JP2009294119A - Fish finder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fish finder removing interference from another ultrasonic device without impairing a useful echo from a small target such as single fish and a target moving in a depth direction. <P>SOLUTION: The echo data at the present time to be subjected to interference removal processing are compared with the echo data with the maximum signal intensity from among the echo data obtained by the previous transmission and reception and belonging to a depth range including the echo data at the present time. The echo data with the smaller signal intensity are output as the interference-removed echo data for the echo data at the present time to be subjected to interference removal processing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a fish finder having an interference removal function for removing interference caused by other ultrasonic equipment.

In general, in a fish finder mounted on a fishing boat or the like, there is a problem of interference caused by ultrasonic waves transmitted by other ultrasonic devices mounted on other ships operating in the sea area near the own ship.

Conventionally, as a means for solving this problem, a fish finder having an interference removal function is known. In this interference removal function, the current data to be subject to interference removal is compared with the previous data at the same depth, and the smaller signal is selected and displayed as an interference-removed signal for the current signal.

This conventional interference cancellation processing is generally based on the following principle.
Through the transmission and reception of the current time and the previous time, echo signals from targets such as the same school of fish are received at substantially the same level at the same depth. For this reason, when comparing the current data to be interference-rejected with the previous data at the same depth and selecting the data with the lower level, the data received this time or the previous data at the same level Is output, and the echo signal from this target is not significantly impaired. On the other hand, the interference signal is often received as a signal having a stronger level than an echo signal from a normal school of fish, etc. at a relatively remote depth position in the previous and present receptions, and is received continuously at the same depth. There are few things. Therefore, when comparing the current data to be subject to interference removal with the previous data at the same depth and selecting the data with the lower level, even if either the current data or the previous data is due to interference, Thus, the data having a smaller signal level and not the interference signal is output, and the data due to the interference is removed.

An underwater detection device using such a conventional interference removal process is disclosed in, for example, Patent Document 1 and the like.

JP 2003-322678 A

By the way, when using the above-described conventional interference cancellation function with a fish finder having a high distance resolution, there arises a problem that not only the interference signal but also a useful echo including information on the fish school and the like is damaged.
This is because in a fish finder with high distance resolution, even if it is an echo signal from a target such as the same fish school, signals with greatly different levels at the same depth are received by this transmission and the previous transmission. Because it becomes.

In order to explain this problem, FIG. 7 schematically shows an enlarged portion where a single fish is reflected from the display screen of the fish finder.
FIG. 7A is a schematic video example when the interference removal processing is not performed. Along with an image of a crescent-shaped single fish, an interference image from an ultrasonic device of another ship is displayed in the shape of a seam of the sewing machine.
On the other hand, FIG. 7B is an image obtained by performing a conventional interference removal process on the same received data as FIG. 7A. When compared with FIG. 7A, the interference image is removed, but the image of the single fish is small and difficult to see.

FIG. 8 is also a diagram for explaining the above problem, and schematically shows an enlarged portion where a single fish moving in the depth direction from the display screen of the fish finder is shown.
FIG. 8A is a schematic video example when the interference removal processing is not performed. Along with an image of a single fish moving in the depth direction, an interference image from an ultrasonic device of another ship is displayed in a seam shape of the sewing machine.
On the other hand, FIG. 8B is an image obtained by performing the same conventional interference removal processing as described above on the same received data as FIG. 8A. Compared to FIG. 8A, the interference image is removed, but the image of the single fish moving in the depth direction is small and difficult to see.

The object of the present invention is to eliminate interference from other ultrasonic devices without damaging useful echoes from small targets such as single fish or targets moving in the depth direction even when distance resolution is high. The purpose is to provide a fish finder.

The reason why the echo signal from a small target such as a single fish or a target moving in the depth direction has been impaired when conventional interference cancellation is performed by a fish finder with high distance resolution is the same. This is because the previous echo having the same level as the current echo from the target was received as data at a depth slightly different from the current echo.

For this reason, in the present invention, rather than focusing only on the previous data at the same depth position as the current data to be subject to interference removal, the depth is slightly the same as the current data to be subject to interference removal. Select the data of the maximum signal level from the data in the predetermined depth range including the position, compare this data with the current data to be subject to interference removal processing, and use the smaller data as interference-removed data Make output. In this way, even if the current echo targeted for interference removal processing is an echo from a small target such as a single fish or a target moving in the depth direction, it is the same as the previous echo to be compared. Since echoes of almost the same level from a single fish are selected, the echoes are hardly impaired by interference removal. On the other hand, the interference signal is often received as data having a depth farther than the predetermined depth range during the current and previous reception, and can be removed by this processing. The present invention is based on such a principle.

The fish finder of the present invention transmits an ultrasonic transmission signal to water and receives an echo signal, and stores the reception signal received by the transmission / reception unit as echo data corresponding to the depth for each transmission / reception. And an interference cancellation unit that performs interference cancellation processing using the echo data stored in the memory, and the interference cancellation unit detects the detection point that is the target of interference cancellation processing obtained by the current transmission / reception. Comparing the echo data with the echo data having the maximum signal intensity among the echo data of the detection points belonging to a predetermined depth range including the depth of the detection point to be subjected to the interference removal processing obtained by the previous transmission and reception; The echo data having the smaller signal intensity is output as interference-removed echo data of the detection point to be subjected to the interference removal process.

