JP4771597B2 - Underwater detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an underwater detection apparatus for detecting an underwater fish or the like, and more particularly to an underwater detection apparatus suitable for detecting a single fish in a plankton layer.
[0002]
[Prior art]
The underwater detection device is installed in a ship and transmits ultrasonic waves from a transducer attached to the hull to receive underwater information by receiving echo signals that are reflected by fish and the like. To display.
[0003]
In such an underwater detection apparatus, a display using a color display is the mainstream, and an echo signal is displayed by being distinguished by color according to its intensity. For example, a strong echo signal returning from a bottom of water with a high reflection intensity is displayed in reddish brown, and a weak echo signal returning from a target with a low reflection intensity is displayed in blue or green.
[0004]
[Problems to be solved by the invention]
By the way, there are a wide variety of underwater fish and the like, but in the case of a group of fish swimming in a group, the reflection intensity is relatively large, so the echo signal of the school of fish appears clearly on the display. On the other hand, in the case of a single fish such as a squid that does not form a flock, for example, the reflection intensity is weak, and the echo signal that appears on the display unit is very small, so that it is difficult to view. In addition, since squid is often in the plankton layer in the water in search of food, the echo signal of the squid is mixed with the echo signal of the plankton layer, making it more difficult to see.
[0005]
FIG. 10 shows an example of a display screen displaying a squid echo signal and a plankton layer echo signal in a conventional underwater detection apparatus. In the figure, 30 is a display screen of the underwater detection device, 31 is an oscillation line indicating the transmission position of the ultrasonic wave, 32 is a scale indicating the depth, 33 is an echo signal reflected by the plankton layer, and 34 is an echo reflected by the squid. Signal. As can be seen from FIG. 10, the squid echo signal 34 is very small, and it is difficult to distinguish it from the plankton layer echo signal 33.
[0006]
The reason why the squid echo signal 34 has to be very small is related to the pulse width of the transmission pulse for transmitting the ultrasonic wave and the display resolution of the display screen 30. That is, in principle, if the pulse width Pw of the transmission signal 40 shown in FIG. 12 is increased, the width of the reception signal due to the reflected echo is also increased accordingly, so that the echo signal 34 is increased to some extent on the display screen 30. Can be displayed. However, when the pulse width Pw is increased, the intensity of the echo signal 33 reflected by the plankton layer increases. That is, in the case of a single fish, even if the pulse width of the transmission signal is increased, the echo signal section is only lengthened and the signal level itself is not changed, but in the case of the plankton layer, the echo signal is volume reverberation. Thus, when the pulse width of the transmission signal is increased, a phenomenon occurs in which not only the interval of the echo signal is increased, but the level of the signal is also increased. Therefore, the plankton layer echo signal 33 and the squid echo signal 34 are displayed in the same color, making it impossible to distinguish the latter from the former.
[0007]
For this reason, there is a limit to increasing the pulse width Pw of the transmission signal 40. Actually, when a transmission frequency of 15 KHz to 200 KHz is used, the pulse width Pw is 0.10 ms regardless of the depth range. About 0.25 msec is selected. The pulse width Pw is preferably as short as possible. For example, a transmission signal having a transmission frequency of 88 KHz, a pulse width of 0.10 ms, and a wave number of about 9 is used. When the pulse width at this time is converted into the distance on the display screen,
1500 (m / sec) × 0.10 (msec) × 1 / 2≈7.5 (cm)
It becomes. Here, 1500 (m / sec) is the speed of sound in water.
[0008]
On the other hand, in an apparatus using a liquid crystal display, the display resolution tends to increase in recent years, and the number of dots on one screen is generally about 600 × 440. Therefore, when displaying in the 100 m range, the above-mentioned 7 When the distance of 5 cm is converted into the number of dots, the number of display dots in the vertical direction is
600 (dots) / 100 (m) × 0.075 (m) = 0.45 (dots)
The number of displayed dots in the horizontal direction is
440 (dots) / 100 (m) × 0.075 (m) = 0.33 (dots), which is less than one dot (however, even in this case, the display for one dot is guaranteed). Even when the pulse width Pw is 0.25 msec, the number of display dots in the vertical direction is 1.2 dots and the number of display dots in the horizontal direction is 0.88 dots. Only to the extent. Therefore, in any case, as shown in FIG. 11, the squid echo signal 34 appears only as a single dot, and this is extracted from the enormous plankton layer echo signal 33. Is extremely difficult.
