimum value data 53c is the first threshold value. It is determined whether or not the following (S20).

When the reflected waves in some directions are reflected by capturing the shallow water bottom, the received intensity of the reflected waves is much larger than the received intensity of the reflected waves reflected from the scatterer G. Then, when the velocity of the tidal current is calculated using the Doppler shift amount of the reflected wave reflected by capturing the bottom of the water, the Doppler shift frequency is not based on the tidal current, and thus the velocity of the tidal current to be calculated includes a large error. It will be. In the process of S20, the reflected waves in some directions are reflected from the water bottom by determining whether the difference between the maximum value and the minimum value of the reception intensity of the reflected waves in the four directions is less than or equal to the first threshold value. Judge whether or not there has been any.

As a result, if the difference between the maximum value and the minimum value of the reception intensity of the reflected waves in the four directions is less than or equal to the first threshold value (S20: Yes), the process proceeds to S21.

In the processing of S21, it is determined whether or not the maximum value of the reception intensity of the reflected waves in the four directions indicated by the maximum value data 52b is less than or equal to the second threshold value (S21). That is, in the process of S21, it is determined whether or not the reception intensity of the reflected wave received in all the directions in which the ultrasonic beam TB is transmitted and received is smaller than the bottom intensity (second threshold value) when the water bottom is captured. .. Then, as a result of the processing in S21, when it is determined that the maximum value of the reception intensity of the reflected waves in the four directions indicated by the maximum value data 52b is equal to or less than the second threshold value (S21: Yes), the processing in S20. It is determined that the reflected waves in all directions are not reflected from the bottom of the water together with the result of (3), and the process proceeds to S22.

When a plurality of analysis depths are set in the analysis depth data 53a, in the processing of S20 and S21, reception of each reflected wave from the deepest analysis depth in the ultrasonic beam TB transmitted/received in four directions. Based on the strength, the maximum value of the reception strength and the difference between the maximum value and the minimum value will be determined. Then, based on the reception intensity of each reflected wave from the deepest analysis depth, it is determined that the difference between the maximum value and the minimum value of the reception intensity is less than or equal to the first threshold value, and the maximum value of the reception intensity is If it is judged to be equal to or less than 2 thresholds, it can be judged that the water bottom is at a position deeper than the deepest analysis depth. That is, in the processing of S20 and S21, even if the judgment is made using only the reflected wave from the deepest analysis depth, the difference between the maximum value and the minimum value of the reception intensity is less than or equal to the first threshold value and the maximum reception intensity. If it is determined that the value is less than or equal to the second threshold value, it can be determined that the reflected waves in all directions are not reflected from the water bottom for all analysis depths.

In the process of S22, it is determined whether or not the minimum value of the reception intensity of the reflected waves in the four directions, which is indicated by the minimum value data 53c, is the third threshold value or more (S22). If the received intensity of the reflected wave is weak in at least some directions, it is difficult to derive a Doppler shift frequency with a small error, and as a result, the calculated flow velocity may include a large error. Becomes higher. In the processing of S22, by determining whether or not the minimum value of the reception intensity of the reflected waves in the four directions is equal to or greater than the third threshold value, the reflected waves in the four directions include those with a weak reception intensity. Judge whether or not.

As a result, if the minimum value of the reception intensity of the reflected waves in the four directions is greater than or equal to the third threshold value (S22: Yes), it is determined that the received intensity of the reflected waves in all directions has a certain level.

By the processing of S20 and S21, it is determined that the reflected waves in all directions are not reflected from the bottom of the water, and by the processing of S22, it is determined that the reception intensity of the reflected waves in all directions has a certain level. If it is (S20: Yes, S21: Yes, S22: Yes), even if the tidal current velocity is calculated using the Doppler shift frequency of these reflected waves, there is a possibility that the tidal current velocity may include a large error. Can be judged to be small.

Therefore, in this case, the Doppler shift frequencies of the reflected waves in the four directions, which are derived in the process of S16 and are subjected to the averaging process in the process of S17, are used for each of the analysis depths indicated by the analysis depth data 53a. Then, the velocity of the tidal current at the analysis depth is calculated (S23). Specifically, first, from the Doppler shift frequencies of the reflected waves from the analysis depths in each of the four directions in which the ultrasonic beam TB is transmitted and received, the four directions, that is, the depression angle θ and the azimuth angle δ _m (m=1, 2, 3, 4) and the velocity component v _m of the tidal current in each of the four directions are calculated.

The velocity v _m of the tidal current calculated here is calculated by the reflected wave of the ultrasonic beam TB having the depression angle θ and the azimuth angle δ _m, and the velocity v _{m of} the tidal current thus calculated is the depression angle θ _m . It is a component indicated by the directions of θ and the radiation azimuth δ _m . On the other hand, the azimuth angle δ ₁ and the azimuth angle δ ₃ are different by 180°, and the tidal current velocities v ₁ and v ₃ calculated based on the ultrasonic beam TB transmitted and received according to the directions have the same direction. It becomes a vector. For the same reason, the power flow velocities v ₂ and v ₄ are also vectors having the same direction.