Further, the fish finder of the present invention transmits an ultrasonic transmission signal into the water and receives an echo signal, and echo data corresponding to the depth for each transmission / reception of the reception signal received by the transmission / reception unit. And an interference cancellation unit that performs interference cancellation processing using the echo data stored in the memory, and the interference cancellation unit detects a target of interference cancellation processing obtained by the current transmission / reception. Among the echo data of the point and the echo data of the detection point belonging to a predetermined depth range including the depth of the detection point to be subjected to the interference removal processing obtained by a plurality of times of transmission / reception up to the previous time, a signal for each transmission / reception Compare the echo data with the highest intensity and output the echo data with the lowest signal intensity as the interference-removed echo data of the detection point that is the target of the interference removal processing. And features.

More preferably, the interference removing unit takes the predetermined depth range wider as echo data obtained by past transmission / reception.

According to the present invention, even when distance resolution is high, a school of fish that eliminates interference from other ultrasonic devices without damaging useful echoes from small targets such as single fish or targets moving in the depth direction A detector can be realized.

The best mode for carrying out the present invention will be described with reference to FIG.
In FIG. 1, a transmitter / receiver 1 mounted on a ship bottom or the like is driven by an electric signal supplied from a transmission unit 3 via a trap circuit 2 to transmit an ultrasonic pulse signal into the water, and an underwater target. The echo reflected and returned by the signal is received, and a reception signal is output to the amplifier 4 via the trap circuit 2. The amplifier 4 amplifies the received signal, and the AD converter 5 converts the amplified signal into a digital signal. The memory 6 sequentially stores the received signals converted into digital signals. The interference removal unit 7 reads the received signal from the memory 6 and performs interference removal processing. The display processing unit 8 generates a display signal from the received signal from which interference has been removed, and displays a detection image on the display.

Here, the structure of the memory 6 will be described with reference to FIG.
The memory 6 includes a plurality of line memories that store a received signal data string obtained in one transmission in the order of depth, and stores the received signal data string over several transmissions. The memory 6 in FIG. 2 includes three lines of line memories 6a, 6b, and 6c, and can store received signals over three transmissions / receptions. In the memory 6, the line memory 6c (D [0; 0] to D [0; N]) stores the current received signal, and the line memory 6b (D [1; 0] to D [1; N]) The previous reception signal is stored, and the line memory 6a (D [2; 0] to D [2; N]) stores the previous reception data. When a new transmission / reception operation is performed, the data sequence of the received signal obtained by the latest transmission is written in the rightmost line memory 6c, and at the same time, the data sequence of the received signal obtained by the previous transmission is one. Each time the data is shifted to the left line memory and rewritten, the old data string stored in the leftmost line memory 6a is erased.

Next, interference removal processing in the interference removal unit 7 will be described with reference to FIG.
As shown in FIG. 3, the interference removal unit 7 reads the current reception data D [0; M] that is the target of the interference removal processing from the memory 6. At the same time, the interference canceling unit 7 has S pieces of upper and lower S centered on data D [1; M] having the same depth as D [0; M] among the previously received data (S = in the example of FIG. 3). 2) That is, a total of (2S + 1) data from D [1; MS] to D [1; M + S] is read, and the signal having the maximum intensity is selected from these (2S + 1) data. . The selected data having the maximum intensity is compared with the current reception data D [0; M] to be subjected to interference cancellation processing, and the data having the smaller intensity is compared with the current reception data D [0; M]. The data is output to the display processing unit 8 as interference-removed data. Similar processing is sequentially performed on the current data to be subjected to interference removal.

As a result, even if the current echo that is the target of interference removal processing is an echo from a small target such as a single fish or a target that moves in the depth direction, Therefore, the echo is hardly damaged by the interference cancellation. On the other hand, the interference signal is often received as data having a depth farther than the predetermined depth range during the current and previous reception, and can be removed by this processing.

Next, with reference to FIGS. 5 and 6, an example of a video when the interference processing of the present invention is performed will be described.

FIG. 5A schematically shows an image when the interference removal processing is not performed, and is the same image as FIG. 7A used for the description of the conventional technology. FIG. 5B shows an image when the interference removal processing of the present invention is performed. In FIG. 5 (B), the interference image is removed, and unlike the image obtained by performing the conventional interference removal in FIG. 7 (B), the fish shadow of the single fish is displayed without being damaged. .

