JP2006047187A - Sound wave beam forming apparatus, underwater sonar and method for controlling sound wave beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound wave beam forming apparatus capable of reducing a cost of an underwater sonar, the underwater sonar in which the sound wave beam forming apparatus is built, and a method for controlling a sound wave beam. <P>SOLUTION: An oscillation signal output from an oscillator 11 is input to wave transmitters 12-15, and each of the wave transmitters 12-15 generates a sound wave having a frequency equal to that of the oscillation signal. Ducts 13b-15b functioning as phase shifters, make phases of sound waves different from each other in series, which are emitted from respective emission apertures 12a-15a. A composite wave made up of sound waves emitted from respective emission apertures 12a-15a is emitted as the sound wave beam in a direction determined by their directivity. The direction in which the sound beam wave is emitted, is changed only by varying the frequency of the oscillation signal output from the oscillator 11, whereby the direction of an object reflecting the sound wave beam can be detected by using one wave detector 20, for example. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an acoustic beam forming apparatus, an underwater sonar, and an acoustic beam control method.

Underwater sonar acquires various information from sound waves propagating in water. The fish frequency characteristic measuring apparatus described in Patent Document 1 is a kind of underwater sonar, and includes a plurality of transducers arranged on a straight line.
Japanese Patent No. 2948092

  In the fish frequency characteristic measuring apparatus described in Patent Document 1, each transducer generates a sound wave having a different frequency and radiates it in a direction perpendicular to a straight line on which the transducer is arranged. The sound wave radiated from each transducer is reflected by an object such as a school of fish or fish, and the frequency characteristic measuring device of the fish measures the frequency of the sound wave reflected by the fish or school of fish.

  In addition, the frequency characteristic measuring apparatus for fish described in Patent Document 1 includes two receiving elements, a phase difference detector, and a displacement angle calculator for each transducer in order to detect the direction of an object. I have. The sound wave reflected from the object is received by the two receiving elements, the phase difference is detected by the phase difference detector, and the displacement angle calculator determines the deviation of the direction of the object from the directional axis (known). Yes.

  In the fish frequency characteristic measuring apparatus of Patent Document 1, the directivity direction of each transducer is fixed in a direction perpendicular to the straight line on which the transducer is arranged. Therefore, in order to change the directing direction, it is necessary to rotate a frame or the like to which a plurality of transducers are attached, or to rotate individual transducers. If a mechanism for rotating a frame or the like or individual transducers is employed, the complexity and size of the apparatus cannot be avoided. In addition, the cost for maintenance inspection cannot be ignored. That is, it has been difficult to reduce the cost of the sonar underwater.

  Further, in order to detect the direction of the object, at least two wave receiving elements are necessary, and a phase difference detector and a displacement angle calculator are necessary. For this reason, it has been difficult to reduce the cost of the apparatus.

  An object of the present invention is to provide an acoustic beam forming apparatus that can reduce the cost of an underwater sonar, an underwater sonar in which the acoustic beam forming apparatus is incorporated, and a method for controlling an acoustic beam.

In order to achieve the above object, an acoustic beam forming apparatus according to a first aspect of the present invention includes an oscillator that generates an oscillation signal having a variable frequency,
A plurality of transmitters connected to the oscillator, each generating a sound wave having a frequency corresponding to the oscillation signal, and radiating the sound wave into water through a correspondingly provided radiation port;
A phase shifting means for delaying the sound wave radiated from each of the radiation ports by a delay amount unique to each of the transmitters;
Control means for controlling the traveling direction of the sound beam formed by the sound waves emitted from the plurality of radiation ports by changing the frequency of the oscillation signal;
It is characterized by providing.

  In addition, the said phase shift means may be comprised by the duct which is provided between each said transmitter and each said radiation | emission opening, and has the length intrinsic | native to this each transmitter.

  Further, the plurality of radiation openings may be arranged on a straight line.

  In addition, the plurality of radiation ports may be arranged at equal intervals.

