JPS5844227B2 - Subpole suppression method for directional beams in underwater detection equipment - Google Patents

Description

[Detailed Description of the Invention] When performing underwater detection over a wide area, it is possible to form a large number of directional beams with slightly different pointing directions in advance, and to switch each directional beam in turn. A wide range of underwater detection can be carried out.

In the above, it is necessary that the directional beam has a subpole as small as possible.

However, when ultrasonic transducers are arranged in a circle in a device and a directional beam is formed by phase synthesis, relatively large sub-poles are likely to occur due to non-uniformity of the synthesis circuit.

The present invention provides a device that can be used in the above-described underwater detection device to form a directional beam while minimizing the number of subpoles.

To explain the embodiments in the drawings below, in FIG. 1, T1 to Tn represent transducer structures, which form directional beams in respective directions of θ1 to θn.

Each of the transducer structures T1 to Tn is actually formed by combining a plurality of ultrasonic transducers arranged in a circle.

FIG. 1 shows the case where the subpole of the directional beam of the transducer assembly Ti having the θi force direction directivity is suppressed.

The directional beam of the transducer assembly T1 is guided to a combiner circuit 1.

A combining circuit 1 combines the directional beam of the transducer assembly Ti which is guided through the level controller 2 and the phase shifter 3 with the directional beam of the transducer assembly Ti.

The combining circuit 1 also combines the directional beam to the transducer structure Ti- guided through the level controller 2' and the phase shifter 3' and the directional beam of the transducer structure Ti.

The directional beam of the transducer assembly Ti has directivity in the force direction θ, and its directional characteristics are expressed as shown in FIG. 2 Bi.

Furthermore, the directional beam of the transducer assembly Ti0 has directivity in the direction θi0, and its directional characteristics are expressed as shown in FIG. 2 Bi+.

This directional beam Bi+ is arranged so that its directional direction coincides with the first sub-pole Bi' generated in the directional beam Bi in the θi direction.

This alignment of the pointing directions can be achieved by appropriately setting the arrangement interval of the ultrasonic transducers arranged on the rice field and the number of ultrasonic transducers to be synthesized.

Furthermore, when there is no directional beam whose directional direction coincides with the first sub-pole Bi', a plurality of directional beams whose directional directions are close to the first sub-pole are combined, and the directional direction of the combined beam is set to the first sub-pole. It may be made coincident with the sub-pole B t/.

The level controller 2 performs level control so that the beam intensity of the directional beam θi+ matches the intensity of the first sub-pole Bi'.

The level-controlled frequency signal of the directional beam θi+ is guided to the phase shifter 3.

The phase shifter 3 shifts the phase of the frequency signal of the directional beam θi so that it is in phase with or in phase with the frequency signal of the directional beam signal θi.

The amount of phase shift at this time is determined by the shape of the vibrator, the sound wave frequency, and the combined state of the vibrator.

The combining circuit 1 generates a directional beam θi phase-shifted by a phase shifter 3.
The frequency signal of + and the frequency signal of directional beam θl are combined.

That is, when the frequency signals of the directional beam θi+ and the frequency signals of the directional beam θi are in phase, the combining circuit 1 performs a subtraction operation, and when they are in opposite phase, it performs an addition operation.

Therefore, the sub-pole portion of the directional beam signal Bi is canceled out by the directional beam signal Bi'+k, resulting in a directivity characteristic in which the sub-pole portion is suppressed as shown in FIG. 3.

On the other hand, the level controller 2 and the phase shifter 3' operate in the same manner as the level controller 2 and the phase shifter 3, and use the directional beam in the direction of θi- to generate the first sub-pole Bi'. suppresses the sub-pole B i// of the directional beam Bi which occurs symmetrically to the directional beam Bi.

As a result of the above, the combining circuit 1 outputs a directional beam with the sub-pole suppressed as shown in FIG. 5, it is possible to suppress received signals in unnecessary directions as much as possible.

Similar to the combining circuit 1, the switching device 4 time-divisionally switches and transmits the outputs of the first to nth combining circuits provided corresponding to each of the receiver structures T1 to Tn.

Note that in the above, the level controller 2 controls the intensity of the directional beam Bi+ instead of controlling the intensity of the directional beam Bi+.
The intensity may be controlled.

In the above embodiment, the first directional beam Bi
We have explained the case of suppressing the subpole, but in the same way,
It is also possible to suppress the second sub-pole, third sub-pole, etc.

As explained above, the present invention is an underwater detection device that performs wide range detection by arranging directional beams in each direction over a wide range. Therefore, it is possible to use a conventional transducer without changing the structure of the transducer by simply adding a combining circuit for synthesizing the directional beams.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and FIGS. 2 and 3 show directional characteristics diagrams for explaining its operation.

Claims (1)

[Scope of Claims] 1. In an underwater detection device that performs underwater detection by sequentially switching a number of directional beams whose directional directions differ by a fixed angle, a subpole that occurs in any directional beam among the number of directional beams. a level control circuit that performs intensity control so that the intensity of a specific directional beam whose directivity matches that of the above-mentioned arbitrary directional beam is balanced with the sub-pole intensity of the above-mentioned arbitrary directional beam; a phase shifter that performs phase control so that the directional beam signal is in the same phase or in opposite phase; and a sub-pole of the specific directional beam and the arbitrary directional beam that have undergone the level control and phase control. The combination circuit is equipped with a synthesis circuit that synthesizes the signals in an antiphase relationship with each other, and the synthesis circuit is configured to sequentially switch the synthesis output of each synthesis circuit in response to each of the plurality of directional beams that are different in order by a certain angle, thereby generating an underwater detection signal. A sub-pole suppression device for a directional beam in an underwater detection device, characterized in that it is used as a directional beam subpole suppressor. 2. The specific directional beam is formed by combining a plurality of directional beams having directivity in the sub-pole and proximity direction of the arbitrary directional beams. A sub-pole suppression device for a directional beam in the underwater detection device according to item 1.