阅读说明：本技术 用于宽带探鱼仪的高效目标分割方法 (Efficient target segmentation method for broadband fish finder ) 是由 汤涛林 李国栋 尹项博 于 2020-05-13 设计创作，主要内容包括：本发明提供一种用于宽带探鱼仪的高效目标分割方法,包括步骤：S1：根据一背景噪声值确定一检测阈值；S2：设定一滑动窗的宽度,滑动窗的宽度小于等于一探鱼仪的距离分辨率；S3：利用一匹配滤波器对探鱼仪的输出信号进行匹配滤波,获得一滤波输出信号的离散滤波数据集,所述离散滤波数据集包括多个波值数据；S4：利用滑动窗和检测阈值对离散滤波数据集分割目标,并输出目标的位置。本发明的一种用于宽带探鱼仪的高效目标分割方法,运算量小,当两个目标回波重叠时,只要目标间隔大于探鱼仪的最小距离分辨率,就可将两个目标区分开来,并快速获得目标的数量和位置。(The invention provides an efficient target segmentation method for a broadband fish finder, which comprises the following steps: s1: determining a detection threshold value according to a background noise value; s2: setting the width of a sliding window, wherein the width of the sliding window is less than or equal to the distance resolution of a fish finder; s3: performing matched filtering on an output signal of the fish finder by using a matched filter to obtain a discrete filtering data set of a filtering output signal, wherein the discrete filtering data set comprises a plurality of wave value data; s4: the discrete filtered data set is segmented into targets using a sliding window and a detection threshold, and the positions of the targets are output. The efficient target segmentation method for the broadband fish finder has small calculation amount, and when two target echoes are overlapped, as long as the target interval is larger than the minimum distance resolution of the fish finder, the two targets can be distinguished, and the number and the positions of the targets can be quickly obtained.)

1. An efficient target segmentation method for a broadband fish finder comprises the following steps:

s1: determining a detection threshold according to a background noise value, wherein the detection threshold is greater than the background noise value;

s2: setting the width of a sliding window, wherein the width of the sliding window is less than or equal to the distance resolution of a fish finder;

s3: performing matched filtering on the output signal of the fish finder by using a matched filter to obtain a discrete filtering data set of a filtering output signal, wherein the discrete filtering data set comprises a plurality of wave value data;

s4: and segmenting the target by using the sliding window and the detection threshold value for the discrete filtering data set, and outputting the position of the target.

2. The method of claim 1, wherein the background noise value is obtained by stopping the emission of the fish finder and recording an echo intensity estimate of the fish finder, and when the emission of the fish finder cannot be stopped, the estimate is made using the echo intensity received beyond the seafloor range or at a distance.

3. The efficient target segmentation method for the broadband fish finder of claim 1, wherein the width M of the sliding window satisfies formula (1):

wherein Δ R represents the distance resolution of the fish finder; f_sRepresenting a sampling rate of the fish finder; c represents the sound velocity in water;

and the width M of the sliding window is the largest integer and odd number which satisfies the formula (1), wherein M is 2N +1, and N is a natural number.

4. The efficient target segmentation method for the broadband fish finder as claimed in claim 3, wherein the analytic expression of the output signal s (t) of the fish finder is:

wherein t is time, tau is signal pulse width, rect represents rectangular function;

the expression of the time domain impulse response function h (t) of the matched filter is as follows:

h(t)＝w(t)s^*(-t) (3)；

wherein w (t) represents a weighting function;

the expression of the filtered output signal r (t) is:

5. the efficient target segmentation method for the broadband fish finder of claim 3, wherein the step of S5 further comprises the steps of:

s51: setting an initial value of a variable n as 1;

s52, judging whether the variable n is more than or equal to the total number L of the wave value data of the discrete filtering data set, if so, ending the step, otherwise, continuing the subsequent steps;

s53: acquiring the largest wave value data from the nth wave value data to the (n + M-1) th wave value data of the discrete filtering data set as target wave value data, wherein the target wave value data is the pth wave value data in the discrete filtering data set, and the position of the target wave value data is set as p; setting a value of a target wave value e as a value of the target wave value data;

s54: judging whether the target wave value e is larger than the detection threshold value; if yes, continuing the subsequent steps; otherwise, assigning the variable N as N +2N +1, and returning to the step S52;

s55: judging whether the position of the target wave value data is equal to N + N or not; if yes, continuing the subsequent steps; otherwise, assigning the variable n as n +1, and returning to the step S52;

s56: taking the target wave value data as the target and outputting the position of the target;

s57: the variable n is assigned to p +1, and returns to step S52.