In order to achieve the above object, an underwater sonar according to the second aspect of the present invention comprises:
An oscillator that generates an oscillation signal having a variable frequency;
A plurality of transmitters connected to the oscillator, each generating a sound wave having a frequency corresponding to the oscillation signal, and radiating the sound wave into water through a correspondingly provided radiation port;
A phase shifting means for delaying the sound wave radiated from each of the radiation ports by a delay amount unique to each of the transmitters;
Control means for controlling the traveling direction of the sound beam formed by the sound waves emitted from the plurality of radiation ports by changing the frequency of the oscillation signal;
A receiver that receives a reflected wave of the sound beam and generates a reception signal corresponding to the reflected wave;
Analyzing means for analyzing the object reflected from the sound beam based on the received signal;
It is characterized by providing.

  In this case, the object may be a fish or a school of fish.

  The analysis unit may detect a direction in which the object is present.

  The analysis unit may detect a moving speed of the object.

  Further, the phase shift means may be configured by a duct provided between each of the transmitters and each of the radiation ports and having a length unique to each of the transmitters.

  Further, the plurality of radiation openings may be arranged on a straight line.

  In addition, the plurality of radiation ports may be arranged at equal intervals.

In order to achieve the above object, a sound beam control method according to a third aspect of the present invention includes:
An oscillator that generates an oscillation signal having a variable frequency;
A plurality of transmitters connected to the oscillator, each generating a sound wave having a frequency corresponding to the oscillation signal, and radiating the sound wave into water through a correspondingly provided radiation port;
A phase shifting means for delaying the sound wave radiated from each of the radiation ports by a delay amount unique to each of the transmitters;
A sound beam forming apparatus comprising: control means for controlling a traveling direction of a sound beam formed by sound waves emitted from the plurality of radiation ports by changing a frequency of the oscillation signal;
A means for changing the frequency of the oscillation signal is provided,
The traveling direction of the sound beam radiated from the plurality of radiation openings is changed by changing the frequency of the oscillation signal.

  According to the present invention, low-cost underwater sonar and the like can be realized.

FIG. 1 is a block diagram showing an underwater sonar according to an embodiment of the present invention.
This underwater sonar detects the position and moving speed of an object such as a fish or a school of fish, and includes an oscillator 11 and, for example, four transmitters 12 connected in parallel to the output side of the oscillator 11. 13, 14, 15 and ducts 13b, 14b, 15b.

  The oscillator 11 is a circuit that generates an oscillation signal having a variable frequency. The transmitters 12 to 15 convert the oscillation signals into sound waves, and radiate sound waves having a frequency equal to the frequency of the oscillation signals toward the radiation ports 12a, 13a, 14a, and 15a. Ducts 13b, 14b, and 15b are disposed between the transmitters 13 to 15 and the radiation ports 13a to 15a, respectively. The ducts 13b to 15b are phase shifters that add a phase difference to the sound waves radiated from the radiation ports 12a to 15a. Each radiation port 12a-15a is arranged on the straight line at equal intervals.

The length of the duct 13b is about 140 [mm], and corresponds to, for example, a wavelength λ ₀ when a sound wave having a frequency f ₀ of 10 KHz propagates through water. The length of the duct 14b is twice that of the duct 13b. The length of the duct 15b is three times that of the duct 13b. By arranging such ducts 13b to 15b, when the oscillator 11 outputs an oscillation signal having a frequency of 10 KHz, the phases of the sound waves emitted from the radiation ports 12a to 15a are aligned.

The oscillator 11, the transmitters 12 to 15, and the ducts 13 b to 15 b form a sound beam forming circuit 10 and emit a sound beam having directivity. The sound beam is a composite wave of sound waves emitted from the radiation ports 12a to 15a.
The underwater sonar further includes a receiver 20, a receiver 21, and a control circuit 22.

  The receiver 20 is composed of a microphone or the like, and converts underwater sound including reflected waves into an electrical signal. The receiver 21 removes a noise component or the like in the electrical signal, extracts a received signal corresponding to the reflected wave, and provides the control circuit 22 with the extracted signal. The control circuit 22 gives a control signal to the oscillator 11 to indicate the frequency of the oscillation signal, and performs various detections based on the reception signal given from the receiver 21. In the detection, for example, the direction in which a school of fish or fish as the object is present is detected, or the moving speed of the object is obtained.

