JP2548315B2 - Approach target detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for detecting that a moving target, which emits sound waves, approaches a target within a predetermined range.

[Prior Art] Conventionally, an apparatus of this type uses one omnidirectional receiver and detects an approaching target from the increase amount of the output level with respect to time.

FIG. 2 is a block diagram showing an example of the configuration of a conventional approaching target detection device, which includes a wave receiver (21), an amplifier (22), a bandpass filter (23), a logarithmic conversion circuit (24) and a differentiation circuit (2).
It consists of 5). Here, it is assumed that the target object (26) emits a sound wave (28) while traveling in the moving direction (27).

The sound wave (28) from the target object (26) is received by the wave receiver (21) and converted into an electric signal, and then the amplifier (22).
After being amplified by, the band pass filter (23) extracts only specific frequency components. The output of the bandpass filter (23) is processed by the logarithmic conversion circuit (24) to be a logarithmic output. This logarithmic output increases with time as the target object (26) approaches, becomes maximum at the closest point, and decreases with time as the target moves away. Therefore, by differentiating this logarithmic output by the differentiating circuit (5) to obtain the time change rate of the signal level, it is judged that the target (26) has approached a certain range.

[Problems to be Solved by the Invention] FIG. 3 is an explanatory view showing an example of use of the apparatus of FIG.
In the figure, (31) is the bottom of the water, (32) is the point directly above the water surface (33) with respect to the receiver (21), (34) is the desired detection range,
This is an example when the target object is a ship (35).

In a conventional device, as shown in FIG. 3, for example, a wave receiver (21) is installed on the bottom (31) of a certain water depth, and a ship (35) approaching the point directly above (32) is located directly above. When trying to detect that the detection range (34) having the point at a distance x from (32) as an area is reached, the case where the ship (35) is heading toward the point (32) directly above and the lateral deviation y is In some cases,
The actual detection distance x when the output is obtained from the differentiator (25) becomes different (x becomes larger as y becomes larger), and the detection distance x is kept at a certain value regardless of the course. There was a problem that I could not do it.

FIG. 4 is a characteristic diagram of the detection distance with respect to the traveling direction (lateral deviation) of the vessel. For example, if the distance from the bottom of the water (31) to the point directly above (32) is D and the lateral deviation is y, output from the device of FIG. The detection distance x when is obtained is expressed by the following equation.

x = (2y ² + D ² ) ^1/2 Therefore, when D = 70m and y = 0m (when facing the point directly above), x = 70m, but when y = 30m, x = 82m
Therefore, the desired detection distance (34) cannot be obtained.

Also, since an omnidirectional receiver is used for the receiver (21), if there is another target (disturbance target) that emits a loud sound near the target to be detected, both sounds will be emitted. Since the signals are received with the same wave receiving sensitivity, the target sound to be detected is masked by the target sound to be detected, which makes it impossible to detect.

The present invention solves the problems of the change in the detection range due to the path of the target and the deterioration of the detection ability due to the obstacle target, and the detection range can be limited regardless of the path of the target, and
It is an object of the present invention to provide an approaching target detection device that can detect a target object without being affected by a disturbing target in the vicinity.

[Means for Solving the Problems] In order to solve the above-described problems, the present invention receives a sound wave emitted from an object moving in water, and approaches from the increase amount of the received output level with respect to the receiving time. In an approaching target detection device for detecting an incoming target, a narrow directional receiver installed in the direction to be detected and a wide directional or omnidirectional receiver installed in the direction to be detected (These are collectively referred to as wide directional receivers below)
A pair of amplifiers for amplifying the output signals from the narrow directional receiver and the wide directional receiver, and a signal of a specific same frequency component from the output signals of the pair of amplifiers 1
A pair of bandpass filters, a pair of detection circuits for respectively detecting output signals of the pair of bandpass filters, and a division circuit for obtaining a ratio of output signals of the pair of detection circuits,
And a determination circuit that compares the output signal of the division circuit with a predetermined reference value and outputs a signal when the output signal becomes the same as the reference value.

[Operation] In the present invention, the output and the wide directivity width of the narrow directional receiver having the narrow directivity width with respect to the same frequency installed in the direction to detect (directly upward direction in the use example of FIG. 2). The output of the wide directional receiver having a is respectively amplified to extract only the signal of a predetermined same frequency component, and after detection, the ratio of both detection outputs is obtained, and when the ratio matches a predetermined reference value, An output signal is sent when the target object approaches the predetermined detection distance.

[Embodiment] FIG. 1 is a block diagram showing the configuration of an approaching target detection apparatus according to an embodiment of the present invention. In this approach target detection device, the output of the narrow directional receiver (1) is the amplifier A.
The output of the amplifier A (2) is connected to the bandpass filter A (3), and the output of the bandpass filter A (3) is connected to the detection circuit A (4). Similarly, the output of the wide directional receiver (5) is the amplifier B.
The output of the amplifier B (6) is connected to the bandpass filter B (7), and the output of the bandpass filter B (7) is connected to the detection circuit B (8). The output of the detection circuit A (4) and the output of the detection circuit B are connected to the division circuit (9), and the output of the division circuit (9) is connected to the determination circuit (10).

