JPH06258415A - Underwater sound scope - Google Patents

Abstract

PURPOSE:To obtain an underwater sound scope by which the sound can be easily collected at a high S/N ratio in accordance with sea areas which are dominated by focusing band wave or multiple route wave. CONSTITUTION:A group 6 to 12 consisting of odd numbers of non-directional wave reception devices is arranged vertically and, at the same time, while a wave reception device 6 is placed at the center, other wave reception devices on both side thereof are arranged in a manner to be symmetrical, then two dipole-type directional wave-reception devices 13 and 14 are placed adjacent to the center position of the group 6 to 12. The direction of detecting target is measured by using the output from a beam former which alternately makes a first broad-side-type directivity having a maximum sensing axis against the angle where the detection target sound reflects on the sea bottom and returns or a second broad-side-type directivity having a maximum sensing axis in a horizontal direction by a switching device 30 on the basis of the respective outputs from the group 6 to 12, and the outputs from the wave reception devices 13 and 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrophone, and in particular, in a sea area where a focused band wave or a multipath wave is dominant, a sound wave from an undersea sound source is received to detect its presence and measure its direction. The present invention relates to a hydrophone that is suitable for performing.

[0002]

2. Description of the Related Art Generally, a sound wave reaching a receiver located in the sea from a target sound source in the sea (or underwater) is reflected by a direct wave coming from a plane parallel to the sea surface (hereinafter referred to as a horizontal plane) or the sea surface and the sea floor. It is a mixture of many multipath waves that are scattered and propagated. FIG. 6 is an explanatory diagram showing a state in which a sound wave propagates in the sea and reaches a receiver. In the figure,
1 is the sea surface, 2 is the seabed, 3 is the medium for propagating sound waves, 4 is the detection target, and 5 is a wave receiver dropped from the buoy or the like into the sea 3. As shown in the figure, when the sound wave from the detection target 4 is received at a distance of about 10 km, the sound wave radiated from the detection target 4 has a small angle of incidence on the sea surface 1 and the seabed 2, so that many multipath waves are added. Due to the effect, the level of the multipath wave becomes higher than that of the direct wave.

Further, in a sea area having a high runway noise (hereinafter referred to as traffic noise) such as a sea area on a ship runway or a coastal sea area, a large low frequency region (for example, 10 to 500 Hz) of an acoustic frequency in sea noise is large. The portion becomes traffic noise and has, for example, the directionality shown in FIG. Therefore, Japanese Patent Publication No. 57-19390 discloses that
Arrange an odd number of omnidirectional receivers on a vertical straight line so that the receivers on both sides are symmetrical with respect to the receiver at the center, and the output of the receiver at the center and other , And the two dipole type directional receivers having the maximum sensitivity axis in the horizontal plane direction are arranged so that their maximum sensitivity axes are shifted by 90 degrees. The output of the directional receiver and the output of the odd number of omnidirectional receivers
It is described that the signal-to-noise ratio (S / N) of the undersea noise level and the target sound level is increased by obtaining the figure 8 directivity as shown in FIG. That is, the figure-8 directivity, which has zero sensitivity in the horizontal plane, suppresses the traffic underwater noise, and receives the multipath waves from the sea surface and the sea floor to increase the S / N ratio.

However, generally, in sound wave propagation in the deep sea, the distance between the sound source and the receiver is intermediate (10 miles to 20 miles).
Up to the mile, the multipath wave is dominant, but in the long distance of about 30 to 40 miles, the focus zone (convergence zone) wave is dominant, so it is effective to hear this focus zone wave. Is. It is known that this focusing band wave reaches the wave receiver from an angle range slightly below (about -10 degrees) and above (about +10 degrees) the sea level 1.