Next, the operation of the underwater sonar of FIG. 1 will be described with reference to FIGS.
FIG. 2 is an explanatory diagram of the operation of the underwater sonar, and shows the acoustic beam forming circuit of the underwater sonar of FIG.
FIG. 3 is an explanatory diagram of sound waves emitted from the radiation ports 12a to 15a, and each sound wave is shown as a sine wave.

Now, when the oscillator 11 gives an oscillation signal having a frequency of f ₀ (= 10 KHz) to each of the transmitters 12 to 15, each of the transmitters 12 to 15 outputs a sound wave having a frequency of f ₀ to the radiation port 12a. Radiates toward ~ 15a.

  The duct 13b delays the phase of the sound wave radiated from the radiation port 13a by the length of 140 [mm] of the duct 13b with respect to the sound wave radiated from the radiation port 12a. That is, as shown in FIG. 3, the phase of the sound wave emitted from the radiation port 13a is delayed by one wavelength with respect to the sound wave emitted from the radiation port 12a.

  The duct 14b delays the phase of the sound wave radiated from the radiation port 14a by two wavelengths corresponding to the length of the duct 14b with respect to the sound wave radiated from the radiation port 12a. The duct 15b delays the phase of the sound wave emitted from the radiation port 15a by three wavelengths corresponding to the length of the duct 15b with respect to the sound wave emitted from the radiation port 12a.

As a result, when an oscillation signal having a frequency of f ₀ (= 10 KHz) is applied to each of the transmitters 12 to 15, sound waves having the same phase are emitted from the radiation ports 12a to 15a. As a result, as shown in FIG. 2, the sound beam, which is the combined wavefront of the sound waves radiated from the radiation ports 12a to 15a, has a direction perpendicular to the row of the radiation ports 12a to 15a, and travels in that direction. become.

  The sound beam is reflected by the object existing in the directivity direction and returns as a reflected wave. The receiver 20 receives the reflected wave, converts it into an electrical signal, and gives it to the receiver 21. The receiver 21 extracts a component corresponding to the reflected wave from the electric signal and gives it to the control circuit 22. The control circuit 22 determines that an object is present in the directivity direction when a component corresponding to the reflected wave is given from the receiver 21.

  If the object reflected from the sound beam is moving, the frequency difference between the frequency of the emitted sound beam and the frequency of the reflected wave changes depending on the moving speed of the object.

  The control circuit 22 calculates the moving speed of the object based on the component corresponding to the reflected wave given from the receiver 21.

  The frequency of the oscillation signal output from the oscillator 11 can be changed in accordance with the control signal from the control circuit 22.

FIG. 4 is an explanatory diagram of a sound beam when the frequency of the oscillation signal is increased.
FIG. 5 is an explanatory diagram of the phase between the sound waves, and shows the sound waves S2, S3, S4, and S5 emitted by the transmitters 12 to 15, respectively.
FIG. 6 is an explanatory diagram of the deflection direction of the sound beam.

When the frequency of the oscillation signal output from the oscillator 11 is increased and the frequency is changed from f ₀ to f ₀ + Δf, the wavelength of the oscillation signal is reduced to λ ₀ −Δλ, and the length of the duct 13b (= λ ₀ ) is reduced. The wavelength of the sound wave S2 generated by the transmitter 12 (λ ₀ −Δλ) is longer by Δλ.

Similarly, when the frequency of the oscillation signal is changed from f ₀ to f ₀ + Δf, the length of the duct 14b (= 2λ ₀ ) becomes 2 of the wavelength (λ ₀ −Δλ) of the sound wave S2 generated by the transmitter 12. 2Δλ longer than twice. Further, the length of the duct 15b (= 3λ ₀ ) is 3Δλ longer than three times the wavelength (λ ₀ −Δλ) of the sound wave S2 generated by the transmitter 12.

  As a result, as shown in FIG. 5, the phases of the sound waves S3, S4, and S5 emitted from the radiation ports 13a to 15a are sequentially delayed by Δλ with respect to the sound wave S2 emitted from the radiation port 12a.