6. The efficient target segmentation method for the broadband fish finder of claim 3, wherein the step of S5 further comprises the steps of:

s51: setting an initial value of a variable n as 1;

s52, judging whether the variable n is more than or equal to the total number L of the wave value data of the discrete filtering data set, if so, ending the step, otherwise, continuing the subsequent steps;

s53: acquiring the largest wave value data from the nth wave value data to the (n + M-1) th wave value data of the discrete filtering data set as target wave value data, wherein the target wave value data is the pth wave value data in the discrete filtering data set, and the position of the target wave value data is set as p; setting a value of a target wave value e as a value of the target wave value data;

s54: judging whether the target wave value e is larger than the detection threshold value; if yes, continuing the subsequent steps; otherwise, assigning the variable N as N +2N +1, and returning to the step S52;

s55: judging whether the position of the target wave value data is smaller than N + N; if yes, the variable N is assigned as N + N, and the step S52 is returned to; otherwise, continuing the subsequent steps;

s56: judging whether the position of the target wave value data is equal to N + N or not; if yes, taking the target wave value data as the target and outputting the position of the target, assigning a variable n as p +1, and returning to the step S52; if not, continuing the subsequent steps;

s57: assigning a variable n to n + 1;

s58, judging whether N is more than L;

if yes, ending the step;

otherwise, judging whether the numerical value of the (n + M-1) th wave value data of the discrete filtering data set is greater than the target wave value e; if yes, assigning the position of the target wave value data as n + M-1, assigning the target wave value e as the value of the n + M-1 wave value data of the discrete filtering data set, and returning to the step S57; otherwise, return to step S56.

Technical Field

The invention relates to the technical field of fish finding, in particular to an efficient target segmentation method for a broadband fish finder.

Background

Echo counting and echo integration methods are used in the acoustic assessment of fishery resources. The method of echo counting can be directly used under the condition that the distance between the single bodies is larger than the distance resolution of the fish detector, the method of echo integration is used when the density is higher, and the echo integration needs to obtain the average target intensity of the single bodies, so the two methods need to carry out distance segmentation on the target.

The current method for distance segmentation is to set a detection threshold P L D L, count the length of the pulse from the time when the echo signal intensity is higher than the detection threshold to the time when the echo signal intensity is lower than the detection threshold, and if the length is in a set range, consider that 1 target is found, and the distance of the target is the position where the peak value appears.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the efficient target segmentation method for the broadband fish finder, the computation amount is small, when echoes of two targets are overlapped, the two targets can be distinguished as long as the target interval is larger than the minimum distance resolution of the fish finder, and the number and the positions of the targets can be quickly obtained.

In order to achieve the above object, the present invention provides an efficient target segmentation method for a broadband fish finder, comprising the steps of:

s1: determining a detection threshold according to a background noise value, wherein the detection threshold is greater than the background noise value;

s2: setting the width of a sliding window, wherein the width of the sliding window is less than or equal to the distance resolution of a fish finder;

s3: performing matched filtering on the output signal of the fish finder by using a matched filter to obtain a discrete filtering data set of a filtering output signal, wherein the discrete filtering data set comprises a plurality of wave value data;

s4: and segmenting the target by using the sliding window and the detection threshold value for the discrete filtering data set, and outputting the position of the target.

Preferably, the background noise value is obtained by stopping the emission of the fish finder and recording the echo intensity estimation of the fish finder, and when the emission of the fish finder cannot be stopped, the background noise value is estimated by using the echo intensity received beyond the seabed range or a long distance.

Preferably, the width M of the sliding window satisfies formula (1):

wherein Δ R represents the distance resolution of the fish finder; f_sRepresenting a sampling rate of the fish finder; c represents the sound velocity in water;

and the width M of the sliding window is the largest integer and odd number which satisfies the formula (1), wherein M is 2N +1, and N is a natural number.

Preferably, the analytic expression of the output signal s (t) of the fish finder is as follows:

wherein t is time, tau is signal pulse width, rect represents rectangular function;

the expression of the time domain impulse response function h (t) of the matched filter is as follows:

h(t)＝w(t)s^*(-t) (3)；

wherein w (t represents a weighting function;

the expression of the filtered output signal r (t) is:

preferably, the step of S5 further comprises the steps of:

s51: setting an initial value of a variable n as 1;

s52, judging whether the variable n is more than or equal to the total number L of the wave value data of the discrete filtering data set, if so, ending the step, otherwise, continuing the subsequent steps;

