JP5592673B2 - Underwater detector, underwater detection method, and underwater detection program - Google Patents

Description

  The present invention relates to a bottom sediment discriminating apparatus that discriminates the bottom sediment of a seabed and performs screen display.

  2. Description of the Related Art Conventionally, a fish finder used for a ship is known that discriminates and displays the bottom sediment (rock, stone, sand, etc.) of the seabed (see, for example, Patent Document 1). The bottom sediment determination is performed by analyzing the sea bottom echo of the ultrasonic transmission pulse. For example, in a place where the sea floor is hard and undulating, such as a rock or stone, the time width of the sea bottom echo is long, and in a soft and flat place such as sand or mud, the time width of the sea bottom echo is short. On the screen, the degree of similarity with each bottom sediment and the bottom sediment most similar to each bottom sediment are displayed.

JP 2008-275351 A

  However, the reliability of bottom sediment determination may be reduced due to sea surface conditions, vibrations from the hull, noise from other ships, and the like. In the conventional apparatus, various noise suppression is performed using filter processing or the like, but noise exceeding an allowable range may occur. Even in such a case, the conventional apparatus displays the most similar bottom sediment or similarity.

  For this reason, for example, when the discrimination result changes, the user cannot grasp whether the sediment has really changed or whether it has changed due to the influence of noise.

  In view of the above, an object of the present invention is to provide a bottom sediment discrimination device that can accurately grasp the situation in which a decrease in the reliability of bottom sediment discrimination has occurred.

  The bottom sediment determination device of the present invention outputs an ultrasonic wave in water to receive an echo, and outputs a reception signal corresponding to the intensity of the received echo, and the bottom sediment on the seabed based on the reception signal. A bottom sediment determination processing unit for determining; a reliability calculation unit for calculating the determination reliability of the bottom sediment determination processing unit; and a notification means for notifying the determination result of the bottom sediment determination processing unit and the determination reliability. It is characterized by having.

  The reliability calculation unit calculates the determination reliability of the bottom sediment based on the received signal. For example, the received signal corresponding to the sea floor is discriminated, and the discrimination reliability is calculated from the noise level of the received signal from the sea surface to the sea floor. Specifically, the received signal corresponding to the depth shallower than the received signal corresponding to the sea floor is divided into a plurality, the maximum value of the received signal in each section is obtained, and the smallest value is selected from each maximum value, Use noise level. When the noise level exceeds the threshold value, a display indicating that the reliability has decreased is displayed.

  In particular, when the discrimination result is displayed as the similarity to each sediment, for example, when the similarity between the sand and the rock is displayed as about 50%, the conventional apparatus is actually using the sand and rock as the sediment. However, according to the present invention, the discrimination reliability is displayed separately from the result of the bottom sediment discrimination. Therefore, when the determination result changes, the user can accurately grasp whether the sediment has really changed or whether it has changed due to the influence of noise.

  According to the present invention, it is possible to accurately grasp the situation in which the reliability of bottom sediment discrimination has decreased.

It is a block diagram which shows the structure of a fish finder. It is a block diagram which shows the structure of a signal processing part. It is the figure which showed the time-axis waveform of the received signal. It is the figure which showed the time-axis waveform of the received signal. It is a figure which shows the example of a display screen.

  FIG. 1 is a block diagram showing a configuration of a fish finder according to an embodiment of the seabed detection apparatus of the present invention. The fish detector includes an operation unit 10, a transducer 11, a transmission / reception switching unit 12, a transmission circuit 13, a control unit 14, a reception circuit 15, an A / D converter 16, a signal processing unit 17, a display unit 18, and a sensor unit. 19 is provided.

  The control unit 14 controls the fish finder in an integrated manner. The control unit 14 sets the transmission cycle, the detection range, and the like of the transmission circuit 13 in accordance with various operations from the operation unit 10 (instruction input for setting the detection range, etc.), and the corresponding A / D converter 16 The sampling cycle is set and an instruction to execute various processes is given to the signal processing unit 17. The display unit 18 displays echo data with the vertical axis on the screen as the depth direction and the horizontal axis as the time direction.

