A sonar noise suppression method and system

Abstract

The present application relates to the field of sonar, specifically to a sonar noise suppression method and system, the method comprising: step 1: obtaining a sonar signal and a noise reference signal; step 2: performing noise suppression processing on the noise signal in the sonar signal according to the noise reference signal to obtain a target sonar signal; step 3: performing image conversion processing on the target sonar signal to obtain a target sonar image. The present application implements efficient noise suppression processing on the sonar signal by accurately capturing the common-mode noise generated during the sonar operation. This is intended to significantly reduce the interference of common-mode noise on the sonar signal, effectively curb the generation of the center bright line, thereby greatly improving the clarity and quality of the target sonar image, and further enhancing the target detection capability. In this process, the original signal characteristics are fully retained and the loss of effective information is avoided.

Description

Technical Field

[0001] The present application relates to the field of sonar, and in particular to a sonar noise suppression method and a sonar noise suppression system. Background Art

[0002] Sonar is a highly advanced underwater acoustic imaging technology device that efficiently receives and analyzes sound wave information through a series of carefully arranged probe arrays, thereby accurately constructing a two-dimensional image of the underwater environment. With its simple structural design, relatively low cost-effectiveness, and excellent performance, sonar has shown a wide range of application potential and significant practical value in many fields such as accurate detection of underwater targets and in-depth exploration of marine resources.

[0003] When the sonar probe performs sampling tasks, it will inevitably generate a kind of in-phase and highly correlated noise, which we call common mode noise. The sources of this noise are wide-ranging, covering many aspects such as interference from the electrical system, vibration of the mechanical system, influence of the external environment, and errors in the signal processing process. It is worth noting that common mode noise has significant similarities in characteristics with the sound wave signal arriving directly from the front, which makes them difficult to distinguish easily. Figure 1 As shown in the figure, when these signals containing common mode noise are processed by the imaging algorithm, a specific phenomenon will appear in the sonar image: an extremely eye-catching bright line located in the center of the image. This central bright line is caused by common mode coherent noise, and its existence greatly damages the clarity of the sonar image. Specifically, this bright line will cover up the target objects that should have been clearly detected in front, causing these targets to become blurred in the image. This interference effect of common mode noise seriously weakens the sonar system's effective detection capability of the target in front.

[0004] At present, the commonly used methods for eliminating common mode noise mainly include digital filtering and hardware optimization. The digital filtering method aims to effectively suppress the central bright line in the sonar image by carefully designing a specific digital filter. However, a significant drawback of this method is that while suppressing noise, it may also unfortunately filter out some useful sound wave signals, thus affecting the integrity and accuracy of the information to a certain extent.

[0005] On the other hand, the hardware optimization method focuses on fundamentally reducing the generation of common-mode noise by improving and optimizing the design of the hardware system. Although this method can theoretically reduce the noise level more effectively, its high cost has become a major obstacle to its widespread application. In addition, even with the most advanced hardware design, it is often difficult to completely eliminate the problems caused by common-mode noise, especially in complex and changeable underwater environments. Summary of the invention

[0006] In view of this, the purpose of this application is to provide a sonar noise suppression method and a sonar noise suppression system for a sonar system to solve the above problems.

[0007] In order to solve the above technical problems, this application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a noise suppression method for a sonar system, which is applied to a sonar system. The sonar system includes: a sonar transmitting device, a first sonar receiving device and a second sonar receiving device. The first sonar receiving device collects a sonar signal transmitted by the sonar transmitting device, and the second sonar receiving device collects a noise reference signal generated when the second sonar receiving device works. The sonar noise suppression method includes: step 1: acquiring a sonar signal and a noise reference signal; step 2: performing noise suppression processing on a noise signal in the sonar signal according to the noise reference signal to obtain a target sonar signal; step 3: performing image conversion processing on the target sonar signal to obtain a target sonar image.

[0009] Furthermore, step 1 specifically includes: performing parallel sampling processing on the first sonar receiving device and the second sonar receiving device to obtain the sonar signal and the noise reference signal.

