A multi-band three-dimensional buried object detection sonar device and method

Abstract

The present invention discloses a multi-band three-dimensional buried object detection sonar device and method, which relates to the field of underwater acoustic imaging application technology. The present invention includes a sonar system, which includes a transducer module, a wet-end electronic module and a dry-end equipment module; the transducer module includes a plurality of transmitting arrays and a receiving array, the receiving array includes a plurality of receiving transducers, and the plurality of receiving transducers and the plurality of transmitting transducers are staggered in array distribution to form an array design, the wet-end electronic module includes a control center, a transmitter and a receiver, the control center is communicatively connected with the dry-end equipment module, and the dry-end equipment module includes a signal processor, which is used to process the data fed back by the control center to complete the three-dimensional imaging of the underwater three-dimensional scene. The present invention is a multi-band three-dimensional buried object detection sonar device and method, which has the advantage of good detection and imaging effect.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater acoustic imaging applications, and in particular to a multi-band three-dimensional buried object detection sonar device and method. Background Art

[0002] Sonar is a device that uses the principle of echo sounding to detect underwater environments and underwater objects. Traditional multi-beam sonar or synthetic aperture sonar uses signal processing methods such as beamforming to image and detect seabed objects and landforms by emitting sound waves and collecting target echoes.

[0003] Traditional multi-beam and synthetic aperture sonars mostly use the technology of sending multiple signals at once. Even if broadband signal technology is used, the frequency of traditional sonar is relatively single, which limits the use environment of sonar. Specifically, high-frequency sound waves have a short wavelength and relatively high resolution, but they have large absorption and attenuation in water, short transmission distance, and no ability to penetrate the seabed. Low-frequency sound waves have a longer wavelength and less absorption and attenuation in water, so they have a longer transmission distance and have the ability to penetrate the seabed, but their long wavelength determines that it is generally difficult to achieve a high level of resolution, and traditional sonars work at a single frequency, and the signal bandwidth utilization is insufficient.

[0004] The existing downward-looking sonar will produce a strong echo directly below. On the one hand, the short sound path leads to a small propagation loss of the sound wave directly below. On the other hand, the small incident and reflection angles lead to a small energy loss. When the seabed is relatively smooth, the wavelength of the sound wave is equal to or less than the seabed undulation. The seabed is a "mirror" relative to the sound wave. At this time, the echo of the seabed directly below will be stronger. The strong echo directly below is a kind of interference for target identification, and because of its strong energy, it is very unfavorable for bottom tracking, target identification, etc. In the end, the sonar wavelength is long, and the mirror reflection directly below has a greater impact, which is easy to cause the increase of the false alarm rate of target identification. The size of general sonar is negatively correlated with the frequency. The lower the frequency, the larger the array is usually to obtain sufficient resolution. At the same time, after installing other types of sensors, electronic systems and other equipment, in order to ensure that the wet-end equipment has a certain strength and streamlined design, the overall equipment size will be greatly increased, and the weight will also be greatly increased, which brings great inconvenience to the installation, transportation, deployment and recovery of the equipment.

[0005] The existing buried object detection sonar has insufficient signal bandwidth utilization and a long sonar wavelength, which causes a greater impact from the mirror reflection directly below. Traditional low-frequency sonar is large in size and heavy in weight, and is inconvenient to install and deploy. Therefore, we propose a multi-band three-dimensional buried object detection sonar device and method. Summary of the invention

[0006] The main purpose of the present invention is to provide a multi-band three-dimensional buried object detection sonar device and method, which can effectively solve the problems in the background technology of insufficient signal bandwidth utilization, long sonar wavelength, resulting in a large impact of mirror reflection directly below, and traditional low-frequency sonar with large size, heavy weight, and inconvenient installation and deployment.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a multi-band three-dimensional buried object detection sonar device, including a sonar system, the sonar system includes a transducer module, a wet-end electronic module and a dry-end equipment module, the transducer module is electrically connected to the wet-end electronic module, and the wet-end electronic module is communicatively connected to the dry-end equipment module;