[0009]
As described above, the conventional underwater detection device has a problem that when detecting a single fish, since the pulse width of the transmission signal is short, the echo signal to be displayed is small and very difficult to see.
[0010]
The present invention solves the above problems, and the problem is that an underwater detection device that can easily display an echo signal reflected and returned from a target even when the transmission pulse width is short. It is to provide.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, underwater detection system according to the present invention, a depth direction of the display length of the echo signal to be displayed on the display screen, an underwater detection system varied depending on the signal strength, the echo signal Displayed by dot display, the number of display dots in the depth direction is increased as the signal intensity of the echo signal increases . By doing this, even if the pulse width of the transmission signal is short and the received echo signal is short, if the signal strength is large, the number of display dots in the depth direction increases, and the echo signal is displayed on the screen. Can be displayed while being elongated in the depth direction, so that the echo signal can be easily identified. Therefore, the present invention exhibits an excellent function when detecting a single fish, particularly a squid in a plankton layer.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a front view showing an example of the underwater detection device according to the present invention. In the figure, 1 is an underwater detection device, 2 is a display screen composed of a liquid crystal display, 3 is an operation panel on which various keys and dials are arranged, 4 is a range dial for adjusting the depth range, and 5 is reception. A sensitivity dial for adjusting the sensitivity of the echo.
[0013]
FIG. 2 is a block diagram showing an electrical configuration of the underwater detection device 1. In the figure, 10 is an ultrasonic transmitter / receiver that transmits an ultrasonic wave into water and receives an echo signal that is reflected by the ultrasonic wave reflected by a fish or the like, and 11 is a transmission operation and reception of the ultrasonic transmitter / receiver 10. Transmission / reception switching unit for switching operations, 12 a transmission circuit for outputting a transmission signal for transmitting ultrasonic waves to the ultrasonic transducer 10, 13 a reception circuit for receiving an echo signal, 14 an A / D converter or CPU And a controller as a control unit, 15 is a memory composed of ROM, RAM, etc. 16 is a display screen 2 (FIG. 1) and for displaying predetermined information on this screen 2 Reference numeral 17 denotes an operation unit including various keys and dials of the operation panel 3 (FIG. 1). The above configuration itself is the same as a conventional underwater detection device, and is not particularly novel.
[0014]
In the above configuration, when the mode, transmission frequency, sensitivity, and the like are set by the operation unit 17, such information is given to the controller 14. Based on the command from the controller 14, the transmission circuit 12 applies the transmission signal 40 shown in FIG. 12 to the ultrasonic transducer 10 via the transmission / reception switching unit 11 switched to the transmission side. The ultrasonic transducer 10 is attached to the bottom of the hull, and an ultrasonic transducer (not shown) vibrates by application of the transmission signal 40 to transmit ultrasonic waves into water. The transmitted ultrasonic wave is reflected by an underwater fish or the like or the bottom of the water, is received as an echo by the ultrasonic transducer 10, and an echo signal is received by the receiving circuit 13 via the transmission / reception switching unit 11 switched to the receiving side. Is received. This received signal is input to the controller 14, which generates display data based on the received echo signal and displays it on the display unit 16. The above operation is basically the same as that of the conventional underwater detection device, but in the present invention, the processing of display data in the controller 14 is different from the conventional one. This will be described in detail later.
[0015]
FIG. 3 is a flowchart showing a processing procedure executed by the controller 14 when receiving an echo signal. When the receiving circuit 13 receives the echo signal, the echo signal is taken into the controller 14 (step S1). The controller 14 samples the acquired echo signal in the A / D converter and converts it into a digital signal (step S2). Then, the sampling value is peak-held for each display section corresponding to one dot, and the peak value is extracted (step S3).
[0016]
FIG. 4 is a diagram for explaining sampling in step S2 and peak hold in step S3. Reference numeral 18 denotes an echo signal received by the receiving circuit 13, where the horizontal axis represents time and the vertical axis represents signal intensity. The echo signal 18 is sampled at an appropriate sampling frequency (for example, 44 KHz), and peak values P1, P2, P3,... Are extracted in each display section corresponding to one dot, and data is thinned out. The extracted peak value is input to the CPU in the controller 14 as 8-bit data. In addition, in FIG. 4, since the case of a general echo signal is shown, there are a plurality of peak values. However, in the case of a single fish such as a squid, the width of the echo signal is short as described above, When displaying in the 100 m range, only about one dot is displayed, so the peak value is also one.
