JPH08211150A - Acoustic buoy - Google Patents

Abstract

PURPOSE: To provide an acoustic buoy, for both a shallow sea area and a deep sea area, which is provided with a function capable of being used in the shallow sea area having large reverberations due to reflection or the like on the surface of the sea and the bottom of the sea and with a function capable of being used in the deep sea area having comparatively small reverberations. CONSTITUTION: A floating part 5 is provided with an antenna 2, and it houses a transmitter 14, a receiver 3 and a signal analyzer 4 which analyzes a command contained in a received signal. An underwater part 6 houses a wave transmitter 13 which transmits an acoustic signal to an underwater part, a wave receiver group 10 which is composed of a plurality of wave receivers receiving an echo signal, a signal processing part 8 which receives a signal from the floating part and which transmits received signals from the wave receiver group to the floating part and a control circuit 11 which controls the transmission of the acoustic signal, the reception of the echo signal and the combination of the wave receivers to be used from the wave receiver group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic buoy which transmits an acoustic signal such as an ultrasonic wave from an underwater transmitter and receives an echo sound reflected from a target or the like.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, an acoustic buoy of this type has been constructed by connecting a water upper part 16a floating above water and an underwater part 16b with a signal cable. The length was fixed and the receiving beam width was fixed before use. Therefore, when changing the reception beam width, another acoustic buoy was used again.

[0003]

In the above acoustic buoy, since the receiving beam width is constant, it is generated by reflected waves from the sea surface or the sea floor, scattered waves from living things and inanimate floating matters in the sea, etc. If the reverberant sound from the target object is lost in the reverberation, change the depth of the receiver in the water to find the best depth for use. If it is still unusable, it may be necessary to re-enter the acoustic buoy with a narrower reception beam width for use. In general, acoustic buoys are often used by being mounted on aircraft and dropped into the sea in the sea area where they are used, and in situations where the weight of mounting on the aircraft is limited, various types of acoustic buoys will be mounted. There was a problem that became difficult.

Therefore, an object of the present invention is to provide an acoustic buoy which can be used in a shallow sea area where reverberation is large due to reflection on the sea surface or the sea bottom, and a function which can be used in a deep sea area where reverberation is relatively small. To provide.

[0005]

An acoustic buoy according to the present invention includes an antenna, a transmitter for transmitting a radio signal through the antenna, a receiver for receiving a signal received through the antenna, and the receiver. An upper part of the water containing a signal analyzer that analyzes the commands included in the signal, a transmitter that transmits an acoustic signal into the water, and a receiver group consisting of a plurality of receivers that receive the echo signal. A signal processing circuit for receiving a signal from the water surface and transmitting a received signal from the wave receiver group to the water surface, transmitting the acoustic signal, receiving the echo signal, and receiving the wave receiver group. It is characterized in that a signal cable is used to connect an underwater portion containing a control circuit for controlling the combination of which wave receiver is used.

The control circuit reduces the number of wave receivers used in the wave receiver group when the reflection from the sea surface or the seabed is small, and the wave receiver when the reflection is large. Control to increase the number of wave receivers used in the group.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, an acoustic buoy of the present invention has a signal cable 7 connecting an upper water portion 5 which is designed to float above water and an underwater portion 6 which is submerged in water. Above the water 5
Is an antenna 2 that receives a radio signal 1 from an aircraft 20
A receiver 3 for amplifying a received signal, and a signal analyzer 4 for analyzing a command included in the received signal,
Transmitter 1 for transmitting radio signals through antenna 2
4 and 4 are built in a watertight structure.

The underwater section 6 detects a signal from the upper water section 5 sent through the signal cable 7, and a receiving circuit 9
A signal processing circuit 8 for transmitting the signal of above to the water 5 and
A control circuit 11 for controlling the transmission and reception of sound and for controlling the combination of wave receivers of the wave receiver group 10 in order to change the reception beam width depending on the reception state of the reverberant sound from the target object or the like.
A transmission circuit 12 for producing an electric signal for obtaining a reverberant sound from a target object, and a wave transmitter 13 for converting the electric signal into sound.
A receiver group 10 including a plurality of receivers for receiving reverberant sound from a target object and the like, and a receiver circuit 9 for amplifying a received signal.
And are built in a watertight structure.