  The transmission circuit 13 inputs a pulse-like signal to the transducer 11 that is a transmission / reception unit via the transmission / reception switching unit 12 including a trap circuit. The signal input timing, level, pulse width, and the like are controlled by the control unit 14. The transmitter / receiver 11 is a vibrator attached to the ship bottom and the like, and outputs ultrasonic waves in water according to a pulsed signal input from the transmission circuit 13.

  The ultrasonic wave output from the transducer 11 is reflected on a target such as a school of fish or the seabed and received as an echo signal. The transducer 11 outputs a reception signal corresponding to the intensity of the received echo signal to the reception circuit 15 via the transmission / reception switching unit 12. The receiving circuit 15 amplifies the input received signal and outputs it to the A / D converter 16. The A / D converter 16 converts the received signal into a digital signal at a predetermined sampling period and outputs the digital signal to the signal processing unit 17. The signal processing unit 17 sequentially records the digitized reception signals in a memory (not shown).

  The signal processing unit 17 performs sea bottom detection processing, bottom sediment determination processing, and determination reliability calculation processing based on the recorded received signal. Information indicating the result of the seabed detection processing, the result of the bottom sediment discrimination and the discrimination reliability is displayed on the display unit 18 on the screen.

  Hereinafter, the processing of the signal processing unit 17 will be described in detail. FIG. 2 is a block diagram illustrating a configuration of the signal processing unit 17. The signal processing unit 17 includes a bottom sediment determination processing unit 171, a noise detection unit 172, a reliability calculation unit 173, and a display processing unit 174.

  A received signal is input from the A / D converter 16 to the bottom sediment determination processing unit 171, the noise detection unit 172, and the display processing unit 174. The bottom sediment determination processing unit 171, the noise detection unit 172, and the display processing unit 174 record a reception signal for one measurement (for one ping) in a memory (not shown), and receive the following processing for one ping. This is done every time a signal is recorded.

  The bottom sediment discrimination processing unit 171 performs processing for discriminating the bottom sediment of the seabed based on the input received signal. Any method may be used for determining the bottom sediment, and for example, the determination is performed based on the degree of matching (similarity) between the received signal and the reference data. That is, the bottom sediment determination processing unit 171 obtains the seabed depth from the received signal, uses the received signal within a predetermined time range (having a level equal to or higher than a predetermined threshold) from the seabed depth as a seabed echo, and performs pattern matching with reference data. By doing so, the similarity is calculated. As a matching method, fuzzy reasoning, a neural network, or the like may be used. As reference data, multiple types of data such as mud, sand, stone, and rock are prepared.

  For example, as shown in FIG. 3 (A), in a hard and undulating place such as a rock or stone, the reflectance is high, so the second peak with respect to the first peak of the seabed echo (primary echo). There is a tendency that the level of (secondary echo received by further reflecting the sound wave reflected on the seabed) is increased. In addition, the tail to the primary echo (high level signal corresponding to the initial reverberation sound) is long, and the integrated value of the received signal tends to increase.

  On the contrary, as shown in FIG. 5B, in a soft and flat place such as sand or mud, the level of the secondary echo with respect to the primary echo is low, and the tailing of the primary echo is short. The integrated value of the signal tends to be small.

  The bottom sediment determination processing unit 171 prepares reference data having a time axis waveform characteristic for each sediment as described above, and performs matching between the received signal and each reference data to obtain the similarity. calculate. The calculated similarity is output to the display processing unit 174.

  In addition, the detection method of the seabed depth is a method based on the timing at which an echo of a predetermined level or higher is received, a method based on the timing at which the differential value becomes the highest, or a waveform equal to the pulse width of the output ultrasonic wave. As a reference signal, a correlation with the received signal is obtained, and various methods such as a method based on the timing at which the correlation value becomes the highest can be used.

  Next, the noise detection unit 172 performs processing for detecting the noise level of the received signal. Any method for detecting the noise level may be used, for example, as follows.

