JPH10132930A - Underwater imaging sonar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underwater imaging sonar so that it can select a display range in the vertical direction with respect to a front image and improve resolution vertically in an underwater imaging sonar employing a cross fan beam. SOLUTION: A scanning control circuit 14 produces a frequency data 142 which scans frequency in sending pulse and phase data 141 which shifts beam direction of sending sound. A sending pulse generating circuit 15 generates excitation signal 151 which continuously changes from a first frequency to a second frequency within the sending pulse. With changing its beam direction according to the phase data 141, for example, vertically, a cable transmitter 101 to 10N radiate transmitting sound 1 whose frequency continuously changes from a first frequency to a second one into underwater. An image control circuit 27 controls variably the center frequency and the frequency band for each filter in frequency separating circuit 281 to 28M when a frequency range of imaging is given. This enables to select a specified frequency component, or a specified degree range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater image sonar, and more particularly to an underwater image sonar that uses a cross fan beam to receive a reflected sound generated when a transmitted sound hits a target to obtain a frontal image of the target.

[0002]

2. Description of the Related Art Conventionally, various underwater image sonars have been proposed which use a cross fan beam, receive a reflected sound generated when a transmitted sound hits a target, and obtain a frontal image of the target (for example, Japanese Unexamined Patent Publication (Kokai) No. 2002-157572). JP-A-59-30078, JP-A-8-5728, and the like.

FIG. 11 is a block diagram showing an example of a conventional underwater image sonar disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-5728. In the figure, N number of transmitters 10 ₁ to 10 _N are arranged in a straight line, also the M receivers for reception of the reflected sound reflected from underwater target for transmitting a transmitting sound in water As shown in FIG. 2, 11 _{1 to} 11 _M are also arranged linearly and orthogonally to the arrangement row of the transmitters 10 ₁ to 10 _N so as to form a cross, thus forming a so-called cross array. .

The operation at the time of transmission will be described. Transmission timing signal 25 output from timing control circuit 25
1 is supplied to the phase shift / frequency control circuit 13, where the frequency and the beam direction of the transmission are converted into frequency data 143 and phase shift data 144 as shown in FIGS. 13A and 13B.

[0005] The frequency data 143 is supplied to the transmission pulse generation circuit 15, where it is pulse-modulated for each frequency.
An excitation signal 152 results. This excitation signal 152 corresponds to FIG.
As shown in (B), the signals P1 to Px that last for the period PW 'at the frequencies F1 to Fx are one-cycle PW burst signals synthesized in time series with a time interval Δt.
The excitation signal 152 is supplied to each of the variable phase shifters 12 ₁ to 12 ₁
Supplied to _2N .

The variable phase shift circuits 12 _{1 to} 12 _N change the phase of the input excitation signal 152 in order to provide a phase shift amount necessary for directing the transmission beam in the direction in which the underwater target exists.
Phase / shift according to the phase data 144 from the frequency control circuit 13, the excitation signal to the power amplifier 11 ₁ to 11 _N
After the power is amplified by the above, the voltage is applied to the corresponding one of the transmitters 10 ₁ to 10 _N to drive the transmitter. Thereby, the transmitter 10 ₁
From 1 to 10 _{N, a} transmission sound 1 is radiated into the water.
FIG. 12A shows an output state of the transmission sound 1. As shown in the figure, the frequencies F1, F2,. . . , Fx respectively have beam angles θ1, θ2,. . . , Θx in each direction.

Next, the receiving operation will be described. After the reflected sound 2 from underwater target is reception respectively receiving transducer 20 ₁ to 20 _M, is converted into received signal 202 is an electrical signal,
The signals are separately amplified by the amplifier circuits 21 _{1 to} 21 _M and then input to the corresponding frequency separation circuits 22 _{1 to} 22 _M. Each frequency separation circuit 22 ₁ through 22 _M are separated frequency F1~Fx inputting a frequency diverse frequency separation signal 222 for each receivers in the image reproduction processing unit 23.

FIG. 14 shows details of the image reproduction processing by the image reproduction processing device 23. In the image reproduction processing unit 23 processes the frequency F1 signal from each receiving transducer 20 ₁ to 20 _M, detecting the level of the received wave beam direction 1~a at frequency F. The image reproducing apparatus 23, the receiving transducer 20 ₁
Frequency F2 from ~20 _M, F3 ,. . . , Fx signals in the same manner, x in the vertical direction and a in the horizontal direction.
The level data is calculated and output to the display 26 as image data 232. The display 26 replaces the level with the luminance and displays as shown in FIG.

