JPH0464433B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an underwater detection device that detects underwater in a wide range of directions by transmitting and receiving ultrasonic pulses in a wide range of directions. Concerning reducing impacts.

(Prior Art) When detecting underwater in a wide range of directions instantaneously, generally, ultrasonic pulses are simultaneously transmitted in a wide range of directions, and reflected waves returning from each direction are extracted separately for each direction. The reflected waves in each direction can be extracted by receiving the reflected waves returning from each direction with multiple ultrasonic transducers and phase-synthesizing the received signals of each transducer in a known manner. A directional reception beam having reception sensitivity in the direction is formed. A large number of directional receiving beams are formed in each direction, and reflected waves returning from each direction are received separately in each direction by the directional receiving beams in each direction.

In the above, when the reception signals of a plurality of ultrasonic transducers are phase-combined, the strongest reception sensitivity is created in a specific direction, and at the same time, extremely weak reception sensitivity is also created in unnecessary directions. This receiving sensitivity in unnecessary directions is usually called a sub-pole beam.

In the above-mentioned wide range underwater detection device, if the intensity of the reflected wave returning from the direction of the sub-pole beam is relatively strong, various problems will occur in the displayed image.
For example, when transmitting ultrasonic pulses in a wide range of angular directions including the seabed directly below and receiving the reflected waves, extremely strong reflected waves return from the direction of the seabed directly below. Therefore, even when the received beam formed by the above phase combination is directed in an oblique direction rather than directly below, the reflected wave from the direction of the seabed directly below is received by the sub-pole beam. Ru. the result,
The received signal from the sub-pole beam is displayed as a virtual image on the displayed image. In FIG. 2, B shows a true seabed line display image, and B shows a virtual image of the seafloor created by the sub-pole beam.

(Problems to be Solved by the Invention) The present invention attempts to reduce the virtual image in the above-mentioned conventional device.

(Means and actions for solving the problem) As a means to solve the problem, we have developed a transducer that transmits and receives ultrasonic pulses in a wide range of angular directions, and a transducer that transmits ultrasonic pulses over a wide range of angles in multiple sections. A transmit signal generator that generates a transmit signal that divides and transmits ultrasound pulses with different frequencies for each section, and a receiver that uses the receive signal of the ultrasonic transducer to form a directional receive beam. A signal phase shifter, a phase composite wave generator for controlling the directivity direction of the directional reception beam, and a display for displaying the reception signals in each direction received by the directional reception beam. provided.

(Example) In FIG. 1, 1 indicates an ultrasonic transducer,
In this embodiment, eight ultrasonic transducers 101
108 to 108 constitute an ultrasonic transducer.

The ultrasonic transducer 1 transmits ultrasonic pulses in a wide range angle θ direction based on the transmission signal generator 2.
Furthermore, when the ultrasonic transducer 1 transmits ultrasonic pulses in the wide angle θ direction, it transmits ultrasonic pulses of different frequencies in each direction obtained by dividing the wide range angle θ for each specific angle. For example, as shown in Figure 3,
The full range angle θ for transmitting ultrasonic pulses is θ ₁ , θ ₂ ,
It is divided into angles of θ ₃ and θ ₄ , and an ultrasonic pulse of f ₀₁ is transmitted between the angle of θ ₁ , and an ultrasonic pulse of f 02 and _{f 03 is} transmitted between the angles of θ ₂ , θ ₃ , and θ ₄ , respectively. , f ₀₄ ultrasonic pulses are transmitted. Note that the transmission signals guided from the transmission signal generator to the ultrasonic transducer 1 are guided to the ultrasonic transducers 101 to 108 via transmission/reception switching circuits 301 to 308, respectively.

The ultrasonic transducer 1 transmits ultrasonic pulses into the water, receives the reflected waves from the water, and transmits the received signals of the ultrasonic transducers 101 to 108 via the transceiver switchers 301 to 308. The signal is sent to phase shifter 4. The phase shifter 4 includes mixing circuits 401 to 408, filters 411 to 418, and mixing circuits 421 to 428. And mixing circuits 401 to 408
The filters 411 to 418 select specific frequency signals from the signals received by the ultrasonic transducers 101 to 108. The mixing circuits 421 to 428 shift the phase of the selected frequency signal by a specific amount. This phase shift amount is determined by the phase shift frequency signal output from the phase shift controller 8. Further, selection of a specific frequency signal is performed based on a mixed signal output from the selection mixed signal generator 9.