Therefore, the velocity v ₁₃ that is the average value of the tidal current velocities v ₁ and v ₃ is calculated, and the velocity v ₂₄ that is the average value of the tidal current velocities v ₂ and v ₄ is calculated. The tidal current velocity v ₁₃ calculated here is the component indicated by the direction of the depression angle θ and the azimuth angle δ _1, and the tidal current velocity v ₂₄ is the component indicated by the direction of the depression angle θ and the azimuth angle δ _2. ..

In the processing in S23 in order to determine the speed of the tidal current flowing parallel to the water surface (horizontal plane), with respect to the two directions of power flow velocity v ₁₃ and v _24, each following formula (1) and ( The depression angle is corrected according to 2), and the component v _n ′ in the direction indicated by the depression angle 0° (horizontal direction) of the velocity of the tidal current and the corresponding azimuth angle δ _n (n=1, 2) is calculated.

v ₁ ′=v ₁₃ /cos θ (1)
v ₂ ′=v ₂₄ /cos θ (2)
Then, vector components of the calculated velocity components v _n ′ of the tidal currents are calculated to calculate the velocity (velocity and direction) of the tidal currents at the analysis depth. In the process of S23, data indicating the calculated speed of the tidal current is stored in the RAM 53 as tidal current data 53d.

When the velocity of the tidal current is calculated in the process of S23, the velocity of the tidal current calculated for the analysis depth is displayed on the display device 15 in association with the calculated analysis depth of the tidal current (S24). ). Then, returning to the processing of S12, when the power flow measurement timing comes again, the processing of S13 and thereafter is executed.

On the other hand, as a result of the process of S20, when the difference between the maximum value and the minimum value of the reception intensity of the reflected waves in the four directions is larger than the first threshold value (S20: No), the reflected waves in some directions are bottomed. It is judged that there is something reflected from. That is, in this case, even if the velocity of the tidal current is calculated using the reflected waves in the four directions received in the process of S15, it is highly possible that the calculated velocity of the tidal current includes a large error. Therefore, in this case, the process proceeds to S25, the calculation of the tidal current velocity which is the process of S23 is not executed, and the computation of the tidal current velocity is invalidated. Therefore, it is possible to suppress the presentation of the tidal current velocity including a large error to the user. Further, in this case, the calculation of the speed of the tidal current itself is not executed, so that it is possible to suppress unnecessary calculation processing.

Further, as a result of the processing of S21, when the maximum value of the reception intensity of the reflected waves in the four directions is larger than the second threshold value (S21: No), at least a part of the ultrasonic beams TB transmitted in the four directions is detected. It is determined that the reception intensity of the reflected wave in the direction is larger than the second threshold value and that the bottom of the water existing near the analysis depth is supplemented. That is, also in this case, since the tidal current velocity cannot be correctly calculated using the reflected waves in the four directions received in the process of S15, the process proceeds to S25, and the tidal current velocity that is the process of S23 is not calculated. As an execution, the calculation of the velocity of the tidal current is invalidated. Therefore, it is possible to suppress the presentation of the tidal current velocity including a large error to the user, and since the tidal current velocity calculation itself is not executed, unnecessary calculation processing is executed. Can be suppressed.

Further, as a result of the processing in S22, when the minimum value of the reception intensity of the reflected waves in the four directions is smaller than the third threshold value (S22: No), the reception intensity of the reflected waves is weak in at least some directions. To be judged. In other words, in this case, even if the velocity of the tidal current is calculated using the reflected waves in the four directions received in the process of S15, it is difficult to derive the Doppler shift frequency with a small error, and thus the tidal current to be calculated is calculated. There is a high possibility that the speed of will include a large error. Therefore, in this case as well, the process proceeds to S25, the calculation of the tidal current velocity which is the process of S23 is not executed, and the computation of the tidal current velocity is invalidated. Therefore, it is possible to suppress the presentation of the tidal current velocity including a large error to the user.

As described above, when a plurality of analysis depths are set in the analysis depth data 53a, in the processing of S20, each reflected wave from the deepest analysis depth in the ultrasonic beam TB transmitted/received in four directions. The magnitude of the difference between the maximum value and the minimum value of the reception intensity and the magnitude of the maximum value based on the reception strength of the, the difference between the maximum value and the minimum value is larger than the first threshold value, Alternatively, when it is determined that the maximum value is larger than the second threshold value, calculation of the tidal current velocity at all analysis depths is invalidated. Further, in the processing of S22, the minimum value of the reception intensity is the third threshold value or more based on the reception intensity of each reflected wave from the deepest analysis depth in the ultrasonic beam TB transmitted/received in four directions. If it is determined that the calculation of the tidal current velocity at all analysis depths is invalid.

That is, in the present embodiment, if there is a large error in the calculated tidal current velocity at least at some of the analysis depths, the tidal current velocity calculation is invalid for all of the analysis depths. As a result, the velocity of the tidal current is presented to the user only when the velocity of the tidal current is effectively calculated at all analysis depths. Therefore, the tidal current meter 12 of the present embodiment does not allow the user to determine, for each analysis depth, whether or not the tidal current velocity calculated for that analysis depth is valid, The user can confirm only the tidal current velocity calculated effectively at all analysis depths without confusion.