As another example of a conventional underwater image sonar, one disclosed in Japanese Patent Application Laid-Open No. 59-30078 is known, but this is a plurality of transducers arranged on a circumference. The cross-fan beam is created, and the cross-fan beam is shifted for each stap to search for an object around the entire circumference in a short time.

[0010]

However, in the conventional underwater image sonar shown in FIG. 11, x pulses of frequencies F1 to Fx are used as excitation signals, and the transmission direction is changed as shown in FIG.
, Θ1, θ2,. . . , In order to have a [theta] x, obtained only data for each beamwidth theta ', In addition, since also fixed filter characteristics of the frequency separating circuit 22 ₁ through 22 _M, and extracts a specific part of the target, the vertical There is a problem that the resolution cannot be increased. Further, even with the conventional underwater image sonar described in JP-A-59-30078, it is not possible to extract a target of a specific portion and to improve the resolution in the vertical direction.

The present invention has been made in view of the above points,
In the underwater image sonar using the cross fan beam, the display range in the vertical direction of the front image can be selected,
It is an object of the present invention to provide an underwater image sonar capable of improving the vertical resolution.

[0012]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a plurality of transmitters for radiating transmitted sound into water.
A plurality of receivers that receive the reflected sound obtained by reflecting the transmitted sound by the target and convert the reflected sound into an electric signal, and scan a beam direction of the transmitted sound emitted from the plurality of transmitters in a fixed direction. And a transmitter exciting means for gradually and continuously changing the frequency of a transmitted sound from a first frequency to a second frequency in synchronization with scanning, and output from a corresponding one of the plurality of receivers. Receiving the received signal and dividing the frequency range from the third frequency to the fourth frequency within the frequency range between the first frequency and the second frequency by x (x is an integer of 2 or more), It has x filters for frequency selecting each divided frequency component, receives a plurality of frequency separation circuits provided corresponding to each of the plurality of receivers, and receives output signals of the plurality of frequency separation circuits, and For each frequency component, the An image reproduction processing apparatus that performs bell detection and generates image data, a display that displays image data, and a third and fourth frequency that are arbitrarily set and correspond to the set third and fourth frequencies. And control means for variably controlling the respective center frequencies and bandwidths of the x filters in each frequency separation circuit.

Here, the plurality of transmitters are arranged linearly, and the plurality of receivers are also arranged linearly and orthogonally to the arrangement row of the plurality of transmitters so as to form a cross. Only the intersecting portion is constituted by a transmitter / receiver having both a transmitting function and a receiving function.

According to the present invention, the beam direction of the transmitted sound emitted from the plurality of transmitters is scanned in a fixed direction, and the frequency of the transmitted sound is gradually increased from the first frequency to the second frequency in synchronization with the scanning. On the receiving side, the frequency range from the third frequency to the fourth frequency within the frequency range from the first frequency to the second frequency is x (x is 2
When the received signal is divided, each divided frequency component of the received signal is frequency-selected by x filters, the level of the receiving beam direction of a plurality of receivers is detected for each divided frequency component, and the image data is The third and fourth frequencies are arbitrarily set, and the respective center frequencies and bandwidths of the x filters in each frequency separation circuit are variably controlled. Therefore, the specific frequency component of the reflected sound, that is, the specific angle range is set to the third and fourth frequencies.
Can be set arbitrarily by setting the frequency.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of an embodiment of an underwater image sonar according to the present invention. In the figure, the same components as those in FIG. 11 are denoted by the same reference numerals. In the embodiment shown in FIG. 1, a sweep control circuit 14 is provided on the transmission side,
Receiving and image control circuit 27 to thereby frequency separation circuit 28 ₁ to 28 in which the filter characteristics are controlled _M provided, which is constituted so as to widen the frequency range used. It is desirable reception sensitivity transmitting sensitivity and wave receiver 20 ₁ to 20 _M of the transmitters 10 ₁ to 10 _N in this frequency range is as uniform as possible.

