JPS6365895B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring water temperature in a predetermined depth underwater using ultrasonic waves.

This invention utilizes the phenomenon that an ultrasonic beam radiated into water generates volume reverberant echoes at all of its passing points. Conventionally, it is known that there is a device that utilizes this phenomenon and detects the echo and extracts the Doppler component contained therein to measure the tidal current speed and the like. That is, the echo has a level that is sufficiently detectable.

Hereinafter, the present invention will be explained based on examples.

Figure 1 shows the basic principle for water temperature measurement, in which 1 is a ship, 2 and 3 are ultrasonic transmitters and It is a sound wave receiver. The wave transmitter 2 and the wave receiver 3 are configured so that each pointing direction can be continuously varied by electronic or mechanical means, and the pointing directions are both on the same plane. In addition, the transmitter 2 and the receiver 3 are equipped with a narrow directional beam and a high frequency (for example,
200kHz) is preferred.

Now, as shown in the figure, wave transmission and reception are performed in directions of directivity angles θ and θ+Δθ (where Δθ is a minute angle). This will be explained geometrically below. For the sake of explanation, the position of the transmitter 2 will be referred to as point A, and the position of the receiver 3 will be referred to as point C.

(1) First process Sound waves are transmitted in the AB direction. At this time, the directivity direction of the receiver 3 is set to the CB direction.
Therefore, only the volume reverberation echo at point B of the transmitted sound wave is received by the receiver 3. In other words, the time t ₁ required from wave transmission to wave reception is the time the sound wave travels ABC
This is the time required to pass through.

(2) Second process Sound waves are transmitted in the AB' direction. At this time, the directivity direction of the receiver 3 is set in the CB' direction.
Therefore, only the volume reverberation echo at point B' of the transmitted sound wave is received by the receiver 3. That is,
The time t ₂ required from sending to receiving waves is the time the sound wave travels.
This is the time required to pass AB′C.

(3) Third process In the above and figures, AB=AD ₁ , BC=D ₂ C
Therefore, the time required for the sound wave to pass through the path D ₁ B′D ₂ is expressed as t ₂ −t ₁ .

By the way, the above D ₁ B′D ₂ , that is, 2D ₁ B′, is l=
AC, θ=∠ACB=∠CAB, θ+Δθ=∠ACB′=
It can be obtained from ∠CAB′ as follows.

That is, AB=l/2cosθ=BC, AB'=l/2cos(θ+Δθ)=B'C, so 2D ₁ B'=2(AB'-AB)=l(1/cos(θ+Δθ)
- 1/cosθ) ...(1) Also, the sound velocity v at T℃ in seawater is from the experimental formula: v(T) = 1448.6 + 4.618T (m/s) Therefore, 2D ₁ B' = (t ₂ - t ₁ ) (1448.6 + 4.618T) ...(2) If we rearrange this regarding T, we get (1),
From equation (2), T=1/4.618{l/t ₂ −t ₁ (1/cos(θ+Δθ)−
1/cosθ) −1448.6} (3)

The above was derived from the fact that since the distance between BB' is relatively short (Δθ is minute), the water temperature between BB' can be regarded as constant, and the depth L is 1/2 (l /2tan(θ+Δθ)+l/2tanθ)=l
It can be expressed as /4(tan (θ+Δθ)+tanθ)...(4).

It should be noted that since it is necessary to accurately represent the depth from the sea surface 4, this can be taken into account in post-processing.

FIG. 2 shows an example of a circuit diagram for implementing the water temperature measuring method described above.

In the figure, reference numeral 5 denotes a directivity angle setting circuit which varies the directivity directions of the transmitter 2 and the receiver 3 in conjunction with each other, and guides the data of the directivity angle at that time to an arithmetic circuit 6, which will be described later. 7 is a transmission trigger generation circuit, and 8 is a transmission pulse generation circuit that sends an excitation pulse to the transmitter 2 based on the transmission trigger. Reference numeral 9 denotes an amplification and detection circuit that amplifies and detects a received signal of a volume reverberation echo from a specific depth position based on the setting of the directivity angle. 10 is a detection circuit that shapes the amplified detection signal and extracts a signal based on the volume reverberation echo. Reference numeral 11 indicates the detection circuit 10 from the transmission trigger generation time point (more precisely, the ultrasonic wave transmission time point) from the transmission trigger generation circuit 7.
This is a timer that measures the time until the time when the signal based on the volume reverberation echo is extracted.The time data is led to the calculation circuit 6.

The calculation circuit 6 calculates the equations (3) and (4) based on the time data t ₁ and the directivity angle θ in the first process and the time data t ₂ and the directivity angle θ+Δθ in the second process.

As explained above, according to the present invention, it is possible to extremely easily measure underwater water temperature, which could not be measured conventionally, and it is also possible to obtain water temperature data at a desired depth by arbitrarily setting the pointing angle. I can do it.

It is known that the sound speed increases by 1.75 m/s per 100 m due to water pressure, so by correcting the sound speed by adding the above increase to the sound speed at depth L, more accurate water temperature measurement becomes possible.

Further, in this embodiment, the directivity angles are set to be equal and symmetrical, but there is generally no basis for setting them to be equal. In such a case, it is only necessary to geometrically calculate the distance corresponding to the path difference D ₁ B′D ₂ .

Furthermore, the influence of ship speed on the pointing angle is also determined by the vectorial intersection of underwater sound speed and ship speed (B, in the example).
B') can be calculated, and from this the depth L and path difference can be determined geometrically. However, since the speed of sound underwater is high, there is no practical effect.

Finally, as mentioned above, it was explained that the directivity angles may be linked to each other to be equal, or although they may be linked to each other, they do not necessarily have to be equal to each other. Even if only the receiver 3 (transmitter 2) is variable, the depth and path difference can be determined geometrically as described above.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the principle of the water temperature measuring method of the present invention. FIG. 2 is a circuit diagram showing an embodiment of a water temperature meter according to the present invention, which utilizes the principle shown in FIG. 1 above.

Claims (1)

[Claims] 1. A transducer for transmitting ultrasonic waves, which is disposed at a certain distance from the bottom of a ship so that the transmitting direction and the receiving direction of the ultrasonic waves intersect on an extension line thereof, and based on the above-mentioned transmitting wave. A receiver that receives the generated volumetric reverberation echo from the above intersection point, a clock that measures the time from the time of wave transmission to the time of wave reception, and a device that changes at least one of the above-mentioned wave transmission and wave reception directions by a small angle. a changing means for changing, and each wave transmission before and after the change by the changing means,
Ultrasonic water temperature consisting of an arithmetic circuit that calculates the water temperature near the depth from each measurement time obtained by the clock by receiving waves, the difference in the sound wave propagation path based on the change and the fixed distance, and the depth near the middle of both intersection points. Total.