The phase shift controller 8 generates multiphase frequency signals having a common frequency and different phase shifts. Since eight mixing circuits 421 to 428 are used in the embodiment, eight phase frequency signals are generated, and each phase frequency signal is guided to each of the mixing circuits 421 to 428. On the other hand, the mixed signal generator 9 generates a plurality of predetermined frequency signals f ₁₁ , f ₁₂ , f ₁₃ , and f ₁₄ and outputs them to the multiplexer 10 . The multiplexer 10 receives the frequency signals f ₁₁ ,
Mixing circuit 40 by switching f ₁₂ , f ₁₃ , f ₁₄ in time series
1 to 408. Note that the multiplexer 10 performs the switching operation based on the count value of the counter 801 of the phase shift controller 8.

Each frequency signal subjected to phase shift control in the phase shifter 4 is guided to an adder 11. The adder 11 adds the frequency signals together and outputs the result.

The frequency signals added by the adder 11 are guided to the filter 12 and a specific frequency signal is extracted.
The signal is guided to the amplifier 16. The amplifier 16 amplifies the extracted signal of the filter 12 and then supplies it to the display 14 . The display 14 is, for example, a cathode ray tube display, and displays the output signal of the amplifier 16 by performing pixel scanning based on the sweep circuit 15.

Next, the operation of each part of the transmission signal generator 2, phase shifter 4, phase shift controller 8, etc. will be explained.

The transmitting signal generator 2 was filed by the applicant in a patent application filed in 1983.
Similar to the multiphase frequency signal generation device provided in No. 137745 (Japanese Unexamined Patent Publication No. 59-27653), a multiphase frequency signal is generated by reading stored data written in advance in a memory. That is, when the data stored in the read-only memory 203 is read by the counter 201, the eight-phase frequency signals output from the latch circuits ₂₀₄₁ to ₂₀₄₈ are guided to the ultrasonic transducers 101 to 108, and the Ultrasonic signals are transmitted from the sonic transducer 1. Note that for the 8-phase frequency signal, the data stored in the read-only memory 203 is read out as a binary value output, so in reality,
Eight-phase rectangular waves are output.

The composite directivity characteristics of the ultrasonic signals transmitted from the ultrasonic transducer 1 are determined by the phase relationship of the excitation signals that excite each vibrator. The phase relationship of the excitation signal, that is, the rectangular wave train, can be arbitrarily set by appropriately setting the stored data in the read-only memory. Therefore, by appropriately writing the data stored in the read-only memory 203,
The combined directivity direction of the ultrasonic waves transmitted from the ultrasonic transducer 1 can be set to any direction.

Data stored in the read-only memory 203 is read out by the counter 201, and the readout area is switched by the numerical value setter 207. In the embodiment shown in FIG. 1, the readout area can be switched into four areas.

The numerical value setter 207 sequentially switches and designates the first area, second area, third area, and fourth area of the storage address of the read-only memory 203 in accordance with the count value of the counter 208. While the first area is designated, the rectangular wave generated by the reading of the counter 201 is transmitted to the ultrasonic transducers 101 to 108.
, an ultrasonic signal is transmitted in the θ ₁ direction in FIG. That is, in the first region, the phase relationship of the rectangular wave train is set so that the composite directivity of the ultrasound signals output from the ultrasound transducers 101 to 108 is in the _θ1 direction.
Next, when switching to the second region, the phase relationship of each rectangular wave train is set so that the transmission direction of the ultrasonic signal is in the range angle direction of θ ₂ shown in FIG. Similarly, when switching to the third area and the fourth area,
The phase relationship of the rectangular wave train is set for each region so that the transmission direction of the ultrasonic signal is in each of the directions θ ₃ and θ ₄ shown in FIG. 3.

Switching of the read area from the first area to the fourth area of the read-only memory 203 is performed using the counter 208.
This is done within a very short time. Counter 208 counts the pulse train of clock pulse source 210 introduced through gate 209. gate 20
9 becomes conductive when the keying pulse is sent out from the keying pulse generation circuit, and the counter 20
8 is conductive until it sends a carry pulse.

