JPH0121471B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to eliminate false images caused by sub-poles of a directional receiving beam in an underwater detection device that performs underwater detection in a wide range of directions.

Underwater detection equipment that detects a wide range of directions generally transmits ultrasonic pulses simultaneously in a wide range of directions and receives the reflected waves returning from each direction as a directional receiving beam with directivity in each direction. It's being done very well. Therefore, it is desirable that the directional receiving beam has directivity only in one specific direction. As is well known, the directional receiving beam is generated by phase-combining the receiving signals of a plurality of transducers.
In this case, the composite directional characteristic has a main pole having directivity in the desired direction and a sub-pole having reception sensitivity also in unnecessary directions. Since this sub-pole receives reflected waves arriving from unnecessary directions, it causes various problems on the display screen. For example, as shown in Figure 1, when receiving a reflected signal in the 0° direction, if there is an object A in the -32° direction of the sub-pole, the reflected wave from this object A will appear in the 0° direction on the display screen. will be displayed as if it were present. Such a false image effect is particularly noticeable when ultrasonic pulses are transmitted downward from the bottom of the ship. For example, as shown in FIG. 2, ultrasonic pulses are transmitted in a wide range of directions from the sea surface S to the seabed G, and the reflected waves return the fastest. This reflected wave is received by the directional receiving beam Br ₀ having directivity directly below, and at the same time, it is also received by the subpoles of the directional receiving beams Br ₁ to Brn in the other direction. Ru. Furthermore, since the reflected wave from the bottom of the ship generally has a relatively strong intensity, it is displayed very clearly on the display even though the signal is received by the sub-pole. Therefore, a false bottom line G' is displayed on the display as if the seabed exists on a line equidistant from the wave transmission position _S0 , and the bottom-based fish F existing near the actual seabed G is displayed. The reflected waves from the image are buried within the false image G' and cannot be identified.

The present invention eliminates the above-mentioned drawbacks and realizes a device that erases the false image G' and displays only the true detected image.

This invention will be explained below.

In FIG. 3, T ₁ to T ₁₅ indicate oscillators,
As shown in Figure 4, they are arranged at 10° intervals on the circumferential surface. Therefore, as is clear from FIG. 4, the transducers T ₁ to T ₁₅ transmit and receive ultrasonic pulses in a direction within a range of 140°.

Transducers T ₁ to T ₁₅ are switched between transmitting and receiving signals by respective switching circuits TR ₁ to TR ₁₅ ,
Each received signal is transmitted through a respective preamplifier A ₁ to
Guided by A ₁₅ . Further, the transmission of the transducers T ₁ to T ₁₅ is performed by one of the transmitters S ₁ , S ₂ , and S ₃ . That is, among the transducers T ₁ to T ₁₅ , the transducers
T ₁ , T ₂ , T ₃ , T ₁₃ , T ₁₄ , T ₁₅ are excited by the transmitter S ₁ and the oscillators T ₄ , T ₅ , T ₆ , T ₁₀ , T ₁₁ ,
T ₁₂ is excited by the transmitter S ₂ and the oscillators T ₇ ,
T ₈ , T ₉ are excited by transmitter S ₃ . Therefore,
When the excitation pulse is sent from the transmitter S ₁ , the transducers T ₁ , T ₂ , and T ₃ transmit the ultrasonic pulse in the angular direction within a range of 30° as shown by angle θ ₁ in FIG. The children T ₁₃ , T ₁₄ , and T ₁₅ transmit ultrasonic pulses in a range angle direction of 30° indicated by θ ₅ . Also, when the transmitter S ₂ operates, the transducers T ₄ , T ₅ , and T ₆ transmit ultrasonic pulses in a range angle direction of 30° in the θ ₂ direction, and at the same time,
Transducers T ₁₀ , T ₁₁ , and T ₁₂ transmit ultrasonic pulses in a range angle direction of 30° in the θ ₄ direction. Further, when the transmitter S ₈ is operated, the ultrasonic pulses are transmitted in a range angle direction of 30 degrees in the θ ₃ direction by the transducers T ₇ , T ₈ , and T ₉ . Therefore, the transducers T ₁ to T ₁₅ are the transmitters S ₁ ,
As shown in FIG. 4, ultrasonic pulses are transmitted by S ₂ and S ₃ in directions of 30 degrees from θ ₁ to θ ₅ , respectively.