When the calculation of the speed of the tidal current is invalidated by the processing of S20, S21, or S22 (S20: No, S21: No or S22: No), the processing proceeds to S25, and the calculation of the tidal speed has a large error. The power flow velocity calculation invalid information indicating that the power flow velocity calculation is invalid because it may be included is displayed on the display device 15 (S25).

The tidal current velocity calculation invalid information is, for example, a graphic with an exclamation mark (!) in a triangle, a rhombus, or a circle, or another graphic, or a character such as "measurement invalid" or "measurement impossible". Is displayed in one of the areas. Further, the tidal current velocity calculation invalid information displays the velocity of all the tidal currents displayed on the display device 15 in a color different from the normal time (for example, the tidal current velocity normally displayed in green is displayed in red). ) May be shown. By displaying the power flow velocity calculation invalidation information on the display device 15, the user can be made aware of the fact that the calculation of the power flow velocity is invalid.

After the processing of S25, the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ in the four directions for transmitting the ultrasonic beam TB are maintained while maintaining the relationship in which the azimuth angles are orthogonal (that is, 90°). The angle is reset so that the angle is different from the angle set so far (S26). Then, the process returns to S15, and the processes after S15 are repeated.

As a result, the ultrasonic beams TB are transmitted and received in four directions at the new azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ reset by the process of S25, and the velocity of the tidal current at each analysis depth is calculated again. Done. By changing the azimuth angle of the ultrasonic beam TB transmitted/received in the four directions, it becomes possible to avoid the shallow water bottom that has been supplemented and to obtain the reception intensity of the reflected wave of the ultrasonic beam TB to a certain extent. There is a possibility that Therefore, it is possible to increase the possibility that the ultrasonic beam TB can be transmitted and received in a direction in which the tidal current velocity can be accurately calculated, and therefore, the tidal current velocity with a small error can be presented to the user as quickly as possible.

As a method for resetting the azimuth angles δ ₁ , δ ₂ , δ ₃ , δ ₄ of the ultrasonic beam TB in the process of S26, for example, the azimuth angles δ ₁ , δ ₂ , δ ₃ , δ that have been set up to that point can be used. _A predetermined angle (for example, 10°) is added to each of the _four . That is, the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ are changed by a predetermined angle (10°). As a result, it is possible to increase the possibility that the ultrasonic beam TB can be transmitted and received in a direction in which the velocity of the tidal current can be accurately calculated without significantly moving the vibrator 31. Therefore, by moving the oscillator 31, it is possible to suppress the possibility that the oscillator 31 and the scan motor 27 that changes the azimuth angle of the ultrasonic beam TB transmitted and received by the oscillator 31 are likely to fail.

In the resetting method of changing the azimuth angle by the predetermined angle (10°), the azimuth angle δ ₁ is reset, so that the azimuth angle δ ₁ is 90° or more than the azimuth angle δ ₁ set by the process of S13. If the large angles, azimuth angle [delta] ₁ 4 direction set in the processing in _{S13, δ 2, δ 3,} δ 4 and azimuth [delta] ₁ for 4 direction has been re-set to thereby of _S26, [delta] _The ultrasonic beam TB is transmitted/received to/from the same area as the transmission/reception area of the ultrasonic beam TB transmitted/received by ₂ , δ ₃ , δ ₄ .

The ultrasound in this case, the azimuth angle [delta] ₁ far, [delta] _2, [delta] _3, even though has been reconfigured [delta] _4, in which the azimuth angle _{δ 1, δ 2, δ 3} , are transmitted and received [delta] ₄ Since the calculation of the velocity of the tidal current based on the beam TB has been invalidated, even if the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ are reset thereafter, the velocity of the tidal current with a small error can be calculated. Unlikely. Therefore, in this case, the processing relating to the calculation of the tidal current may be temporarily suspended until the timing of the tidal current measurement is reached again from the processing of S26 to the processing of S12. As a result, even if the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ are reset, if it is determined that it is unlikely that the velocity of the tidal current with a small error can be calculated, the same area is wasted many times. By transmitting and receiving the ultrasonic beam TB to and from the transducer 31, it is possible to suppress the possibility that the oscillator 31 and the scan motor 27 that changes the azimuth angle of the ultrasonic beam TB transmitted and received by the oscillator 31 are likely to fail.

Further, as another method of resetting the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ of the ultrasonic beam TB in the process of S26, the tidal current measurement timing is set in the process of S12, and the azimuth is set in the process of S13. Only after the angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ are set (hereinafter, δ ₁₀ , δ ₂₀ , δ ₃₀ , and δ ₄₀ having the azimuth angles set by the process of S13), the process of S26 is executed. If so, first, δ ₁ is reset to δ ₁₀ +45°, δ ₂ is reset to δ ₂₀ +45°, δ ₃ is reset to δ ₃₀ +45°, and δ ₄ is reset to δ ₄₀ +45°. Reset to °.

