JP2620983B2 - Fish finder and transducer for weighing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a weighing fish finder that can be used in a dual beam system and a split beam system, and a transducer therefor.

(Prior Art) In conducting efficient fishery or resource amount surveys, it is necessary to know the body length and weight of the fish forming the fish school. Therefore, the sound pressure reflectance, so-called target length, which is the ratio of the sound pressure level of the emitted sound wave to the sound pressure level of the reflected wave from the fish, is proportional to the square of the fish length and proportional to the 2/3 power of the fish weight. A fish finder for weighing is used.

Generally, the sound pressure of a sound wave is strongest in front of the transducer, that is, on the directivity main axis, and attenuates as the distance from the main axis increases. Therefore, even if the fish F has the same sound pressure reflectance, the reception level varies depending on the angle θ between the directivity main axis M of the transducer SR as shown in FIG. It cannot be prevented.

Therefore, in order to solve the problem, it is possible to know from what angle the reflected wave from the fish F is returned from the directivity main axis of the transmitter / receiver and correct the received wave level corresponding to the angle. However, accurate calculations cannot be obtained unless the calculation of the fish length and fish weight is performed using the results.
Therefore, a dual beam method and a split beam method have been devised as means for knowing the angle between the reflector and the directivity main axis of the transducer, and correction is performed independently or in combination. ing.

In this method, for example, in a case where the dual beam method and the split beam method are used in combination, a wide directional transmitting / receiving element A having a circular cross section as shown in FIG. A narrow directivity transmitting / receiving element, whose directivity main axis coincides with the main axis of the wide directivity transmitting / receiving element A, formed by the transmitting / receiving elements B, C, D, and E having the same shape and dimensions having a sector shape in cross section. Use something.

When the dual beam method is used, FIG. 3 (a)
As shown in Fig. 3 (b), a sound wave is emitted downward with narrow directivity by the transmitting and receiving elements A, B, C, D, and E, and the reflected wave due to this is emitted.
As shown in FIG. 3 (a).
As shown in FIG. 4, signals are simultaneously received by the narrow directivity transmitting / receiving elements A, B, C, D, and E, and reflected from the level difference between these two reception outputs with respect to the main directivity axis M. The level of the reflected wave by the element A + B + C + D + E beam is corrected by determining how many times the body F is displaced.

When the split beam method is used, similarly to the transmission of the dual beam, the narrow directional transmitting / receiving elements A, B, C, D, and E are excited in phase to emit a sound wave downward and receive an echo.
At the same time, the reception outputs of the elements B and D and the reception outputs of the elements C and E are respectively added, and two beams having a distance L between the geometric area center points in the X-axis direction of the elements B and D and C and E are formed. Form. Further, the reception outputs of the elements B and C and the reception outputs of the elements D and E are added, and the elements B and C are added.
Two beams having a distance L between the center points of the geometric areas in the Y-axis direction of C, C, and E are formed. Then, as shown in FIG. 5, the electric phase angle φ _x between the X axis and the reflector F, the Y axis and the reflector F
Obtains the electrical phase angle phi _y between, these angle gamma _x for directional main axis M of the reflector F, gamma _y and φ = (2πL / λ) · sinγ where between lambda: presence wavelength becomes relation This is a method of obtaining γ _x and γ _y by utilizing the above, and further obtaining θ by combining these to correct the level of the signal received by the elements A, B, C, D and E.

(Problems to be solved by the prior art) However, in the case of the split beam method as described above,
In order to know the angle θ between the directivity main axis M of the reflector F and the electric phase angle φ, as shown in FIGS.
It is necessary to know the distance L between the geometric area center points between BD and CE and between elements BC and DE.

However, since the distance L necessarily changes when the size of the transducer changes, the coefficient to be input to the angle θ calculation circuit must be changed each time the size of the transducer changes. Therefore, the design and production become more complicated. In addition to this, in the arrangement of the transmitting and receiving elements, the area of the transmitting and receiving element becomes large, and when the distance L between the elements becomes larger than 1/2 wavelength of the emitted sound wave, the X axis shown in FIG. The same electrical phase angle φ within an angle of 0 to ± 90 ° between the main axis and the Y axis and the directivity main axis
Many occur. Therefore, there is a disadvantage that φ cannot be specified and correction cannot be performed.

(Object of the Invention) The present invention has been made to provide a fish finder for weighing which uses the dual beam and split beam methods together and which solves the problems described above, and a transducer for the same.

(Means of the Invention for Solving the Problems) FIG. 7 is a plan view showing the configuration of a dual beam / split beam combined transducer of the present invention, and FIG. 8 is a processing circuit diagram of each element output. The features of the present invention are as follows. That is, a transmitting / receiving element B provided with a transmitting / receiving element A having a circular cross section concentrically at the center, and the length of one side arranged on one of four sides of the element B is the same as the length of one side of the element B. And each of the transmitting and receiving elements C, each having a rectangular cross section having a width of l,
D, E, F and so as to be concentric with the transmitting and receiving element A,
A transceiver, which is provided on the outer periphery of the elements C, D, E, and F and includes a transmitting and receiving element G having a circular outer shape, and a processing circuit for the output thereof is operated as described below. It is assumed that.