[0008] The transducer module includes a plurality of transmitting arrays and receiving arrays, each of the transmitting arrays has its own serial number, and each of the transmitting arrays includes a plurality of transmitting transducers, and the plurality of transmitting transducers are arranged in an array, and the receiving array includes a plurality of receiving transducers, and the plurality of receiving transducers are distributed in an array, and the plurality of receiving transducers and the plurality of transmitting transducers are distributed in an interlaced array to form an array design;

[0009] The wet-end electronic module includes a control center, a transmitter and a receiver. The control center is in communication connection with the dry-end equipment module. The control center controls the transmitter to transmit electrical signals of different frequency bands. The transmitter drives the transmitting array through the electrical signals of different frequency bands to convert the electrical signals into acoustic signals through a plurality of transmitting transducers and transmit them. The receiving array receives the reflected acoustic signals through a plurality of receiving transducers, and converts them into electrical signals again and transmits them to the receiver. The receiver amplifies, filters, and performs analog-to-digital conversion on the electrical signals to generate digital signals, and then performs data sorting on the digital signals. The control center feeds back the data sorted by the receiver to the dry-end equipment module.

[0010] The dry-end equipment module includes a signal processor, which is used to process the data fed back by the control center to complete the three-dimensional imaging of the underwater three-dimensional scene.

[0011] Preferably, a first communication unit is provided in the wet-end electronic module, and a second communication unit is provided in the dry-end equipment module. The first communication unit and the second communication unit realize bidirectional signal transmission by establishing a local area network.

[0012] Preferably, the sonar system also includes a data storage unit and a display and control console. The data storage unit is mainly used to store data, and the data is all data generated during the operation of the sonar system. Display and control software runs on the display and control console to perform parameter configuration and system control of the sonar system, and display it in one-dimensional, two-dimensional and three-dimensional forms.

[0013] Preferably, the control center includes a host computer, a power module, a switch and a synchronous controller, which are mainly used for power supply, data exchange and synchronous control.

[0014] Preferably, the wet-end electronic module also includes a sensor module, which includes a high-precision GNSS, a high-precision inertial navigation and an attitude meter. The high-precision GNSS is used to obtain standard time signals from GPS satellites, the high-precision inertial navigation is mainly used to obtain positioning data, and the attitude meter is mainly used to provide high-precision three-dimensional attitude.

[0015] A method for using a multi-band three-dimensional buried object detection sonar comprises the following specific steps:

[0016] S1: Use the display console at the dry end to set the working parameters of the sonar system. In the developer mode, you can configure detailed working parameters, including: the frequency of the sound waves emitted in the emission mode, the serial number of the emission array), the working center frequency f 0 , working bandwidth B, pulse period PRT, pulse width T, signal type (CW or FM, etc.), transmission power ρ, sampling delay, number of sampling points N, TVG linear term, TVG logarithmic term, TVG constant term, transmitting array element position, receiving array element number, receiving array element position, in user mode, only the minimum imaging depth H needs to be configured min , maximum imaging depth H max , the upper computer display and control software can calculate the above working parameters according to these two parameters;

[0017] S2: Control the sonar device to start working. After sending a start command to the sonar system, the sonar system starts working. The transmitter transmits electrical signals of different frequency bands. The transmitter drives the transmitting array through the electrical signals of different frequency bands, and then converts the electrical signals into acoustic signals through a number of the transmitting transducers and transmits them out, thereby realizing the periodic transmission of high-power sound waves. Suppose the transmitting signal is P(t), and the transmitting signal is one of a CW signal linear frequency modulation signal and a hyperbolic frequency modulation signal. The receiving array receives the reflected acoustic signal through a number of the receiving transducers, and converts it into an electrical signal again and transmits it to the receiver. The receiver amplifies, filters, and performs analog-to-digital conversion on the electrical signal to generate a digital signal, and then performs data sorting on the digital signal. The data sorted by the control center is fed back to the dry-end equipment module;

[0018] S3: the signal processor performs signal processing, including pulse compression, beam forming, and synthetic aperture processing;

[0019] S4: The signal processor synchronously receives data acquired by the high-precision GNSS, the high-precision inertial navigation and the attitude indicator external sensor.