FIG. 6A schematically shows an image when the interference removal processing is not performed, and is the same image as FIG. 8A used for the description of the conventional technology. FIG. 6B shows an image when the interference removal processing of the present invention is performed. In FIG. 6 (B), the interference image is removed, and unlike the image obtained by performing conventional interference removal in FIG. 8 (B), the fish shadow of the single fish moving in the depth direction is displayed without being damaged. I understand that

Next, another embodiment of the interference removal processing in the interference removal unit 7 will be described with reference to FIG.
The current received data to be subjected to interference removal processing stored in the memory 6 is assumed to be D [0; M]. In executing the interference removal processing for the current data D [0; M], the interference removal unit 7 focuses on data D [1; M] having the same depth as D [0; M] among the previous received data. 4 (S = 2 in the example of FIG. 4), that is, a total of (2S + 1) data from D [1; MS] to D [1; M + S] is read, and these (2S + 1) data Among the data, the signal U1 having the maximum intensity is selected. Further, the interference canceling unit 7 has T pieces of data D [2; M] having the same depth as D [0; M] from the previous reception data (T = 4 in the example of FIG. 4), that is, A total of (2T + 1) data from D [2; M−T] to D [2; M + T] is read out, and the signal U2 having the maximum intensity is selected from these (2T + 1) data. The selected two data U1 and U2 are compared with the current reception data D [0; M] to be subjected to interference removal processing, and the data with the smallest signal strength is compared with the current reception data D [0; M]. Is output to the display processing unit 8 as interference-removed data. Similar processing is sequentially performed on the current data to be subjected to interference removal. In this case, it is desirable that S <T. This is because the amount of change in the distance between the detection target of interest and the transducer often increases with time.

In this way, when interference removal processing is performed using not only the previous received signal but also the previous received signal, stronger interference has occurred, such as when the interference signal is received at approximately the same depth. Even in this case, interference cancellation can be performed. Also, here, an example has been described in which interference cancellation processing is performed using the received signal of the previous time, but interference cancellation processing using previous data can also be performed.

In the above description, the same number of data is used in the vertical direction with reference to the data to be subjected to interference removal processing in the previous and previous data reading, but different numbers of data can be used in the upper and lower directions. It is.

Further, in the vicinity of the upper and lower ends of the memory 7, a part of the previous and previous data used for the interference removal processing does not exist, but the processing may be performed using only existing data, or the vicinity of these upper and lower ends. May be excluded from the object of the interference removal process.

Further, the current echo data is directly input to the interference removal unit 7 without going through the memory 6, and the previous or previous echo data is read as needed, and the interference-removed signal for the current echo data is read. May be generated and output to the display processing unit 8. In this way, echo data from which interference has been removed can be generated and displayed in real time with respect to the latest echo data.

It is a block diagram of an embodiment of the present invention. 3 is a diagram for explaining the structure of a memory 6. FIG. It is a figure for demonstrating the Example of the interference removal process in the interference removal part. It is a figure for demonstrating the other Example of the interference removal process in the interference removal part. (A) is an example of a video before performing the interference removal process, and (B) is an example of a video when the interference removal process of the present invention is performed on the same received data as the video example of (A). (A) is another video example before performing the interference removal processing, and (B) is a video example when the interference removal processing of the present invention is performed on the same received data as the video example of (A). (A) is an example of a video before performing the interference removal process, and (B) is an example of a video when the conventional interference removal process is performed on the same received data as the video example of (A). (A) is another video example before performing the interference removal process, and (B) is a video example when the conventional interference removal process is performed on the same received data as the video example of (A).

Explanation of symbols

1 Transmitter / Receiver 2 Trap Circuit 3 Transmitter 4 Amplifier 5 AD Converter 6 Memory 7 Interference Remover 8 Display Processor

Claims (3)

A transmission / reception unit for transmitting an ultrasonic transmission signal into water and receiving an echo signal;
A memory that stores the received signal received by the transmission / reception unit as echo data corresponding to the depth for each transmission / reception;
Using echo data stored in the memory, an interference removal unit for performing interference removal processing,
The interference removal unit is a predetermined depth range including echo data of a detection point to be subjected to interference removal processing obtained by the current transmission / reception and a depth of the detection point to be subjected to interference removal processing obtained by the previous transmission / reception. The echo data with the maximum signal strength is detected from the echo data of detection points belonging to
By comparing the echo data of the detection point to be subjected to the interference removal processing and the echo data having the maximum signal intensity of the previous transmission / reception, the echo data having the smaller signal strength is set to the detection point to be the interference removal processing target. A fish finder that outputs echo data after interference cancellation. A transmission / reception unit for transmitting an ultrasonic transmission signal into water and receiving an echo signal;
A memory that stores the received signal received by the transmission / reception unit as echo data corresponding to the depth for each transmission / reception;
Using echo data stored in the memory, an interference removal unit for performing interference removal processing,
The interference removal unit includes echo data of a detection point to be subjected to interference removal processing obtained by the current transmission / reception, and a depth of the detection point to be subjected to interference removal processing obtained by a plurality of times of transmission / reception up to the previous time. Among the echo data of the detection points belonging to a predetermined depth range, the echo data having the maximum signal intensity for each transmission / reception is detected,
By comparing the echo data of the detection point to be subjected to the interference removal processing and the echo data having the maximum signal strength for each transmission / reception, the echo data having the smallest signal strength is set as the detection point of the interference removal processing target. A fish finder that outputs echo data after interference cancellation. The fish finder according to claim 2,
The interference detector is configured to increase the predetermined depth range including the depth of the detection point to be subjected to the interference removal process as the echo data obtained by transmission / reception in the past in terms of time is increased. .

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