JPH02228580A - Sonar transmission circuit - Google Patents

Abstract

PURPOSE:To enable execution of continuously-rotating beam transmission along an entire circumference or in a required angular range, attainment of a high sorting capacity and execution of distance measurement with an error suppressed, by forming a pair of split transmission beams and by controlling continuously a phase difference between the right and left beams. CONSTITUTION:A transducer 1, a transmission switching circuit 2, power amplifiers 3-1R to 3-kR and 3-1L to 3-kL, transmission phasing circuits 4-1R to 4-kR and 4-1L to 4-kL, variable phase-shifting circuits 5a and 5b, a pulse modulation circuit 6, a transmission circuit 7 and an RDT control circuit 8 are provided. The transducer 1 transduces a supplied signal electroacoustically, forms split beams directed in the same direction and further forms a synthetic beam as the synthesis thereof. Next, when one transmission pulse is ended, the circuit 2 shifts the correspondence of the amplifiers 3-1R to 3-kR and 3-1L to 3-kL with the steep of the transducer one by one in the circumferential direction under the control of the circuit 8 and the same operation is conducted. By repeating this operation sequentially, rotating beam transmission continuing by a required transmission angle is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sound transmitting circuit, and in particular, it emits sound waves into water, receives echoes from a target object, displays the echoes as images, and searches for a target. In active sonar devices that perform detection, rotating beam transmission (Rotating Dire
ctional Transmission, hereinafter referred to as RD
This invention relates to a sonar transmitter circuit that performs a sonar transmission circuit (abbreviated as T).

[Conventional technology]

For active sonar devices, in order to obtain a high target search ability, it is necessary to concentrate 1% of the transmission energy in a fixed direction, rotate this sequentially for each transmission pulse, and transmit in an omnidirectional range or a specific angular range. It is necessary to do so.

FIG. 4 is a block diagram of a conventional sonar transmitter circuit that performs DT.

The sonar transmitting circuit shown in FIG. 4 is an i-stave.

A circumferentially arrayed transducer 1 consisting of j-stack transducer elements and a transmission switching circuit 2a that switches the m-stave transducer elements used for each transmission pulse, necessary for transmitting beam formation by RDT. m staple, 10 in the case of Figure 4
Applying transmission power to the transducer element of the tape 1
0 channel power amplifiers 10-1 to 10-10. Transmission phasing circuits 9-1 to 9-5 perform phasing of transmission signals supplied to power amplifiers 10-1 to 10-10, a pulse modulation circuit 6 forms a PCW wave as a transmission signal, and oscillates a transmission frequency. In addition to the transmitting circuit 7, it is provided with an RDT control circuit 8a that controls the timing and pulse width of RDT transmission.

To perform rotating beam transmission, that is, RDT transmission, the transducer 1 is normally expanded by 1 step on each side of the circumference on the same right or left side for each transmission in consecutive 9 m steps determined by taking into account the beam's directivity characteristics, etc. By cutting out while shifting, delaying the input signal of the power amplifier corresponding to each stave for each stave that is symmetrical in the circumferential direction, and eliminating the difference in path between the transducer elements due to the circumferential array position, Acoustically speaking, a transmitting beam is obtained by an equivalent rectangular plate arrangement of m-staves, and the transmitting beam is successively formed in the circumferential direction in steps for each stave.

In the case of Figure 4, beam rotation is performed by shifting the transducer elements of 10 staves clockwise one stave at a time.
In the case of T, phasing that uses the two end staves of the 10 staves as a reference and delays each two symmetrical steps until reaching the two central staves so that the phase is the same as that of the reference stave. is performed to form an equivalent rectangular plate array.

The transmission phasing circuits 9-1 to 9-5 provide a reference phase ψ□ to the power amplifiers 10-1 and 10-10 corresponding to the staves at both ends of the 10 staves, and the power amplifiers 10 corresponding to the two adjacent staves in the center. -5.The phase amount ψ for 10-6 is applied to each phase between 91 and 95 as described above,
Therefore, the ten staples are driven with no apparent difference in stroke.

Every time one transmission pulse is transmitted by such a transmission beam, the transmission switching circuit 2a switches the power amplifier 10-
1 to 10-10 and the stave correspondence of the transducer 1 are shifted by one stave to the right or left, and a transmission beam is formed in the direction shifted by the arrangement angle difference α between the staves to perform the next transmission. This is then repeated over the required angle range.