Therefore, in Japanese Patent Publication No. 4-41312, an odd number of omnidirectional receivers are placed in the sea on a straight line perpendicular to the sea surface and on both sides of the center receiver. Arrange the receivers symmetrically, and place two dipole type directional receivers near the center position of the array of omnidirectional receivers, with each maximum sensitivity axis parallel to the sea surface. In addition to arranging them so that they are offset by 90 degrees from each other, as shown in FIG. 8, each output of the omnidirectional receiver has an 8-shaped directivity with zero sensitivity on a plane parallel to the sea surface. By providing a beamformer and a second beamformer that creates broadside type directivity in which the beam is directed slightly below or above the direction parallel to the sea surface shown in FIG. The / N ratio was high.

[0006]

[Problems to be Solved by the Invention]
In the conventional hydrophone of JP-A-41312, in the sea area where the multipath waves are dominant, in order to receive the sound waves of the multipath waves without receiving the trafic noise, the underwater sounding direction is applied to the sea surface and the seabed. It has an 8-shaped directivity with the maximum sensitivity axis. However, this 8-shaped directivity has the maximum sensitivity in the vertical direction in which the sound wave from the detection target does not enter even when trying to receive a multipath wave with a good S / N ratio, so the S / N ratio is high. However, there was a problem that it was not sufficiently improved. Further, according to Japanese Examined Patent Publication No. 4-41312, in a sea area where the focusing band wave is dominant, the sound is received at a high S / N ratio.
By creating a broadside type directivity in which the beam is directed slightly below or above the direction parallel to the sea surface, the focused band wave is received with a high S / N ratio.

However, even if a broadside type directivity in which the maximum sensitivity axis of the beam is directed slightly downward or upward from the direction parallel to the sea surface is made, the incidence of traffic noise having the directivity as shown in FIG. 7 is introduced. Since the angle of incidence and the angle of incidence of the concentrated band wave are almost the same, there is a problem that it is difficult to prevent the influence of traffic noise. In other words, there is a problem in that the traffic noise is received even though the maximum sensitivity is set to 10 degrees downward from the horizontal plane in order not to receive the traffic noise. there were. That is, the conventional hydrophone has a problem that it cannot receive sound with a high S / N ratio depending on the sea area where the focusing band waves are dominant or the sea area where the multipath waves are dominant. The present invention has been made to solve the above problems, and can easily receive sound with a high S / N ratio depending on the sea area where the focusing band wave or the multipath wave is dominant. Aim to get a hearing aid.

[0008]

SUMMARY OF THE INVENTION A hydrophone according to the present invention has an odd number of omnidirectional receiver groups vertically in the sea and on both sides of the center receiver. Arrange the wave receivers symmetrically, and place two dipole-type directional wave receivers near the center position of the array of omnidirectional wave receiver groups, each with its maximum sensitivity axis in the horizontal direction. The first broadside type directivity or horizontal plane direction, which is arranged so as to be deviated by 90 degrees and has a maximum sensitivity axis at an angle at which the detection target sound is reflected by the seabed and arrives based on each output of the omnidirectional receiver group The direction of the detection target is measured by the output of the beam former which selectively creates the second broadside type directivity having the maximum sensitivity axis and the output of the two dipole type directional receivers. is there.

[0009]

In the present invention, depending on the selection,
The beamformer creates a first broadside type directivity having a maximum sensitivity axis at an angle at which it reflects from the seabed or a second broadside type directivity having a maximum sensitivity axis in a horizontal plane direction, and outputs the output of this beamformer. The direction of the detection target is measured based on the outputs of the two dipole type directional receivers arranged near the center position of the odd number of omnidirectional receiver groups.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram showing an embodiment of the present invention. In the figure, 1 to 3 are the same as above.
6 to 12 are omnidirectional receivers, 13 and 14 are dipole type directional receivers, 15 to 21 are phase shifters (PSCs), 30
Is a switch, which includes contacts 22 to 28, and switches each contact based on a switch signal input to the control terminal 29.
The switch 30 uses an analog switch or the like. Three
1, 32 and 35 are adders, 33 is a low pass filter (hereinafter referred to as LPF), 34 is a high pass filter (hereinafter referred to as HLP).
, 36 is an output terminal of the adder 35, 37 is an output terminal of the dipole directional receiver 13, and 38 is an output terminal of the dipole directional receiver 14. The hydrophone has such a circuit.