  As shown in FIGS. 4A and 4B, the noise detection unit 172 first detects the seabed depth, and the received signal corresponding to the depth shallower than the seabed depth is divided into a plurality of sections (T1, T2, ..., TN). The number of sections may be fixed (for example, about 10), and the time length of each section may be variable according to the seabed depth, or the time length of each section may be fixed, and The number may be variable.

  And the noise detection part 172 calculates | requires the maximum value (T1max, T2max, ..., TNmax) of the received signal in each area, and also detects the received signal which shows the smallest value from these maximum values as a noise level. . The noise detection unit 172 outputs the detected noise level to the reliability calculation unit 173.

  In this way, the noise detection unit 172 obtains a maximum value for each section, and further uses the smallest value among the maximum values of each section as the noise level, thereby suddenly including a low level signal. In this case, the noise level is not mistakenly recognized, and the echo of a target such as a school of fish with a high level signal is not mistaken for noise.

  Next, the reliability calculation unit 173 performs processing for calculating the determination reliability of the bottom sediment determination processing unit 171 based on the noise level detected by the noise detection unit 172. The reliability calculation unit 173 calculates the determination reliability based on whether or not the noise level is equal to or higher than a predetermined threshold value. For example, if the noise level is less than the first threshold NL1, the reliability “high” is calculated, and if the noise level is not less than the first threshold NL1 and less than the second threshold NL2, the reliability “medium” is calculated. If the noise level is equal to or higher than the second threshold value and equal to or higher than NL2, the reliability “low” is calculated.

  The reliability calculation unit 173 inputs the level of the received signal at the seabed depth (the seabed depth level) from the noise detection unit 172, obtains the value of the noise level with respect to the seabed depth level (so-called SN ratio), The determination reliability may be calculated based on whether the SN ratio is equal to or higher than a predetermined threshold value. Further, the peak level of the primary echo on the sea floor is input from the noise detection unit 172, and the value of the noise level with respect to the peak level of the primary echo is obtained, and the ratio with the peak level of the primary echo is a predetermined threshold value or more. Depending on whether or not, the determination reliability may be calculated.

  Further, the determination reliability is not limited to three levels of “high”, “medium”, and “low”, and may be further divided into a plurality of levels. Alternatively, a relative value (continuous data) may be calculated with the most reliable state being 100% and the lowest being 0%.

  Information indicating the discrimination reliability calculated as described above is output to the display processing unit 174.

  The display processing unit 174 performs processing for visualizing various information input from the A / D converter 16, the bottom sediment determination processing unit 171, and the reliability calculation unit 173. That is, the display processing unit 714 performs a process of displaying the input reception signal on the display unit 18 as echo data corresponding to the depth according to the elapsed time after outputting the ultrasonic wave. Furthermore, the display processing unit 174 displays an image corresponding to the result of bottom sediment discrimination and the reliability on the display unit 18.

  FIG. 5 is a diagram illustrating an example of a display screen displayed on the display unit 18. FIG. 5A shows a mode in which the bottom sediment with the highest similarity is displayed as a texture image, and FIG. 6B shows a mode in which the similarity calculation result is displayed as a graph. The screens of FIGS. 6A and 6B show an example in which two screens having different transmission ultrasonic frequencies are arranged on the left and right. In the following description, the screens are displayed on the right screen as a representative. A description will be given of the image (in particular, the sections A to D near the center of the right screen will be described).

  As shown in FIGS. 6A and 6B, the display processing unit 174 includes an echo display area 30 in which echo data corresponding to the depth is displayed, and a bottom sediment discrimination result image display area 40 (or similarity). A graph display area 41) and a reliability display area 50 are displayed on the display unit 18. Since the echo display area 30 is the most important image for displaying the echoes of the seabed and targets, a display area of about 70 to 80% is secured from the upper part of the screen to the lower part of the screen. The bottom quality discrimination result image display area 40 has a display area of about 30% at the bottom of the screen.