[0010] Furthermore, step 2 specifically includes: step A1: performing signal amplification processing on the noise reference signal and the sonar signal respectively to obtain a first noise reference amplified signal and a first sonar amplified signal; step A2: performing analog signal subtraction processing on the first noise reference amplified signal and the first sonar amplified signal to obtain a first analog sonar signal; step A3: converting the first analog sonar signal into a digital signal to obtain a target sonar signal.

[0011] Furthermore, step 2 specifically includes: step B1: performing signal amplification processing on the noise reference signal and the sonar signal respectively to obtain a second noise reference amplified signal and a second sonar amplified signal; step B2: converting the second noise reference amplified signal and the second sonar amplified signal into digital signals respectively to obtain a second noise reference digital signal and a second sonar digital signal; step B3: performing digital signal subtraction processing on the second noise reference digital signal and the second sonar digital signal to obtain a target sonar signal.

[0012] Furthermore, step 2 specifically includes: step C1: performing subtraction processing on the noise reference signal and the sonar signal to obtain a third sonar signal; step C2: performing signal amplification processing on the third sonar signal to obtain a third sonar amplified signal; step C3: converting the third sonar amplified signal into a digital signal to obtain a target sonar signal.

[0013] In a second aspect, the present application provides a sonar noise suppression system, comprising: a sonar transmitting device for transmitting a sonar signal; a first sonar receiving device for collecting sonar signals; a second sonar receiving device, comprising a noise sampling probe assembly, the noise sampling probe assembly being used to collect a noise reference signal generated when the sonar receiving device is working; a noise suppression device, comprising an acquisition module, a first processing module and a second processing module, the acquisition module being used to acquire the sonar signal and the noise reference signal; the first processing module being used to perform noise suppression processing on the noise signal in the sonar signal according to the noise reference signal to obtain a target sonar signal; and the second processing module being used to perform image conversion processing on the target sonar signal to obtain a target sonar image.

[0014] Further, the noise sampling probe assembly is a blind probe assembly and / or a zero signal channel assembly.

[0015] Furthermore, the blind probe assembly includes: a transducer, which is arranged near the first sonar receiving device, and the transducer has the same electrical characteristics as the first sonar receiving device; a signal shielding shell, which is arranged on the outer surface of the transducer and is used to shield the transducer from receiving sonar signals.

[0016] Furthermore, the zero signal channel component includes: a wire, which is short-circuited to both ends of the sampling signal circuit input of the second sonar receiving device, and is used to obtain a noise reference signal related to the first sonar receiving device.

[0017] Furthermore, the first sonar receiving device includes a plurality of linearly arranged piezoelectric transducer elements, the operating frequency range of the piezoelectric transducer elements is 900kHz-1200kHz, the spacing between the piezoelectric transducer elements is λ / 2, and λ is the wavelength corresponding to the sonar operating frequency.

[0018] It can be seen from the above technical solutions that the advantages and positive effects of the sonar noise suppression method and sonar noise suppression system proposed in this application are:

[0019] This application aims to accurately capture the common mode noise generated during sonar operation, and then implement efficient noise suppression processing on the sonar signal. This is intended to significantly reduce the interference of common mode noise on the sonar signal, effectively curb the generation of the center bright line, thereby greatly improving the clarity and quality of the target sonar image, and further enhancing the target detection capability. In this process, the original signal characteristics are fully preserved and the loss of effective information is avoided.

[0020] In addition, this solution also performs well in reducing system complexity. It does not rely on complex digital signal processing algorithms, but only requires simple subtraction operations to easily eliminate noise, greatly reducing the use of computing resources. From an economic perspective, its hardware structure design is simple and clear, easy to implement, not only with low computing resource consumption, but also significantly reducing the overall cost of the system.

[0021] In terms of reliability, this application also performs well, with low maintenance costs, excellent real-time processing performance, and minimal processing delay, which is very suitable for real-time image display to ensure that the system can respond quickly. In summary, this application is not only technologically advanced, but also shows significant advantages in terms of economy, reliability and real-time performance, bringing a new solution to the field of sonar signal processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above content of the present application and the following specific implementation methods will be better understood when read in conjunction with the accompanying drawings. It should be noted that the accompanying drawings are only examples of the technical solutions claimed for protection.

