JP2010066128A - Fish finder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fish finder capable of removing interference from other ultrasonic devices without impairing a useful echo from a small target such as single fish. <P>SOLUTION: The fish finder is provided with an interference removal part for comparing a first characteristic value determined from current data belonging to a first depth range including the depth of data subjected to interference removal processing and a second characteristic value determined from previous data belonging to a second depth range including the depth of data subjected to interference removal processing, outputting the data subjected to interference removal processing without performing any processing when the first characteristic is smaller than the other, and outputting the previous data of the same depth as that of the data subjected to interference removal processing when the second characteristic value is smaller than the other. <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 from an ultrasonic device mounted on another ship operating in the sea area near the own ship.

Conventionally, a fish finder having an interference removal function is known as a solution to this problem. In this interference removal function, the current transmission / reception data to be subjected to interference removal is compared with the previous transmission / reception data at the same depth, and the smaller signal is selected to be the 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 the target is not significantly impaired. On the other hand, the interference signal is often received at a different depth position at a different depth position as a signal of a stronger level than an echo signal from a normal fish school or the like, and is received continuously at the same depth. Few. 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, if the conventional interference removal function described above is used in a fish finder having a high distance resolution, there arises a problem that not only an interference signal but also a useful echo from a small target such as a single fish is lost.

This problem will be described with reference to FIG.
FIG. 6A is a video example of a fish finder when interference removal processing is not performed. Along with an image of a single fish moving in the depth direction, a seam-like interference image of a sewing machine caused by an ultrasonic device of another ship is displayed.

On the other hand, FIG. 6B is an image obtained by performing a conventional interference removal process on the same received data as FIG. 6A. Compared with FIG. 6A, the interference image is removed, but the image of the single fish is small and difficult to see. In particular, as shown in FIG. 6, this problem becomes significant in the case of an image of a single fish moving in the depth direction.

An object of the present invention is to provide a fish finder that eliminates interference caused by other ultrasonic devices without damaging useful echoes from small targets such as single fish even when the distance resolution is high. is there.

The reason why the echo signal from a small target such as a single fish was damaged when conventional interference cancellation was performed with a fish finder with high distance resolution was that the previous echo from the same target was This is because echo is received as data at a slightly different depth.

Therefore, in the fish finder of the present invention, the current data itself is output as interference-removed data for the current data to be subjected to interference removal, or the previous data at the same depth position as the current data is output. When determining whether or not to perform the determination, it is not determined based on a comparison between these values as in the conventional case, but the depth of a predetermined width including the depth of data to be subjected to interference removal for each of the previous and current transmission / reception. An average value or the like of data belonging to the range is obtained as a feature value reflecting the signal intensity of the data belonging to the depth range, and a determination is made based on a comparison between these feature values. Specifically, if the feature value obtained from the current data is smaller, the current data that is the object of interference removal is output as it is as interference-removed data, and if the feature value obtained from the previous data is smaller, interference occurs. The previous data at the same depth position as the current data to be removed is output as interference-removed data.

In this way, when the received signal is an echo from a single fish, the feature values such as the average value obtained from the echo data of the previous and current depth ranges in the vicinity of the echo data to be subject to interference removal are all relevant. This value reflects the presence of echoes from a single fish, and even if any of these values is small, the previous or current echo data from the same single fish will be output as interference-removed data. Due to this, the echo is hardly damaged.
On the other hand, the interference signal is often received as data having a depth farther than the depth width of the depth range used for calculating the feature value in the current and previous receptions. For this reason, when the current signal to be subjected to interference removal is an interference signal, the feature value obtained from the previous transmission / reception data is a value that is not affected by the interference signal, and is obtained from the current data including the interference signal. It is likely that the value will be smaller than the value. As a result, instead of the current data that is an interference signal, previous data that is not an interference signal is output, and the interference signal is removed.
The present invention is based on the principle as described above.