In the approaching target detection device configured as described above, when an acoustic signal enters the narrow directional receiver (1) at an incident angle, the acoustic signal is converted into an electric signal there, and after being amplified by the amplifier A (2). , And a specific frequency component is extracted by being filtered by the bandpass filter A (3). The component is detected by the detection circuit A (4).

At the same time, the acoustic signal that has entered the wide directional receiver (5) at the same incident angle is also converted into an electrical signal, amplified by the amplifier B (6), and then filtered by the bandpass filter B (7) to identify it. Only the frequency components of are extracted. In this case, the bandpass filter A (3) and the bandpass filter B (7)
With the same characteristics of and, the bandpass filter B (7) extracts only the signal of the same frequency component as that of the bandpass filter A (3). The component is detected by the detection circuit B (8). Here, the output of the detection circuit A (4) is E ₁ , and the output of the detection circuit B (8) is E ₂ .

FIG. 5 is a characteristic diagram showing the directional characteristics of the narrow directional receiver (1) and the wide directional receiver (5) at a specific frequency. In the figure, A is the directional characteristic of the narrow directional receiver (1),
B indicates the directional characteristic of the wide directional receiver (5), and C indicates the arrival direction of the sound wave.

FIG. 6 shows the output E ₁ of the detection circuit A (4) and the detection circuit B.
It is a characteristic view of the output E ₂ of (8). Narrow directional receiver (1)
Since the directional characteristic A of E and the directional characteristic B of the wide directional receiver (5) have the characteristics shown in FIG. 5, E ₁ and E ₂ are functions of the sound wave incident angle θ, and the sound wave of the incoming sound wave is also generated. It also changes depending on the pressure level, that is, the loudness of the sound emitted by the target.

Output E ₂ of the detection circuit A (4) of the output E ₁ and the detection circuit B (8) is applied to the divider circuit (9), it is obtained E ₁ / E _2,
The value is added to the determination circuit (10) and is compared with the reference value for determination, and when the value is the same as the reference value, a detection signal is output. If the sound pressure level of the incoming sound wave increases or decreases, E ₁ and E ₂
The value of E ₁ / E ₂ is no longer related to the magnitude of the sound pressure level of the incoming sound wave because it increases and decreases at the same rate, and is determined only by the sound wave incident angle θ.

Therefore, the reference value of the judgment circuit (10) is set to the sound wave incident angle θ.
If it is defined as a function of, it is possible to detect that the approaching target has entered a certain range. For example, in the case of the use example of FIG. 3, the installation water depth of the receiver and the sound wave incident angle θ
Is set, the detection distance x is set to a certain distance from the point directly above regardless of the magnitude of the traveling sound of the ship and the course.

Therefore, as shown in FIG. 4, if D = 70 m, for example, the detection distance is 70 m even if y = 0 m or y = 30 m, and the detection distance does not change even if there is lateral deviation.

Further, when another treble target that interferes is present in the vicinity (position of large sound wave incident angle θ), the wide directional receiver (5) also receives the sound of the disturbing target with relatively high sensitivity. However, for the narrow directional receiver (1), the interference target sound is received with low sensitivity due to its directivity, so the E ₁ / E ₂ ratio becomes extremely small, and as a result, the nearby You can detect the original target object without being affected by the target.

It is needless to say that the wide directional receiver (5) may be an omnidirectional receiver in the present invention because of its function.

[Advantages of the Invention] As described above, according to the present invention, the narrow directional receiver and the wide directional (non-directional) receiver are used, and the ratio of their outputs is taken. The detection range can be fixed regardless of the size of the sound emitted by the player and the course of the target.
Also, since a narrow directional receiver is used, if there is another target that emits high-pitched sound in the vicinity of the target to be detected, the effect of those sound waves is greatly reduced, and the original target The effect of surely detecting an object can be expected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an approaching target detecting device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a conventional approaching target detecting device, and FIG. 3 is an approaching target shown in FIG. Explanatory diagram showing an example of use of the detection device, FIG. 4 is a characteristic diagram of the detection distance with respect to the traveling direction of the ship, FIG. 5 is a characteristic diagram of the receiver at a specific frequency, and FIG. 6 is an output characteristic diagram of the detection circuit. is there. In the figure, (1) is a narrow directional receiver, (2) is an amplifier A, (3) is a bandpass filter A, (4) is a detection circuit A, (5) is a wide directional receiver, ( 6) is amplifier B,
(7) is a bandpass filter B, (8) is a detection circuit B,
(9) is a division circuit, and (10) is a determination circuit.

Claims (1)

(57) [Claims] 1. An approaching target detection device for detecting an approaching target object by receiving a sound wave emitted from an object moving underwater and detecting an approaching target object from an increase amount of the received output level with respect to the reception time. A narrow directional receiver installed towards
Wide directional or omnidirectional receiver installed in the direction you want to detect (hereinafter these are collectively referred to as wide directional receiver)
A pair of amplifiers for amplifying the output signals from the narrow directional receiver and the wide directional receiver, and a signal of a specific same frequency component from the output signals of the pair of amplifiers 1
A pair of bandpass filters, a pair of detection circuits for respectively detecting output signals of the pair of bandpass filters, and a division circuit for obtaining a ratio of output signals of the pair of detection circuits,
An approaching target detection apparatus comprising: a judgment circuit which compares the output signal of the division circuit with a predetermined reference value and outputs a signal when the output signal becomes equal to the reference value.