  As a result, the traveling direction of the sound beam, which is the combined wavefront of the sound waves S2 to S5, is not perpendicular to the rows of the radiation ports 12a to 15a, but is deflected in the direction of the white arrow (right of the page) as shown in FIG. .

Here, if the distance between the radiation ports 13a to 15a and the adjacent radiation ports 12a to 14a is x and the deflection angle of the sound wave beam is θ, the sound waves emitted from the radiation ports 13a to 15a are adjacent to each other. Since it is delayed by Δλ with respect to the sound wave emitted from the mouths 12a to 14a, it can be expressed as shown in FIG.
Therefore,
sin θ = Δλ / x
And θ is
θ = sin ⁻¹ (Δλ / x)
It is represented by

FIG. 7 is an explanatory diagram of a sound beam when the frequency of the oscillation signal is lowered.
FIG. 8 is an explanatory diagram of the phase between the sound waves, and shows the sound waves S2, S3, S4, and S5 emitted from the transmitters 12 to 15, respectively.
FIG. 9 is an explanatory diagram of the deflection direction of the sound beam.

When the frequency of the oscillation signal output from the oscillator 11 is lowered and the frequency is changed from f ₀ to f ₀ −Δf, the wavelength of the oscillation signal is as long as λ ₀ + Δλ, and the length of the duct 13b (= λ ₀ ) is It becomes shorter by Δλ than the wavelength (λ ₀ + Δλ) of the sound wave S 2 generated by the transmitter 12.

Similarly, when the frequency of the oscillation signal is changed from f ₀ to f ₀ −Δf, the length of the duct 14 b (= 2λ ₀ ) becomes 2 of the wavelength (λ ₀ + Δλ) of the sound wave S 2 generated by the transmitter 12. 2Δλ shorter than twice. Further, the length of the duct 15b (= 3λ ₀ ) is 3Δλ shorter than three times the wavelength (λ ₀ + Δλ) of the sound wave S2 generated by the transmitter 12.

  As a result, as shown in FIG. 7, the phases of the sound waves S3, S4, and S5 emitted from the radiation ports 13a to 15a are sequentially advanced by Δλ with respect to the sound wave S2 emitted from the radiation port 12a.

  Therefore, the traveling direction of the sound wave beam, which is the combined wavefront of the sound waves S2 to S5, is not perpendicular to the rows of the radiation ports 12a to 15a but is deflected in the direction of the white arrow (left side of the paper) as shown in FIG.

Here, assuming that the distance between the radiation ports 13a to 15a and the adjacent radiation ports 12a to 14a is x and the deflection angle of the sound wave beam is θ1, sound waves radiated from the radiation ports 13a to 15a are adjacent to each other. Since Δλ advances with respect to the sound wave radiated from the mouths 12a to 14a, it can be expressed as shown in FIG.
Therefore,
sin θ = Δλ / x
And θ1 is
θ1 = sin ⁻¹ (Δλ / x)
It is represented by

  In this way, by changing the frequency of the oscillation signal output from the oscillator 11, the directivity direction of the sound wave beam can be controlled. Therefore, when measuring the presence / absence of an object or the moving speed of the object, these can be measured by controlling the frequency of the transmission signal and directing the radio beam toward the moving object.

  It is also possible to obtain the intensity of the reflected wave by changing the directing direction of the sound beam and detect the direction in which the object exists from the intensity.

  As described above, in the underwater sonar of this embodiment, the traveling direction of the sound beam is deflected by changing the frequency of the oscillation signal output from the oscillator 11. Therefore, a mechanism for changing the direction of the individual transmitters 12 to 15 and a mechanism for rotating the arranged transmitters 12 to 15 as a whole are unnecessary. Further, the direction of the object can be detected even with one receiver 20. Therefore, the configuration of the underwater sonar can be simplified, reduced in size, and reduced in cost.

In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible.
For example, the length of each of the ducts 13b to 15b is set based on the wavelength λ ₀ of the oscillation signal and is a wavelength corresponding to the frequency range of the oscillation signal, but this is outside the frequency range of the oscillation signal. You may set to the wavelength corresponding to this frequency. In this case, the direction of the sound beam is offset.