A fish finder according to the present invention includes a transmission / reception unit that transmits an ultrasonic signal into water and receives an echo, and a memory that stores a reception signal received by the transmission / reception unit as echo data corresponding to a depth for each transmission / reception And an interference removal unit that sequentially performs interference removal processing on echo data of each depth using the echo data stored in the memory, and the interference removal unit Among the echo data obtained in the above, the first feature value is obtained from a plurality of echo data belonging to the first depth range including the depth of the interference removal target echo data, and among the echo data obtained in the previous transmission and reception, A second feature value is obtained from a plurality of echo data belonging to the second depth range including the depth of the interference removal target echo data, and the obtained first feature value is compared with the second feature value to obtain a first When the characteristic value is smaller, the interference removal target echo data is directly output as interference-removed echo data, and when the second feature value is smaller, echo data from the previous transmission and reception at the same depth as the interference removal target echo data is output. Output as interference-removed echo data for the interference-removal target echo data.

In the embodiment of the fish finder of the present invention, the first feature value is an average value of a plurality of echo data belonging to the first depth range obtained by the current transmission / reception, and the second feature value is It is an average value of a plurality of echo data belonging to the second depth range obtained by transmission / reception.

Here, the average value is not limited to a simple average value obtained by dividing the total sum of echo data by the number of data, but may be a weighted average value obtained by appropriately weighting data.

In the embodiment of the fish finder of the present invention, the first feature value is the signal strength of the echo data having a predetermined rank among the plurality of echo data belonging to the first depth range obtained by the current transmission / reception. The second feature value is characterized in that the signal strength is the signal strength value of the echo data having a predetermined rank among the plurality of echo data belonging to the second depth range obtained in the previous transmission / reception.

As described above, instead of the average value, the feature value may be a signal strength value of echo data having a predetermined signal strength among a plurality of echo data belonging to the first depth range and the second depth range. .

In the embodiment of the fish finder of the present invention, the interference canceling unit may use the first feature value that has already been acquired as the second feature value at the next transmission / reception of the ultrasonic signal. .

In this embodiment, when the calculation method for acquiring the first feature value and the second feature value is common between the previous time and the current time, the first feature value used for the current interference removal is used in the next interference removal. This is based on the fact that it can be used as it is as the second feature value.

Further, in the embodiment of the fish finder of the present invention, the interference canceling unit includes one echo data obtained from past transmission / reception (excluding the previous transmission / reception) in addition to the first feature value and the second feature value. The above feature values are acquired, the first feature value, the second feature value, and the one or more acquired feature values are compared, and interference cancellation is performed among echo data used for calculating the smallest feature value. Echo data having the same depth as the target echo data is output as interference-removed echo data for the interference-reject target echo data.

  With this configuration, even when strong interference occurs, the interference can be removed more accurately.

According to the present invention, even if distance resolution is high, a fish finder capable of removing the influence of interference signals from other ultrasonic devices without impairing useful echoes from a small target such as a single fish is realized.

The best mode for carrying out the present invention will be described with reference to FIG.
In FIG. 1, a transducer 1 mounted on a ship bottom or the like is driven by an electrical signal supplied from a transmission unit 3 via a trap circuit 2 to transmit an ultrasonic signal into the water, and also by an underwater target. The echo reflected and returned 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 for storing a data sequence of received signals obtained in one transmission in order of depth, and stores a data sequence of received signals 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 has S upper and lower pieces (S = 2 in the example of FIG. 3) centered on the current reception data D [0; M] to be subjected to interference removal processing from the memory 6. That is, a total of (2S + 1) data belonging to the depth range (first depth range) from D [0; MS] to D [0; M + S] is read, and the average value of these (2S + 1) data is calculated. Ask. This is defined as a first feature value A [0; M]. Similarly, the interference removal unit 7 moves the upper and lower S around the data D [1; M] having the same depth as the current reception data D [0; M] to be subjected to interference removal processing among the previous reception data. Data, that is, a total of (2S + 1) data belonging to the depth range (second depth range) from D [1; MS] to D [1; M + S], and the average value of these (2S + 1) data Ask for. This is the second feature value A [1; M].
Next, the interference removal unit 7 compares the first feature value A [0; M] with the second feature value A [1; M], and if the first feature value A [0; M] is smaller, The current reception data D [0; M] to be subjected to interference removal processing is output as is to the display processing unit 8 as interference-removed data for the reception data, and the second feature value A [1; M] is output. If it is smaller, the data D [1; M] having the same depth as the current reception data D [0; M] to be subjected to the interference removal processing is replaced with the current reception data D [0; M] is output to the display processing unit 8 as interference-removed data.
The above processing is sequentially executed for the current echo data to be subjected to interference removal.