s53: acquiring the largest wave value data from the nth wave value data to the (n + M-1) th wave value data of the discrete filtering data set as target wave value data, wherein the target wave value data is the pth wave value data in the discrete filtering data set, and the position of the target wave value data is set as p; setting a value of a target wave value e as a value of the target wave value data;

s54: judging whether the target wave value e is larger than the detection threshold value; if yes, continuing the subsequent steps; otherwise, assigning the variable N as N +2N +1, and returning to the step S52;

s55: judging whether the position of the target wave value data is equal to N + N or not; if yes, continuing the subsequent steps; otherwise, assigning the variable n as n +1, and returning to the step S52;

s56: taking the target wave value data as the target and outputting the position of the target;

s57: the variable n is assigned to p +1, and returns to step S52.

Preferably, the step of S5 further comprises the steps of:

s51: setting an initial value of a variable n as 1;

s52, judging whether the variable n is more than or equal to the total number L of the wave value data of the discrete filtering data set, if so, ending the step, otherwise, continuing the subsequent steps;

s53: acquiring the largest wave value data from the nth wave value data to the (n + M-1) th wave value data of the discrete filtering data set as target wave value data, wherein the target wave value data is the pth wave value data in the discrete filtering data set, and the position of the target wave value data is set as p; setting a value of a target wave value e as a value of the target wave value data;

s54: judging whether the target wave value e is larger than the detection threshold value; if yes, continuing the subsequent steps; otherwise, assigning the variable N as N +2N +1, and returning to the step S52;

s55: judging whether the position of the target wave value data is smaller than N + N; if yes, the variable N is assigned as N + N, and the step S52 is returned to; otherwise, continuing the subsequent steps;

s56: judging whether the position of the target wave value data is equal to N + N or not; if yes, taking the target wave value data as the target and outputting the position of the target, assigning a variable n as p +1, and returning to the step S52; if not, continuing the subsequent steps;

s57: assigning a variable n to n + 1;

s58, judging whether N is more than L;

if yes, ending the step;

otherwise, judging whether the numerical value of the (n + M-1) th wave value data of the discrete filtering data set is greater than the target wave value e; if yes, assigning the position of the target wave value data as n + M-1, assigning the target wave value e as the value of the n + M-1 wave value data of the discrete filtering data set, and returning to the step S57; otherwise, return to step S56.

Due to the adoption of the technical scheme, the invention has the following beneficial effects:

according to the efficient target segmentation method for the broadband fish finder, when echoes of two targets are overlapped, the two targets can be distinguished as long as the target interval is larger than the minimum distance resolution of the fish finder; and the calculation amount is small, and the number and the positions of the targets can be quickly obtained.

Drawings

FIG. 1 is a flow chart of an efficient target segmentation method for a broadband fish finder according to an embodiment of the present invention;

FIG. 2 is a flowchart of a step of segmenting target wave value data according to a first embodiment of the present invention;

FIG. 3 is a graph showing the echo intensity of the fish finder according to the first embodiment of the present invention;

FIG. 4 is a diagram of the output signals of a fish finder with 5 targets according to a first embodiment of the present invention;

FIG. 5 is a diagram of a target segmentation result according to a first embodiment of the present invention;

fig. 6 is a flowchart of a step of segmenting the target wave value data according to a second embodiment of the present invention.

Detailed Description

The following description of the preferred embodiments of the present invention will be provided in conjunction with the accompanying drawings of fig. 1 to 6, and will make the functions and features of the present invention better understood.

Referring to fig. 1, a high-efficiency target segmentation method for a broadband fish finder according to an embodiment of the present invention includes:

s1: and determining a detection threshold value according to a background noise value, wherein the detection threshold value is greater than the background noise value.

Wherein, the background noise value is obtained by stopping the emission of the fish detector and recording the echo intensity estimation of the fish detector; when the transmission of the fish detector cannot be stopped, the intensity of the echo wave received beyond the seabed range or a long distance is used for estimation.

S2: setting the width of a sliding window, wherein the width of the sliding window is less than or equal to the distance resolution of a fish detector.

Wherein the width M of the sliding window satisfies formula (1):

wherein, the delta R represents the distance resolution of the fish finder; f_sRepresenting the sampling rate of the fish finder; c represents the sound velocity in water;

and the width M of the sliding window is the largest integer and odd number which satisfies the formula (1), wherein M is 2N +1, and N is a natural number.

And S3, performing matched filtering on the output signal of the fish finder by using a matched filter to obtain a discrete filtering data set r (n) of the filtering output signal, wherein the discrete filtering data set r (n) comprises L wave value data.