  The bottom quality discrimination result image display area 40 displays a texture image having a dozen pixels vertically for each ping. For example, in the section A and the section B shown in FIG. 5A, the similarity with the bottom sediment of the rock is the highest among the similarities input from the bottom sediment determination processing unit 171. A texture image is displayed. On the other hand, the similarity graph display area 41 further displays a graph image of several tens of pixels vertically for each ping. For example, in the section A and the section B shown in FIG. 5B, information on the state in which the sand bottom sediment and the rock bottom sediment are mixed from the bottom sediment discrimination processing unit 171 (the similarity between the sand and the rock The degree of similarity is about 20 to 80%, respectively, and the inputted degree of similarity is displayed as a graph.

  Here, the display processing unit 174 displays a reliability display area 50 of several vertical pixels between the echo display area 30 and the bottom sediment discrimination result image display area 40. For example, in the section A, since the noise level is less than the first threshold NL1 and the reliability “high” is input, the high reliability image (white plain image in the example in the figure) 51 is displayed. . On the other hand, in the section B and the section D, the noise level is not less than the first threshold NL1 and less than the second threshold, and the reliability “medium” is input. Dot pattern image) 52 is displayed. In section C, since the noise level is equal to or higher than the second threshold and the reliability level is “low”, an indistinguishable image (a hatched image in the example in the figure) 53 is displayed. In particular, in this example, the indistinguishable image 53 is displayed so as to cover not only the reliability display area 50 but also the bottom sediment discrimination result image display area 40 so that the bottom sediment discrimination result is not displayed.

  The display mode of the image is not limited to the above example, and the color may be changed according to the reliability, for example, the high reliability image is displayed in green and the attention image is displayed in yellow.

  By performing the display as described above, in the fish finder of the present embodiment, when the bottom sediment discrimination result changes, whether the bottom sediment discrimination reliability is lowered or whether the bottom sediment has actually changed. It can be accurately grasped. For example, in the section A and the section B, the state in which the bottom sediment judgment processing unit 171 has input the information in which the bottom sediment of the sand and the bottom sediment of the rock are intermingled. Although it was difficult to determine whether it was in a mixed state or whether it could not be correctly determined due to the effect of noise, the fish detector of this embodiment displays the determination reliability at the top of the bottom sediment determination result Therefore, in section A, the determination reliability is high, and it can be determined that the sediment is actually a mixture of sand and rock. In section B, the determination reliability is low and is correctly determined by noise. It can be determined that it is not done. Further, as in section D, there is a case where it is displayed that the state is almost 100% mud due to the influence of noise even though it is actually in a rock state. With the conventional device, it is impossible to judge whether it is really the sediment of the rock, and since it is displayed that the state is 100% mud, the net was accidentally dropped and the dropped net Sometimes it hit the rock and it was torn. However, in the fish finder of the present embodiment, the caution image 52 is displayed even if the fact that the state is 100% mud is displayed (or the indistinguishable image 53 is the bottom sediment discrimination result image as in the section C). Since the display area 40 is also covered), it can be determined that it is not actually mud bottom. Thus, in the fish finder of the present embodiment, when the bottom sediment discrimination result changes, the user can accurately grasp whether the bottom sediment has really changed or has changed due to the influence of noise.

  In the above-described example, the method of calculating the discrimination reliability based on the noise level has been described. However, for example, the discrimination reliability may be calculated based on the seabed depth. As the depth of the seabed becomes deeper, the received signal will contain a lot of noise. Therefore, a predetermined threshold is set for the seabed depth, and the reliability level is high, reliability level is medium, and reliability level is as above. It is also possible to display the degree “low”.

  Further, the reliability may be calculated based on the peak level of the primary echo. For example, when there is an obstacle such as a ship bottom between the transducer 11 and the sea, the noise level is low, but the echo level is also low, so the reliability is low even when the peak level of the primary echo is low. It is set as the aspect displayed as a thing.