Even if the resetting invalidates the calculation of the tidal current velocity and the process of S26 is executed again, δ ₁ is reset to δ ₁₀ +67.5° and δ ₂ is set to δ ₂₀ +67.5°. Reset and reset δ ₃ to δ ₃₀ +67.5° and δ ₄ to δ ₄₀ +67.5°. Even if the resetting invalidates the calculation of the tidal current velocity and the process of S26 is executed for the third time, δ ₁ is reset to δ ₁₀ +78.75°, and δ ₂ is δ ₂₀ +78.75. 0, reset δ ₃ to δ ₃₀ +78.75°, and δ ₄ to δ ₄₀ +78.75°.

If the resetting also invalidates the calculation of the velocity of the tidal current and the process of S26 is executed for the fourth time, δ ₁ is reset to δ ₁₀ +56.25°, and δ ₂ is δ ₂₀ +56.25. 0, reset δ ₃ to δ ₃₀ +56.25°, and δ ₄ to δ ₄₀ +56.25°. If the calculation of the velocity of the tidal current is invalidated by this resetting and the process of S26 is executed for the fifth time, δ ₁ is reset to δ ₁₀ +22.5°, and δ ₂ is δ ₂₀ +22.5. 0, reset δ ₃ to δ ₃₀ +22.5°, and δ ₄ to δ ₄₀ +22.5°. Even if the resetting invalidates the calculation of the tidal current velocity and the process of S26 is executed for the sixth time, δ ₁ is reset to δ ₁₀ +33.75°, and δ ₂ is δ ₂₀ +33.75. 0, reset δ ₃ to δ ₃₀ +33.75°, and δ ₄ to δ ₄₀ +33.75°. Even if the resetting invalidates the calculation of the tidal current velocity and the process of S26 is executed for the seventh time, δ ₁ is reset to δ ₁₀ +11.25°, and δ ₂ is δ ₂₀ +11.25. , Δ ₃ to δ ₃₀ +11.25° and δ ₄ to δ ₄₀ +11.25°. Even if the resetting invalidates the calculation of the tidal current velocity and the process of S26 is executed for the eighth time, the process shifts from the process of S26 to the process of S12 until the timing of the tidal current is measured again. The process related to the calculation of the tidal current is once interrupted.

With this method, by resetting the azimuth angles δ ₁ , δ ₂ , δ ₃ , and δ ₄ of the ultrasonic beam TB, the velocity of the tidal current can be accurately calculated while greatly changing the transmitting and receiving directions of the ultrasonic beam TB. Since the transmission/reception direction of the ultrasonic beam TB can be searched, it is possible to increase the possibility that the transmission/reception direction of the ultrasonic beam TB whose speed of the tidal current can be accurately calculated can be quickly found.

As described above, according to the tidal current meter 12 in the first embodiment, when the velocity of the tidal current at the analysis depth indicated by the analysis depth data 53a is measured, the transducer 31 causes the ultrasonic beam TB to travel in a plurality of directions ( The transducer 31 receives the reflected wave from the scatterer G in each direction in which the ultrasonic beam TB is transmitted in the four directions in the present embodiment). Then, by the processing of S16, frequency analysis is performed on the reflected wave received in each direction, and the Doppler shift frequency of the reflected wave from the analysis depth is derived. Then, based on the Doppler shift frequency of the reflected wave in each direction, the velocity of the tidal current at the analysis depth is calculated by the process of S23, and the calculated velocity of the tidal current is displayed on the display device 15.

On the other hand, the reception intensity of the reflected wave in each direction received by the vibrator 31 is determined by the process of S20. Then, when the difference between the maximum intensity and the minimum intensity among the respective reception intensities is larger than the first threshold value (S20: No), the calculation of the velocity of the tidal current based on the reflected wave whose reception intensity is judged is not executed. And is invalidated. As a result, even if the ultrasonic waves in some directions of the ultrasonic beams TB transmitted in a plurality of directions capture and reflect the shallow water bottom and the reflected waves are received by the transducer 31, the reception intensity thereof. Becomes extremely large as compared with the reception intensity of the reflected wave from the scatterer G existing at the analysis depth, and in such a case, the calculation of the tidal current velocity is invalidated by the processing of S20. Therefore, the velocity of the tidal current at a desired depth can be calculated, and the velocity of the tidal current with a small error can be presented to the user.

Also, by the processing of S21, even when the maximum intensity is higher than the second threshold value among the reflected waves (S21: No), the calculation of the velocity of the tidal current based on the reflected wave whose reception intensity is determined is not executed. And is invalidated. Accordingly, it is possible to determine the presence of a reflected wave that may have been reflected from the water bottom in at least some directions of the ultrasonic beam TB transmitted in a plurality of directions. Therefore, even if the difference between the maximum intensity and the minimum intensity of the received intensity of the reflected wave in each direction is smaller than the first predetermined value, the velocity of the tidal current based on the reflected wave that may have been reflected from the bottom of the water The calculation can be invalidated. Therefore, the velocity of the tidal current at a desired depth can be calculated, and the velocity of the tidal current with a small error can be presented to the user.

