JPH0125031B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to horizontal linear receiver arrays for use underwater.

[Prior art]

In the conventional horizontal linear receiver array, which consists of multiple receivers extended horizontally underwater to form a linear arrangement,
Multi-beams are created by phasing with a delay line, etc., and a signal detector is connected to each beam output for listening, so the S/N ratio is improved for the beam output in the direction where the sound source, which is the measurement target, exists. Can be heard. The directivity pattern of the beam output at this time forms a conical shape symmetrical to the array axis.

Such a horizontal linear receiver array is shown in FIG.

As shown in this figure, when the receiver array 28 is extended horizontally in a straight line and the beam is directed, for example, in a 60° direction, the directivity is a conical shape with the central receiver a as the apex. (horn-shaped) and detects all sound sources in the circumferential direction of the bottom of this cone.

For example, if there is a sound source at point A, this is detected.

However, even if this point A is detected, since point B exists as a false sound source for this point, it is not possible to determine which of point A and point B is the true sound source.

Therefore, when the receiver array 28 is being towed by a ship, by changing the course of the ship,
It is necessary to find the direction of the sound source.

FIG. 7 is an explanatory diagram when determining the direction of a sound source by changing the course of a ship.

In this figure, a ship 29 detects sound sources A and B with a receiver array 28 at position A, and then changes the course of the ship 29 to, for example, a right angle direction to change the extension direction of the receiver array 28. , B. If sound sources A and C are detected at positions B, it can be determined that sound source A in the direction that appears in these two detections is the true sound source.

However, although the conventional receiver array 28 can measure the true direction of the sound source when towed by a ship as described above, it is suspended from a buoy moored on the water and expanded using ocean currents. The method of use has the disadvantage that the direction of extension of the receiver array 28 cannot be changed and therefore the true direction of the sound source cannot be measured.

[Purpose of the invention]

The present invention was made to solve the above-mentioned drawbacks of the prior art, and it is possible to accurately measure the true direction of a sound source even when suspended from a buoy moored above water and expanded by ocean currents. The object of the present invention is to realize a horizontal linear receiver array that can be used to measure data with high accuracy.

[Structure of the invention]

In order to achieve the above-mentioned object, the present invention arranges directional receivers having cosine and sine patterns at the acoustic center position of a receiver array using omnidirectional receivers, respectively, at right angles and parallel to the array axis. This is what I did.

〔Example〕

FIG. 1 is a side view showing an embodiment of a horizontal linear receiver array according to the present invention.
1 is an omnidirectional receiver, and 18 is a multicore cable for transmitting receiver signals. Reference numeral 19 denotes a drogue provided at the end of the multicore cable 18, which allows the receiver array consisting of the omnidirectional receivers 1 to 17 and the multicore cable 18 attached thereto to be moved horizontally and in a straight line by ocean currents. It is a resistor that expands into a shape.

20 is an electronic circuit that constitutes the terminal end of the receiver array, 21 is a cable that suspends the receiver array several hundred meters below the water surface and transmits the receiver array signal to the surface of the water, and 22 is the cable that connects the receiver array to the surface of the water. a dipole directional receiver placed perpendicular to the array axis;
23 is a dipole directional receiver installed parallel to the array axis, and 24 is a compass.

In this configuration, 1 to 21 are the same as the conventional horizontal linear receiver array, but the present invention has a cosine pattern at the acoustic center position of the receiver array, that is, at the position of the omnidirectional receiver 9. A dipole directional receiver 22, a dipole directional receiver 23 having a sine pattern, and a compass 24 are installed to measure direction.

That is, the acoustic signals of the omnidirectional receivers 1 to 17 and the dipole directional receivers 22 and 23 and the signal of the compass 24 are collected in the termination circuit 20, multiplexed, and sent out through the cable 21. At the observation station, this multiplexed signal is separated and demodulated, and the received signals of omnidirectional receivers 1 to 17 are phased to create a beam for listening. Direction calculation is performed using the signals from the directional receivers 22 and 23. In this case, phase shifts caused by multiplexed transmission, beam forming, etc. should be corrected. The compass 24 signal is also used to convert the azimuth along the array axis to an absolute azimuth.

Figure 2 shows the directivity when looking at the receiver array from above. The direction perpendicular to the array axis is 0°, and the beam output has the maximum S/N in the +60° direction.
It was assumed that the ratio was

FIG. 3 is a perspective view showing the receiver structure at the acoustic center position of the receiver array. The multicore cable 18 is connected to a container 25, and the omnidirectional receiver 9 and the compass 24 are installed in the container 25. is set up. A container 27 is suspended from this container 25 via three rubber pieces 26, and inside this container 27, two frequencies are arranged as dipole directional receivers 22 and 23 for cosine and sine. It is housed in a position perpendicular to and parallel to the axis.

In this configuration, the container 27 vibrates due to a sound pressure difference applied to the container 27 underwater, and the vibrations are picked up by the dipole directional receivers 22 and 23.

