JP2013213826A - Seabed detection method and fish finding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for calculating, for each predetermined depth, a seabed detection level at the depth and detecting a seabed by moving the seabed detection level, and to provide a method and a device for stably detecting the seabed by storing the depth at which a reflected signal including seabed reflection crosses the seabed detection level and setting difference between the maximum value of the reflected signal and the seabed detection level to be within a predetermined range when the reflected signal exceeds the detection level.SOLUTION: In a method for detecting a seabed, a seabed detection level is calculated for each predetermined depth, a reflected signal amplified/detected by a receiver is compared with the seabed detection level calculated for each predetermined depth, and the calculated seabed detection level is moved on the basis of comparison result.

Description

  The present invention relates to a method for detecting a seabed in a fish finder, a sounding instrument, a sonar, and the like, and a fish finder for performing seabed detection.

Directivity angle of the ultrasonic pulses, pulse width, underwater sound velocity determined by the depth, the reflected signal from the sea V = 20 log ₁₀ r or, amplifying means for amplifying process by the amplifier characteristic of V = 30log ₁₀ r, the amplification characteristics Patent Document 1 discloses a technique for detecting the seabed by means of using and setting a slice level corresponding to the depth. Here, r represents the depth.

  In Patent Document 1, in order to detect the seabed in the initial state, a depth gate covering the entire detection range is set in the gate circuit. The slice level is set at the lower end depth of the depth gate. When the seabed is detected in the initial state, a depth value corresponding to several meters above and below is set again in the gate circuit as a predetermined depth gate based on the detected seabed depth. Further, when the seabed is not detected within the predetermined depth gate, the depth gate width is increased beyond the predetermined depth gate.

As another technique, when the seafloor depth data is obtained, the level of the corresponding reflected signal is detected. Then, assuming that the depth data is the seabed, the level of the seabed reflection signal that should theoretically exist at that depth (V = 20 log ₁₀ r (30 log ₁₀ r)) is calculated. Further, the reflected signal level obtained by calculation is compared with the detected reflected signal level, and when the detected level of the corresponding reflected signal is higher than the calculated reflected signal level, it is determined as the seabed.

  Conversely, if the detected level of the corresponding reflected signal is lower than the calculated reflected signal level, or the detected level of the corresponding reflected signal is higher than the calculated reflected signal level, but is smaller than a certain value, it is not the seabed. to decide. At this time, the depth gate is changed. Etc. are described.

  In the above technique, the depth gate is set, and the level of the seabed reflection signal that should theoretically exist at the depth at the lower end of the depth gate is set as the slice level as the seabed detection level (slice level) at the depth gate. . For this reason, in the depth gate, the seabed is detected at the same slice level. That is, within the depth gate, except for the lower end, there is a problem that the seabed is not detected based on the level of the seafloor reflection signal that should theoretically exist at that depth.

  Further, seabed detection is performed with only the set depth gate width for each transmission. For this reason, as the depth gate width, a depth gate over the entire detection range, a predetermined depth gate, a depth gate having a depth gate width wider than a predetermined depth gate, and any depth gate are selected. This selection is performed depending on whether or not the seabed is detected for each transmission. If the seabed is not detected within the predetermined depth gate, the depth gate width is widened. If the seabed is not detected yet, the depth gate is set over the entire detection range. As described above, since the seabed is detected based on the selection of the depth gate and the slice level at the depth at the lower end of the depth gate, there is a problem that a reflected signal from a large school of fish at a shallow depth is erroneously detected as the seabed.

Also, V = 20 log ₁₀ r, or, by using the amplification characteristic of only V = 30log ₁₀ r, since that sets the slice level corresponding to the depth, underwater sound speed, directional angle of the ultrasonic pulse, pulse width, etc. Therefore, there is a problem that the reflected signal from the seabed that changes due to the above cannot be detected stably.