The N transmitters 10 ₁ to 10 _N for transmitting the transmitted sound into the water are linearly arranged, and are M receivers for receiving the reflected sound reflected from the underwater target. 11 ₁ to 1
1 _M to linear as shown in FIG. 2, and the wave transmitter 10 ₁ -
It is the same as the prior art in that it is arranged orthogonally to the arrangement row of 10 _N so as to form a cross. It should be noted that only the center one indicated by O in FIG. 2 is a transmitter / receiver having both a transmitting function and a receiving function, and is switched as a transmitting device during transmission and as a receiving device during reception. The point of use is the same as before. In addition, a transmitter group including _N transmitters 10 ₁ to 10 _{N is referred} to as 10
In, also the receivers group of M receivers 11 ₁ to 11 _M shown at 20.

Next, the operation of this embodiment will be described. The timing control circuit 25 outputs the transmission timing signal 251 to the sweep control circuit 14 and the transmission pulse generation circuit 15, respectively. As shown in FIG. 3, the sweep control circuit 14 generates frequency data 142 that linearly changes the frequency of the transmission sound from F1 ′ to F2 ′ over time PW, outputs the frequency data 142 to the transmission pulse generation circuit 15, and 4
As shown in FIG.
The phase shift data 141 that changes linearly in the vertical direction from θ degrees to −θ degrees is generated.

The transmission pulse generation circuit 15 receives the transmission timing signal 251 and the frequency data 142 as input signals, and continuously changes the frequency from F1 'to F2' for a duration PW as shown in FIG. the excitation signal 151 indicating the constant amplitude of the burst wave which changes occur, this N number of transmitters 10 ₁ to 10 respectively variable phase circuit 12 ₁ to 12 _N which are provided N pieces so as to correspond to _N Supply.

The variable phase shifters 12 _{1 to} 12 _N use the phase shift data 141 input from the sweep control circuit 14 to change the phase of the excitation signal 151 over a time period PW.
0 by works phase shift processing for changing the linearly vertically transmit beam direction from + theta degrees to -θ degrees, the power amplifier circuit 11 ₁ to 11 an excitation signal after the phase shift processing as the transmission signal 121 output to _N, where exciting drive it is supplied to the corresponding transmitters 10 ₁ to 10 _N after power amplification.

As a result, the transmitters 10 ₁ to 10 _N generate sound waves and radiate them as transmitted sound (transmitting fan beam) 1 into water. This transmission sound 1 is, as schematically shown in FIG. 6, a cross-sectional rectangular area of 2θ in the vertical direction and a certain angle in the horizontal direction, transmitted from a transmitter group 10 composed of transmitters 10 ₁ to 10 _N. At the upper end in the vertical direction of the rectangular section 32, the frequency F1 ', at the lower end, the frequency F2', and the frequency gradually changes between them.

When the transmitted sound 1 hits the target and is reflected, the
The shooting sound 2 is M receivers 20₁~ 20_NIs received by
Here, as shown in FIG.₁-10_NIs vertical
While the receiver 20₁~ 20_NIs
Since they are arranged horizontally, the receiver 20₁~ 20_NTo
The reflected sound 2 that is received from the
It is an orthogonal cross fan beam. Receiver 20₁~ 2
0_NThe reflected sound 2 received by the
The obtained electric signal is amplified by the amplifying circuit 21. ₁~ 21_MIn each
After being amplified and converted into a reception signal 211, the frequency separation circuit
Road 28₁~ 28_MRespectively.

Here, the filter characteristics of the frequency separation circuits 28 _{1 to} 28 _M will be described. For example, the image control circuit 27
Are given F1 ′ to F2 ′ as image frequency data 271. At this time, the image control circuit 27 determines the start frequency F1 ′ and the bandwidth ΔB = (F2′−F1 ′) /
b as the filter control data 272
And outputs it to the 8 ₁ ~28 _M.

The frequency separation circuits 28 _{1 to} 28 _M respectively have center frequencies f1, f2,. . . , Fb in parallel, and the center frequencies f1, f2,. . . , Fb and the bandwidth are set as follows based on the filter control data 272 described above.