The dipole directional receivers 22 and 23 are sensitive only in their axial directions, and have directivity in a cosine-sine figure-eight pattern as shown in FIG.

FIG. 4 shows the dipole directional receivers 22, 2.
FIG. 3 is a sectional view showing the structure of No. 3;

In the figure, 30 is a cylindrical housing with both ends closed, 31 and 32 are disc-shaped diaphragms, and 33 and 3 are disc-shaped diaphragms.
4 is a disk-shaped piezoelectric element made of ceramic or the like, 35 is a cylindrical internal material made of lead or the like, and 36 is a viscous liquid such as oil.

Here, the internal member 35 is supported at both ends by diaphragms 31 and 32 to which piezoelectric elements 33 and 34 are attached, respectively, and is disposed in the center of the housing 30. The peripheral edges of the diaphragms 31 and 32 are fixed to the inner wall of the housing 30 with an adhesive or the like, and the viscous liquid 36 is filled between the diaphragms 31 and 32.

In the dipole directional receivers 22 and 23 configured in this way, the casing 30 vibrates in the same manner as the container 27 described above, and the vibration is transmitted to the internal member 35 via the diaphragms 31 and 32, and the casing Body 30 and internal material 35
The difference in movement causes the piezoelectric elements 11, 12 to bend and produce an output voltage.

Next, azimuth measurement of the horizontal linear receiver array of this embodiment with the above-described configuration will be explained.

As described above, dipole directional receivers 22 and 23 having cosine and sine directivity shown in FIG. 2 are placed at the acoustic center of the receiver array.
The cosine and sine directional outputs from the dipole directional receivers 22 and 23 have the characteristic that, with the phase of the beam output as a reference, they are in phase when in the direction of the solid line, and in antiphase (180° inversion) when in the direction of the dotted line. is set to .

The output of each is shown as follows.

Beam output = Ke ⁱ 〓 ^tCosine output = A・Kcosθ・e ⁱ 〓 ^tSine output=A・Ksinθ・e ⁱ 〓 ^tHere , the direction within the 1/4 quadrant is θ=tan ^-1 sine output/cosine output It can be found by

Furthermore, to determine the quadrant, the beam output, cosine output, and sine output may be compared as shown in FIG.

For example, as shown in Figure 2, when the sound source is in the 60° direction, the beam output will cause the sound to move between 60° and 120°.
Since the direction is determined, 60° can be determined as the true sound source direction using the above method from the cosine output and the sine output. Then, by correcting the array axis using the output of the compass 24, the true absolute direction of the sound source can be determined.

Although Fig. 1 shows an example in which 17 omnidirectional receivers are arranged, it is not limited to 17, and in general, a larger number of omnidirectional receivers are arranged. used. Furthermore, in FIG. 1, the omnidirectional receivers are arranged at smaller intervals as they approach the acoustic center in order to cover a wide acoustic frequency band.

〔Effect of the invention〕

As explained above, the present invention provides a reference for azimuth measurement by installing directional receivers having cosine and sine patterns at the acoustic center position of the receiver array at right angles and parallel to the array axis. Since the beam output of the horizontal array is used as the signal instead of the omnidirectional output, there is an effect that accurate measurement values can be obtained even when the S/N ratio of underwater sound from the sound source is low.

In addition, by providing a pair of directional receivers as described above, it is possible to accurately measure the true direction of the sound source without changing the direction of extension of the receiver array. It can be expanded horizontally by ocean currents.

[Brief explanation of drawings]

Fig. 1 is a side view showing an embodiment of a horizontal linear receiver array according to the present invention, Fig. 2 is an explanatory diagram of the directivity pattern used in the present invention, and Fig. 3 is an acoustic center position of the receiver array. 4 is a cross-sectional view showing the structure of a dipole directional receiver; FIG. 5 is a diagram showing an example of the phase of each output for determining the quadrant during azimuth measurement; FIG. 6 is a plan view showing a conventional horizontal linear receiver array, and FIG. 7 is an explanatory diagram showing an example of conventional azimuth measurement. 1 to 17... Omnidirectional receiver, 18... Multicore cable, 19... Drogue, 20... Termination circuit,
21... Transmission cable, 22, 23... Dipole directional receiver, 24... Compass, 25... Container, 26... Rubber, 27... Container, 30... Housing, 31, 32... Vibration Plate, 33, 34... piezoelectric, 35... internal material, 36... viscous liquid.

Claims (1)

[Claims] 1. A directional receiver having cosine and sine patterns is placed at the acoustic center of a receiver array consisting of a plurality of omnidirectional receivers extending horizontally and linearly underwater. A horizontal linear receiver array characterized by being installed perpendicular to and parallel to the array axis. 2. The horizontal linear wave receiver array according to claim 1, characterized in that a compass is provided at the same position as the directional wave receiver.