JP-A-60-171472

  An object of the present invention is to provide a method and apparatus for calculating a seabed detection level at a predetermined depth for each predetermined depth and detecting the seabed by moving the seabed detection level. Further, the depth at which the reflected signal including the seafloor reflection traverses the seabed detection level is stored, and when the reflected signal exceeds the detected level, the difference between the maximum value of the reflected signal and the seabed detected level is set to a predetermined range. Accordingly, an object of the present invention is to provide a method and apparatus for detecting the seabed stably.

  Another object of the present invention is to provide a method and apparatus that does not erroneously detect a reflected signal from a large school of fish at a shallow depth, an interference signal from another ship, marine noise, or the like as the seabed.

In a method for detecting the seabed,
The seabed detection level is calculated for each predetermined depth, the reflected signal amplified and detected by the receiver is compared with the seabed detection level calculated for each predetermined depth, and the seabed detection level calculated according to the comparison result is moved. .

  Since the seabed detection level at that depth is calculated for each predetermined depth and the seabed is detected by moving the seabed detection level, the seabed can be detected stably. In addition, when the seabed detection level is compared with the reflected signal including the seafloor reflection, and the reflected signal exceeds the detected level, the difference between the reflected signal and the detected level is set within a predetermined range, thereby stably stabilizing the seabed. There is an effect that can be detected.

The figure explaining the structural example of the fish finder which demonstrates the Example of this invention The figure explaining the relationship between the initial seabed detection level BL and the received signal RS received every transmission The figure explaining the state when the seabed is detected The figure explaining the state which detected the seabed in several depths Explanatory drawing of the main process routine of the fish finder which implements this invention The figure explaining the details of a seabed detection processing routine The figure explaining the detail of the processing routine which moves or initializes the seabed detection level BL

  The calculated seabed detection level is initially set to be greater than the level of the reflected signal including the seafloor reflection, and movement of the calculated seabed detection level is configured to subtract the seabed detection level.

  The reflected signal including the seafloor reflection and the moved seabed detection level are compared for each predetermined depth, and when the reflected signal is larger than the seabed detection level, the difference between the reflected signal and the seabed detection level is predetermined. A predetermined constant is added to or subtracted from the moved seabed detection level so as to be within the range.

  FIG. 1 is a configuration example of a fish finder according to an embodiment of the present invention. Reference numeral 1 denotes a transducer that transmits and receives ultrasonic waves in the sea. An ultrasonic transmitter 10 excites the transducer 1 with a predetermined frequency, a predetermined power, and a predetermined pulse width. Reference numeral 11 denotes a reception logarithmic amplifier, which amplifies a received wave from the sea received by the transducer 1 using a logarithmic amplifier and detects it. An A / D converter 12 quantizes the detected received signal with a predetermined resolution.

  Reference numeral 100 denotes a control unit that controls the entire apparatus. A display control unit 101 performs necessary display control under the control of the control unit 100. Reference numeral 102 denotes a memory which stores predetermined data such as a control program of the apparatus and received signal strength. It consists of RAM and ROM.

  Reference numeral 103 denotes a seabed level computing means for computing a predetermined seabed detection level. Reference numeral 104 denotes a seabed level moving means for performing addition / subtraction on the seabed level calculated by the seabed level calculating means 103 under a predetermined condition to change the seabed detection level. A level comparison unit 105A compares the seabed detection level with the received signal strength (level) for each predetermined depth. Reference numeral 105B denotes an allowable amount comparison unit that compares a difference between a predetermined target allowable amount, a seabed detection level at the time of seabed detection, and a maximum intensity (level) of a received signal (level). Details of the operation will be described later.

  Reference numeral 106 denotes a transmission / reception control unit that outputs control signals such as the pulse width, transmission cycle, and STC of the transmitter to the transmitter 10 and the reception logarithmic amplifier 11 under the control of the control unit 100. An operation unit 13 is provided with key switches for designating the operation and functions of the apparatus. By operating these key switches, operations, functions, etc. are designated. Reference numeral 14 denotes a display for displaying a reflected signal from the sea, displaying the depth of the seabed, and the like. Display devices such as LCD and EL can be used.