Further, by the processing of S22, even when the minimum intensity among the received intensities of the reflected waves is smaller than the third threshold value (S22: No), the velocity of the tidal current is calculated based on the reflected waves whose received intensity is determined. Is not executed and is disabled. As a result, the reception intensity of the reflected wave of the ultrasonic beam TB is weak in at least a part of the ultrasonic beams TB transmitted in a plurality of directions, and as a result, when the velocity of the tidal current cannot be calculated accurately. However, the calculation of the speed of the tidal current is invalidated. Therefore, the velocity of the tidal current with less error can be more reliably presented to the user.

Further, when the difference between the maximum intensity and the minimum intensity among the respective reception intensities is larger than the first threshold value by the process of S20, the maximum intensity among the respective reception intensities is larger than the second threshold value by the process of S21. In the case where the minimum intensity is smaller than the third threshold among the reception intensities by the process of S22, the calculation of the speed of the tidal current is not performed by the process of S23 based on the reflected wave whose reception intensity is determined. Therefore, the calculation of the velocity of the tidal current is invalidated. In other words, when there is a possibility that a large error is included in the calculated tidal current speed, the tidal current speed is not calculated, so that only the tidal current speed with less error can be presented to the user and the unnecessary tidal current speed can be presented. Execution of the calculation process of can be suppressed.

Further, when the calculation of the tidal current velocity by the processing of S23 is not executed by the processing of S20, the processing of S21, or the processing of S22, and the computation of the tidal current velocity is invalid, the calculation of the tidal current velocity is performed. The power flow velocity calculation invalid information indicating that the power flow velocity has been invalidated is displayed on the display device 15. This allows the user to grasp the fact that the calculation of the tidal current velocity is invalid.

Further, when the calculation of the tidal current velocity by the processing of S23 is not executed and the computation of the tidal current velocity is invalid by the processing of S20, the processing of S21, or the processing of S22, the ultrasonic beam TB is transmitted and received. The azimuth angles of the plurality of directions are changed by the process of S26. As a result, it is possible to increase the possibility of transmitting and receiving the ultrasonic beam TB at an azimuth angle at which the velocity of the tidal current can be accurately calculated, so that the velocity of the tidal current with less error can be presented to the user as quickly as possible.

Next, the tidal current meter 12 according to the second embodiment will be described with reference to FIG. 7. FIG. 7 is a flowchart showing the tidal current measuring process executed by the controller 50 of the tidal current meter 12 according to the second embodiment.

The tidal current meter 12 in the first embodiment has a large tidal current velocity calculated from the received intensity of each reflected wave of the ultrasonic beam TB transmitted and received in four directions by the processing of S20 to S22 based on the reflected wave. When it is determined that an error is included, the calculation of the speed of the tidal current (S23) is not executed, and the calculation of the speed of the tidal current is invalidated.

On the other hand, the tidal current meter 12 according to the second embodiment calculates the tidal current calculated from the reception intensity of each reflected wave of the ultrasonic beam TB transmitted and received in four directions based on the reflected wave by the processing of S20 to S22. If it is determined that the velocity of the tide includes a large error, the velocity of the tide is calculated, but the velocity of the tide is calculated by hiding the calculated velocity of the tide on the display device 15. The calculation is invalid.

The configuration of the tidal current meter 12 according to the second embodiment is different from the tidal current meter 12 according to the first embodiment in that a part of the tidal current measurement processing executed by the control device 50 is different from that of the tidal current meter 12 according to the first embodiment. Is the same as Hereinafter, the tidal current meter 12 according to the second embodiment will be described focusing on the differences from the tidal current meter 12 according to the first embodiment, and the same components as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted. Omit it.

As shown in FIG. 7, in the tidal current measurement processing executed by the controller 50 of the tidal current meter 12 according to the second embodiment, by the frequency analysis of the processing of S16, each of the analysis depths indicated by the analysis depth data 53a is super-measured. In each of the four directions in which the acoustic beam TB is transmitted, the Doppler shift frequency of the reflected wave from the corresponding analysis depth is derived, and in the processing of S17, the Doppler shift derived in each direction for each analysis depth. When the averaging process is performed on the frequency, the tidal current calculated based on the reflected waves from the reception intensity of each reflected wave of the ultrasonic beam TB transmitted and received in the four directions by the processes of S18 to S22. Before determining whether the velocity includes a large error, the velocity of the tidal current at the analysis depth is calculated for each analysis depth using the Doppler shift frequencies of the reflected waves in the four directions for which the averaging process has been performed. Calculate (S31). The processing of S31 is the same as the processing of S23 (see FIG. 6) of the tidal current measurement processing executed by the controller 50 of the tidal current meter 12 of the first embodiment.

Then, by the processing of S20 and S21, it is determined that the reflected waves in all directions are not reflected from the water bottom, and by the processing of S22, the reception intensity of the reflected waves in all directions has a certain level. If it is determined (S20: Yes, S21: Yes, S22: Yes), it can be determined that the velocity of the tidal current calculated using the Doppler shift frequencies of these reflected waves is unlikely to include a large error. .. Therefore, in this case, the process proceeds to S24, and the velocity of the tidal current calculated by the process of S31 is displayed on the display device 15 in association with the analysis depth at which the velocity of the tidal current is calculated (S24).