As a result, even if the current echo to be subjected to interference removal processing is an echo from a small target such as a single fish, the feature value reflects the presence of echoes of almost the same level from the same single fish in the previous transmission and reception. Therefore, the possibility of removing useful echoes from a single fish as an interference signal as in the conventional interference removal is reduced. On the other hand, when the interference removal target data is an interference signal, the interference signal is often received as data at a depth that is further away from the predetermined depth range in the current and previous receptions. The feature value is not affected by the interference signal having strong signal strength and is smaller than the second feature value based on the current data, and is not an interference signal at the same depth as the interference removal target data by the previous transmission / reception. Data is output instead of the interference signal received this time, and the interference signal can be removed by this processing.

With reference to FIG. 5, an image when the interference processing of the present invention is performed will be described.

FIG. 5A shows an image when the interference removal process is not performed, and FIG. 5B shows an image when the interference removal process of the present invention is performed. In FIG. 5B, the interference image is removed, and it is understood that the fish shadow of the single fish is displayed without being damaged.

Note that the first feature value A [0; M] obtained from the data transmitted / received this time in the interference removing unit 7 is directly used as the second feature value A [1; M]. Therefore, a separate memory for storing the first feature value A [0; M] is provided in the interference removal unit 7, and when the interference removal is performed on the data in this memory for the data by the next transmission / reception, the second feature A configuration may be adopted in which the value A [1; M] is read and used. According to this configuration, it is possible to increase the processing speed by reducing the amount of calculation required for the interference removal processing.
In addition, the first feature value and the second feature value may be a weighted average calculated by giving each data a weight instead of a normal simple average (the sum of data divided by the number of data). It is.

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 includes upper and lower S data centered on D [0; M] among the current received data (in the example of FIG. 4). S = 2), that is, a total of (2S + 1) data belonging to the depth range (first depth range) from D [0; MS] to D [0; M + S] is read, and these (2S + 1) data Average value A [0; M] is obtained (first characteristic value). Similarly, the interference removal unit 7 has S pieces in the upper and lower sides centered on data D [1; M] having the same depth as D [0; M] among the previous received data, that is, D [1; MS]. A total of (2S + 1) data belonging to the depth range (second depth range) from D to [1; M + S] is read, and an average value A [1; M] of these (2S + 1) data is obtained (second) Characteristic value). Further, the interference canceling unit 7 has T pieces of data D [2; M] at 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 belonging to the depth range (third depth range) from D [2; M−T] to D [2; M + T] is read, and the average value A [2 of these (2T + 1) data M] is obtained (third feature value). The interference removal unit 7 compares the three feature values A [0; M], A [1; M], and A [2; M] thus obtained, and uses the echo data used to calculate the smallest feature value. Among them, data having the same depth as the interference removal target data D [0; M] is output to the display processing unit 8 as interference-removed data for D [0; M]. That is, if A [0; M] is minimum, D [0; M] is selected. If A [1; M] is minimum, D [1; M] is selected. If A [2; M] is minimum, D [2; M is selected. ] Is output to the display processing unit 8 as interference-removed data for D [0; M]. Similar processing is sequentially executed 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 strong interference occurs, such as when receiving an interference signal twice at substantially the same depth twice by performing interference removal processing using not only the previous reception signal but also the previous reception signal However, interference removal can be performed. In addition, here, the example of performing the interference removal process using the reception signal of the previous time and the last time has been described here, but it is also possible to perform the interference removal process using the previous data.