  The object of the present invention is to detect the seabed. Here, description of a general fish finder will be omitted. 2 and 3 are diagrams for explaining the relationship between the received signal and the seabed detection level in the seabed detection according to the present invention.

FIG. 2 is a diagram for explaining the relationship between the initial (initial state) seabed detection level BL and the received signal RS received every transmission. Initially, the seabed detection level BL is
BL = K-20Log ₁₀ D (1)
Calculate by K is a constant, and is determined to be a signal strength larger than the signal strength of the oscillation line, which is the strongest signal among the reception signals RS in the initial state. D is a depth, and the seabed level calculation means 103 calculates the seabed detection level BL for each predetermined depth resolution. The seabed detection level BL calculated for each predetermined depth is stored in the memory 102 as a seabed detection level table. The seabed detection level BL in the figure is obtained by connecting the calculated values for each predetermined depth.

  The detection start depth DS is set to an arbitrary depth by operating a key switch of the operation unit 13. Normally, the depth is set so that the oscillation line is not displayed. Then, for each transmission of ultrasonic waves, the received signal RS and the seabed detection level BL are compared by the level comparison means 105A at each depth. At this time, if the received signal RS is smaller than the seabed detection level BL at each depth, the seabed level moving means 104 subtracts a predetermined constant from the seabed detection level BL for each predetermined depth resolution to obtain the seabed detection level BL. Move to the left as shown in FIG. That is, the seabed detection level table is rewritten. This operation is continued until the reception signal RS exceeds the seabed detection level BL.

  FIG. 3 is a diagram illustrating a state when the seabed is detected. When the seabed detection level BL moves to the left as described above, the level comparison unit 105A detects the depth at which the seabed signal BS in the received signal RS exceeds the seabed detection level BL. Here, the depth at which the seabed signal BS exceeds the seabed detection level BL is stored in the memory 102 as the seabed depth BD.

  Further, the allowable amount comparing means 105B stores the maximum level ML of the seabed signal BS in the memory 102. The difference between the maximum level ML and the seabed detection level BL at the depth at which the seabed signal BS exceeds the seabed detection level BL (seabed depth BD) is stored in the memory 102 as the current allowable amount NV. Here, the level comparison means 105B compares the target allowable amount TV having a predetermined value stored in the memory in advance with the current allowable amount NV.

  In FIG. 3, the target allowable amount TV <the current allowable amount NV. At this time, the seabed level moving means 104 adds a predetermined constant to move the seabed detection level BL to the right in the figure. Further, when the target allowable amount TV> the current allowable amount NV, a predetermined constant is subtracted to move the seabed detection level BL to the left in the figure. This operation is performed every time ultrasonic waves are transmitted and received. Due to the functions of the permissible amount comparing means 105B and the seabed level moving means 104, the seafloor signal BS can always be detected stably.

  FIG. 4 is a diagram for explaining a state in which the seabed is detected at a plurality of depths as a result of the level comparison unit 105 comparing the received signal RS and the seabed detection level BL for each predetermined depth. In this embodiment, the fish signal FS exceeds the seabed detection level BL at a relatively shallow depth. Similarly, the seabed signal BS exceeds the seabed detection level BL at a deep depth.

  At this time, the fish school signal FS is set as the seabed candidate 0, and the seabed signal BS is set as the seabed candidate 1. Here, the seabed position of seabed candidate 0 is BD0, and the seabed position of seabed candidate 1 is BD1. A difference between the maximum level ML0 of the seabed candidate 0 and the seabed detection level BL at the seabed position BD0 is defined as a level difference A. The difference between the maximum level ML1 of the seabed candidate 1 and the seabed detection level BL at the seabed position BD1 is defined as a level difference B. Then, the maximum level ML0 of the seabed candidate 0 and the maximum level ML1 of the seabed candidate 1 are compared. Here, since the maximum level ML0 of the seabed candidate 0 <the maximum level ML1 of the seabed candidate 1, the seabed position BD1 of the seabed signal BS is set as the current seabed and stored in a predetermined memory. The value of the level difference B is stored in a predetermined memory as the current allowable amount NV.