[0020] S5: The data storage unit performs data storage, specifically including: storing sonar raw data, sonar image data, external sensor data and sonar operating parameters, the raw data includes echo data and demodulated data, the sonar operating parameters are the operating parameters set in S1, and the external sensor data are the data collected by the external sensor in step S5.

[0021] S6: The display console displays sonar images, sonar operating parameters, and external sensor data in real time, and the display forms include digital form, one-dimensional curve, two-dimensional plane, and three-dimensional solid.

[0022] Preferably, after the signal in S2 is transmitted in the water body, the signal returned to the receiver is S r =p(tt 0 ), perform Fourier transform, The reference signal for pulse compression in the frequency domain is H(f) = P * (f), the signal after pulse compression is: The amplitude term |P(f)| 2 is a rectangular window function, which becomes a sinc function after inverse Fourier transformation, i.e. s 1 (t) = IFT(S 1 (f))=sinc(KT(tt 0 )), set at r 0 The target intensity at is A(r 0 ), then after the above pulse compression or matched filtering process, we can get r 0 The result of signal processing is According to the properties of the sinc function, we know that only when When , the above formula obtains the maximum value, that is to say, when the time and the target distance satisfy the above relationship, the signal amplitude obtains the maximum value at this moment, and finally determines the linear relationship between time and target distance.

[0023] Preferably, for the case of multiple receiving subarrays, in order to make the signal-to-noise ratio of the target at a specific distance and azimuth larger, beamforming technology is used for enhancement to make full use of the array gain. The specific implementation method is to first set the position of the transmitting array element to Assume the position of the i-th element of the receiving array is Assume that the signal of each channel after pulse compression processing is s RC (i, t); Let the coordinates of a pixel point in the space to be calculated be Then calculate the distance between the pixel to be determined and the transmitting array, also known as the sound path, that is, the distance the sound travels: Then the distance between the pixel and the i-th receiving array element is calculated as: The total distance that the sound wave travels from emission to target and then to reception is The time corresponding to the above total sound path is C is the speed of sound in water, and the beamforming result at this point is Based on beamforming, aperture synthesis processing is performed to further improve array gain. The basic idea is that for the same target area, when multiple consecutive pulses are irradiated to the area, these multiple pulses obtain its reflected echo. At this time, the results corresponding to the same position in the multiple pulse beamforming results are coherently superimposed to obtain further array gain. The result is modulo-calculated, and the entire area is filtered, equalized, and other processes are performed to obtain the amplitude value of the k-th pixel point, and finally a two-dimensional or three-dimensional image is determined.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] In the present invention, full use is made of multi-frequency transmission and broadband receiving technology to expand the signal bandwidth of the system, thereby expanding its applicable scenarios and taking into account the needs of buried depth detection and buried imaging resolution.

[0026] In the present invention, array technology is used to reduce the impact of the sound energy reflected by the mirror directly below.

[0027] In the present invention, the layout is compact, the volume size is reduced, and the underwater weight of the equipment is reduced, making the equipment more convenient to install and store. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a system block diagram of a sonar system in a multi-band three-dimensional buried object detection sonar device of the present invention;

[0029] Figure 2 A flow chart of a method for using a multi-band three-dimensional buried object detection sonar device according to the present invention;

[0030] Figure 3 It is a schematic diagram of the distribution of the transmitting array and the receiving array in the present invention;

[0031] Figure 4 It is a schematic diagram of acoustic signal transmission in the present invention.