The keying pulse generation circuit 13 generates a pulse train with a period T ₀ as shown in FIG. 4a, thereby performing an ultrasonic pulse transmission operation.

When keying pulse a is output, gate 2
09 becomes conductive, the counter 208 is reset. As shown in FIG. 4b, the counter 208 performs quaternary counting during time Ts when the gate 209 is conductive, and switches the readout area from the first area to the fourth area of the read-only memory 203. Let's do it. This switching time Ts is performed in an extremely short time. For example, an ultrasonic pulse transmitted in the θ ₁ direction in FIG. 3 based on the data stored in the first area and an ultrasound pulse transmitted in the θ ₄ direction based on the stored data in the fourth area are equidistant. When the ultrasonic pulse is reflected from the reflector on the line and returns home, the distance deviation corresponding to the time deviation in transmitting the ultrasonic pulse is set to an almost negligible degree in consideration of the distance resolution of the ultrasonic pulse.

The gate 209 is turned on for a time Ts until the carry pulse (FIG. 4c) of the counter 208 is outputted by the easing pulse a, and the pulse train of the clock pulse source 210 is passed to the counter 208.
Send to 8. At the same time, this pulse train is also guided to the gate pulse generation circuit 214. Then, the gate pulse generation circuit 214 generates gate pulses P ₁ , P ₂ , P ₃ ,
Generate _P4 . These gate pulses P ₁ , P ₂ , P ₃ ,
P ₄ allows the rectangular wave trains output from the gates 215 ₁ to 215 ₈ to pass only when gate pulses P ₁ , P ₂ , P ₃ , and P ₄ appear. The rectangular wave train passing through the gates 215 ₁ to 215 ₈ is converted into power amplifiers 216 ₁ to 216 ₈
After being amplified at , the signals are transmitted as ultrasonic pulses from the ultrasonic transducers 101 to 108 via switchers 301 to 308.

The counter 208 controls the numerical value setter 207 as described above to control the transmission direction of the ultrasonic pulse, and at the same time controls the frequency of the ultrasonic wave transmitted in each direction. This frequency control is performed by introducing the count value of the counter 208 to the decoder, and the decoder 212 controlling the gates 211 ₁ to 211 ₄ .

When the counter 208 changes from the reset value, the decoder 212 sequentially turns on the gates 211 ₁ to 211 ₄ according to the change in the count value. gate 2
The frequency divided waves of the frequency dividing circuit 202 are guided to 11 ₁ to 211 ₄ . The frequency dividing circuit 202 is connected to the clock pulse source 2.
06 pulse train is frequency-divided to generate four types of frequency-divided waves having different frequencies. Therefore, gate 2
When 11 ₁ to 211 ₄ conduct in order, divided waves with different frequencies are guided to the counter 201 via the OR circuit 213, and the data stored in the read-only memory 203 is read out at different speeds, resulting in the latch circuits 204 ₁ to 204 The frequency of the rectangular wave train outputted by ₈ changes every time the count value of the counter 208 changes.
Therefore, when the gate pulses P ₁ , P ₂ , P ₃ , P ₄ are output from the gate pulse generation circuit 214, rectangular wave trains with different frequencies are transmitted to the ultrasonic transducers 101 to 1.
08, ultrasonic pulses having different frequencies f ₀₁ , f ₀₂ , f ₀₃ , and f ₀₄ are transmitted in each direction of θ ₁ , θ ₂ , θ ₃ , and θ ₄ in FIG. In this case, since the ultrasonic transducers 101 to 108 are commonly used for each frequency, the ultrasonic pulse frequencies f ₀₁ , f ₀₂ ,
It is desirable that f ₀₃ and f ₀₄ be set within the resonance frequency of the ultrasonic transducer.

Next, the phase shifter 4 and the phase shift controller 8 will be explained.

In the phase shifter 4, the ultrasonic transducers 101 to 1
The received signals of 08 are guided to mixing circuits 401 to 408. Each of the mixing circuits 401 to 408 mixes the received signals of the ultrasonic transducers 101 to 108 and the mixed signal output from the mixed signal generator 9.