The analytic expression of the output signal s (t) of the fish finder is as follows:

wherein t is time, tau is signal pulse width, rect represents rectangular function;

the expression of the time domain impulse response function h (t) of the matched filter is:

h(t)＝w(t)s^*(-t) (3)；

wherein w (t represents a weighting function;

the expression for the filtered output signal r (t) is:

s4: the discrete filtered data set r (n) is segmented using a sliding window and a detection threshold, and the position of the target is output.

Starting from the 1 st wave value data of the discrete filtering data set, searching the maximum value of the wave value data in the width M of the sliding window, when the maximum value of the wave value data is greater than the detection threshold value and the position of the wave value data is in the center of the sliding window, considering that 1 target wave value data is found, moving the sliding window, and repeating the steps until all the wave value data are searched.

Referring to fig. 2, the step S5 further includes the steps of:

s51: setting an initial value of a variable n as 1;

s52, judging whether the variable n is more than or equal to the total number L of the wave value data of the discrete filtering data set, if so, ending the step, otherwise, continuing the subsequent steps;

s53: acquiring the largest wave value data from the nth wave value data to the (n + M-1) th wave value data of the discrete filtering data set as target wave value data, wherein the target wave value data is the p-th wave value data in the discrete filtering data set, and the position of the target wave value data is set as p; setting a value of a target wave value e as a value of target wave value data;

s54: judging whether the target wave value e is larger than a detection threshold value; if yes, continuing the subsequent steps; otherwise, assigning the variable N as N +2N +1, and returning to the step S52;

s55: judging whether the position of the target wave value data is equal to N + N or not; if yes, continuing the subsequent steps; otherwise, assigning the variable n as n +1, and returning to the step S52;

s56: taking the target wave value data as a target and outputting the position of the target;

s57: the variable n is assigned to p +1, and returns to step S52.

For example, a chirp (L FM) signal with bandwidth B of 60kHz and pulse width τ of 1ms is used, the sampling rate is 2MHz, the weighting function w (t) is used as a hamming window, and the echo intensity of the fish finder is output after matched filtering, as shown in fig. 3.

It can be seen that the minimum distance resolution of the fish finder is about 40mm, and then M is 53.

The simulation had 5 targets at 100m distance, which were: 100.0m 100.08m 100.12m100.15m100.17m, echo state of 5 targets please refer to fig. 4.

Please refer to fig. 5, which illustrates a target segmentation result graph obtained by segmenting a target according to a first embodiment of the present invention.

The first three targets are identified with a separation distance greater than the distance resolution, and the last two targets with a separation distance less than the minimum resolution are identified as 1 target.

Referring to fig. 6, the steps of a second method for efficient object segmentation for a broadband fish finder according to the second embodiment of the present invention are substantially the same as the first embodiment, except that the step S5 further includes the steps of:

s51: setting an initial value of a variable n as 1;

s52, judging whether the variable n is more than or equal to the total number L of the wave value data of the discrete filtering data set, if so, ending the step, otherwise, continuing the subsequent steps;

s53: acquiring the largest wave value data from the nth wave value data to the (n + M-1) th wave value data of the discrete filtering data set as target wave value data, wherein the target wave value data is the p-th wave value data in the discrete filtering data set, and the position of the target wave value data is set as p; setting a value of a target wave value e as a value of target wave value data;

s54: judging whether the target wave value e is larger than a detection threshold value; if yes, continuing the subsequent steps; otherwise, assigning the variable N as N +2N +1, and returning to the step S52;

s55: judging whether the position of the target wave value data is smaller than N + N; if yes, the variable N is assigned as N + N, and the step S52 is returned to; otherwise, continuing the subsequent steps;

s56: judging whether the position of the target wave value data is equal to N + N or not; if so, taking the target wave value data as a target and outputting the position of the target, assigning the variable n as p +1, and returning to the step S52; if not, continuing the subsequent steps;

s57: assigning a variable n to n + 1;

s58, judging whether N is more than L;

if yes, ending the step;

otherwise, judging whether the numerical value of the (n + M-1) th wave value data of the discrete filtering data set is greater than the target wave value e; if so, assigning the position of the target wave value data as n + M-1, assigning the target wave value e as the numerical value of the n + M-1 wave value data of the discrete filtering data set, and returning to the step S57; otherwise, return to step S56.

While the present invention has been described in detail and with reference to the embodiments thereof as illustrated in the accompanying drawings, it will be apparent to one skilled in the art that various changes and modifications can be made therein. Therefore, certain details of the embodiments are not to be interpreted as limiting, and the scope of the invention is to be determined by the appended claims.