[0032] In the figure: 1, transmitting array; 101, transmitting transducer; 2, receiving array; 201, receiving transducer. DETAILED DESCRIPTION

[0033] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0034] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention 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 cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Please refer to Figure 1-4 As shown, the present invention is a multi-band three-dimensional buried object detection sonar device, including a sonar system, the sonar system includes a transducer module, a wet-end electronic module and a dry-end equipment module, the transducer module is electrically connected to the wet-end electronic module, and the wet-end electronic module is communicatively connected to the dry-end equipment module;

[0037] like Figure 3 As shown, the transducer module includes a plurality of transmitting arrays and receiving arrays, each transmitting array has its own serial number, and each transmitting array includes a plurality of transmitting transducers, and a plurality of transmitting transducers are arranged in arrays, and the receiving array includes a plurality of receiving transducers, and a plurality of receiving transducers are arranged in arrays, and a plurality of receiving transducers and a plurality of transmitting transducers are arranged in staggered arrays to form an array design;

[0038] like Figure 1 As shown, the wet-end electronic module includes a control center, a transmitter and a receiver. The control center is connected to the dry-end device module for communication. The control center controls the transmitter to transmit electrical signals of different frequency bands, such as Figure 4 As shown, the transmitter drives the transmitting array through electrical signals of different frequency bands, and then converts the electrical signals of different frequency bands into acoustic signals through a number of transmitting transducers and transmits them. The receiving array receives the reflected acoustic signals through a number of receiving transducers, and converts them into electrical signals again and transmits them to the receiver. The receiver amplifies, filters, and performs analog-to-digital conversion on the electrical signals to generate digital signals, and then sorts the digital signals. The control center feeds back the sorted data of the receiver to the dry-end equipment module.

[0039] The dry-end equipment module includes a signal processor, which is used to process the data fed back by the control center to complete the three-dimensional imaging of the underwater three-dimensional scene.

[0040] Among them, a first communication unit is provided in the wet-end electronic module, and a second communication unit is provided in the dry-end equipment module. The first communication unit and the second communication unit realize two-way signal transmission by establishing a local area network.

[0041] Among them, the sonar system also includes a data storage unit and a display and control console. The data storage unit is mainly used to store data. The data is all data generated during the operation of the sonar system. The display and control software runs on the display and control console to configure the parameters and control the system of the sonar system, and display it in one-dimensional, two-dimensional and three-dimensional forms.

[0042] The control center includes a host computer, a power module, a switch and a synchronization controller, which are mainly used for power supply, data exchange and synchronization control.

[0043] Among them, the wet-end electronic module also includes a sensor module, which includes a high-precision GNSS, a high-precision inertial navigation and an attitude meter. The high-precision GNSS is used to obtain standard time signals from GPS satellites, the high-precision inertial navigation is mainly used to obtain positioning data, and the attitude meter is mainly used to provide high-precision three-dimensional attitude.

[0044] like Figure 2 As shown, a method for using a multi-band three-dimensional buried object detection sonar includes the following specific steps:

[0045] S1: Use the display and control console of the dry end to set the working parameters of the sonar system. In the developer mode, you can configure detailed working parameters, including: the frequency of the sound waves transmitted in the transmitting mode, the serial number of the transmitting array), the working center frequency, the working bandwidth, the pulse period, the pulse width, the signal type, the transmitting power, the sampling delay, the number of sampling points, the TVG linear term, the TVG logarithmic term, the TVG constant term, the position of the transmitting array element, the number of the receiving array elements, and the position of the receiving array elements. In the user mode, you only need to configure the minimum imaging depth and the maximum imaging depth. The upper computer display and control software can calculate the above working parameters based on these two parameters.

[0046] S2: Control the sonar device to start working. After sending the start command to the sonar system, the sonar system starts working. The transmitter transmits electrical signals of different frequency bands. The transmitter drives the transmitting array through electrical signals of different frequency bands, and then converts the electrical signals into sound signals through a number of transmitting transducers and transmits them, thereby realizing the periodic transmission of high-power sound waves. Suppose the transmitting signal is p(t), and the transmitting signal is an LFM signal in the form of: in The frequency modulation is called linear frequency modulation. The receiving array receives the reflected sound signal through a number of receiving transducers and converts it into an electrical signal again for transmission to the receiver. The receiver amplifies, filters, and converts the electrical signal into an analog-to-digital signal to generate a digital signal. The digital signal is then sorted. The sorted data of the control center is fed back to the dry-end equipment module.