Subsequently, as described above, the current allowable amount NV (level difference B) is compared with the target allowable amount TV. Normally, as shown in FIG. 4, when the fish signal FS exceeds the seabed detection level at a shallow depth, the seabed signal BS is stronger, so that the current allowable amount NV (level difference B)> target allowable amount TV. Become. The seabed level moving means 104 adds a predetermined constant and moves the seabed detection level BL to the right in the figure. This operation is performed until the current allowable amount NV (level difference B) = target allowable amount TV. Thereby, the fish school signal FS of FIG. 4 does not exceed the seabed detection level BL. In this way, the seabed can be detected correctly. Here, the number of signals exceeding the seabed detection level has been described as two, but even when the number of signals exceeds three, the same process is performed, so that the seabed can be detected correctly.
When the seabed has been detected last time, the seabed position BD closest to the previous seabed is stored as the seabed.

  FIG. 5 is an explanatory diagram of the main processing routine of the fish finder according to the present invention. S10 is an initialization process, in which various initialization processes and necessary key switch operations are performed, and the initial seabed detection level BL is calculated for each predetermined depth according to Equation (1). Here, K is set to a value larger than the maximum output of the reception logarithmic amplifier 11 as described above. Here, the explanation has been made using the equation (1) for the calculation of the seabed detection level BL, but this does not stick to this, and the seabed detection level BL can be calculated by an arbitrary calculation formula.

  S100 is a transmission / reception processing routine, and performs the necessary control according to the detection range, the used frequency, the STC, etc., as in the case of a normal fish detection device, and will not be described here.

  S200 is a seabed detection processing routine, which will be described later in detail. S300 is an image creation processing routine of the fish finder, and various display forms are selected by operating the key switch of the operation unit 13 or the like. This is the same as a normal fish finder, and a description thereof is omitted. S400 is a processing routine for moving or initializing the seabed detection level BL, which will be described later in detail.

  FIG. 6 is a diagram for explaining the details of the seabed detection processing routine for the received signal RS received by one transmission. Here, the reception intensity of the reception signal RS is stored in the memory for each predetermined depth. In the seabed detection processing routine, the received signal RS is sequentially read from the memory every predetermined depth from a shallow depth.

  In S210, it is determined whether or not the detection start depth DS. As described above, the detection start depth DS is set to an arbitrary value at a depth below the oscillation line by operating the key switch of the operation unit 13. If the detection start depth has not been reached, the process returns to 210 again based on the determination of the end of S215 reception data, and a determination is made as to whether or not the detection start depth DS is at the next depth. The loop is repeated until the detection start depth DS is reached. When the detection start depth DS is reached, the determination in S211 is performed.

  Here, since the undersea detection flag is OFF during the initialization process, it is determined that the determination in S211 is not initially detecting the seabed, and the determination process of S212 seabed detection is performed. Here, the received signal RS having a predetermined depth read from the memory is compared with the seabed detection level BL at the depth. If the received signal RS <the seabed detection level BL, the process of S213 is performed. If the received signal RS ≧ the seabed detection level BL, the process of S216 is performed.

  As described with reference to FIG. 2, the seabed detection level BL moves to the left side when the seabed detection is not performed. In the process of S213, a determination is made to return to the initial state when the seabed detection level BL reaches a preset level by this movement to the left. When the seabed detection level BL reaches a preset level, the initialization flag is set to ON in the process of S225, and the process proceeds to the next process S215.

  When the seabed detection level BL has not reached the preset level, the process proceeds to S214, the maximum level in the received signal is stored in a predetermined memory address, and the process proceeds to the next process S215. In S215, it is determined whether or not all the received signals RS have been read from the memory. If all the received signals RS have not been read, the process of S210 is repeated again.