On the other hand, as a result of the process of S20, when the difference between the maximum value and the minimum value of the reception intensity of the reflected waves in the four directions is larger than the first threshold value (S20: No), the reflected waves in some directions are bottomed. Even if it is determined that there is something reflected from the tide and the velocity of the tidal current is calculated, it is highly possible that the calculated velocity of the tidal current includes a large error. Therefore, in this case, the process proceeds to S25, and the calculation of the power flow velocity is invalidated by not displaying the calculated power flow velocity in the process of S24. Therefore, it is possible to suppress the presentation of the tidal current velocity including a large error to the user.

In addition, as a result of the processing in S21, when the maximum value of the reception intensity of the reflected waves in the four directions is larger than the second threshold value (S22: No), the reflected waves reflected in at least a part of the directions from the bottom of the water are There is a high possibility that it will not be possible to correctly calculate the tidal current speed. Therefore, also in this case, the process proceeds to S25, and the calculation of the power flow velocity is invalidated by not executing the display of the calculated power flow velocity in the process of S24. Therefore, it is possible to suppress the presentation of the tidal current velocity including a large error to the user.

Further, as a result of the processing in S22, when the minimum value of the reception intensity of the reflected waves in the four directions is smaller than the third threshold value (S22: No), the reception intensity of the reflected waves is weak in at least some directions. There is a high possibility that a large error will be included in the speed of the tidal current that is determined and calculated. Therefore, also in this case, the process proceeds to S25, and the calculation of the power flow velocity is invalidated by not executing the display of the calculated power flow velocity in the process of S24. Therefore, it is possible to suppress the presentation of the tidal current velocity including a large error to the user.

As described above, according to the tidal current meter 12 in the second embodiment, when the difference between the maximum intensity and the minimum intensity among the respective reception intensities is larger than the first threshold value by the process of S20, the process of S21 causes If the maximum intensity is higher than the second threshold value among the respective reception intensities, or if the minimum intensity is lower than the third threshold value among the respective reception intensities by the processing of S22, the reception intensity is judged. Since the speed of the tidal current calculated based on the wave is hidden, the calculation of the speed of the tidal current is invalidated. That is, when there is a possibility that a large error is included in the calculated tidal current velocity, the calculated tidal current velocity is not displayed, and therefore only the tidal current velocity with less error can be presented to the user.

In addition, the tidal current meter 12 in the second embodiment has the same effect as the first embodiment because of the same configuration.

Next, the tidal current meter 12 according to the third embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing the tidal current measuring process executed by the control device 50 of the tidal current meter 12 according to the third embodiment.

The tidal current meter 12 according to the second embodiment is configured such that the tidal current meter 12 according to the second embodiment reflects the reflection intensity of each reflected wave of the ultrasonic beam TB transmitted and received in four directions by the processing of S20, S21, and S22. When it is determined that the tidal current velocity calculated based on the waves includes a large error, the calculated tidal current velocity is hidden on the display device 15 to invalidate the tidal current velocity calculation. And

On the other hand, the tidal current meter 12 in the third embodiment calculates from the reception intensity of each reflected wave of the ultrasonic beam TB transmitted and received in four directions based on the reflected wave by the processing of S20, S21, and S22. When it is determined that the velocity of the tidal current to be generated includes a large error, the calculated velocity of the tidal current is displayed on the display device 15, while indicating that the displayed velocity of the tidal current is invalid. Displaying the tidal velocity invalid information invalidates the tidal velocity calculation.

The configuration of the tidal current meter 12 according to the third embodiment is different from the tidal current meter 12 according to the second embodiment in that a part of the tidal current measurement processing executed by the control device 50 is different from that of the tidal current meter 12 according to the second embodiment. Is the same as Hereinafter, the tidal current meter 12 according to the third embodiment will be described focusing on the points different from the tidal current meter 12 according to the second embodiment, and the same components as those in the second embodiment will be denoted by the same reference numerals and the description thereof will be omitted. Omit it.

As shown in FIG. 8, in the tidal current measurement processing executed by the controller 50 of the tidal current meter 12 according to the third embodiment, as a result of the processing of S20, the maximum value and the minimum value of the reception intensity of the reflected waves in the four directions are shown. Is larger than the first threshold value (S20: No), the result of the processing of S21 is that the maximum value of the reception intensity of the reflected waves in the four directions is larger than the second threshold value (S21: No), S22. When the minimum value of the reception intensity of the reflected waves in the four directions is smaller than the third threshold value as a result of the processing of (S22: No), that is, the velocity of the tidal current calculated in S31 includes a large error. When it can be determined that there is a high possibility that the process is performed, the process of S41 is executed instead of the process of S24.