[0047] S3: The signal processor performs signal processing, including pulse compression, beam forming, and synthetic aperture processing;

[0048] S4: The signal processor synchronously receives data from high-precision GNSS, high-precision inertial navigation, and attitude indicator external sensors.

[0049] S5: The data storage unit performs data storage, specifically including: storing sonar raw data, sonar image data, external sensor data and sonar operating parameters, the raw data includes echo data and demodulated data, the sonar operating parameters are the operating parameters set in S1, and the external sensor data are the data collected by the external sensor in step S5.

[0050] S6: The display console displays sonar images, sonar operating parameters, and external sensor data in real time in various forms including digital, one-dimensional curve, two-dimensional plane, and three-dimensional.

[0051] Among them, after the signal in S2 is transmitted in the water body, the signal returned to a certain array element of the receiver is: Perform signal demodulation to obtain the baseband signal. The reference signal for pulse compression or matched filtering is: For b Convolve with h and get: Set at r 0 The target intensity at is A(r 0 ), then after the above pulse compression or matched filtering process, we can get r 0 The result of signal processing is According to the properties of the sinc function, we know that only when When , the above formula obtains the maximum value, that is to say, when the time and the target distance satisfy the above relationship, the signal amplitude obtains the maximum value at this moment, and finally a linear relationship diagram between time and target distance is obtained.

[0052] Among them, the receiving array receives the reflected sound signal through several receiving transducers. For the case of multiple receiving sub-arrays, in order to make the signal-to-noise ratio of the target at a specific distance and azimuth larger, the beamforming technology is used to enhance it and make full use of the array gain. The specific implementation method is: first, the position of the transmitting array element is set to Assume the position of the i-th element of the receiving array is Assume that the signal of each channel after pulse compression processing is s RC (i, t); Let the coordinates of a pixel point in the space to be calculated be Then calculate the distance between the pixel to be determined and the transmitting array, also known as the sound path, that is, the distance the sound travels: The distance between the pixel to be determined and the i-th receiving array element is: The total distance that the sound wave travels from emission to target and then to reception is The time corresponding to the above total sound path is: Where C is the speed of sound in water, the beamforming result at this point is: Based on beamforming, aperture synthesis processing is performed to further improve array gain. The basic idea is that for the same target area, when multiple consecutive pulses irradiate the area, these multiple pulses obtain its reflected echo. At this time, the results corresponding to the same position in the multiple pulse beamforming results are coherently superimposed to obtain further array gain. The result is modulo-calculated, and the entire area is filtered, equalized, and other processes are performed to obtain the amplitude value of the kth pixel point, and ultimately determine the two-dimensional image or three-dimensional model.

[0053] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A multi-band three-dimensional buried object detection sonar device, characterized in that: A sonar system is included, wherein the sonar system includes a transducer module, a wet-end electronic module and a dry-end device module, wherein the transducer module is electrically connected to the wet-end electronic module, and the wet-end electronic module is communicatively connected to the dry-end device module; The transducer module includes a plurality of transmitting arrays and receiving arrays, each of the transmitting arrays has its own serial number, and each of the transmitting arrays includes a plurality of transmitting transducers, and the plurality of transmitting transducers are arranged in an array, and the receiving array includes a plurality of receiving transducers, and the plurality of receiving transducers are distributed in an array, and the plurality of receiving transducers and the plurality of transmitting transducers are distributed in an interlaced array to form an array design; The wet-end electronic module includes a control center, a transmitter and a receiver. The control center is in communication connection with the dry-end equipment module. The control center controls the transmitter to transmit electrical signals of different frequency bands. The transmitter drives the transmitting array through the electrical signals of different frequency bands to convert the electrical signals into acoustic signals through a plurality of transmitting transducers and transmit them. The receiving array receives the reflected acoustic signals through a plurality of receiving transducers, and converts them into electrical signals again and transmits them to the receiver. The receiver amplifies, filters, and performs analog-to-digital conversion on the electrical signals to generate digital signals, and then performs data sorting on the digital signals. The control center feeds back the data sorted by the receiver to the dry-end equipment module. The dry-end equipment module includes a signal processor, which is used to process the data fed back by the control center to complete the three-dimensional imaging of the underwater three-dimensional scene.

