Method for processing echo signals of a fishfinder device, fishfinder device and storage medium

Abstract

This invention provides a method for processing echo signals from a fish finder, the fish finder itself, and a storage medium, comprising: S1, receiving an echo signal; S2, performing envelope processing on the echo signal to obtain an envelope signal; S3, calculating the variance of data within a selected sliding window until a signal segment with a variance value less than a predetermined variance threshold is found; S4, determining the noise floor value of the envelope signal based on the average amplitude of the found signal segment; S5, determining the starting position of a weak signal data segment based on the location of signal points with amplitudes less than the noise floor value; S6, performing partial filtering on the envelope signal to obtain the image signal to be displayed, and performing IIR filtering or FIR filtering on the weak signal data segment; signal segments other than the weak signal data segment retain their original values. Using the above technical solution, weak signals in the echo signal can be identified, thereby improving the sensitivity of the fish finder.

Description

Technical Field

[0001] This invention relates to the field of signal processing technology for fish finder equipment, and in particular to a method for processing echo signals from fish finder equipment, fish finder equipment, and storage medium. Background Technology

[0002] Fish finding equipment, such as digital fish finders, is an important means of detecting aquatic biological resources and is widely used in fisheries resource development. Ultrasonic fish finders, for example, consist of a display unit, an ultrasonic sensor, and other components. They primarily operate based on the principles of ultrasonic wave emission, reflection, and reception. Currently, the application of sonar technology for fish resource assessment is quite common internationally. Using ultrasound as a detection method requires both generating and receiving ultrasonic waves. The device that performs this function is the ultrasonic sensor, commonly referred to as an ultrasonic transducer. When the fish finder is working, the ultrasonic sensor first emits a signal, which propagates in the water. When the emitted signal encounters a medium different from water, such as a solid or gas, a portion of the signal is reflected back. This reflected signal is filtered and then input to the display unit for analysis and processing.

[0003] Currently, various filtering techniques are commonly used to filter the acoustic echoes (reflected signals) emitted by fish finders in order to clearly display the position and shape of underwater objects in the image. These filtering techniques include, for example:

[0004] FPGA chip filtering technology: FPGA chip filtering is currently the most commonly used sonar filtering method. It receives sonar signals through a receiver, filters them, and outputs the filtered sonar signals; however, FPGA chips will increase the cost.

[0005] IIR filtering can reduce the noise floor and improve the signal-to-noise ratio, but because the initial value of the echo data received by sonar is very large, it will cause severe image distortion.

[0006] FIR filtering: The filtered image has better stability and can also improve the signal-to-noise ratio; however, since the initial value of the echo data received by sonar is very large, if there are not many FIR filter stages, the improvement in signal-to-noise ratio by FIR will not be significant; if there are many FIR filter stages, FIR will cause signal distortion; and the delay of FIR filter depends on the length of the filter. A longer FIR filter will introduce a longer delay, which may cause unacceptable delay for some real-time applications.

[0007] In summary, none of the filtering techniques currently used can effectively identify weak or small signals reflected back from objects by the ultrasonic sensors emitted by fish finders without increasing hardware costs. This results in low sensitivity of fish finders, making them unsuitable for various scenarios requiring high sensitivity. Summary of the Invention

[0008] The embodiments of the present invention provide a method for processing echo signals from a fish finder, a fish finder, and a storage medium, so as to identify weak signals of sound waves emitted by the fish finder probe reflected back by an object, thereby improving the sensitivity of the fish finder.

[0009] To achieve the above objectives, on the one hand, a method for processing echo signals from a fish finder is provided, wherein the fish finder includes an ultrasonic sensor, characterized in that it includes:

[0010] S1, receive echo signals from the ultrasonic sensor;

[0011] S2, perform envelope processing on the echo signal to obtain the envelope signal of the echo signal;

[0012] S3, calculate the variance of the data within the sliding window in the envelope signal according to the selected sliding window size, until a signal segment with a variance value less than a predetermined variance threshold is found;

[0013] S4, determine the noise floor value of the envelope signal based on the average value of the signal amplitude of the found signal segment;

[0014] S5, determine the starting position of the weak signal data segment based on the location of the signal point with a signal amplitude less than the noise floor value, and the signal after the starting position belongs to the weak signal data segment;

[0015] S6, perform partial filtering on the envelope signal to obtain the image signal to be displayed, wherein the partial filtering includes: performing IIR filtering or FIR filtering on the weak signal data segment in the envelope signal; and maintaining the original value of the signal segments in the envelope signal other than the weak signal data segment.