In the case of the use by the dual beam method, as shown in FIG. 8, the elements A to G are vibrated in the same phase by the input from the oscillation source (1) at the time of transmitting the wave and transmitted. At the time of receiving a wave, the outputs of the elements A to G are used as preamplifiers (2a) (2b) (2c)
.. (2g), the wide directional beam output _DW of only the element A as shown in FIG. 9 (a) and the elements A to _G as shown in FIG. 9 (b) and FIG. Adders (3a), (3b), (3c) ...
The narrow directional beam output D _N obtained by adding (3f),
That is, dual beam correction calculation can be performed by the correction calculation circuit (4a) using the two beam outputs of the wide directivity and the narrow directivity.

In the case of the split beam method, a preamplifier (2a) obtained by in-phase oscillation of elements A to G as shown in FIG.
The outputs of (2b) and (2c) and the outputs of (2a), (2b) and (2d) are added to adders (3c) and (3d), and a weighting coefficient is applied as shown in FIG. , B, C and the outputs of the elements A, B, D are added to obtain two beam outputs S _x1 and S _x2 having a distance difference in the X-axis direction.

The outputs of the preamplifiers (2a) (2b) (2e) and (2a)
(2b) The output of (2f) is added to adders (3e) and (3f),
10 As shown in Fig. 10 (b), the elements A, B, E
Are added to the outputs of the elements A, B, and F to obtain two beam outputs S _y1 and S _y2 having a distance difference in the Y-axis direction. Then, from these S _x1 , S _x2 and S _y1 and S _y2 , a correction operation circuit (4
According to b), the phase angles of the reflector F in the X-axis direction and the Y-axis direction are detected as shown in FIG. 5, and γ _x and γ _y are obtained from φ = (2πL / λ) · sin γ in the same manner as described above. From the combination, the angle θ of the reflector F in the far field is obtained. And thereby correcting the receiving level of the addition output D _N of the wave transceiver device A~G by the adder (3b) of the angle theta.

(Effects of the Invention) If the transducer is formed by combining the above-described elements, the elements A and B are maintained as shown in FIGS. The size of the transducer can be changed by changing the size of B and G. Therefore, element A + B
The distance L between the center points of the geometric areas of + C and A + B + D and between the center points of the geometric areas of the elements A + B + E and A + B + F (not shown) are always a constant value determined by the width l of the elements C to F. There is no difference depending on the size unlike the transducer using the split beam. This facilitates design and manufacture.

Further, as described above, the distance L is determined by the width l of the elements C to F. Since l is constant even if the size, that is, the area of the transducer is changed, the width of the elements C to F is set to be within 1/2 wavelength. If this is the case, the detection phase angles φ _x and φ _y of the reflected waves in the lower hemisphere of the transducer will not exceed 180 ° as in the prior art. For this reason, the angle can be reliably detected by the split beam method, and the problem of the above-described conventional dual beam transmitter / receiver combined with the split beam method can be solved.

In addition to this, in the present invention, the above basic element A
By changing the area of each element in the combination of G, a directivity width suitable for measurement can be obtained. By subdividing the elements A to G and changing the weight coefficient at the time of addition, various advantages in correction by the split beam method, such as suppression of side lobes, can be obtained.

Note that the elements A to G shown in FIG. 7 are described as one element each. However, the same effect can be obtained by arranging and adding small elements and equivalently distinguishing A to G. Needless to say.

Further, similar effects can be obtained even if A and ΔA to G are not circular but rectangular.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a measurement error based on an angle between a directivity main axis and a reflector in a fish finder for measurement, FIG. 2, FIG.
4, 5 and 6 are explanatory views of a correction method using a transducer used in combination with the dual beam method and the split beam method, and FIGS. 7, 8, 9, 10 and 11. FIG. 3 is an explanatory diagram of one embodiment of the present invention. A, B, C, D, E, F, G …… Transceiver element, (1)… Vibration source, (2
a) (2b) (2c) (2d) (2e) (2f) ... preamplifier,
(3a) (3b) (3c) (3d) (3e) (3f) ... Adder,
(4a) (4b) ... Correction calculation circuit.

Claims (2)

(57) [Claims] 1. A transmitting and receiving element B having a square cross section and a transmitting and receiving element B having a square cross section and having the same shape and dimensions having a width of l and arranged on the four circumferences thereof. Elements C, D, E, F, and a transducer equipped with a transmitting and receiving element G coaxially arranged with the transmitting and receiving elements A and B on the outer periphery thereof, and from each of the transmitting and receiving elements by in-phase excitation. Output of only the transmitting / receiving element A obtained by adding the reflected signals of
An addition circuit for obtaining a total addition output up to G, an addition output of A, B, C, an addition output of A, B, C, an addition output of A, B, E, and an addition output of A, B, F; Broad directional beam output of transmitting / receiving element A and A to G
A dual beam correction circuit that corrects the measurement level error of the sum output of the elements A to G by using the output of the narrow directional beam by using the output of the narrow beam and the angle of the reflector with respect to the main axis of directivity using the level difference between the wide and narrow beam outputs. And the transmitting and receiving elements A, B, C
A, B, D and A, B, E and A, B, F split beam correction for correcting the measurement level error of the added output of the elements A to G due to the angle with respect to the directivity main axis of the reflector using the added output of A, B, F A fish finder for weighing, comprising a circuit. 2. A wave transmitting / receiving element B having a square cross section and a wave transmitting / receiving element A having a circular cross section provided coaxially at the center thereof, and a wave transmitting / receiving element having a rectangular cross section having the same shape and dimensions having a width of l and arranged on four sides thereof. A transmitter / receiver for a fish finder for measurement, comprising: elements C, D, E, F, and a transmitting / receiving element G arranged coaxially with the transmitting / receiving elements A, B on the outer periphery thereof.