[0023] Figure 1 This is a schematic diagram of the bright line in the center of the sonar image caused by common mode noise;

[0024] Figure 2 is a structural diagram of the sonar noise suppression system provided by the present application;

[0025] Figure 3 is a flow chart of the sonar noise suppression method provided by the present application;

[0026] Figure 4 This is a flow chart of the first implementation method of acquiring a target sonar signal of the present application;

[0027] Figure 5 It is a flow chart of a second implementation method of acquiring a target sonar signal of the present application;

[0028] Figure 6 is a flowchart of a third implementation method of acquiring a target sonar signal in the present application;

[0029] Figure 7 It is the target sonar image provided by this application.

[0030] The reference numerals are described as follows:

[0031] Sonar transmitter: 10;

[0032] First sonar receiving device: 20;

[0033] Second sonar receiving device: 30;

[0034] Noise suppression device:40. DETAILED DESCRIPTION

[0035] The detailed features and advantages of the present application are described in detail in the specific implementation manner below, and the content is sufficient to enable any technical personnel in this field to understand the technical content of the present application and implement it accordingly. According to the description, claims and drawings disclosed in this specification, the technical personnel in this field can easily understand the relevant purposes and advantages of the present application.

[0036] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0037] In the description of this embodiment, it should be noted that the terms "upper", "lower", "inner", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product is usually placed when in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0038] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0039] Please refer to Figure 2 As shown, the present application provides a sonar noise suppression system, which includes a sonar transmitting device 10, a first sonar receiving device 20, a second sonar receiving device 30 and a noise suppression device 40. The sonar transmitting device 10 is used to transmit sonar signals. It can be understood that the sonar transmitting device 10 is a component in the sonar system that is responsible for generating electrical signals and stimulating the transducer to convert these electrical signals into sound signals and transmit them into the water. The working principle of the sonar transmitting device 10 is based on the propagation characteristics of sound waves in water. When the sonar transmitting device 10 transmits sound waves, these sound waves will propagate in the water and be reflected back when encountering underwater objects to form echoes.

[0040] The first sonar receiving device 20 includes 72 linearly arranged transducer elements (also called main probes) for receiving underwater acoustic signals. The spacing between each piezoelectric transducer element is λ / 2 (λ is the wavelength corresponding to the sonar operating frequency), and the operating frequency range is 900kHz-1200kHz. During operation, the first sonar receiving device 20 collects the sonar signals of these echoes and converts them into electrical signals for processing, thereby determining the position and distance of underwater objects. However, at the same time, the common mode noise generated by the first sonar receiving device 20 itself will also affect the sonar signal.

[0041] The second sonar receiving device 30 may specifically be a blind probe component or a zero signal channel component, or a combination of a blind probe component and a zero signal channel component.

[0042] Specifically, the blind probe assembly includes: a transducer, a signal shielding housing, and a mounting bracket. The transducer has the same electrical and mechanical characteristics as the first sonar receiving device 20. The signal shielding housing is made of an acoustic shielding material and is disposed on the outer surface of the transducer to enable the transducer to receive only common mode noise signals and shield the sonar signal. The mounting bracket fixes the transducer of the second sonar receiving device 30 near the first sonar receiving device 20.

[0043] It can be understood that the electrical characteristics and mechanical characteristics of the transducer in the blind probe assembly are the same as those of the transducer in the first sonar receiving device 20. The difference is that the transducer in the blind probe assembly has been acoustically shielded, which can effectively capture various common mode noises in the system, including mechanical resonance coupling, external mechanical vibration, and common mode noise introduced by the transducer conditioning circuit, and cannot or is difficult to receive sonar signals in the environment.

[0044] The zero signal channel component includes a wire. The wire is short-circuited to both ends of the sampling signal circuit input of the second sonar receiving device 30. The sampling signal circuit of the second sonar receiving device 30 is the same as that of the first sonar receiving device 20. Therefore, the noise reference signal related to the first sonar receiving device 20 can be directly obtained by short-circuiting the wire.

