JPH0312557A - Ultrasonic tidal current measuring instrument - Google Patents

Abstract

PURPOSE:To always automatically set a tidal current measuring layer of the prescribed depth of water by measuring the depth of water of the sea bottom at every transmission time, deriving the depth of water of the tidal current measuring layer being shallower by a prescribed distance than the depth of water at that time and controlling a gate circuit thereby. CONSTITUTION:An arithmetic circuit 15 calculates the time tau1 extending from transmission to reception of a sea bottom reflecting signal (RBa) of the shallowest depth of water out of the sea bottom reflecting signal. Also, based on the designation from a water depth setting circuit 16, the time tau3 being shorter by a prescribed time tau2 than the depth of water of a necessary tidal current measuring layer in which the time corresponding to the depth of water of the sea bottom at the time of starting the measurement is set as '1', that is, the depth of water of the sea bottom is calculated and stored. At the next time of transmission, when a transmission control signal P1 is inputted from a control part 1, a gate signal g2 of prescribed time width is made by a gate signal generating circuit 17 after the time tau3. Gate circuits 12a - 12d open the gates by prescribed time width by the signal g2, obtain reflecting signals RPa - RPd sent from plankton in the depth of water being always shallower by a prescribed distance H from the signal RBa, out off the reflecting signals obtained through an amplifier and add them to an arithmetic circuit 8.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention automatically makes the depth of the tidal current measurement layer constant with respect to the seabed, thereby reducing the complexity of setting the tidal current measurement layer and the measurement process. This relates to an ultrasonic power flow measurement device that eliminates inaccuracies and impossibilities.

(Prior art and its problems to be solved) A tidal current measuring device based on the following principle using ultrasonic waves is used to create distribution maps of the velocity and direction of tidal currents in the sea.

For example, as shown in FIGS. 1(a) and 2, this device is connected to the bottom of the ship by a transmission drive signal Pg from a transmitting section (2) which is controlled by a transmission control signal P from a control section (1). Four ultrasonic beams S, , S, , S, , St+ are emitted from the installed transducers (3a) and (3b) simultaneously in the diagonal direction of the seabed B in the longitudinal and lateral directions of the ship. Based on these, the reflected wave R2□RPb+ in Figure 3 (a) from plankton floating in the sea.
LCI R□ (only R□ is shown in the figure),
Reflected wave from seabed B in Figure 3 (a) R1r R1b+R
, , R□ (only Rlm is shown in the figure) and converts them into electrical signals. After that, the receiving amplifiers (4a), (4b), (4c), and (4d) shown in Figure 2 are used to amplify each signal to the required level. Using this, the slice circuit (5a) (
5b) (5c) Based on (5d), the seabed reflection signal Rl m + is equal to or higher than the threshold level shown by the broken line in FIG. 3(d).
RIb*Rl. .

Rld is detected, and this causes the gate signal generation circuit (6a
) (6b) (6c) (6d) to control Fig. 3 (
Gate signal g Ia+ g Ib+ g shown in C)
Make let g la. With these gate circuits for acquiring seabed reflected signals (7a) (7b) (7c)
(7a) is opened for a certain period of time, and a seabed reflection signal Rn□R1b+R8°, RI, of a certain time width is extracted for each wave transmission and is added to the arithmetic circuit (8).

On the other hand, the slice circuits (5a) (5b) (5c)
Seafloor reflection signal R1+ R11b+ obtained from (5d)
The comparison circuit (9) compares RIC+Rld and detects the shallowest seabed reflection signal from among them.

Based on this, a gate is controlled by the output signal of a manual water depth setting circuit (10) that manually sets the time from the transmission of the wave corresponding to the water depth of the tidal current measurement layer to the return of the reflected wave from the tidal current measurement layer. The third signal generation circuit (11)
The gate signal g2 shown in figure (b) is generated. These gate circuits (12a) for acquiring reflected signals from plankton, etc.
) (12b) (12c) (12d) are opened by a certain time width, and each wave transmission generates a signal RPa+ RPb+ RPCl R of a certain time width based on reflections from plankton, etc. at a set water depth shallower than the depth of the seabed.
pa is extracted and input to the arithmetic circuit (8).

Then, the arithmetic circuit (8) calculates the seabed reflection signal R[la+Rllb+RIIC+Ra
d and the reflected signal Rl' a r from plankton etc.
Utilizing the fact that the frequency components included in RP b + RP C + RP d change due to the Doppler effect, the transmission control signal P is transmitted from the control unit (1) for each wave transmission.
, the reflected signal RP of plankton etc.
a + RP b + RF C+ RP d to ship speed over water V W a + V W b + ” W
e + V W (l is calculated, and the seabed reflected signal RBa+
RBb+ R□, R□ to ground speed V Ea+ V
Eb+ ■l! (Calculate + V Ed respectively. Then, calculate the difference between the ship's speed against the water and the ship's speed against the ground in the longitudinal and lateral directions, convert it into a vector, and calculate the speed and direction of the tidal current for each wave transmission.) Vectorwise,
It is designed to be displayed on a display device (13).

By the way, when using this device to measure the tidal current in the tidal current measurement layer at a constant water depth as shown by the broken line a in Figure 1 (C), when the water depth of the seabed B becomes shallow, reflected signals from plankton, etc. and the reflected signals from the ocean floor overlap or are very close to each other. For this reason, it is impossible to avoid making the measurement impossible or making the measurement result inaccurate.