In this embodiment, when S = T, the first feature value A [0; M] and the second feature value A [1; M] are respectively used when performing interference removal processing on data by the next transmission / reception. The second feature value A [1; M] and the third feature value A [2; M] can be used. Therefore, a separate memory for storing the first feature value A [0; M] and the second feature value A [1; M] is provided in the interference removal unit 7, and the data in this memory is used for the next transmission / reception data. When performing the interference removal, the second feature value A [1; M] and the third feature value A [2; M] may be read and used. According to this configuration, it is possible to increase the processing speed by reducing the amount of calculation required for the interference removal processing.

  In any of the above-described embodiments, as the feature value, a weighted average calculated by giving weight to each data can be used instead of the normal simple average (the sum of data divided by the number of data). It is.

In addition, as the feature value, it is possible to use the median value of data belonging to a predetermined depth range with the current time and the previous time, or echo data with a predetermined order of signal strength. As described above, the feature value may be an index that reflects the signal strength of a plurality of data existing in the focused depth range.

In the above-described embodiment, the same number of data is used in the vertical direction on the basis of the depth of the data to be subjected to the interference removal processing in this time, when reading the data of the previous time and the previous time this time. It is also possible to use. In addition, this time, the width of the previous depth range is not necessarily the same.

In addition, for the vicinity of the upper and lower ends of the memory 6, there is no part of the previous and previous data used in the interference removal processing this time, but the processing may be performed using only the existing data. The vicinity of the end 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 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).

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 (5)

A transmission / reception unit for transmitting an ultrasonic signal into water and receiving echoes;
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 the echo data stored in the memory, an interference removal unit that sequentially performs interference removal processing on the echo data of each depth,
The interference cancellation unit obtains a first feature value from a plurality of echo data belonging to a first depth range including the depth of interference cancellation target echo data among echo data obtained by transmission and reception this time,
Of the echo data obtained in the previous transmission and reception, a second feature value is obtained from a plurality of echo data belonging to a second depth range including the depth of the interference removal target echo data,
Comparing the first feature value and the second feature value,
When the first feature value is smaller, the interference removal target echo data is output as it is as interference-removed echo data, and when the second feature value is smaller, the previous depth of the same depth as the interference removal target echo data is output. A fish finder characterized by outputting echo data obtained by transmission / reception as echo data whose interference has been removed with respect to the interference-rejected echo data. The fish finder according to claim 1,
The first feature value is an average value of a plurality of echo data belonging to the first depth range obtained in the current transmission / reception,
The fish finder according to claim 2, wherein the second feature value is an average value of a plurality of echo data belonging to the second depth range obtained in the previous transmission / reception. The fish finder according to claim 1,
The first characteristic value is a signal strength value of echo data having a predetermined order of signal strength among a plurality of echo data belonging to the first depth range obtained in the current transmission / reception,
The fish detector according to claim 2, wherein the second feature value is a signal strength value of echo data having a predetermined rank among the plurality of echo data belonging to the second depth range obtained in the previous transmission / reception. . The fish finder according to claim 1,
The said interference removal part uses the said 1st feature value already acquired as said 2nd feature value at the time of transmission / reception of the next ultrasonic signal, The fish finder characterized by the above-mentioned. The fish finder according to claim 1,
In addition to the first feature value and the second feature value, the interference removing unit obtains one or more feature values from echo data obtained in past transmission / reception (excluding previous transmission / reception),
Comparing the first feature value, the second feature value, and the acquired one or more feature values;
A fish finder for outputting echo data having the same depth as the interference removal target echo data among echo data used for calculation of the smallest feature value as interference-removed echo data for the interference removal target echo data .

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