In the process of S41, the tidal current velocity calculated in the process of S31 is displayed on the display device 15 in association with the analysis depth in which the tidal current velocity is calculated, while the tidal current velocity invalid information is also displayed on the display device 15. Yes (S41). The tidal current invalid information is, for example, a triangle, a rhombus, a figure with an exclamation mark (!) in a circle, another figure, or a character such as "measurement invalid" or "measurement impossible" in the display device 15. Displayed in either area. Further, the tidal current velocity invalid information displays the velocity of all the tidal currents displayed on the display device 15 in a color different from the normal time (for example, the tidal current velocity normally displayed in green is displayed in red). It may be displayed depending on the situation. The fact that the tidal current velocity invalid information is displayed on the display device 15 causes the fact that the velocity of the tidal current calculated and displayed on the display device 15 may include a large error and is invalid, Can be grasped. After the processing of S41, the processing shifts to the processing of S26.

As described above, according to the tidal current meter 12 in the third embodiment, when the difference between the maximum intensity and the minimum intensity among the respective reception intensities is larger than the first threshold value by the process of S20, the process of S21 causes If the maximum intensity is higher than the second threshold value among the respective reception intensities, or if the minimum intensity is lower than the third threshold value among the respective reception intensities by the processing of S22, the reception intensity is judged. By the process of S41, the tidal current velocity invalid information indicating that the tidal current velocity is invalid is displayed on the display device 15 together with the tidal current velocity calculated in the process of S31 based on the wave. This indicates to the user that the velocity of the tidal current is invalid for the velocity of the tidal current that may include a large error, so present it to the user so that the velocity of the tidal current with less error can be known. it can.

In addition, the tidal current meter 12 according to the third embodiment has the same configuration as that of the second embodiment and exhibits the same effect.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be easily made without departing from the spirit of the present invention. It can be guessed. For example, each of the embodiments, by adding a part or a plurality of parts of the configuration of the other embodiment to the embodiment, or by replacing with a part or a plurality of parts of the configuration of the embodiment, The embodiment may be modified and configured. Further, the numerical values mentioned in the above embodiments are examples, and it is naturally possible to adopt other numerical values.

In each of the above-described embodiments, the magnitude of the difference between the maximum value and the minimum value of the reception intensity is determined based on the reception intensity of each reflected wave from the deepest analysis depth among the analysis depths indicated by the analysis depth data 53a. The case has been described in which it is determined that the reflected waves in some directions are reflected from the bottom of the water when the difference is equal to or larger than the first threshold. On the other hand, for all the analysis depths indicated by the analysis depth data 53a, the maximum value and the minimum value of the reception intensity are calculated for each analysis depth based on the reception intensity of each reflected wave from the analysis depth. The magnitude of the difference is determined, and when the difference is equal to or greater than the first threshold, it is determined that the reflected waves in some directions among the reflected waves from the analysis depth are reflected from the water bottom. May be. Then, of the analysis depths indicated by the analysis depth data 53a, if it is determined by the determination that the reflected waves from the analysis depth are not reflected from the water bottom in all directions, based on the reflected waves. The tidal current velocity calculated by the above is displayed on the display device 15 as an effective one, and it is determined that the reflected waves in a part of the reflected waves from the analysis depth are reflected from the bottom of the water by the judgment. In that case, the calculation of the velocity of the tidal current based on the reflected wave from the analysis depth may be invalidated.

Further, in each of the above-described embodiments, the maximum value of the reception intensity is determined based on the reception intensity of each reflected wave from the deepest analysis depth among the analysis depths indicated by the analysis depth data 53a, and the maximum value is determined. The case where it is determined that the reflected waves in at least a part of the directions are reflected from the water bottom when the value is equal to or more than the second threshold value has been described. On the other hand, for all analysis depths indicated by the analysis depth data 53a, the maximum value of the reception intensity is determined for each analysis depth based on the reception intensity of each reflected wave from the analysis depth, When the maximum value is equal to or larger than the second threshold value, it may be determined that the reflected wave in a part of the reflected waves from the analysis depth is reflected from the bottom of the water. Then, of the analysis depths indicated by the analysis depth data 53a, if it is determined by the determination that the reflected waves from the analysis depth are not reflected from the water bottom in all directions, based on the reflected waves. The tidal current velocity calculated by the above is displayed on the display device 15 as an effective one, and it is determined that at least a part of the reflected waves from the analysis depth is reflected from the bottom of the water by the judgment. If it is determined, the calculation of the tidal current velocity based on the reflected wave from the analysis depth may be invalidated.

In this way, it is possible to judge that the tidal current velocity can be calculated effectively according to the analysis depth, even if the tidal current velocity is invalid at other analysis depths. The calculated speed of the tidal current can be presented to the user. Therefore, the user can grasp the effectively calculated velocity of the tidal current even if only a part of the analysis depth is used.