[0017]
Next, the controller 14 reads the sensitivity value set by the operation unit 17 (step S4). The sensitivity is set by the sensitivity dial 5 (FIG. 1). If the sensitivity is set high, the level of the received signal is increased even with a slight reflection echo, so the color displayed on the display screen 2 differs depending on whether the sensitivity is low or high. Therefore, when detecting a squid in the plankton layer, it is necessary to set the sensitivity low so that the echo signal from the plankton layer is not emphasized. By setting the sensitivity low, the plankton layer is displayed in dark blue or blue and becomes inconspicuous.
[0018]
Next, the controller 14 determines a display color for each display section corresponding to one dot based on the peak value of the extracted echo signal and the set sensitivity value, and 8-bit data (peak) in each section. Value) is converted into 4-bit display color data (step S5). Here, 8 colors of blue, blue, light blue, green, yellow, orange, red, and red brown are used as display colors. Since the display color data is 4 bits, it is possible to display up to 16 colors. It is. Subsequently, the process of assigning dots to be displayed is performed according to the type of display color (step S6), and display is performed on the display screen 2 based on the result (step S7). Here, step S6 is a part that characterizes the present invention, and details thereof will be described below.
[0019]
FIG. 5 is a table showing specific contents of the dot assignment process in step S6. The contents of this table are stored in advance in the ROM of the memory 15. As described above, the display colors are eight colors, i.e., blue, blue, light blue, green, yellow, orange, red, and red brown, and these eight colors are classified into four classes. In other words, 紺 and blue are weak A class for echo signals, light blue and green are B class for weak echo signals, yellow and orange are C class for slightly strong echo signals, red and red brown are D class for strong echo signals, Each is classified. As for the display color, the intensity of the echo signal increases as it goes from 紺 to red brown, and the peak value for each one-dot display section extracted in step S3 is one of eight colors according to the signal intensity. Corresponding to the color, it is assigned to one of the classes A to D, and the following processing is performed.
[0020]
That is, if the signal intensity (peak value) belongs to the A class, no processing is performed. Therefore, the number of dots in the depth direction remains 1 and does not change.
[0021]
Next, when the signal intensity belongs to the B class, the display dot is lengthened by one dot in the depth direction. As a result, the number of dots in the depth direction is 2 dots as shown in FIG. Here, the colors of the display dots may all be the same color (here, green) as shown in FIG. 6 (a), or one may be green as shown in FIG. 6 (b). May be light blue belonging to the same category.
[0022]
Further, when the signal intensity belongs to the C class, the display dot is lengthened by 2 dots in the depth direction. As a result, the number of dots in the depth direction is 3 dots as shown in FIG. Here, the colors of the display dots may be all the same color (in this case orange) as shown in FIG. 7A, or orange and yellow belonging to the same section as shown in FIG. 7B. The green may belong to an adjacent section.
[0023]
Further, when the signal intensity belongs to the D class, the display dot is lengthened by 3 dots in the depth direction. As a result, the number of dots in the depth direction is 4 dots as shown in FIG. Here, the colors of the display dots may be all the same color (here, reddish brown) as shown in FIG. 8A, or red browns belonging to the same section as shown in FIG. 8B. Red and orange and yellow belonging to adjacent sections may be used.
[0024]
In the dot assignment process in step S6 in FIG. 3, after performing the above process, a moving average of colors (color average between adjacent dots) is obtained in the horizontal direction of the display screen, as in the prior art. Finally, data to be displayed on the display screen 2 is determined.
[0025]
In this way, in this embodiment, the number of display dots in the depth direction is changed according to the signal intensity (peak value) in the 1-dot display section, and when the signal intensity is high, the number of display dots is increased to increase the display length. To be long. Therefore, when a short pulse is transmitted to detect a single fish such as a squid that does not form a flock, if the sensitivity is set low, the echo signal reflected and returned from the plankton layer has a small intensity. Since the class is entered, the display color on the screen is blue or blue, and since the number of dots is one, the display is not emphasized. On the other hand, the intensity of the echo signal reflected back from the squid is somewhat larger than the intensity of the echo signal reflected back from the plankton layer. For example, in the case of an echo signal entering the C class, Since the display color is yellow or orange and the length on the screen is extended to three times that of the conventional display, the display is emphasized. As a result, the squid echo signal can be clearly distinguished from the plankton layer echo signal.