[0016] Preferably, in the processing method, step S4 includes:

[0017] The noise floor value is set as a predetermined multiple of the average signal amplitude of all signal points in the found signal segment.

[0018] Preferably, in the processing method, the predetermined multiple is 3 to 5 times.

[0019] Preferably, in the processing method, step S5 includes:

[0020] A first signal point with a signal amplitude less than the noise floor value is determined. If a predetermined number of signal points with signal amplitudes less than the noise floor value appear consecutively after the first signal point, the position where the first signal point appears is determined as the starting position of the weak signal data segment.

[0021] Preferably, in the processing method, the predetermined number is greater than or equal to 19.

[0022] Preferably, in the processing method, the step of enveloping the echo signal in step S2 includes:

[0023] S21, traverse all signal points of the echo signal, and determine whether the first signal amplitude of the current signal point is greater than or equal to the second signal amplitude of the previous signal point; if so, set the signal amplitude of the current signal point to the first signal amplitude; otherwise, proceed to step S22.

[0024] S22, determine whether the amplitude of the first signal is greater than or equal to a predetermined percentage of the initial peak value of the echo signal; if so, set the amplitude of the signal at the current signal point to be the second signal amplitude multiplied by a first proportional coefficient; otherwise, set the amplitude of the signal at the current signal point to be the second signal amplitude multiplied by a second proportional coefficient; wherein, both the first proportional coefficient and the second proportional coefficient are less than 1, and the first proportional coefficient is greater than the second proportional coefficient.

[0025] Preferably, in the processing method, the predetermined percentage is 20%, the first proportionality coefficient is 19 / 20, and the second proportionality coefficient is 1 / 2.

[0026] Preferably, the processing method further includes a step of detecting the estimated background noise value of the fish finder during the commissioning phase of the fish finder, including:

[0027] Without using an ultrasonic sensor, the echo signal received by the fish finder adjusted to a predetermined range is divided into 4 signal segments, and the average signal amplitude of the 3rd signal segment is calculated.

[0028] The estimated noise floor value is determined based on a predetermined multiple of the average signal amplitude of the third signal segment.

[0029] On the other hand, a fish finder is provided, including an ultrasonic sensor, a memory, and a processor, the memory storing at least one program, which is executed by the processor to implement any of the processing methods described above.

[0030] In another aspect, a computer-readable storage medium is provided, wherein at least one program is stored therein, the at least one program being executed by a processor to implement the processing method as described in any of the above descriptions.

[0031] The above technical solution has the following technical effects:

[0032] The technical solution of this invention identifies weak signal data segments, i.e., small signal data segments, and applies IIR or FIR filtering only to the weak signal data segments within the envelope signal of the original echo signal. Data segments outside the weak signal data segments are not subject to IIR or FIR filtering and retain their original values. Thus, the filtered weak signal data segments and the unfiltered data segments or their original values ​​constitute a partially filtered image signal used for display. This filtering of the weak signal data segments reduces the noise floor of these segments, allowing the weak signal to stand out from the mixture of weak and noisy signals, facilitating identification. Simultaneously, it preserves the signal values ​​of the active signals in the non-weak signal data segments, improving the sensitivity of the fish finder. This solution can be fully utilized in sonar systems, reducing reliance on FPGA chips, simplifying the implementation process, and lowering costs. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating a method for processing echo signals from a fish finder according to an embodiment of the present invention. Detailed Implementation

[0034] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments and to explain the operating principles of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0035] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0036] Example 1:

[0037] Figure 1 This is a schematic flowchart illustrating a method for processing echo signals from a fish finder according to an embodiment of the present invention. In this embodiment, the fish finder includes an ultrasonic sensor. Figure 1 The method for processing the echo signal of the fish finder in this embodiment includes the following steps:

[0038] S1, receives echo signals from the ultrasonic sensor;

[0039] S2, perform envelope processing on the echo signal to obtain the envelope signal of the echo signal;

[0040] S3, calculate the variance of the data within the sliding window in the envelope signal according to the selected sliding window size, until a signal segment with a variance value less than a predetermined variance threshold is found;

[0041] Preferably, the sliding window size is selected as 100; preferably, the variance threshold is 0.05.