[0045] It can be understood that compared with the blind probe assembly, the zero signal channel assembly has a simpler mechanical structure and can obtain the common mode noise signal introduced by the transducer conditioning circuit associated with the first sonar receiving device 20 without the need for actual transducers and acoustic isolation measures.

[0046] The noise suppression device 40 includes an acquisition module, a first processing module, and a second processing module. The acquisition module is used to acquire a sonar signal and a noise reference signal, the first processing module is used to perform noise suppression processing on the noise signal in the sonar signal according to the noise reference signal to obtain a target sonar signal, and the second processing module is used to perform image conversion processing on the target sonar signal to obtain a target sonar image.

[0047] For the convenience of explanation, the second sonar receiving device 30 described below is a blind probe component, and a zero signal channel component may also be applicable to this method, but the present application is not limited thereto.

[0048] Please refer to Figure 3 Based on the above sonar noise suppression system, the present application also provides a sonar noise suppression method, which is applied to the sonar system, and the specific steps are:

[0049] Step 1: Acquire the sonar signal of the first sonar receiving device and the noise reference signal of the second sonar receiving device.

[0050] Specifically, the first sonar receiving device and the second sonar receiving device are subjected to parallel sampling processing to obtain the sonar signal and the noise reference signal, so as to ensure signal synchronization between the sonar signal and the noise reference signal.

[0051] Step 2: Perform noise suppression processing on the noise signal in the sonar signal according to the noise reference signal to obtain the target sonar signal.

[0052] like Figure 4 In the first embodiment of the present application shown, step 2 may include: step A1: amplifying the noise reference signal and the sonar signal respectively to obtain a first noise reference amplified signal and a first sonar amplified signal. Step A2: performing analog signal subtraction processing on the first noise reference amplified signal and the first sonar amplified signal to obtain a first analog sonar signal; step A3: converting the first analog sonar signal into a digital signal to obtain a target sonar signal.

[0053] In step A1, the amplification signal processing of the noise reference signal and the sonar signal can adopt the same amplification circuit architecture. Specifically, the amplification circuit architecture adopts a low-noise preamplifier with a fixed gain of 30dB in the first stage amplification, and a variable gain amplifier with a gain range of 0-30dB in the second stage amplification. Preferably, a precision operational amplifier is used to ensure that the gain matching is better than 0.1dB.

[0054] In step A2, a high-precision differential amplifier is used to perform analog signal subtraction processing. The differential amplifier is designed with low offset voltage, a common mode rejection ratio better than 80dB, a bandwidth covering the entire operating frequency range, and an output stage providing adjustable gain in the range of 0-20dB.

[0055] In step A3, the analog signal is converted into a digital signal by sampling with a single 16-bit ADC (Analog to Digital Converter) at a sampling rate of 2MHz, DMA (Direct Memory Access) data transmission, and FPGA (Field Programmable Gate Array) to implement digital signal preprocessing.

[0056] It can be understood that the advantage of this embodiment is that it can suppress the common mode noise introduced by the signal amplification link, and at the same time only requires the ADC channel of the main probe of the first sonar receiving device.

[0057] like Figure 5In the second embodiment of the present application shown, step 2 may specifically include: step B1: amplifying the noise reference signal and the sonar signal respectively to obtain a second noise reference amplified signal and a second sonar amplified signal. step B2: converting the second noise reference amplified signal and the second sonar amplified signal into digital signals respectively to obtain a second noise reference digital signal and a second sonar digital signal. step B3: performing digital signal subtraction processing on the second noise reference digital signal and the second sonar digital signal to obtain a target sonar signal.

[0058] In step B1, the noise reference signal and the sonar signal correspond to two signal channels respectively. Both signal channels adopt a two-stage amplification architecture. The first stage of the amplification architecture adopts a variable gain amplifier (VGA) with a gain range of 0-40dB for dynamic range adjustment. The second stage of the amplification architecture adopts a fixed gain amplifier with a gain of 20dB to ensure that the signal amplitude meets the ADC input requirements. After the signal is amplified, a bandpass filter can also be used for anti-aliasing filtering with a passband range of 800kHz-1300kHz.