The transducers T ₁ to T ₁₅ receive reflected waves returning from respective directions after transmitting ultrasonic pulses.
Each received signal is transmitted through each switching circuit TR ₁ to
Via TR ₁₅ , each preamplifier A ₁ to A ₁₅ is led to a phase synthesizer M ₁ to M ₁₃ .

The phase synthesis circuits M ₁ to M ₁₃ form directional reception beams, and the phase synthesis circuits M ₁ to M 13 form directional reception beams.
_M13 synthesizes the phases of the received signals of three of the transducers _T1 to _T15 to form a directional received beam with a main beam having a directivity angle of 10 degrees. That is, the phase synthesis circuit M ₁ phase-synthesizes the reception signals of the transducers T ₁ , T ₂ , and T ₃ to form a reception beam with a directivity angle of 10° in the direction of the transducer T ₃ . Similarly, phase synthesis circuits M ₃ to
M ₁₈ synthesizes the received signals of three transducers, and has a directivity angle in the directions of transducers T ₄ to T ₁₄ , respectively.
Forms receiving beams of 10° each.

Of the directional reception beams formed by each of the phase synthesis circuits M ₁ to M ₁₃ , the phase synthesis circuits M ₆ ,
The directional reception beams other than M ₇ and M ₈ are guided to the switching circuit Sw via delay circuits D ₁ to D ₁₀ . The switching circuit Sw switches and transmits the received beams of the phase synthesis circuits M ₁ to M ₁₀ in a time-divisional manner, and performs the switching operation based on the switching wave generation circuit Sc. The directional reception beam sent out in a time-division manner from the switching circuit Sw is guided to the brightness terminal of the cathode ray tube CRT, and brightness-modulates the electron beam. In the cathode ray tube CRT, the electron beam is swept in a spiral manner by a sweep circuit SG. At the same time, the sweep circuit SG drives the switching wave generation circuit Sc to transfer the signal from the switching circuit Sw to the cathode ray tube.
A receiving beam is transmitted in the direction corresponding to the spiral sweep position of the CRT. The switching wave generating circuit Sc causes the switching circuit Sw to repeatedly perform switching operations in conjunction with the spiral sweep of the cathode ray tube CRT. Therefore, reflected waves sweeping from the object to be detected are displayed on the display screen of the cathode ray tube CRT at respective corresponding azimuth and distance positions. Note that after the spiral sweep is completed, the sweep circuit SG performs the spiral sweep in the same manner as described above when a pulse wave is sent out from the reference pulse source KP. FIG. 5 shows a specific example of the sweep circuit SG, in which a pulse wave from a reference pulse source KP is guided to a sweep voltage generator SV. The sweep voltage SV generates a sawtooth wave based on the reference pulse and amplitude modulator
Send to AM ₁ and AM ₂ . The amplitude modulator _AM1 modulates the amplitude of the positive wave sent out from the sine wave generator SIN into a sawtooth shape and sends it out to the X-axis orientation circuit Lx of the cathode ray tube CRT. Further, the amplitude modulation circuit AM ₂ modulates the amplitude of the cosine wave sent out from the cosine wave generator COS in a sawtooth shape and guides it to the Y-axis deflection coil Ly of the cathode ray tube CRT. Therefore, the electron beam of the cathode ray tube CRT is deflected in a spiral manner. Note that the cosine wave generator COS generates a cosine wave based on the sine wave generator SIN. Furthermore, the sine wave voltage of the sine wave generator SIN is also sent to the brightness control voltage generator BC. The brightness control voltage BC is based on a sine wave voltage, and the spirally swept electron beam _is
A control voltage is sent such that brightness control is performed only while sweeping in the direction corresponding to the arrangement direction of _T15 .

As described above, the reflected waves returning to the transducers T ₁ to T ₁₅ are displayed in the corresponding azimuth directions of the cathode ray tube CRT, while the transducers T ₁ to T ₁₅ are connected to the transmitters S ₁ , S ₂ ,
The transmitters S ₁ , S ₂ , S ₃ are excited by S ₃ , and their transmitting operations are controlled by a timing circuit TC.
That is, the timing circuit TC connects the transmitters S ₁ , S ₂ ,
This regulates the order of _S3 transmission operations, and when a pulse wave is sent out from the reference pulse generation circuit KP,
First, the transmitter S ₁ is operated, and after t ₁ hours, the transmitter S ₂ is operated, and further, after t ₂ hours, the transmitter S ₃ is operated. Therefore, when transmitter S ₁ operates, the oscillator
As a result of excitation of T ₁ , T ₂ , T ₃ as well as T ₁₃ , T ₁₄ , and T ₁₅ , ultrasonic pulses are sent out in the 30° direction of θ ₁ and θ ₅ shown in FIG. After the ultrasonic pulse is transmitted in the θ ₁ and θ ₅ directions, the transmitter S ₂ transmits the transducers T ₄ , T ₅ , T ₆ and T ₁₀ , T ₁₁ , T ₁₂ after t ₁ hour. It is excited and sends out ultrasonic pulses in the 30° direction shown by θ ₂ and θ ₄ in FIG. Furthermore, after t ₂ hours the transmitter
When S ₃ operates, transducers T ₇ , T ₈ , and T ₉ are excited, and ultrasonic pulses are transmitted in the 30° direction indicated by θ ₃ in FIG. 4.