The omnidirectional receivers 6 to 12 are omnidirectional with the omnidirectional receiver 6 centered on a straight line perpendicular to the sea surface 1 in the sea 3 with a distance d1 on both sides thereof. Sex receiver 7
And the omnidirectional receiver 8 are arranged at a distance d2,
An omnidirectional receiver 9 and an omnidirectional receiver 10 are arranged,
An omnidirectional receiver 11 and an omnidirectional receiver 12 are arranged at a distance d3. Further, the dipole type directional receiver 13 and the dipole type directional receiver 14 are located near the center positions of the omnidirectional receivers 6 to 12, their maximum sensitivity axes are both in the horizontal plane direction, and are 90 degrees from each other. It is arranged so as to be offset. The phase shifters 15 to 21, the switcher 30, the adder 31, the adder 32, the low-pass filter (LPF) 33,
The high-pass filter (HPF) 34 and the adder 35 constitute a beam former.

In such a configuration, the phase shifter 15 to the phase shifter 21 respectively respond to the outputs of the omnidirectional wave receiver 6 to the omnidirectional wave receiver 12 according to the distances d1, d2, d3. 2 is added to obtain a signal whose phase is aligned below the horizontal direction by about 40 degrees by adding a time advance or delay amount. The switching device 30 switches the contacts 22 to 28 by a switching signal input to the control terminal 29. For example, when the control signal is at the L level, the contacts 22 to 28 select the phase shifter 15 to the phase shifter 21. , Each of which outputs the signal of the phase shifter, and when the control signal is set to the H level, each contact 2
2 to 28 select the omnidirectional wave receiver 6 to the omnidirectional wave receiver 12 and output the output signals of the respective omnidirectional wave receivers.

The adder 31 inputs and adds the signals of the contact point 27, the contact point 25, the contact point 22, the contact point 26, and the contact point 28 of the switching device 30, and the switching device 30 causes the switching device 30 to shift the phase shifter 15 to 21 by the control signal. If was selected, distance d2 and distance d3
The first blowside type directivity having a maximum sensitivity axis at a lower frequency of about 40 degrees below the horizontal plane direction described in the following figure. Figure 3 shows about 40 below the horizontal plane.
It is explanatory drawing of the 1st blow side type directivity which has a maximum sensitivity axis | shaft every time. As shown in the figure, this directivity has a maximum sensitivity axis about 40 degrees below the horizontal plane and receives sound waves reflected from the seabed 2 and therefore does not receive traffic noise. It receives a reflected wave from the seabed 2 with a high S / N ratio.

When the switcher 30 selects the omnidirectional receiver 6 to the omnidirectional receiver 12 by the control signal, the adder 31 operates at a lower frequency depending on the distance d2 and the distance d3. The directivity (second broadside type directivity) having the maximum sensitivity axis in the horizontal plane direction described below is obtained. FIG. 4 is an explanatory diagram of directivity having the maximum sensitivity axis in the horizontal plane direction. As shown in the figure, since the maximum sensitivity axis of this directivity is in the horizontal plane direction, traffic noise and
The focused band wave is received at the same time. This is below the horizontal plane to avoid traffic noise,
Although the directivity has a maximum sensitivity axis of 10 degrees, it is difficult to eliminate the influence of traffic noise because the arrival angle of traffic noise is larger than the arrival angle of the focusing band wave, and conversely in the horizontal plane direction. This is because the S / N ratio is higher when the maximum sensitivity axis is provided and all focusing band waves are received. That is, it is used for the focusing band wave.