[0026]
FIG. 9 shows an example of a display screen displaying the squid echo signal and the plankton layer echo signal in the underwater detection device according to the present invention. In the figure, 2 is a display screen of the underwater detection device 1, 20 is an oscillation line indicating an ultrasonic transmission position, 21 is a scale indicating depth, 22 is an echo signal reflected by a plankton layer, and 23 is reflected by a squid. This is an echo signal. As is clear from comparison with FIG. 10, in FIG. 9, the squid echo signal 23 is enlarged and displayed in the depth direction, making it easy to distinguish it from the echo signal 22 of the plankton layer.
[0027]
The present invention can adopt various forms other than the above-described embodiments. For example, in the above embodiment, the display color is divided into four categories, but it may be divided into eight categories.
[0028]
In the above-described embodiment, an example in which a liquid crystal display is used for the display screen 2 has been described. Does not matter.
[0029]
Further, the underwater detection device 1 may be provided with both a function of detecting a normal school fish and a function of detecting a single fish such as a squid, and these functions may be switched on the operation panel 3. In this case, when detecting a school of fish, display processing as before may be performed, and when detecting a single fish, display enhancement processing shown in FIG. 5 may be performed.
[0030]
【The invention's effect】
According to the present invention, even when a fish or the like is detected with a transmission signal having a short pulse width, the display length of the echo signal can be increased in the depth direction, so that the echo signal is emphasized and identification can be performed easily. Therefore, it is possible to realize an underwater detection device that is optimal for detecting a single fish.
[Brief description of the drawings]
FIG. 1 is a front view showing an example of an underwater detection device according to the present invention.
FIG. 2 is a block diagram showing an electrical configuration of the underwater detection device.
FIG. 3 is a flowchart showing a processing procedure when an echo signal is received.
FIG. 4 is a diagram for explaining echo signal sampling and peak hold;
FIG. 5 is a table showing specific contents of dot allocation processing.
FIG. 6 is an explanatory diagram when the number of display dots is two.
FIG. 7 is an explanatory diagram when the number of display dots is three.
FIG. 8 is an explanatory diagram when the number of display dots is four.
FIG. 9 is an example of a display screen in the underwater detection device of the present invention.
FIG. 10 is an example of a display screen in a conventional underwater detection device.
FIG. 11 is a diagram showing dot display of echo signals.
FIG. 12 is a diagram showing a waveform of a transmission signal.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Underwater detection apparatus 2 Display screen 3 Operation panel 10 Ultrasonic transducer 11 Transmission / reception switching part 12 Transmission circuit 13 Reception circuit 14 Controller 15 Memory 16 Display part 17 Operation part 18 Echo signal 22 Plankton layer echo signal 23 Squid echo signal 40 Transmission signal Pw Pulse width

Claims (5)

Transmitting ultrasonic waves into water, and displays on the ultrasound display screen receives the echo signal to hate reflected in water, depending on the signal strength of the echo signal, the display in the depth direction of the echo signals An underwater detection device that changes the length ,
An underwater detection apparatus characterized by displaying the echo signal by dot display and increasing the number of display dots in the depth direction as the signal intensity of the echo signal increases . The underwater detection device according to claim 1 ,
When dots are displayed with display colors divided according to the signal intensity of the echo signal, and the number of display dots in the depth direction is plural, all display dots are the same color belonging to the classification corresponding to the signal intensity An underwater detection device characterized by displaying with. The underwater detection device according to claim 1 ,
When dots are displayed with display colors divided in accordance with the signal intensity of the echo signal, and there are a plurality of display dots in the depth direction, some of the display dots are displayed in colors belonging to the classification corresponding to the signal intensity. An underwater detection device that displays and displays the remainder in a section corresponding to the signal intensity or another color belonging to an adjacent section. The underwater detection device according to any one of claims 1 to 3 ,
An underwater detection apparatus for detecting a single fish by transmitting an ultrasonic wave into the water with a transmission signal having a short pulse width. The underwater detection device according to claim 4 , wherein the underwater detection device detects a squid.

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