Further, the number of the transmitters 12 to 15 is not limited to 4, and may be 2 or 3, or 5 or more.
Moreover, although the control circuit 22 detected the presence and moving speed of the moving object, the control circuit 22 may detect the presence of the moving object. For example, by measuring the time difference between the sound beam and the reflected wave, it is possible to measure the distance to an object that does not move.

It is a block diagram which shows the underwater sonar concerning embodiment of this invention. It is explanatory drawing of operation | movement of underwater sonar. It is explanatory drawing of the sound wave radiated | emitted from each radiation port. It is explanatory drawing of the sound wave beam at the time of making the frequency of an oscillation signal high. It is explanatory drawing of the phase between sound waves. It is explanatory drawing of the deflection | deviation direction of a sound beam. It is explanatory drawing of the sound wave beam at the time of making the frequency of an oscillation signal low. It is explanatory drawing of the phase between sound waves. It is explanatory drawing of the deflection | deviation direction of a sound beam.

Explanation of symbols

11 Oscillator 12-15 Transmitter 12a-15a Radiation port 13b-15b Duct 20 Receiver 21 Receiver 22 Control circuit

Claims (12)

An oscillator that generates an oscillation signal having a variable frequency;
A plurality of transmitters connected to the oscillator, each generating a sound wave having a frequency corresponding to the oscillation signal, and radiating the sound wave into water through a correspondingly provided radiation port;
A phase shifting means for delaying the sound wave radiated from each of the radiation ports by a delay amount unique to each of the transmitters;
Control means for controlling the traveling direction of the sound beam formed by the sound waves emitted from the plurality of radiation ports by changing the frequency of the oscillation signal;
A sound beam forming apparatus comprising:   The phase-shifting means is configured by a duct provided between each transmitter and each outlet and having a length unique to each transmitter. The acoustic beam forming apparatus as described.   The acoustic beam forming apparatus according to claim 1, wherein the plurality of radiation openings are arranged on a straight line.   The acoustic beam forming apparatus according to claim 1, wherein the plurality of radiation openings are arranged at equal intervals. An oscillator that generates an oscillation signal having a variable frequency;
A plurality of transmitters connected to the oscillator, each generating a sound wave having a frequency corresponding to the oscillation signal, and radiating the sound wave into water through a correspondingly provided radiation port;
A phase shifting means for delaying the sound wave radiated from each of the radiation ports by a delay amount unique to each of the transmitters;
Control means for controlling the traveling direction of the sound beam formed by the sound waves emitted from the plurality of radiation ports by changing the frequency of the oscillation signal;
A receiver that receives a reflected wave of the sound beam and generates a reception signal corresponding to the reflected wave;
Analyzing means for analyzing the object reflected from the sound beam based on the received signal;
An underwater sonar characterized by comprising.   The underwater sonar according to claim 5, wherein the object is a fish or a school of fish.   The underwater sonar according to claim 5 or 6, wherein the analysis means detects a direction in which the object exists.   The underwater sonar according to any one of claims 5 to 7, wherein the analyzing means detects a moving speed of the object.   6. The phase-shifting means is constituted by a duct provided between each of the transmitters and each of the radiation ports and having a length unique to each of the transmitters. The underwater sonar according to any one of 8.   The underwater sonar according to any one of claims 5 to 9, wherein the plurality of radiation openings are arranged on a straight line.   The underwater sonar according to any one of claims 5 to 10, wherein the plurality of radiation openings are arranged at equal intervals. An oscillator that generates an oscillation signal having a variable frequency;
A plurality of transmitters connected to the oscillator, each generating a sound wave having a frequency corresponding to the oscillation signal, and radiating the sound wave into water through a correspondingly provided radiation port;
A phase shifting means for delaying the sound wave radiated from each of the radiation ports by a delay amount unique to each of the transmitters;
A sound beam forming apparatus comprising: control means for controlling a traveling direction of a sound beam formed by sound waves emitted from the plurality of radiation ports by changing a frequency of the oscillation signal;
A means for changing the frequency of the oscillation signal is provided,
A method of controlling a sound wave beam, wherein the traveling direction of the sound beam emitted from the plurality of radiation ports is changed by changing a frequency of the oscillation signal.

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