The mixed signal generation circuit 9 has frequencies f ₁₁ , f ₁₂ , f ₁₃ ,
Generate four types of mixed signals of f ₁₄ . The mixed signals of frequencies f ₁₁ , f ₁₂ , f ₁₃ , and f ₁₄ are time-seriesized by the multiplexer 10 and guided to mixing circuits 401 to 408. This time series operation is performed as described below based on the count value of the counter 801 of the phase shift controller 8.

The mixed outputs of the mixing circuits 401 to 408 are guided to filters 411 to 418 to extract specific frequency signals. The extracted signals from the filters 411 to 418 are guided to mixing circuits 421 to 428, where they are mixed with the frequency signal output from the phase shift controller 8.

The phase shift controller 8 generates a plurality of types of frequency signals whose phase relationships are regulated in advance, eight-phase frequency signals in the embodiment shown in FIG.
8, perform each mixing. Then, phase-shifted signals for the input signals derived from the filters 401 to 408 are generated using the phase-shifted components included in the mixed output.

The generation of the frequency signal by the phase shift controller 8 is carried out by a counter 801 in a read-only memory 802, as previously provided by the applicant in Japanese Patent Application No. 57-121439.
The binary value storage data of is read out, and the read data is latched in the latch circuits _{803 1} to 803 ₈ .
3 ₈ outputs an 8-phase frequency signal. Note that the counter 801 counts the pulse train input from the frequency dividing circuit 804, and counts the pulse train inputted from the frequency dividing circuit ₈₀₄ , and
3 ₈ performs a latch operation using a latch pulse output from a latch pulse generation circuit 805.
Further, the latch pulse generation circuit 805 generates a latch pulse using the pulse train of the clock pulse source 806 and the output of the frequency divider circuit 804.

Therefore, the latch circuits 803 ₁ to 803 ₈ output a rectangular wave train whose phase corresponds to the binary value data output from the read-only memory 802. each phase, while each phase relationship has a specific phase relationship,
Strictly speaking, the frequency of each rectangular wave train changes. Therefore, the phase relationship of the mixed outputs of the mixing circuits 421 to 428 also changes in accordance with the phase relationship of the rectangular wave train.

The mixed outputs of the mixing circuits 421 to 428 are added in the adding circuit 11, and a specific frequency signal is selected from the added signals in the filter 12.

Therefore, on the output side of the filter 12, a frequency signal obtained by phase-synthesizing specific frequency signals among the mixed signals of the mixing circuits 421 to 428 is obtained, so that the rectangular wave train output from the latch circuits 803 ₁ to 803 ₈ By setting the phase relationship of can be scanned at This scanning is performed, for example, as in the previous Japanese Patent Application No. 57-121439, by using the latch circuit 803 ₁ so that the combined output of the mixed outputs of the mixing circuits 421 to 428 is formed into a directional beam in a specific direction. This is done by setting the phase relationship of the rectangular wave trains of the latch circuits 803 ₁ to 803 8 and gradually changing the phase (frequency) of the rectangular wave trains of the latch circuits 803 ₁ to 803 ₈ . Note that the phase (frequency) change of the rectangular wave train has a certain phase relationship, that is, the mixing circuits 421 to 42
The additive synthesis characteristics of the 8 mixed outputs are performed while maintaining a phase relationship such that a directional beam in a specific direction is formed.

In addition, the reception directivity characteristic in this case is the latch circuit 8
It is determined by the phase relationship of the rectangular wave trains output from 03 ₁ to 803 ₈ , and since the phase relationship of the rectangular wave trains corresponds to the count value of the counter 801, it is possible to know the reception directivity characteristic from the count value of the counter 801. I can do it.

The count value output of the counter 801 is guided to the multiplexer 10, and the multiplexer 10 switches the output frequency signals f ₁₁ , f ₁₂ , f ₁₃ , and f ₁₄ of the mixed signal generator 9 every time the reception direction changes by a specific angle. and leads to mixing circuits 401 to 408. That is, in FIG. 3, when scanning the detection range angle θ ₁ from the S ₁ direction to the S ₂ direction, the mixed signal of frequency f ₁₁ is sent to the mixing circuit 401 while scanning the detection range θ ₁ .
to 408. Then, while the wave receiving direction scans the next detection range θ ₂ , the mixed signal of frequency f ₁₂ is switched and guided to the mixing circuits 401 to 408 . Similarly, the receiving wave direction is the detection range θ ₃ , θ ₄
When the frequency changes to
The mixing circuit 40 switches the mixed signals of f ₁₃ and f ₁₄ in order.
1 to 408.