  Further, as shown in FIG. 2, various kinds of information may be input from the sensor unit 19 to the reliability calculation unit 173 to calculate the determination reliability. The reliability calculation unit 173 receives various types of information indicating the state of the hull such as ship speed information, roll angle, and pitch angle from the sensor unit 19. For example, when the boat speed is fast, the hull sways and the noise becomes large. Therefore, when the boat speed is fast, the display is made with low reliability.

  Further, the discrimination reliability may be calculated according to the continuity of the bottom sediment discrimination result. For example, when the same determination result is continuously calculated, a display with high reliability is performed on the assumption that the influence of noise is small.

  Further, any one of the various reliability calculation methods described above may be used, or a plurality of methods may be combined (of course, all methods may be combined). When combining a plurality of methods, weighting may be performed. For example, the weight of the reliability calculation result based on the noise level is increased, the weight of the other calculation results is decreased, and the total reliability is calculated.

  In the present embodiment, a line display of about several pixels is displayed on a screen that displays echo data and bottom sediment discrimination results. However, the discrimination reliability is shown to the user using another display (such as an LED). May be notified. For example, a red LED can be turned on when the reliability is “low”, or a warning can be issued by voice.

DESCRIPTION OF SYMBOLS 10 ... Operation part 11 ... Transmitter / receiver 12 ... Transmission / reception switching part 13 ... Transmission circuit 14 ... Control part 15 ... Reception circuit 16 ... A / D converter 17 ... Signal processing part 18 ... Display part 19 ... Sensor part

Claims (9)

A transmission / reception unit that outputs an ultrasonic wave in water to receive an echo, and outputs a reception signal according to the intensity of the received echo;
A bottom sediment determination processing unit for determining the bottom sediment of the seabed based on the received signal;
A reliability calculation unit for calculating the determination reliability of the bottom sediment determination processing unit;
A notification means for notifying the determination result of the bottom sediment determination processing unit and the determination reliability;
A display for displaying echo data corresponding to the level of the received signal;
A fish finder equipped with
The notification means displays an image corresponding to the determination result and the determination reliability together with the echo data on the display. The underwater detector according to claim 1, wherein the reliability calculation unit calculates the determination reliability based on the received signal. The underwater detector according to claim 2, wherein the reliability calculation unit calculates the discrimination reliability by calculating a noise level with respect to a level of a reception signal corresponding to the seabed. The reliability calculation unit divides a received signal corresponding to a depth shallower than a received signal corresponding to the seabed into a plurality of sections, and calculates the noise level based on a level of the received signal in each section. The underwater detector according to claim 3. The underwater detector according to claim 3 or 4, wherein the reliability calculation unit calculates the determination reliability by comparing the noise level with a predetermined threshold value. The underwater detector according to any one of claims 1 to 5, wherein the notification unit displays the determination result as a degree of similarity with a plurality of bottom sediments. The underwater detector according to any one of claims 1 to 6, wherein the notification unit does not display the determination result when the determination reliability is lower than a predetermined reliability. Outputting an ultrasonic wave in water to receive an echo, and outputting a received signal corresponding to the intensity of the received echo;
Bottom sediment determination step for determining the bottom sediment of the seabed based on the received signal;
A reliability calculation step of calculating the determination reliability of the bottom sediment determination step;
A notification step of notifying the determination result of the bottom sediment determination step and the determination reliability;
A display step for displaying echo data corresponding to the level of the received signal;
An underwater detection method comprising:
In the display step, an image corresponding to the discrimination result and the discrimination reliability is displayed together with the echo data. Outputting an ultrasonic wave in water to receive an echo, and outputting a received signal corresponding to the intensity of the received echo;
Bottom sediment determination step for determining the bottom sediment of the seabed based on the received signal;
A reliability calculation step of calculating the determination reliability of the bottom sediment determination step;
A notification step of notifying the determination result of the bottom sediment determination step and the determination reliability;
A display step for displaying echo data corresponding to the level of the received signal;
An underwater detection program that causes a computer to execute
In the display step, an image corresponding to the discrimination result and the discrimination reliability is displayed together with the echo data.