  In the determination process of the seabed detection in S212, if the received signal RS ≧ the seabed detection level BL at the predetermined depth, the process of S216 is performed next. In S216, the flag during seabed detection is set to ON, and the process proceeds to S217.

  In S217, the seabed detected at the shallowest depth is set as the seabed candidate 0, and the depth value BD0 and the seabed detection level BL0 at that time are stored in a predetermined memory address. Then, the process proceeds to S214. Thereafter, every time when the seabed is detected before the reception signal RS is finished, the seabed candidate 1, seabed candidate 2... Seabed candidate N in the order of increasing depth, the depth value BD1, seabed detection level BL1, depth at that time The value BD2, the seabed detection level BL2,..., The depth value BDN, and the seabed detection level BLN are stored in predetermined memory addresses, respectively. Then, the process proceeds to S214 described above. Subsequently, in S215, if the received data is not completed, the processes of S210 and S211 are performed.

  If the seabed detection flag is ON in S211, that is, if the seabed is being detected, the processes of S218 and S219 are performed until the seabed detection is completed. In this process, the maximum received signal level ML during seabed detection is stored in S218. As described above, the seabed detected at the shallowest depth is set as the seabed candidate 0, and the maximum received signal level ML0 of the seabed candidate 0 is stored in a predetermined memory. In S219, the current allowable amount NV that is the difference between the seabed detection level BL and the maximum received signal level ML is stored. Again, the current allowable amount NV0 of the seabed candidate 0 is stored in a predetermined memory.

  In S218, the current received signal level is compared with the previous received signal level, and a signal having a higher received signal level is stored. As a result, the maximum received signal level from when the seabed is detected to when the seabed detection is completed can be stored.

  Similarly, in S219, the difference between the current received signal level and the seabed detection level is compared with the difference between the previous received signal level and the seabed detection level, and a signal having a large signal level difference is stored. . Thereby, the maximum signal level difference (current allowable amount NV) from the time of seabed detection to the time of the seabed detection end can be stored. By the time the received signal ends, the received signals that pass through the processing of S218 and S219 are received in the prescribed memory in the order of increasing depth as the seabed candidate 0, the seabed candidate 1, the seabed candidate 2. The signal level ML and the maximum signal level difference (current allowable amount NV) are stored.

  In S220, it is determined whether or not the seabed detection is finished. Here, the received signal level at the current depth is compared with the seabed detection level at the depth, and if the received signal level ≧ the seabed detection level, it is determined that the seabed is being detected, and the process proceeds to S214. As a result of the comparison, if the received signal level <the seabed detection level, it is determined that the seabed detection is finished. In S221, the flag under seabed detection is turned OFF, and the process proceeds to S214. The process in S214 is as described above.

  If it is determined in S215 that the operation of sequentially reading the received signal RS from the memory at a predetermined depth from a shallow depth is completed, the process proceeds to S222. In S222, it is determined whether or not there is a reception signal for the seabed candidate. If there is no seabed candidate, the seabed detection processing routine is terminated.

  If it is determined that there is a seabed candidate in S222, the process proceeds to S223. Here, the maximum received signal level ML0 of seabed candidate 0 is compared with the maximum level in the received signal stored in S214. If the maximum received signal level ML0 of the seabed candidate 0 <the maximum level in the received signal, the process proceeds to S225. In S225, the seabed depth BDN of the seabed candidate N closest to the seabed depth determined in the previous seabed detection process routine is set as the seabed, and the seabed detection process routine is terminated.

  If the determination in S223 is not the maximum received signal level ML0 of the seabed candidate 0 <the maximum level in the received signal, that is, if the maximum received signal level ML0 of the seabed candidate 0 ≧ the maximum level in the received signal, the process proceeds to S224. In the processing, the seabed detection processing routine is ended by setting the seabed depth BD0 of the seabed candidate 0 as the seabed.

  FIG. 7 is a diagram for explaining the details of the processing routine for moving or initializing the seabed detection level BL in S400. In S410, it is determined whether the seabed detection level initialization flag is ON. If the initialization flag is ON, the process proceeds to S411, and the seabed detection level is initialized as described above. Then, this process ends.