In FIG. 3, ultrasonic signals having different frequencies are transmitted and received in each direction of the detection ranges θ ₁ , θ ₂ , θ ₃ , and θ ₄ . Therefore, while the reception direction scans the detection range angle θ ₁ , the reception signal of frequency f ₀₁ and the mixed signal of frequency f ₁₁ are mixed in the mixing circuits 401 to 408 . Similarly, the detection range angles θ ₂ , θ ₃ , θ ₄
When the reception direction changes, the frequencies f ₀₂ , f ₀₃ ,
The received signal of f ₀₄ is mixed with mixed signals of frequencies f ₁₂ , f ₁₃ , and f ₁₄ .

The phase shifter 4 mixes the received signals of the ultrasonic transducers 101 to 108 and the mixed signals f ₁₁ , f ₁₂ , f ₁₃ , f ₁₄ output from the mixed signal generator 9 as described above, A specific frequency signal is selected from the mixed signal. At this time, the filters 411 to 418 of the phase shifter 4 extract the common frequency signal f ₀ from each mixed signal.
Extract. For example, the received signal in the detection range θ ₁ direction
When f ₀₁ and mixed signal f ₁₁ are mixed, the mixed frequency signal f ₁₁ is set so that the difference frequency component of the mixed frequency signal f ₀₁ ±f ₁₁ becomes f ₀₁ − f ₁₁ = f ₀ . .

Similarly, when mixing the received signal f ₀₂ from the detection range θ ₂ and _the mixed signal f ₁₂ , _the mixed frequency signal _{f 12} is set.

Furthermore, the received signals f ₀₃ , from the detection ranges θ ₃ , θ ₄ ,
The mixed frequency signals f _{13 ,} f such that the difference frequency component of the mixed frequency signal between f 04 and each mixed signal f 13 , f ₁₄ becomes f _{03 −} f ₁₃ = f ₀ f ₀₄ − f ₁₄ = f ₀ . ₁₄ is set. Then, the multiplexer 10 switches and outputs the output frequency signal of each phase shifter as described above.

As a result of the above, the filter 12 outputs a directional reception signal whose reception direction changes within the detection range angle θ shown in FIG. This directional received signal is guided to the display 14 via an amplifier 16. Then, as a result of the sweep circuit 15 performing pixel scanning of the electron beam based on the keying pulse of the keying pulse generation circuit 13, the display 14 has a pixel scan linked to the directivity direction of the receiving beam within the detection range angle θ. The received signal within the detection range angle θ is displayed at the corresponding position on the display screen. In addition, in FIG. 1, the transducer 1 includes ultrasonic transducers 101 to 108.
Although shown as being arranged in a straight line, the ultrasonic transducers 101 to 108 may be arranged in a circular or curved shape. The composite directional characteristics of the ultrasound waves transmitted from the ultrasound transducers 101 to 108 are as follows:
The phase relationship of the excitation signals is determined by the phase relationship of the excitation signals of each vibrator, and the phase relationship of the excitation signals is determined by the read-only memory 20.
It can be set arbitrarily by writing the stored data in step 3. Therefore, the arrangement shape of the ultrasonic transducers 101 to 108 does not need to be limited to a specific shape. or,
Although the transmission signal generator 2 and the phase shift controller 8 have been described as outputting a rectangular wave train, the generated rectangular wave train may be converted into a sine wave and output.