First filter: f1 = F1 ′, bandwidth ΔB Second filter: f2 = F1 ′ + ΔB, bandwidth ΔB Third filter: f3 = F1 ′ + 2ΔB, bandwidth ΔB - - - - - - - of the x filter: fb = F1 '+ (x -1) ΔB = F1' + bΔB = F2 ', for each of the bandwidth .DELTA.B received signal from each receiving transducer 20 ₁ to 20 _M X frequency components f in the frequency separation circuits 28 _{1 to} 28 _M
1 to fb are separated, and their frequency components are input to the image reproduction processing device 23 as a frequency separation signal 221.

The image reproducing apparatus 23, the receiving transducer 20 ₁
Based on the signal component of the frequency F1 ′ (= f1) separated by the first filter from the received signal from ２０20 _M ,
The level scanned in each receiving beam direction (horizontal direction) at the frequency F1 ′ (= f1) is obtained by a known numerical processing. That is, the image reproduction processing device 23 outputs the frequency component F
As for 1 ′, as shown in FIG. 7, by numerical processing, 1, 2,. . . , A when a region is scanned. Image reproduction processing unit 23 processes similarly for the frequency components f2~fb from the filter of each of the second filter, second x frequency separating circuit ₂₈ 1 to 28 in _M. As a result, the image reproduction processing device 23
As shown in FIG.
The level at the time of division into a plurality of regions is obtained by numerical processing.

Here, the frequency components f1 to fb are reception signal frequency components obtained when the beam direction is scanned vertically from top to bottom by the transmitter group 10, so that the image reproduction processing device 23 Calculates x level data in the vertical direction and a level data in the horizontal direction as shown in FIG. Display 2
At 6, the level is replaced with the luminance and displayed in an array as shown in FIG.

[0027]

Next, an embodiment of the present invention will be described with reference to FIGS.
It will be described together with 0. When F1 ′ to F2 ′ are given as image frequency data 271 to the image control circuit 27, FIG.
As shown in (A) and (B), it is assumed that the front image 31 of the target is captured at the frequency f3 to f4. In this case, since the vertical direction of the front image 31 is captured only at the frequency f3 to f4, the target unevenness is not faithfully reproduced.

Therefore, in the embodiment, the image control circuit 2
Given as the image frequency data 271 F3'~F4 '7, thereby setting as follows each filter of the frequency separating circuit ₂₈ 1 ~ 28 _M.

Start frequency F3 ', bandwidth ΔB' =
(F4′−F3 ′) / b f1 = F3 ′, f2 = F3 ′ + ΔB ′, f3 = F3 ′ +
2ΔB ′,. . . , Fx = fb = F3 ′ + bΔB ′ = F
4 ′ Here, ΔB′≪ΔB, and according to the above setting, FIG.
0 (A), the displayed image range is the frequency F
3 'to F4' are vertically divided into x parts. Therefore, the front image 31 displayed by the display 26 is displayed.
Is enlarged in the vertical direction as shown in FIG. 10 (B), the target unevenness is displayed in more detail, and the resolution is improved.

Next, a modified example of another embodiment of the present invention will be described. In Figure 2, to place the wave transmitter ₁₀ 1 to 10 _N in the vertical direction, but are arranged receiving transducer ₂₀ 1 to 20 _M in the horizontal direction, the wave transmitter ₁₀ to the contrary 1 to 10 _N was placed in a horizontal direction, it may be disposed receiving transducer ₂₀ 1 to 20 _M in the vertical direction. Although the frequency is changed from low F1 'to high F2' in FIG. 3, it may be changed from F2 'to F1'. Further, in FIG. 4, the direction of the transmission beam is shifted from the upper side (+ θ) to the lower side (−θ), but may be shifted from the lower side (−θ) to the upper side (+ θ). Further, when the minimum value of ΔB required for imaging is determined, the transmission frequency is set to F1 ′, F1 ′ + Δ
B, F1 ′ + 2ΔB, F1 ′ + 3ΔB,. . . There is a variation in which the frequency is changed and the beam is shifted in minute steps.

[0031]

As described above, according to the present invention,
Since the image range to be displayed can be arbitrarily set by setting the third and fourth frequencies, an arbitrary portion of the target can be extracted and displayed as an image, and the target image can be enlarged and displayed, thus improving the resolution as compared with the related art. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an arrangement diagram of an example of a transmitter and a receiver used according to the present invention.