[0059] In step B2, the second noise reference amplified signal and the second sonar amplified signal are analog signals. A 16-bit high-precision ADC can be used to convert the analog signals of the two into digital signals. The sampling rate is set to 2MHz to meet the Nyquist sampling theorem. The two signals are sampled synchronously to ensure phase consistency. DMA is used to transmit data to reduce CPU load.

[0060] In step B3, real-time digital signal subtraction processing can be implemented in FPGA, and a digital fixed-point operation unit is designed to ensure calculation accuracy. FPGA supports programmable digital gain adjustment, and data cache management can be implemented to ensure data synchronization.

[0061] It can be understood that the advantage of this embodiment is that it can suppress the common mode noise introduced by all links including signal amplification and conditioning circuits, and the system noise suppression effect is good.

[0062] like Figure 6 In the third embodiment of the present application shown, step 2 may specifically include: step C1: performing subtraction processing on the noise reference signal and the sonar signal to obtain a third sonar signal. step C2: performing signal amplification processing on the third sonar signal to obtain a third sonar amplified signal. step C3: converting the third sonar amplified signal into a digital signal to obtain a target sonar signal.

[0063] In step C1, a differential amplifier can be used to perform subtraction processing on the noise reference signal and the sonar signal. The input stage gain of the differential amplifier is set to 1:1, and the differential output gain is adjustable, with a typical value of 20 dB. It should be noted that the differential amplifier is set to a suitable common mode level to ensure that the signal is in the linear region.

[0064] In step C2, the signal amplification process may adopt a two-stage amplification circuit, wherein the first stage is a variable gain amplifier with a gain range of 0-40dB, and the second stage is a fixed gain amplifier with a gain of 20dB and an output signal swing range of ±5V.

[0065] In step C3, the analog signal of the third sonar amplified signal is converted into a digital signal by using an ADC sampling resolution of 16 bits and a sampling rate of 2 MHz, using DMA to transmit data, and FPGA to implement digital signal preprocessing.

[0066] It can be understood that this embodiment can suppress the mechanical resonance coupling between the main probes of the first sonar receiving device, the external mechanical vibration effect and the common mode noise introduced by the transducer conditioning circuit. Its advantage is that there is no need to add additional signal amplification and digital-to-analog conversion circuits of the blind probe, the system structure is simple, the cost is low, and the reliability is high.

[0067] In this application, users can make a trade-off between system complexity, cost and performance according to the requirements of specific application scenarios and choose the most suitable technical solution. For example, for cost-sensitive applications, the third implementation method can be selected, and for occasions with higher performance requirements, the second implementation method can be selected; while the first implementation method provides a better balance between performance and cost.

[0068] Step 3: Perform image conversion processing on the target sonar signal to obtain the target sonar image.

[0069] Specifically, a real-time processing architecture can be used to convert the target sonar signal into an image, so as to ensure that the target sonar image finally obtained has good timeliness and continuity.

[0070] like Figure 7 As shown, the target sonar signals are integrated, and the integrated data are presented as images on a display device (eg, a display screen) using image processing technology.

[0071] It should be noted that the main core purpose of this application is to accurately capture the common mode noise generated during the sonar operation process, and based on this, implement efficient noise suppression processing on the sonar signal, aiming to significantly weaken the interference effect of common mode noise on the sonar signal, and effectively suppress the occurrence of the center bright line phenomenon, thereby significantly improving the clarity and overall quality of the target sonar image, and further enhancing the system's target detection capability.

[0072] The terms and expressions used herein are for descriptive purposes only and the present application should not be limited to these terms and expressions. The use of these terms and expressions does not mean to exclude any equivalent features of the illustrations and descriptions (or parts thereof), and it should be recognized that various modifications that may exist should also be included in the scope of the claims. Other modifications, variations and substitutions may also exist. Accordingly, the claims should be deemed to cover all such equivalents.

