JPH0160773B2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) This invention provides that when an ultrasonic wave is transmitted underwater and the ultrasonic wave that is diffusely reflected in the water is received, the time from the sending of the ultrasonic wave to the reception of the ultrasonic wave is The present invention relates to smooth transmission and reception of ultrasonic waves in a method of measuring water temperature based on changes in water temperature.

(Object of the invention) In FIG. 1, when an ultrasonic wave is transmitted from point P in the θ ₁ direction and received at point Q by a receiver having directivity in the θ ₂ direction, θ ₁ and θ ₂ It is possible to receive the ultrasonic waves that are diffusely reflected at the intersection point R. At this time, P
The time it takes for the ultrasonic wave transmitted from a point to be reflected at point R and reach point Q is determined by the propagation speed of the ultrasonic wave, and the propagation speed is influenced by the water temperature in the propagation path PRQ. Therefore, the time it takes for a sound wave transmitted from point P to be reflected at point R and reach point Q,
The propagation speed of the sound wave in the propagation path PRQ is determined based on the propagation distance of the propagation path PRQ calculated from the distance between PQ and the angles θ ₁ and θ ₂ . Therefore, the water temperature in the propagation path PRQ can be determined from the propagation speed.

In the above, since the propagation distance of PRQ is calculated by the distance between PQ and the angles θ ₁ and θ ₂ , the directivity direction of the transmitting beam at point P and the directivity direction of the receiving beam at point Q are exactly θ ₁ and θ ₂ . Unless the directivity angles X ₁ and X ₂ of the transmitted beam and the received beam are made as sharp as possible, the reflected wave from point R cannot be accurately received. Therefore, the transmitting beam and the receiving beam must be arranged so that the pencil-shaped beams with sharp directivity angles intersect at point R.

However, when arranging such a beam,
The directions on the horizontal plane must be matched very precisely, and even if the horizontal directions are slightly shifted, the transmitting beam and the receiving beam cannot intersect at point R.

An object of the present invention is to smoothly transmit and receive ultrasonic signals by devising the beam shape of a transmitting beam or a receiving beam.

(Embodiment of the invention) In FIG. 2, the ultrasonic transmitter Z ₁ is θ ₁ from the point P.
The ultrasonic signal is transmitted in the direction. This transmitting beam
B ₁ has a sharp, pencil-like beam angle.

On the other hand, an ultrasonic receiver _Z2 is installed at point Q, and receives the reflected wave from point R in the same manner as in FIG.
This received beam B ₂ is installed toward the θ ₂ direction.
The directivity angle is sharp in the vertical direction and slightly wide in the horizontal direction.

When transmitting beam B ₁ and receiving beam B ₂ are arranged in this way, transmitting beam B ₁ only needs to be installed so that its horizontal direction falls within the horizontal directivity angle β of receiving beam B ₂ . Reflected waves from a point can be easily received.

Since the vertical directivity angle α of the receiving beam B ₂ is set to an acute angle, the reflection point R is located at the transmitting beam.
Even if the horizontal azimuth of B ₁ is changed within the horizontal directivity angle β of the received beam B ₂ , it only changes slightly in the horizontal direction and does not change in the depth direction.

In general, water temperature has a strong tendency to change in the depth direction, so even if the measurement point changes slightly in the horizontal direction, almost no measurement error occurs. Also, the receiving beam
Since the distance between PQ is sufficiently large compared to the horizontal spread of _B2 , even if the reflection point R changes slightly in the horizontal direction, the change in distance given to the propagation distance PRQ is so small that it can be almost ignored. Therefore, the ultrasonic propagation path PRQ can be accurately calculated based on the distance between PQ and the directivity directions θ ₁ and θ ₂ of the beams B ₁ and B ₂ .

(Effects of the Invention) By slightly widening the horizontal directivity angle of the receiving beam, it is possible to easily cause the transmitting beam and the receiving beam to intersect.

(Other embodiments of the invention) Transmitting beam B ₁ and receiving beam B ₂ in FIG.
may be reversed. In other words, the horizontal directivity angle of the transmitted beam may be slightly widened to give the received beam a sharp, pencil-like directivity characteristic.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of water temperature measurement, and FIG. 2 shows an embodiment of the present invention.

Claims (1)

[Claims] 1. When an ultrasonic wave transmitted into the water from a first point is diffusely reflected in the water and the diffusely reflected reflected wave is received at a second point, the In a method of measuring water temperature based on the fact that the time until wave reception changes depending on the water temperature, a transmission beam that transmits ultrasonic waves from the first point or receives the ultrasonic waves at a second point is used. Water temperature measurement characterized by using one of the receiving beams as a beam with a pencil-like sharp directivity angle, and the other as a beam with a sharp vertical directivity angle and a slightly wide horizontal directivity angle. A method of transmitting and receiving ultrasonic beams used in