[0042] The variance of the data within the sliding window can indicate the magnitude and dispersion of the data changes within the sliding window. Generally, a larger variance value means that the data changes more and the dispersion is higher within the sliding window. The waveform of the mixed signal of noise floor and weak signal usually has a lower dispersion, so the signal segment that can be used to determine the noise floor value can be found by analyzing the variance of the signal segment or data segment.

[0043] S4. Determine the noise floor value of the envelope signal based on the average value of the signal amplitude of the found signal segment;

[0044] In one specific implementation, a predetermined multiple of the average signal amplitude of all signal points in the found signal segment is set as the noise floor value; preferably, the predetermined multiple is 3 to 5 times.

[0045] When the selected sliding window size is 100, the average signal amplitude of 100 signal points in the found signal segment is calculated, and the above noise floor value is determined based on the average value.

[0046] S5. Determine the starting position of the weak signal data segment based on the location of the signal point where the signal amplitude is less than the noise floor value. The signal after the starting position belongs to the weak signal data segment.

[0047] In one specific implementation, step S5 includes: determining a first signal point whose signal amplitude is less than the aforementioned noise floor value; if a predetermined number of signal points with signal amplitudes less than the aforementioned noise floor value appear consecutively after the first signal point, then determining the position where the first signal point appears as the starting position of the weak signal data segment; preferably, the predetermined number is greater than or equal to 19; preferably, when 20 consecutive signal points with signal amplitudes less than the noise floor value appear starting from the first signal point, the first signal point is determined as the starting position of the weak signal data segment;

[0048] Since the signal of a signal point received later in the echo signal is weaker, the signal segment consisting of signal points after the starting position in the echo signal can be considered as a weak signal data segment.

[0049] S6, perform partial filtering on the envelope signal to obtain the image signal to be displayed, wherein the partial filtering includes: performing IIR filtering or FIR filtering on the weak signal data segment in the envelope signal; and maintaining the original value of the signal segments in the envelope signal other than the weak signal data segment;

[0050] In this step, only the weak signal data segments within the envelope signal undergo IIR filtering, while the data segments outside the weak signal data segments are not subject to IIR or FIR filtering and retain their original values. Thus, the filtered weak signal data segments and the unfiltered data segments (or their original values) constitute a partially filtered image signal used for display. This processing reduces the noise floor of the weak signal data segments, allowing the weak signal to stand out from the mixture of weak and noisy signals, facilitating identification. Simultaneously, it preserves the signal values ​​of the active signals in the non-weak signal data segments, improving the sensitivity of the fish finder.

[0051] Preferably, when displaying image signals, different colors are mapped to different values ​​to enhance the display effect. Preferably, in embodiments using the present invention, if no suitable noise floor value is found through steps S1 to S4, it indicates that the data dispersion of the echo signal is high and it cannot participate in the filtering operation.

[0052] The embodiments of the present invention can reduce the background noise value and keep the active signal value in the echo signal unchanged through the above steps, thereby improving the signal-to-noise ratio and sensitivity of the fish finder.

[0053] Example 2:

[0054] In this embodiment, the envelope processing of the echo signal in step S2 includes traversing all signal points of the echo signal. When the first signal amplitude of the current signal point is greater than or equal to the second signal amplitude of the previous signal point, the signal amplitude of the current signal point is set to the first signal amplitude. When the first signal amplitude of the current signal point is less than the second signal amplitude of the previous signal point, the signal amplitude of the current signal point is set to the value after a predetermined attenuation coefficient of the second signal amplitude. Preferably, the predetermined attenuation coefficient is 1 / 20, that is, the signal amplitude of the current signal point is set to 19 / 20 of the second signal amplitude.

[0055] Example 3:

[0056] In this embodiment, the envelope processing of the echo signal in step S2 includes:

[0057] S21, traverse all signal points of the echo signal, and determine whether the first signal amplitude of the current signal point is greater than or equal to the second signal amplitude of the previous signal point; if so, set the signal amplitude of the current signal point to the first signal amplitude; otherwise, proceed to step S22.