FIG. 3 is an explanatory diagram of frequency data output by a sweep control circuit in FIG. 1;

FIG. 4 is an explanatory diagram of phase shift data output by a sweep control circuit in FIG. 1;

FIG. 5 is a waveform diagram of an example of an excitation signal.

FIG. 6 is a diagram illustrating a region of the transmitted sound in FIG. 1;

FIG. 7 is a diagram for explaining the operation of the image reproduction processing device in FIG. 1;

8 is a diagram showing an array display of image data obtained by the image reproduction processing device in FIG. 1;

FIG. 9 is a diagram illustrating an example of a target image obtained from FIG.

FIG. 10 is an enlarged view of the target image of FIG. 9 according to FIG. 1;

FIG. 11 is a block diagram of an example of the related art.

FIG. 12 is a diagram illustrating a transmitted sound radiated according to FIG. 11;

FIG. 13 is a diagram illustrating frequency data and phase shift data output from the phase shift / frequency control circuit in FIG. 11;

FIG. 14 is a diagram showing an example of a transmission sound area and a target image obtained from FIG. 11;

FIG. 15 is a diagram showing the target image of FIG. 14 obtained from FIG. 11;

[Explanation of symbols]

1 transmitting sound 2 reflected sound 10 ₁ to 10 _N transmitters 10 transmitting unit group 11 ₁ to 11 _N power amplifying circuit 12 ₁ to 12 _N variable phase circuit 14 sweep control circuit 15 sends a pulse generating circuit 20 ₁ to 20 _M Receiver 20 Receiver group 21 _{1 to} 21 _M amplification circuit 23 Image reproduction processing device 25 Timing control circuit 26 Display 27 Image control circuit 28 _{1 to} 28 _M frequency separation circuit 121 Transmission signal 141 Phase shift data 142 Frequency data 151 Excitation signal 211 Received signal 221 Frequency separation signal 231 Image data 271 Image frequency data 272 Filter control data O Transmitter / receiver

Claims (3)

[Claims] 1. A plurality of transmitters for emitting a transmitted sound into water; a plurality of receivers for receiving a reflected sound obtained by reflecting the transmitted sound by a target and converting the reflected sound into an electric signal; The beam direction of the transmitted sound emitted from the plurality of transmitters is scanned in a fixed direction, and the frequency of the transmitted sound is gradually and continuously changed from the first frequency to the second frequency in synchronization with the scanning. A transmitter exciting means for changing, a receiving signal output from a corresponding one of the plurality of receivers, and receiving a reception signal output from a corresponding one of the plurality of receivers within a frequency range from the first frequency to a second frequency. When the frequency range from the third frequency to the fourth frequency is divided by x (x is an integer of 2 or more), the frequency range includes x filters for frequency-selecting each divided frequency component. A plurality of frequency separation circuits provided corresponding to the Receiving the output signal of the frequency separation circuit, detecting the level of the receiving beam direction of the plurality of receivers for each of the divided frequency components, generating an image data, and displaying the image data An indicator to be set, and the third and fourth frequencies are arbitrarily set, and the respective center frequencies and bands of the x filters in each of the frequency separation circuits are set according to the set third and fourth frequencies. An underwater image sonar having control means for variably controlling widths thereof. 2. The transmitter exciting means includes: a timing control circuit for generating a timing signal; and a linear controller for linearly changing the frequency of the transmitted sound from one of the first and second frequencies to the other in a predetermined period based on the timing signal. Frequency control data, and a sweep control circuit for generating phase shift data for scanning the beam direction of the transmitted sound in the fixed direction, and a frequency in the fixed period based on the timing signal and the frequency data. A transmission pulse generation circuit that generates an excitation signal that changes linearly from one of the first and second frequencies to the other, and a plurality of transmission pulse generation circuits are provided corresponding to the plurality of transmitters, and the excitation signal is 2. The water according to claim 1, further comprising a plurality of variable phase shift circuits for performing a phase shift process in accordance with the phase shift data and outputting to a corresponding one of the plurality of transmitters. Medium image sonar. 3. The plurality of transmitters are arranged linearly,
And the plurality of receivers are also linearly arranged, and are arranged orthogonally so as to form a cross with the arrangement row of the plurality of transmitters, and only the intersecting portion has both the transmitting function and the receiving function. 2. A transmitter / receiver comprising:
Or the underwater image sonar according to 2.