In the above, after transmitter S ₁ is activated, the transmitter
Delay time t ₁ until S ₂ operates, plus transmitter S ₂
The delay time t ₂ from when the transmitter S 3 operates to when the transmitter S ₃ operates is determined as follows. In Figure 6, the depth from the sea surface S to the seabed G is D, and the fourth
It is assumed that ultrasonic pulses are transmitted in the θ ₁ to θ ₅ directions using the transducers T ₁ to T ₁₅ in the figure.

Now, a detection pulse is transmitted in each of the θ ₁ and θ ₂ directions, and the delay time t ₁ of the transmitter S ₂ is set so that the reflected wave from the sea floor P ₁ and the reflected wave from the sea bed P ₃ return at the same time. Determine. Furthermore, the delay time _{t 2 of} the transmitter S 3 is set by transmitting a detection pulse in each of the θ ₂ and θ ₃ directions so that the reflected waves from the ocean floor P ₂ and the reflected waves from the ocean floor P ₄ return at the same time. Determine. Therefore,
The reflected wave from the seabed _{3 3} ′ in the θ ₃ direction is at least θ ₂
It returns after the reflected waves from the seabed in the direction _{2 3} return. Similarly, the reflected wave from the ocean _{floor 23 in} the θ ₂ direction returns at least after the reflected wave from the ocean floor ′ _{1 2} in the θ ₁ direction returns. Therefore, the seafloor reflected wave in the θ ₂ direction is θ ₁
When received by the sub-beam of the directional receiving beam in the θ ₂ direction, the seabed reflected wave in the θ 2 direction appears after the seabed reflected wave in the θ ₁ direction is received, so the display screen shows the seafloor reflection wave in Fig. 2. Such a false image G′ will never occur. Similarly, when the seabed reflected wave in the θ ₃ direction is received by the sub beam of the directional reception beam in the θ ₂ direction, the seabed reflected wave in the θ ₃ direction is the received seafloor reflected wave in the θ ₂ direction. Since it appears later, on the display screen, the false image due to the seabed reflected wave in the θ ₃ direction appears at a position farther away than the display position of the seafloor reflected wave in the θ ₂ direction.

In the above, the delay times of transmitters S ₂ and S ₃ are determined as follows.

First, since the delay time t ₁ of the transmitter S ₂ is the round trip time difference of the sound waves from the transmission source S ₀ to the seabed points P ₁ and P ₃ ,
If the propagation speed of sound waves is 1500m/sec Similarly, the delay time t 2 of transmitter S ₃ is equal to the delay time _{t 2} of transmitter S ₃
Since it is the round trip time difference of the sound waves from to the seafloor points P ₂ and P ₄ , The transmission timing of the detection pulses transmitted from the transducers T ₁ to T ₁₅ is determined as described above according to the respective division directions θ ₁ to θ ₅ . Therefore, the reflected waves from the detection object on the equidistant line are also received with a delay of the above-mentioned time t ₁ or t ₂ depending on the respective division directions θ ₁ to θ ₅ . In other words, the received signal in the θ ₂ direction is received with a delay of t ₁ time compared to the received signal in the θ ₁ direction, and the received signal in the θ ₃ direction is received with a delay of t 1 time compared to the received signal in the θ ₁ direction. The signal is then received with a delay of (t ₁ + t ₂ ) time.