[0058] S22, determine whether the amplitude of the first signal is greater than or equal to a predetermined percentage of the initial peak value of the echo signal; if so, set the signal amplitude of the current signal point to the maximum value between the signal value obtained by multiplying the second signal amplitude by the first proportional coefficient and the first signal amplitude; otherwise, set the signal amplitude of the current signal point to the minimum value between the signal value obtained by multiplying the second signal amplitude by the second proportional coefficient and the first signal amplitude; wherein, both the first proportional coefficient and the second proportional coefficient are less than 1, and the first proportional coefficient is greater than the second proportional coefficient. The first proportional coefficient being greater than the second proportional coefficient means that, compared with the case where the first signal amplitude is greater than or equal to the predetermined percentage of the initial peak value of the echo signal, when the first signal amplitude is less than the predetermined percentage of the initial peak value of the echo signal, the signal decreases faster.

[0059] Preferably, the predetermined percentage is preset according to the range of the fish finder. Preferably, the predetermined percentage is 20% when the range is 0 to 80 meters; 15% when the range is 80 to 150 meters; 10% when the range is 150 to 300 meters; and 5% when the range is 300 to 800 meters.

[0060] Preferably, the specific selection of the first and second proportional coefficients is determined based on the desired signal descent rate; the value of the first proportional coefficient ranges from 1 / 2 to 99 / 100, with a larger value resulting in a slower signal descent; the value of the second proportional coefficient ranges from 1 / 100 to 1 / 2, with a smaller value resulting in a faster signal descent. Preferably, the first proportional coefficient is 19 / 20, and the second proportional coefficient is 1 / 2.

[0061] Generally, the peak of the initial wave in an echo signal is the strongest signal point in the entire echo signal, and this value usually does not change. The aforementioned determination of whether the amplitude of the first signal is greater than or equal to a predetermined percentage of the peak value of the initial wave of the echo signal is used to determine whether the descent rate of the echo signal is accelerating. If the conventional envelope processing steps in Embodiment 2 are used, for example, continuously using the signal value of the previous signal point attenuated by 1 / 20, the problem of small signals being filtered into large signals may occur. The envelope processing steps of this embodiment use different proportional coefficients to perform different attenuation processes based on the descent rate of the echo signal to obtain the corresponding envelope signal.

[0062] Using a first scaling factor, such as 19 / 20, can ensure the peak trend of the echo signal without waveform jitter. Using a second scaling factor, such as 1 / 2, can ensure that if there is a whole segment of small signal, i.e. weak signal, in the original echo signal, the weak signal can appear faster through envelope processing, instead of being delayed due to envelope filtering.

[0063] The first and second proportional coefficients mentioned above are preferred values. Depending on the actual application scenario, under the premise of ensuring the peak trend of the echo signal without waveform jitter and ensuring that weak signals are not delayed due to envelope filtering, other appropriate proportional coefficients can be selected in the envelope processing to appropriately attenuate the echo signal to obtain the envelope signal.

[0064] Example 4:

[0065] The method for processing the echo signal of the fish finder in this embodiment of the invention further includes a step of detecting the estimated noise floor value of the fish finder during the debugging phase of the fish finder, including:

[0066] Without using an ultrasonic sensor, the echo signal received by the fish finder adjusted to a predetermined range is divided into four signal segments, and the average signal amplitude of the third signal segment is calculated; preferably, the predetermined range is 300 meters.

[0067] The estimated noise level of the fish finder is determined by a predetermined multiple of the average signal amplitude of the third signal segment.

[0068] In step S4, which determines the noise floor value of the envelope signal based on the average value of the signal amplitude of the found signal segment, the estimated noise floor value can be referenced. For example, the estimated noise floor value can be referenced to determine how many times the average value of the signal amplitude of all signal points in the found signal segment should be set as the noise floor value.

[0069] Example 5:

[0070] The present invention also provides a fish finder, which includes an ultrasonic sensor, a processor, a memory, and a computer program stored in the memory and executable on the processor. The processor includes one or more processing cores, and the memory is connected to the processor and is used to store program instructions. When the processor executes the program, it implements the steps in the processing method of the above embodiments of the present invention.