FIG. 5 is a characteristic diagram of the transmission beam direction in conventional RDT transmission. When the acoustic reference direction is #□, the transmission beam direction in RDT changes in steps of the stave arrangement angle difference α for each transmission, and the transmission pulses by the PCW wave are θ□, θ□+α, θ. +2α . . . shows a state in which data is transmitted at a transmission interval δ for each α.

The directivity of the subsequently formed transmit beam is usually adjusted so that it intersects the adjacent beam with approximately 3a-wave attenuation.

[Problem to be solved by the invention]

The RDT transmission beams from the conventional transducer transmitter circuit described above are set so that adjacent beams intersect with each other at approximately 3 dB attenuation points, so the radiated energy is approximately uniform over the entire circumference of the transducer. In addition to the normal transmission pulse, in the intermediate direction of each transmission beam, a transmission pulse with a time difference of the transmission pulse width is also emitted.
Two echoes from the same target are generated, causing a large error in distance measurement, and in the case of a deep target, the two echoes are superimposed, significantly interfering with target classification based on waveforms.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sonar transmitting circuit which eliminates the above-mentioned drawbacks and can significantly suppress distance errors and deterioration of target classification function even in intermediate directions of a transmitted beam.

[Means to solve the problem]

The circuit of the present invention drives each part of a transducer consisting of transducer elements arranged in a cylindrical shape with a transmission pulse, and switches the transducer while shifting in a predetermined step in the circumferential direction for each transmission pulse. In a sonar transmission circuit that transmits a rotating beam that emits sound waves, the transducer element group that is driven for each transmission pulse is divided into two in the circumferential direction, allowing overlap, and the transducer element group is divided into right and left transducer element groups, respectively. A split beam forming means for forming a split beam consisting of a pair of left and right beams oriented in the same direction, and a left and right beam forming means for forming the split beam so as to continuously perform a shift between steps in the rotation of the split beam. and a phase difference applying means for continuously applying a phase difference to.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a receiver transmitting circuit according to the present invention.

The embodiment shown in FIG. 1 includes a transducer 1, a transmission switching circuit 2,
power amplifiers 3-IB, 3-2B, 3- for supplying transmission power for the right beam forming a split beam;
3R...1 power amplifier 3-IL for supplying transmission power for the left beam.

3-2L, 3-3L...3-kL, power amplifier 3-I
Transmission phasing circuits 4-IR to 4-kJ to give the phase amount ψIRtψ5iteψ31L·-·ψkm for phasing required for right beam formation corresponding to R~3-kR 4-IR to 4-kJ phasing required for left beam formation The phase amount ψ□1. ψ2Ltψ3L
...Transmission phasing circuits 4-IL to 4 to give ψkL
-kL.

A variable phase shift circuit 5a for the right beam, a variable phase shift circuit 5b for the left beam, and a variable phase shift circuit 5b for the left beam to provide a continuously variable phase for continuously changing the transmission beam rotation between the staves.
The device is configured to include a pulse modulation circuit 61 that generates a transmission pulse of w, a transmission rotation 7, and an RDT control circuit 8.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

Before explaining the operation of each part, the split beam will be explained. A split beam refers to a pair of transmitted beams consisting of right and left beams formed in the same directivity direction by transducer elements of the same number of left and right staves, and in the example in Figure 1, the right beam is , the left beam is formed by the staple 1Ni-4, and this split beam is transmitted and received as a spatially combined composite beam, and is operated for the purpose of detecting targets with high discrimination in the spatial intersection area of the two beams. .

In FIG. 1, a continuous SIN wave transmission signal generated by a transmitting circuit 7 is supplied to a pulse modulating circuit 6, and converted into a pulse modulated wave having a pulse width specified by an RDT control circuit 8.

The output signal of the pulse modulation circuit 6 is applied to variable phase shift circuits 5a and 5b corresponding to left and right split beams, and is phase-shifted by φR.

Phase shift amount ψR1 given to the right beam of the split beam by variable phase shift circuits 5a and 5b Phase shift amount ψ given to the left beam
8 is the acoustic center direction θ of the left and right beams at the beginning of the transmission pulse, as shown in FIG. 2(a).

are shifted to the left by 1/2 of the arrangement angle difference α of the staples, and the acoustic position is perpendicular to the azimuth, and the combined beam of the split beams is directed in the direction θ The phase difference (ψ, -ψR) is controlled, and at the center of the transmission beam, the combined beam coincides with the acoustic center direction θm of the left and right beams as shown in Figure 2 (b), and furthermore, at the end of the transmission pulse, the combined beam coincides with the acoustic center direction θm of the left and right beams as shown in Figure 2 (C). ), contrary to the starting point, the acoustic center direction of the left and right beams is 1/2 of the staple arrangement angle difference α.
The combined beam of the split beam is controlled to be directed at θ□+α/2 by controlling the acoustic position to intersect at right angles to the azimuth shifted to the right by θ□−α.
/2 to θ. Continuously change by +α/2t.