The delay times D ₁ to D ₁₀ are for correcting these delay times, and are determined according to the directional reception beams of the divided sections θ ₁ to θ ₅ . For example, the received beams in the θ ₁ and θ ₅ directions are transmitted through the phase synthesis circuit M ₁ ,
Since the delay circuits D ₁ , D ₂ , D 9 , and D 10 are formed by M ₂ as well as M ₁₂ and M ₁₃ , the delay circuits D 1 , D 2 , D ₉ , and D ₁₀ delay the respective phase synthesis outputs by the time (t ₁ +t ₂ ). Furthermore, θ ₂
The _received beam in the _{direction of}
Since it is formed by M ₅ , M ₉ , M ₁₀ , and M ₁₁ ,
Delay circuits D ₃ , D ₄ , D ₅ and D ₆ , D ₇ , D ₈ delay their respective phase synthesis outputs by time t ₂ .

In this way, the delay circuits D1 to D10 control the reflected waves returning from each direction of the detection range angular directions θ1 to θ5 caused by the difference in the emission time of the ultrasonic pulses sent in the detection range angular directions θ1 to θ5. A compensation circuit is configured to compensate for the distance difference with reflected waves returning from other detection range angular directions.

Therefore, the reflected waves from the detection object on equidistant lines in each direction from θ ₁ to θ ₅ are simultaneously guided to the switching circuit SW, and the switching circuit SW transmits them at high speed in synchronization with the spiral sweep of the cathode ray tube CRT. By switching, objects to be detected on equidistant lines can be displayed at respective corresponding azimuth positions.

In the above, the delay circuits D ₁ to D ₁₀ are θ ₁ to θ ₅
Although the time delay of the received signal in each direction is corrected, it is not necessary to use a delay circuit when the received signal is displayed using a memory circuit.
For example, by storing received signals in each direction in a memory circuit that has a memory address corresponding to each pixel of a cathode ray tube (CRT), and repeatedly reading out and displaying the stored signals, stable image display can be achieved without using the afterglow characteristics of the cathode ray tube. can be done. Therefore,
In this case, by changing the write address at which the received signal is written to the memory circuit, it is possible to
can be displayed at any display position. Therefore, it is only necessary to write to different memory addresses by a distance corresponding to each delay time of delay circuits _D1 to _D10 .

In this way, using the memory circuit, the reflected waves returning from each direction of the detection range angular directions θ1 to θ5 and other It is also possible to configure a compensation circuit that compensates for the distance difference between the reflected wave and the reflected wave returning from the detection range angular direction.

As described above, the present invention divides the detection range of a wide range underwater detection device into a plurality of sections, and makes the transmission time of the detection pulse different for each section. The difference in transmission time is that when the seabed reflected wave is received by the sub-beam of the directional reception beam in another section direction, the main beam of the directional reception beam receives the seabed. It is set so that the sub-beam's seabed reflected waves are received later than the reflected waves. Therefore, clear underwater detection can be performed without generating false images due to waves reflected from the ocean floor, unlike conventional devices.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining the main beam and sub-beam of the directional reception beam, Figure 2 is a diagram for explaining the state in which a wide range of directions is detected by the directional reception beam, and Figure 3 4 is a diagram for explaining the arrangement of the vibrator, FIG. 5 is a specific example of the sweep circuit, and FIG. 6 is a block diagram showing an embodiment of the invention. A diagram for explaining a direction detection operation is shown.

Claims (1)

[Claims] 1. Directional reception in which an ultrasonic pulse signal is transmitted in a wide range of directions, and an incoming signal caused by this ultrasonic pulse signal is directed in a plurality of different directions in this wide range of directions. In a wide range underwater detection device that receives waves with a beam and displays the received signal at a corresponding distance and direction on a display screen, the first one of the wide range directions set in advance is used.
a first transmitter that transmits a first ultrasonic pulse signal in a range angle direction, and a second ultrasonic pulse signal in a second range angle direction that is different from the first range angle among the wide range directions; a second transmitter that transmits a signal; and a second transmitter that directs reflected signals caused by the first and second ultrasonic pulse signals in a plurality of different directions within the first and second range angle directions. a receiver that receives a directional reception beam formed as described above, and a first ultrasonic pulse signal transmitted from the first transmitter that is transmitted from the second transmitter. a wave transmission control circuit that delays the second ultrasonic pulse signal by a specific time; and a wave transmission control circuit that delays the second ultrasonic pulse signal by a specific time; A compensation circuit that compensates for the distance difference between the reflected wave returning from the first range angle direction and the reflected wave returning from the second range angle direction, which is caused by a delay in the emission time of the first ultrasonic pulse signal. and a display device that displays the received signal compensated by the compensation circuit and the received signal from the first range angle direction at corresponding distances and azimuths. .