Therefore, in such a case, it is necessary to change the water depth setting of the tidal current measurement layer as shown by the broken line in Figure 1 (C).
In the conventional apparatus, this setting is manually performed as described above, and therefore, the setting operation becomes extremely troublesome, especially when the undulations of the seabed are changing rapidly. Therefore, conventional devices have problems that must be solved in terms of measurement operations and maintaining measurement accuracy.

(Objective of the Invention) The present invention aims to solve the above-mentioned problems of conventional devices by automatically setting a tidal current measurement layer at a constant depth that is shallower than the depth of the seabed. be.

(Means of the present invention for solving the problem) In the present invention, the water depth of the seabed is measured every time a wave is transmitted, and from this, the water depth of the tidal current measurement layer that is a certain distance shallower than the seabed depth at that time is determined each time. By controlling the gate circuit,
Automatically always follows changes in the depth of the seabed, and allows reflection signals from plankton and other objects at a shallow depth of a certain distance from the seafloor to be obtained, eliminating the troublesome operation of conventional devices and eliminating the need for seafloor reflection signals and plankton reflections. This is to prevent reflected signals from such sources from overlapping.

Next, the present invention will be explained by examples.

FIG. 4 is a block circuit diagram of one embodiment of the present invention, (
The same reference numerals as in the conventional device shown in FIG. 2 indicate equivalent parts. ) In the figure, (1) is the control section, (2) is the transmission section, (
3a) (3b) is the front-rear and left-right transducer (
4a) (4b) (4c) (4d) is a receiving amplifier,
(5a) (5b) (5c (5d) is a slice circuit,
(6a) (6b) (6c (6d) is a game-l signal generation circuit, (7a) (7b) (7c) (7d) is a gate circuit for acquiring submarine reflected signals, (8) is an arithmetic circuit, (
12a) (12b) (12c) ((12d) is a gate circuit for acquiring reflected signals from plankton etc., (9)
(13) is a comparison circuit, and (13) is a display circuit, the configuration of which is the same as that of the conventional device shown in FIG.

The circuit designated by reference numeral (14) is an automatic water depth setting circuit for a tidal current measurement layer provided for carrying out the present invention, and is formed from the following parts. (15) is an arithmetic circuit, (16) is a water depth setting circuit, and (17) is a gate signal generation circuit.

The arithmetic circuit (15) is connected to the control unit (1) as shown in FIG. 5(a).
and the ultrasonic beams S-, Sb+ SC+ Sd obtained by the comparison circuit (9).
Seabed reflection signal based on Rla+ Rlb+ Rlc+
The seafloor reflection signal at the shallowest depth in Rma, for example, R
From o, calculate the time τ6 from wave transmission to wave reception, that is, the time τ1 corresponding to the depth of the seabed shown in FIG. 5(b),
Furthermore, based on the designation from the water depth setting circuit (16), the water depth of the required tidal current measurement layer is determined by a certain time τ2 from the seabed depth shown in Fig. 5(e), where 1 is the time corresponding to the seabed water depth at the time of starting the measurement. A short time τ3 is calculated and stored.

Then, at the time of next wave transmission, the control unit sends a transmission control signal P,
, the gate signal generating circuit (17) generates a gate signal g2 with a constant time width shown in FIG. 5(d) after a time τ3, and the gate circuit (12a) (12b) ) (12c) (12d)
opens the gate for a certain time width by the gate signal g2, and the receiving amplifiers (4a) (4b) (4c) (4d
), as shown in Fig. 5(e), there is a reflection signal RPa+ from plankton, etc. at a constant distance H from the seafloor reflection signal R11, as shown in Fig. 5(e).
Rrb+Rpc+R□ is obtained (only Ro is shown in the figure) and added to the arithmetic circuit (8).

That is, according to the present invention, it is possible to automatically always obtain reflection signals from plankton and the like at a constant depth shallower than the seabed, regardless of changes in the depth of the seabed, thereby eliminating the drawbacks of the conventional apparatus.

Note that the above circuit may be provided with a manual setting circuit similar to the conventional one so that either automatic or manual setting can be selected.

(Effects of the Invention) As described above, the present invention can automatically set the current measurement layer at a constant depth shallower than the seabed based on water depth information. Therefore, the trouble associated with manual setting operations as in conventional devices, and disadvantages such as measurement errors and inability due to overlap between signals reflected from plankton and the seafloor are eliminated. This is highly effective for measuring tidal currents on the rugged seabed.

Figure 1 Broom 3

[Brief explanation of drawings]

Figures 1, 2 and 3 are explanatory diagrams of the conventional device;
FIG. 5 is an explanatory diagram of an embodiment of the present invention.

Claims (1)

[Claims] From among the reflected signals based on ultrasonic beams emitted diagonally towards the seabed in the front and back and left and right directions, a gate circuit extracts the seabed reflection signals with a certain time width and the reflection signals from plankton, etc. at a set required water depth, respectively. In an ultrasonic tidal current measurement device that calculates and displays the speed and direction of tidal currents by adding these to an arithmetic circuit, it includes a circuit that measures the depth of the ocean floor when the ultrasonic beam is transmitted, and a circuit that measures the water depth of the ocean floor at a desired fixed distance from this ocean floor depth signal. a circuit for obtaining a shallow water depth signal, and a circuit that is controlled by this water depth signal and extracts a reflected signal from plankton, etc. at a water depth shallower than the seabed depth by a predetermined distance from among the reflected signals from the plankton, etc. during the next wave transmission. An ultrasonic tidal current measuring device characterized by being provided with.