In each of the above embodiments, the minimum value of the reception intensity is determined based on the reception intensity of each reflected wave from the deepest analysis depth among the analysis depths indicated by the analysis depth data 53a, and the minimum value is the third value. The case has been described in which, when the received signal strength is equal to or less than the threshold value, it is determined that the reception intensity is weak, and there is a high possibility that the calculated flow velocity includes a large error. On the other hand, for all analysis depths indicated by the analysis depth data 53a, the minimum value of the reception intensity is determined for each analysis depth based on the reception intensity of each reflected wave from the analysis depth, and When the minimum value is equal to or less than the third threshold value, it may be determined that there is a high possibility that a large error is included in the tidal current velocity calculated for the analysis depth. Then, in the analysis depth indicated by the analysis depth data 53a, when it is determined by the determination that the speed of the tidal current calculated with respect to the analysis depth is not likely to include a large error, the reflected wave The tidal current velocity calculated based on is displayed on the display device 15 as an effective one, and it is determined by the judgment that the tidal current velocity calculated with respect to the analysis depth is likely to include a large error. In this case, the calculation of the tidal current velocity based on the reflected wave may be invalidated. In this way, it is possible to judge that the tidal current velocity can be calculated effectively according to the analysis depth, even if the tidal current velocity is invalid at other analysis depths. The calculated speed of the tidal current can be presented to the user. Therefore, the user can grasp the effectively calculated velocity of the tidal current even if only a part of the analysis depth is used.

In each of the above-described embodiments, one ultrasonic wave transmitting/receiving unit 16 configured by the all-round type sonar is used to transmit/receive the ultrasonic beam TB in four directions while setting the depression angle θ and sequentially changing the azimuth angle δ. The case of applying the present invention has been described. On the other hand, a transmission/reception unit capable of transmitting/receiving the ultrasonic beam TB toward each of the four azimuth angles δ directions (or two or more azimuth angles δ) is provided, and each transmission/reception unit changes the depression angle θ. The present invention can be applied even if the ultrasonic beam TB is transmitted and received.

11 Vessel 12 Tidal current meter 31 Vibrator 15 Display device (output means)
S13 to S15, S26 (transmission/reception control means)
S16 (deriving means)
S20, S21, S22 (determination means)
S20: No, S21: No, S22: No (invalidating means)
S23, S31 (calculation means)
TB ultrasonic beam

Claims (8)

A tidal current meter that is mounted on a ship and that measures the speed of tidal current around the ship at the depth of measurement,
A transducer that transmits ultrasonic waves into the water and can receive the reflected waves,
Transmitting and receiving ultrasonic waves in a plurality of directions by the vibrator, in each direction in which the ultrasonic waves are transmitted, a transmission and reception control means for controlling the reflected wave of the ultrasonic waves to be received by the vibrator,
Derivation means for deriving each of the Doppler shift frequencies of the reflected wave from the depth in each direction, based on the received signal based on the reflected wave received in each direction by the control of the transmission/reception control means,
Based on the Doppler shift frequency of the reflected wave in each of the directions derived by the derivation means, calculating means for calculating the velocity of the tidal current at the depth,
Output means for outputting the velocity of the tidal current calculated by the calculating means,
Determination means for determining the reception intensity of the reflected wave in each of the directions received by the vibrator,
When the difference between the maximum intensity and the minimum intensity among the respective reception intensities judged by the judging means is larger than a first predetermined value, the tidal current by the calculating means based on the reflected wave whose reception strength is judged And a nullifying unit that nullifies the calculation of the speed of the tidal current meter. When the difference between the maximum intensity and the minimum intensity among the respective reception intensities judged by the judging means is larger than the first predetermined value, the invalidating means applies the reflected wave whose reception strength is judged. The tidal current meter according to claim 1, wherein the calculation of the speed of the tidal current based on the calculation means is made non-executable to invalidate the calculation of the speed of the tidal current by the calculation means. When the difference between the maximum intensity and the minimum intensity among the respective reception intensities judged by the judging means is larger than the first predetermined value, the invalidating means applies the reflected wave whose reception strength is judged. 2. The calculation of the speed of the tidal current by the calculating means is invalidated by not executing the output of the speed of the tidal current calculated by the calculating means on the basis of the output means. Tide meter. When the invalidation unit invalidates the calculation of the speed of the tidal current by the invalidation unit, the output unit outputs information indicating that the calculation of the speed of the tidal current has been invalidated. The tidal current meter according to any one of claims 1 to 3. When the difference between the maximum intensity and the minimum intensity among the respective reception intensities judged by the judging means is larger than the first predetermined value, the invalidating means applies the reflected wave whose reception strength is judged. 2. The tidal current meter according to claim 1, wherein the output means outputs the speed of the tidal current calculated by the calculating means together with information indicating that the speed of the tidal current is invalid. The invalidating unit further calculates the reception intensity based on the reflected wave for which the reception intensity is determined, even when the reception intensity determined by the determination unit is greater than a second predetermined value. The tidal current meter according to any one of claims 1 to 5, wherein calculation of the velocity of the tidal current by means is invalidated. The invalidating means further calculates the calculating means based on the reflected wave for which the received intensity is determined even when the minimum intensity is smaller than the third predetermined value among the received intensities determined by the determination means. The tidal current meter according to any one of claims 1 to 6, wherein the calculation of the velocity of the tidal current is invalidated. The transmission/reception control unit changes the plurality of directions for transmitting/receiving the ultrasonic waves when the invalidation unit invalidates the calculation of the velocity of the tidal current by the calculation unit. The tidal current meter according to any one of 1 to 7.

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