The adder 32 inputs and adds the signals of the contact 25, the contact 23, the contact 22, the contact 24, and the contact 26 of the switching unit 30, and the switching unit 30 causes the switching unit 30 to shift the phase shifter 15 to the phase shifter 21. If was selected, distance d1 and distance d2
, The directivity (first broadside type directivity) having the maximum sensitivity axis at about 40 degrees below the horizontal plane of FIG. 3 at higher frequencies is obtained. Further, when the switcher 30 selects the omnidirectional wave receiver 6 to the omnidirectional wave receiver 12 by the control signal, the adder 32 uses the distance d1 and the distance d2, and the horizontal plane of FIG. 4 at a higher frequency. A directivity having a maximum sensitivity axis in the direction (second broadside type directivity) is obtained.

The output of the adder 31 is output to the adder 35 via the low pass filter 33, and the output of the adder 32 is output to the adder 35 via the high pass filter 34. A combined output corresponding to the first broad type directivity as shown in FIG. 3 is obtained from the low frequency to the high frequency at the output terminal 36. Or
Similar to the above, an output corresponding to the second broadside type directivity as shown in FIG. 4 is obtained from the low frequency to the high frequency at the output terminal 36. As described above, the phase shifters 15 to 21, the switching device 30, the adder 31, the adder 32, and the low-pass filter 3
3, the beam former composed of the high-pass filter 34 and the adder 35 is controlled by the control signal inputted to the control terminal 29 so that the directivity thereof is about 40 degrees below the horizontal plane (hereinafter referred to as the first type direction). ), When the maximum sensitivity axis is created, as shown in FIG. 4, the horizontal direction (hereinafter referred to as the second type direction)
Even when the maximum sensitivity axis is made, the beam pattern is omnidirectional on the horizontal plane.

Moreover, the low-pass filter 33 and the high-pass filter 34 are constituted by a normal Butterworth type filter to separate the frequency regions covered by the intervals of the omnidirectional receivers and to make their cutoff frequencies and cutoff characteristics the same. By this, even if the frequency changes from the low frequency to the high frequency, the phase change of the output signal at the output terminal 36 of the adder 35 becomes zero. Then, the first broadside type directivity output or the second broadside type directivity output obtained at the output terminal 36 and the maximum sensitivity axis are both oriented in the horizontal plane direction, and the dipoles are deviated from each other by 90 degrees. Both outputs obtained at the output terminals 37 and 38 of the type directional receiver are transmitted by the transmission method described in detail in, for example, Japanese Patent Publication No. 53-22038, and Japanese Patent Publication No. 55-28.
The measurement method described in detail in Japanese Patent No. 514 can be used to detect the direction of the target. In the above embodiment, the case where the number of wave receivers for which the phases are aligned and added is five is shown, but if the number of the wave receivers is increased and the phases are aligned and added, then FIG. The beam width of the directivity shown in can be narrowed, and the S / N ratio can be further improved. Further, by increasing the number of the wave receivers and providing the wave receivers on the outer side, for example, by increasing the frequency band such as low frequency, intermediate frequency and high frequency, a combination of a phase shifter, an adder and a filter is provided. If so, the band can be further widened, and the directivity of FIGS. 3 and 4 can be maintained with respect to the target sound of a wider frequency band.

FIG. 5 is a diagram for explaining the purpose of directing the maximum sensitivity axis to about 40 degrees below the horizontal plane (direction of the first type). That is, the direction of the first type of the present invention is, as shown in FIG. 5, about 40 degrees from the horizontal plane for the single ocean bottom reflected wave.
Orient the main axis of the beam downwards. As a result, the S / N ratio can be improved by the beam width of its own and the submarine reflected wave can be received without being affected by the underwater noise. However, in this case, for example, in a sea area with a depth of 4 km, the distance to the target of the receiver group 5 in FIG. 5 is about 8 km,
A ring-shaped region having a radius of 8 km from the wave receiver group 5 serves as a detection region, and the width of this ring is determined by the beam width in FIG.