(Effects of the Invention) As described above, according to the present invention, the underwater detection range angle θ by ultrasonic pulses is divided into a plurality of sections, and ultrasonic pulses of different frequencies are transmitted for each section. Then, a directional receiving beam is formed for each frequency signal. Therefore, since the detection range angle of each section is separated by frequency, for example, in Fig. 3, the detection range angle θ ₂
The reflected wave returning from the directional wave does not generate a reception signal in the directional reception beam formed at the detection range angle θ ₁ . That is, even if a sub-pole occurs in the directional reception beam at the detection range angle θ ₁ , the reflected wave from the direction of the detection range angle θ ₂ will not be received by the sub-pole. Therefore, the reflected waves returning from the water can be accurately displayed without creating a virtual image on the display screen due to the subpole of the receiving beam, unlike the conventional wide-range underwater detection device.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, FIG. 2 shows an example of a display by a conventional underwater detection device, FIG. 3 is a diagram for explaining the transmission operation in the embodiment of this invention, and FIG. The figure shows a waveform diagram for explaining the operation. 1... Ultrasonic transducer, 101 to 108...
Ultrasonic transducer, 2... Transmission signal generator, 201...
... Counter, 202 ... Frequency divider circuit, 203 ...
Read-only memory, 204 ₁ to 204 ₈ ... Latch circuit, 205 ... Latch pulse generation circuit, 20
6...Clock pulse source, 207...Numeric value setter, 208...Counter, 209...Gate,
210...Clock pulse source, 211 ₁ to 21
1 ₄ ...Gate, 212...Decoder, 213...
...OR circuit, 214...gate pulse generation circuit,
215 ₁ to 215 ₈ ... gate, 216 ₁ to 2
16 ₈ ...Power amplifier, 301 to 308...Transmission/reception switch, 4...Phase shifter, 401 to 408...
Mixing circuit, 411 to 418... Filter, 4
21 to 428...mixing circuit, 8...phase shift controller, 801...counter, 802...read-only memory, ₈₀₃₁ to ₈₀₃₈ ...latch circuit,
804... Frequency divider circuit, 805... Latch pulse generation circuit, 806... Clock pulse source, 9... Mixed signal generation circuit, 10... Multiplexer, 11
... Addition circuit, 12 ... Filter, 13 ... Keying pulse generation circuit, 14 ... Display device, 15
...sweep circuit, 16...amplifier.

Claims (1)

[Claims] 1. An ultrasonic transducer constituted by an array of n ultrasonic transducers, a read-only memory that transmits stored data as an output of n bits, and a read-only memory that transmits stored data in the read-only memory. The clock pulse train comprises a generation circuit for a clock pulse train to be read out and a frequency switching circuit for switching the frequency of the clock pulse train to a different frequency within a transmission time for causing the ultrasonic transducer to transmit the ultrasonic pulses. By reading out the data using The direction of transmission by the first frequency and the direction of transmission by the second frequency are determined by
a transmission signal generator in which a phase relationship is set so that the transmission direction differs depending on the frequency, and each of the ultrasonic transducers is excited based on the n-phase frequency signal; First and second mixed signals are generated in a time-division manner for the first and second frequency signals, and the first and second mixed signals are generated by combining the first transmission frequency signal and the first transmission frequency signal. a mixed signal generation circuit that is determined so that a common frequency component is generated in a mixed output of the first mixed signal and a mixed output of the second transmission frequency signal and the second mixed signal; a first set of mixing circuits composed of n mixing circuits that separately mix the mixed signal output from the generation circuit and the reception signals of the n ultrasonic transducers; and a mixing circuit of the first set. n filters each separately extracting the common frequency signal from the mixed outputs of each of the circuits, and a mixed signal generated corresponding to each of the extracted outputs of the n filters and each of the extracted outputs. a phase shifter consisting of a second set of mixing circuits, which is made up of n mixing circuits that set the phase relationship of each of the extracted signals to a specific phase relationship by mixing them separately; It has a read-only memory that outputs data and a clock pulse train generation circuit that reads the data stored in the read-only memory, and generates an n-phase frequency signal by reading the stored data using the clock pulse train. and furthermore, said n
The phase frequency signals are changed so that the phase relationship of each phase frequency signal has a predetermined specific phase relationship by appropriately writing the above-mentioned memory data, and the n-phase frequency signals are mixed with the first set. a phase controller that shifts the phase of the extracted outputs of the n filters by supplying it as a mixed signal with the extracted outputs of the n filters constituting the circuit; and a second set of mixing circuits of the phase shifters. a phase synthesis circuit that performs phase synthesis by adding together n-phase frequency signals output from n filters; a filter that extracts a specific frequency signal from the phase synthesis output; and a phase synthesis circuit that extracts a specific frequency signal from the phase synthesis output; An underwater detection device comprising a display device.