[0073] Similarly, it should be pointed out that although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should realize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions may be made without departing from the spirit of the invention. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A sonar noise suppression method, applied to a sonar system, characterized in that: The sonar system comprises: a sonar transmitting device, a first sonar receiving device and a second sonar receiving device, wherein the first sonar receiving device collects the sonar signal transmitted by the sonar transmitting device, and the second sonar receiving device collects the noise reference signal generated when the second sonar receiving device works. The sonar noise suppression method comprises: Step 1: Acquire the sonar signal and the noise reference signal; Step 2: performing noise suppression processing on the noise signal in the sonar signal according to the noise reference signal to obtain a target sonar signal; Step 3: Perform image conversion processing on the target sonar signal to obtain a target sonar image.

2. The sonar noise suppression method according to claim 1, characterized in that: The step 1 specifically includes: performing parallel sampling processing on the first sonar receiving device and the second sonar receiving device to obtain the sonar signal and the noise reference signal.

3. The sonar noise suppression method according to claim 1, characterized in that: The step 2 specifically includes: Step A1: performing signal amplification processing on the noise reference signal and the sonar signal respectively to obtain a first noise reference amplified signal and a first sonar amplified signal; Step A2: performing analog signal subtraction processing on the first noise reference amplified signal and the first sonar amplified signal to obtain a first analog sonar signal; Step A3: Convert the first analog sonar signal into a digital signal to obtain the target sonar signal.

4. The sonar noise suppression method according to claim 1, characterized in that: The step 2 specifically includes: Step B1: performing signal amplification processing on the noise reference signal and the sonar signal respectively to obtain a second noise reference amplified signal and a second sonar amplified signal; Step B2: converting the second noise reference amplified signal and the second sonar amplified signal into digital signals respectively to obtain a second noise reference digital signal and a second sonar digital signal; Step B3: performing digital signal subtraction processing on the second noise reference digital signal and the second sonar digital signal to obtain the target sonar signal.

5. The sonar noise suppression method according to claim 1, characterized in that: The step 2 specifically includes: Step C1: performing a subtraction operation on the noise reference signal and the sonar signal to obtain a third sonar signal; Step C2: amplifying the third sonar signal to obtain a third sonar amplified signal; Step C3: converting the third sonar amplified signal into a digital signal to obtain the target sonar signal.

6. A sonar noise suppression system, characterized in that: include: A sonar transmitting device, used for transmitting sonar signals; A first sonar receiving device, used for collecting the sonar signal; The second sonar receiving device includes a noise sampling probe assembly, wherein the noise sampling probe assembly is used to collect a noise reference signal generated when the noise sampling probe assembly is working; The noise suppression device comprises an acquisition module, a first processing module and a second processing module, wherein the acquisition module is used to acquire the sonar signal and the noise reference signal; the first processing module is used to perform noise suppression processing on the noise signal in the sonar signal according to the noise reference signal to obtain a target sonar signal; and the second processing module is used to perform image conversion processing on the target sonar signal to obtain a target sonar image.

7. The sonar noise suppression system according to claim 6, characterized in that: The noise sampling probe assembly is a blind probe assembly and / or a zero signal channel assembly.

8. The sonar noise suppression system according to claim 7, characterized in that: The blind probe assembly comprises: a transducer, the transducer being disposed near the first sonar receiving device, the transducer having the same electrical characteristics as the first sonar receiving device; A signal shielding shell is arranged on the outer surface of the transducer and is used to shield the transducer from receiving the sonar signal.

9. The sonar noise suppression system according to claim 7, characterized in that: The zero signal channel component comprises: A wire is short-circuited to two ends of a sampling signal circuit input of the second sonar receiving device, and is used to obtain a noise reference signal related to the first sonar receiving device.

10. The sonar noise suppression system according to claim 6, characterized in that: The first sonar receiving device includes a plurality of linearly arranged piezoelectric transducer elements, the operating frequency range of the piezoelectric transducer elements is 900kHz-1200kHz, the spacing between the piezoelectric transducer elements is λ / 2, and λ is the wavelength corresponding to the sonar operating frequency.

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