Further, the directivity having the maximum sensitivity axis in the horizontal plane direction (direction of the second kind) shown in FIG. 4 hangs the receiver group 5 at a relatively shallow depth (for example, 100 m), This is for receiving a focused band wave coming from a long distance with a good S / N ratio. In this case, since the simple adder described with reference to FIG. 1 can be used, there is also an advantage that it can be easily realized with a small and inexpensive hardware. The user pre-controls the control terminal 29 of the hydrophone to select a phase shifter or an omnidirectional receiver, and switches to the directivity of FIG. 3 or 4 for use. Further, the angle of about 40 degrees in FIG. 3 is desired to be a large value for the purpose of avoiding the traffic noise of FIG. 7, but it is desired to be a small value for the purpose of reducing the sea bottom reflection loss of the target signal. It is set as an intermediate value. Further, in the above embodiment, the switch is an analog switch, but it may be a general relay having a plurality of contacts.

[0020]

As described above, according to the present invention, an odd number of omnidirectional receiver groups are arranged in the vertical direction, and the receivers on both sides are symmetrical with respect to the center receiver. Are arranged in the same manner, and two dipole type directional receivers are arranged in the vicinity of the center position of the array of the omnidirectional receivers such that the maximum sensitivity axes are displaced from each other by 90 degrees with respect to the horizontal plane direction. Based on each output of the omnidirectional receiver group, the first broadside type directivity having the maximum sensitivity axis at the angle at which the detection target sound is reflected by the seabed and arrives or the maximum sensitivity axis in the horizontal direction is set. The direction of the detection target is measured by the output of the beam former that selectively creates the second broadside type directivity and the output of the two dipole type directional receivers. In the sea area where the path wave is dominant, the first broadside type directivity Manner to the sound receiving the seabed reflected wave S /
In the sea area where the N ratio is improved and the focused band wave is dominant, the S / N ratio is improved because the focused band wave coming from the horizontal direction is received by the second broadside type directivity, so the focused band wave is improved. Or, in the sea area where the multipath wave is dominant, the effect that the incoming sound wave from the detection target can be received with a good S / N ratio, the presence of the target can be detected, and the direction of the target can be accurately measured can be obtained. ing. Further, the beam former of the hydrophone according to the present invention is adapted to create the first broadside type directivity or the second broadside type directivity depending on the selection. The effect is that it can be easily realized by wear.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory view showing the manner of phasing in the beam former according to the present invention.

FIG. 3 is an explanatory diagram of directivity having a maximum sensitivity axis at about 40 degrees below the horizontal plane direction.

FIG. 4 is an explanatory diagram of directivity having a maximum sensitivity axis in a horizontal plane direction.

FIG. 5 is a diagram illustrating the purpose of orienting the maximum sensitivity axis about 40 degrees below the horizontal plane.

FIG. 6 is an explanatory diagram showing a state in which a sound wave propagates in water and reaches a receiver.

FIG. 7 is a diagram showing the directionality of traffic noise.

FIG. 8 is a diagram showing a conventional 8-shaped directivity.

FIG. 9 is a diagram showing a directivity in which a beam is directed about 10 degrees below a conventional horizontal direction.

[Explanation of symbols]

 1 sea surface 2 seabed 3 underwater 6-12 omnidirectional wave receiver 15-21 phase shifter 30 switcher 31 adder 32 adder 33 low-pass filter 34 high-pass filter

Claims (1)

[Claims] 1. An odd number of omnidirectional receiver groups are vertically arranged in the sea so that the receivers on the other sides are symmetrical with respect to the center receiver. In the vicinity of the center position of the array of directional receivers, two dipole type directional receivers are arranged so that their maximum sensitivity axes are offset from each other by 90 degrees with respect to the horizontal plane, A first sensitivity axis having a maximum sensitivity axis at an angle at which the detection target sound is reflected by the seabed and arrives based on each output of the receiver group.
By the output of the beamformer that selectively creates the broadside type directivity or the second broadside type directivity having the maximum sensitivity axis in the horizontal plane direction and the output of the two dipole type directional receivers. , A hydrophone that measures the direction of the detection target.