In other words, from the sending of the transmission pulse to the end, the combined beam by the split beam is swung while continuously changing its direction from -α/2 to +α/2 over the stave arrangement angle difference α with the center at θ□. This state is repeated every time the stave advances.

Phases ψ1R to ψkin given to each of the transmission phasing circuits 4-IR to 4-kR and transmission phasing circuits 4-1L to 4
The phases ψ1L to ψkL given to each of -kL are set to give the phase shift amount necessary for forming the right and left beams of the split beam, and each phase shift amount is one phase shift amount as described above. A fixed amount determined by the arrangement position, i.e., arrangement angle and arrangement radius, of each staple in a continuous group of staples necessary to form a transmitting directional beam of It is. Usually, ψIR, ψ2R, ψ3R"'ψkR and ψIL
- ψ2L, ψ3L... The same amount is set for ψ for left and right.

Transmission phasing circuit 4-IR~4-kn, , 4-IL~
The outputs of 4-kL are respectively connected to power amplifiers 3-IR to 3-k.
R, 3-IL ~ 3kL is supplied to perform power amplification,
The signal is supplied to the transducer 1 via the transmission switching circuit 2.

The transducer 1 electrically converts the provided signal to form split beams oriented in the same direction, and further forms a composite beam as a combination of the split beams.

Next, when one transmission pulse ends, the transmission switching circuit 2 switches the power amplifiers 3-IR to 3 under the control of the RDT control circuit 8.
-kR, 3-IL to 3-kL and the transducer staples are shifted one by one in the circumferential direction.

A similar operation is performed. By sequentially repeating this process, continuous rotating beam transmission can be obtained for the required transmission angle.

FIG. 3 is a characteristic diagram of the transmission beam direction of the embodiment shown in FIG. The transmission beam direction in this embodiment changes continuously from -a/2 to +α/2 centering on the blue tatami reference direction θ□, and this change pattern is +α, +2α...+n
It shows a state of continuous rotation over α and the entire radiation angle range.

In this way, step shifts between stacks in beam rotation can be performed continuously.

Note that the rotational speed of the beam in the above-described embodiment is normally set to an angle corresponding to 3 dB transmission beam width in the transmission pulse width period, in order to ensure the energy radiated to the target. .

Further, in the above-described embodiment, a split beam is formed in which the stave is divided into left and right equal parts, but it is clear that the same method can be implemented in which a portion of the stave is used redundantly instead of this.

〔Effect of the invention〕

As explained above, the present invention forms a pair of split transmission beams and continuously controls the phase difference between the left and right beams, thereby making it possible to perform continuous rotational beam transmission over the entire circumference or within a required angular range. Step-controlled beam transmission also has the advantage of significantly higher classification ability and distance measurement with significantly suppressed errors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the sonar transmission circuit of the present invention, FIG. 2 is an explanatory diagram showing the content of split beam phase shift during beam rotation between staples in the embodiment of FIG. 1, and FIG. FIG. 1 is a characteristic diagram of the transmission beam direction in the embodiment, FIG. 4 is a block diagram of a conventional sonar transmission circuit that performs RDT, and FIG. 5 is a characteristic diagram of the transmission beam in the conventional R and DT transmission. 1... Transducer/receiver, 2, 2a... Transmission switching circuit, 3-
IR~3-kR, 3-IL~3-kL, 10-1~10
-10...Power amplifier, 4-IR to 4-kR, 4-I
L~4-kL. 9-1 to 9-5... Transmission phasing circuit, sa, sb...
Variable phase shift circuit, 6... Pulse modulation circuit, 7... Transmission circuit, 8°8a... RDT control circuit. Agent: Susumu Uchihara, Patent Attorney, 41 Ward 3 Betohe Figure 5

Claims (1)

[Scope of Claims] A transmitter/receiver consisting of transducer elements arranged in a cylindrical shape is driven by a transmitting pulse, and is switched while being shifted in a predetermined step in the circumferential direction for each transmitting pulse, thereby transmitting sound waves into the water. In a sonar transmission circuit that transmits a rotating beam that emits a split beam forming means for forming a split beam consisting of a pair of left and right beams oriented in the direction of the left and right beams; A sonar transmission circuit comprising: a phase difference imparting means for imparting a phase difference to; and a sonar transmitting circuit.