[0071] Furthermore, as an executable solution, the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc. The processor is the control center of the computer unit, connecting various parts of the entire computer unit via various interfaces and lines.

[0072] The memory can be used to store the computer programs and / or modules. The processor implements various functions of the computer unit by running or executing the computer programs and / or modules stored in the memory and by calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a function; the data storage area may store data created based on the use of the mobile phone, etc. In addition, the memory may include high-speed random access memory and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0073] Example 6:

[0074] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the processing method described above in the embodiments of the present invention.

[0075] If the modules / units integrated in the computer unit are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), and software distribution media, etc. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0076] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A method for processing echo signals from a fish finder, the fish finder comprising an ultrasonic sensor, characterized in that, include: S1, receive echo signals from the ultrasonic sensor; S2, perform envelope processing on the echo signal to obtain the envelope signal of the echo signal; S3, calculate the variance of the data within the sliding window in the envelope signal according to the selected sliding window size, until a signal segment with a variance value less than a predetermined variance threshold is found; S4, determine the noise floor value of the envelope signal based on the average value of the signal amplitude of the found signal segment; S5, determine the starting position of the weak signal data segment based on the location of the signal point with a signal amplitude less than the noise floor value, and the signal after the starting position belongs to the weak signal data segment; S6, perform partial filtering on the envelope signal to obtain the image signal to be displayed, wherein the partial filtering includes: The weak signal data segment in the envelope signal is subjected to IIR filtering or FIR filtering; and the signal segments in the envelope signal other than the weak signal data segment are kept at their original values.

2. The processing method according to claim 1, characterized in that, Step S4 includes: The noise floor value is set as a predetermined multiple of the average signal amplitude of all signal points in the found signal segment.

3. The processing method according to claim 2, characterized in that, The predetermined multiple is 3 to 5 times.

4. The processing method according to claim 1, characterized in that, Step S5 includes: A first signal point with a signal amplitude less than the noise floor value is determined. If a predetermined number of signal points with signal amplitudes less than the noise floor value appear consecutively after the first signal point, the position where the first signal point appears is determined as the starting position of the weak signal data segment.

5. The processing method according to claim 4, characterized in that, The predetermined number is greater than or equal to 19.

6. The processing method according to claim 1, characterized in that, The step of envelope processing of the echo signal in step S2 includes: S21, traverse all signal points of the echo signal, and determine whether the first signal amplitude of the current signal point is greater than or equal to the second signal amplitude of the previous signal point; if so, set the signal amplitude of the current signal point to the first signal amplitude; otherwise, proceed to step S22. S22, determine whether the amplitude of the first signal is greater than or equal to a predetermined percentage of the initial peak value of the echo signal; if so, set the amplitude of the signal at the current signal point to the maximum value between the signal value obtained by multiplying the amplitude of the second signal by the first proportional coefficient and the amplitude of the first signal; otherwise, set the amplitude of the signal at the current signal point to the minimum value between the signal value obtained by multiplying the amplitude of the second signal by the second proportional coefficient and the amplitude of the first signal; wherein, both the first proportional coefficient and the second proportional coefficient are less than 1, and the first proportional coefficient is greater than the second proportional coefficient.

7. The processing method according to claim 6, characterized in that, The predetermined percentage is preset according to the range of the fish finder, and the value range of the predetermined percentage is 5% to 20%; the value range of the first proportional coefficient is 1 / 2 to 99 / 100, and the value range of the second proportional coefficient is 1 / 100 to 1 / 2.

8. The processing method according to claim 1, characterized in that, It also includes a step of detecting the estimated background noise value of the fish finder during the commissioning phase of the fish finder, including: Without using an ultrasonic sensor, the echo signal received by the fish finder adjusted to a predetermined range is divided into 4 signal segments, and the average signal amplitude of the 3rd signal segment is calculated. The estimated noise floor value is determined based on a predetermined multiple of the average signal amplitude of the third signal segment.

9. A fish finder, comprising an ultrasonic sensor, characterized in that, It also includes a memory and a processor, the memory storing at least one program, the at least one program being executed by the processor to implement the processing method as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The storage medium stores at least one program segment, which is executed by a processor to implement the processing method as described in any one of claims 1 to 8.

Images