  If the initialization flag is OFF, the process moves to S412 to determine whether there is a seabed candidate. Here, if there is no seabed candidate, the process proceeds to S413. In S413, a predetermined constant is subtracted from the current seabed detection level at every predetermined depth. Then, the result is stored in the memory as a seabed detection level table as described above, and the processing is completed. If there is a seabed candidate, the process proceeds to S414.

  In S414, determination is made that target allowable amount> current allowable amount. Here, if it is determined that target allowable amount> current allowable amount, the process proceeds to S413 and the above-described process is performed. If it is determined that target allowable amount> current allowable amount is not satisfied, the process proceeds to S416.

  In S416, determination is made that target allowable amount <current allowable amount. If it is determined that the target allowable amount is smaller than the current allowable amount, the process proceeds to S417. In S417, a predetermined constant is added to the current seabed detection level at every predetermined depth. Then, the result is stored in the memory as a seabed detection level table as described above, and the processing is completed. When it is determined that the target allowable amount <the current allowable amount is not satisfied, that is, it is determined that the target allowable amount = the current allowable amount, the seabed detection level is not changed, and the process ends.

  In the description of the present embodiment, the calculation of the seabed detection level has been described by using the expression (1) as an example. However, it is obvious that the present invention can be applied to any calculation expression of the seabed detection level other than this example.

DESCRIPTION OF SYMBOLS 1: Transducer, 10: Ultrasonic transmitter, 11: Receive logarithmic amplifier, 12: A / D converter, 13: Operation part, 14: Display, 100: Control part, 101: Display control means, 102: Memory part , 103: Submarine level calculation means, 104: Submarine level movement means, 105A: Level comparison means, 105B: Allowable amount comparison means, 106: Transmission / reception control unit, BL: Submarine detection level, RS: Reception signal, BD: Submarine depth, ML: maximum level, NV: current allowable amount, TV: target allowable amount, DS: detection start depth

Claims (8)

In a method for detecting the seabed,
Calculating the seabed detection level at each predetermined depth, comparing the reflected signal amplified and detected by the receiver with the calculated seabed detection level at each predetermined depth, and moving the calculated seabed detection level according to the result of the comparison; As a feature,
The seabed detection method in which the calculated seabed detection level is initially greater than the level of the reflected signal In claim 1,
The movement of the calculated seabed detection level is a seabed detection method in which a predetermined constant is added to or subtracted from the calculated seabed detection level. In claim 1,
The calculated seabed detection level is initially obtained by subtracting the seabed detection level at each predetermined depth. In any one of Claims 1 thru | or 3,
The reflected signal and the moved seabed detection level are compared for each predetermined depth, and when the reflected signal is greater than the seabed detection level, the maximum level of the reflected signal and the seabed detection level at the time of seabed detection A seabed detection method in which a predetermined constant is added to or subtracted from the moved seabed detection level so that the difference between the two is a predetermined range. Means for calculating the seabed detection level for each predetermined depth; means for comparing the reflected signal amplified and detected by the receiver with the calculated seabed detection level for each predetermined depth; and means for moving the calculated seabed detection level; With
The fish detecting device characterized in that the means for calculating initially sets a seabed detection level at a predetermined depth to be higher than a level of the reflected signal. In claim 5,
The fish finder according to claim 1, wherein the moving means adds or subtracts a predetermined constant to the calculated seabed detection level at every predetermined depth. In claim 5,
The fish detecting device characterized in that the moving means initially subtracts the seabed detection level for each predetermined depth calculated by the calculating means. In any of claims 5 to 7,
Further, an allowable amount comparing means is provided, the allowable amount comparing means compares the difference between the maximum level of the reflected signal and the seabed detected level at the time of detecting the seabed, and the moving means is configured to compare the maximum of the reflected signal. A fish finder, wherein a predetermined constant is added or subtracted so that a difference between a level and the seabed detection level at the time of seabed detection falls within a predetermined range.

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