This acoustic buoy is used by being dropped onto the sea from an aircraft or the like. When it is dropped and reaches the sea surface, the water upper part 5 and the underwater part 6 are mechanically separated, and the water upper part 5 floats on the sea surface, but the underwater part 6 sinks while feeding out the signal cable 7. In a normal use state, the control circuit 11 causes a predetermined number of the plurality of wave receivers 15 constituting the wave receiver group 10 to be expanded and the remaining wave receivers to be solidified, as shown in FIG. Allow to settle. In this state, when trying to deepen the depth further, the solidified receiver at the bottom functions as a weight, and the sinking speed is not limited and sinks. Of course, the plurality of wave receivers 15 are not only mechanically connected but also electrically connected.

The number of expansions is set in advance, and the control circuit 11 sends a signal to the wave receiver group 10 according to the set value to expand a predetermined number. As a method of expanding the wave receivers 15 by a predetermined number, for example, when the adjacent wave receivers 15 are connected to each other by a connecting line different from a mechanical connecting line, and the expanding lines are expanded, the connecting line is connected to the control circuit 11. It is conceivable to energize the heater such as a nichrome wire to cut it under the control of 1), but the method is not limited to this.

In this state of use, such as a place where the seabed is relatively shallow, a place where the reverberation of the sea surface, the seabed, and volume reverberation generated by scattered waves from living things and inanimate suspended matter in the sea are large. Then, the echo signal from the target object is lost in the reverberation, which makes it difficult to detect the echo signal from the target object. Therefore, in such a case, a command is sent from the aircraft, and the control circuit 11 expands the remaining wave receivers 15 as shown in FIG. The number of 15 can be increased.

The wave receivers 15 of the wave receiver group 10 are arrayed at preset equal intervals λ / 2 (λ: signal wavelength),
As the number of wave receivers 15 increases, the reception beam width can be made sharper. By making the received beam width sharper, the sensitivity for sound incident from an oblique direction will be lowered compared to the case of the beam width that has been used so far, such as sea surface reverberation, sea bottom reverberation, volume reverberation, etc. It is possible to control the reverberant sound from the diagonal direction of. As a result, the level of the reverberant sound from the target object becomes higher than the level of the reverberant sound, and the signal can be detected.

However, although always narrowing the beam is effective in suppressing reverberant sound, at the same time, it may be difficult to detect the signal of the target object depending on the incident angle. On the other hand, as in the present invention, it is effective that the control circuit 11 switches between the beam width normally used and the beam width used under reverberation so that the beam width can be used.

[0014]

As described above, according to the present invention, the receiving beam width can be changed by selecting the number of receivers of the receiver group used in the underwater portion. When used in a place where sea surface reverberation, sea floor reverberation, volume reverberation, etc. are large, the reverberation can be suppressed by sharpening the reception beam width. Since the number of receivers in the receiver group can be selected in this manner, it is possible to select the reception beam width depending on the sea area used. Conventionally, it is possible to use an acoustic buoy that could not be used where there is a large influence of reverberation, such as a normal buoy and a case where the reverberation is large.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an acoustic buoy according to the present invention.

FIG. 2 is a diagram for explaining a normal use state of the wave receiver group according to the present invention.

FIG. 3 is a diagram when the receiving beam width of the receiver group shown in FIG. 2 is sharpened.

FIG. 4 is a diagram for explaining a usage state of a conventional acoustic buoy.

[Explanation of symbols]

 1 wireless signal 2 antenna 5 water upper part 6 underwater part 7 signal cable 15 wave receiver

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshikazu Iwasawa 5-7-1, Shiba, Minato-ku, Tokyo NEC Corporation

Claims (2)

[Claims] 1. A transmitter including an antenna, for transmitting a radio signal through the antenna, a receiver for receiving a signal received through the antenna, and a signal for analyzing a command included in the received signal. An upper part of the water containing the analyzer, a transmitter for transmitting an acoustic signal into the water, a receiver group consisting of a plurality of receivers for receiving an echo signal, and a signal from the upper part of the water, A combination of a signal processing circuit for transmitting a reception signal from the wave receiver group to the upper part of the water, a transmission of the acoustic signal, a reception of the echo signal, and which wave receiver of the wave receiver group is used. An acoustic buoy characterized in that it is formed by connecting a control circuit to be controlled and an underwater portion accommodating with a signal cable. 2. The acoustic buoy according to claim 1, wherein the control circuit reduces the number of wave receivers to be used in the wave receiver group when the reflection from the sea surface, the sea floor, etc. is small. Is large, the acoustic buoy is controlled so that the number of wave receivers in the wave receiver group is increased.