2. A multi-band three-dimensional buried object detection sonar device according to claim 1, characterized in that: The wet-end electronic module is provided with a first communication unit, and the dry-end equipment module is provided with a second communication unit. The first communication unit and the second communication unit realize bidirectional signal transmission by establishing a local area network.

3. The multi-band three-dimensional buried object detection sonar device according to claim 2, characterized in that: The sonar system also includes a data storage unit and a display and control console. The data storage unit is mainly used to store data, which is all data generated during the operation of the sonar system. The display and control console runs display and control software for parameter configuration and system control of the sonar system, and displays it in one-dimensional, two-dimensional and three-dimensional forms.

4. The multi-band three-dimensional buried object detection sonar device according to claim 3, characterized in that: The control center includes a host computer, a power module, a switch and a synchronization controller, which are mainly used for power supply, data exchange and synchronization control.

5. The multi-band three-dimensional buried object detection sonar device according to claim 4, characterized in that: The wet end electronic module also includes a sensor module, which includes a high-precision GNSS, a high-precision inertial navigation and an attitude meter. The high-precision GNSS is used to obtain standard time signals from GPS satellites, the high-precision inertial navigation is mainly used to obtain positioning data, and the attitude meter is mainly used to provide high-precision three-dimensional attitude.

6. A method for using a multi-band three-dimensional buried object detection sonar, characterized in that: The method comprises the multi-band three-dimensional buried object detection sonar device as claimed in claim 5, and further comprises the following specific steps: S1: Use the display console of the dry end to set the working parameters of the sonar system. In the developer mode, you can configure detailed working parameters, including: the frequency of the sound waves transmitted in the transmission mode, the serial number of the transmitting array, the working center frequency, the working bandwidth, the pulse period, the pulse width, the signal type, the transmission power, the sampling delay, the number of sampling points, the TVG linear term, the TVG logarithmic term, the TVG constant term, the position of the transmitting array element, the number of the receiving array elements, and the position of the receiving array elements. In the user mode, you only need to configure the minimum imaging depth and the maximum imaging depth. The upper computer display and control software can calculate the above working parameters based on these two parameters. S2: Control the sonar device to start working. After sending a start command to the sonar system, the sonar system starts working. The transmitter transmits electrical signals of different frequency bands. The transmitter drives the transmitting array through the electrical signals of different frequency bands, and then converts the electrical signals into acoustic signals through a number of transmitting transducers and transmits them out, thereby realizing the periodic transmission of high-power sound waves. The transmitting signal is one of a CW signal linear frequency modulation signal and a hyperbolic frequency modulation signal. The receiving array receives the reflected acoustic signal through a number of receiving transducers, and converts it into an electrical signal again and transmits it to the receiver. The receiver amplifies, filters, and performs analog-to-digital conversion on the electrical signal to generate a digital signal, and then performs data sorting on the digital signal. The data sorted by the control center is fed back to the dry end equipment module; S3: the signal processor performs signal processing, including pulse compression, beam forming, and synthetic aperture processing; S4: The signal processor synchronously receives data acquired by the high-precision GNSS, the high-precision inertial navigation and the attitude indicator external sensor; S5: the data storage unit performs data storage, specifically including: storing sonar raw data, sonar image data, external sensor data and sonar operating parameters, the raw data includes echo data and demodulated data, the sonar operating parameters are the operating parameters set in S1, and the external sensor data are the data collected by the external sensor in step S5; S6: The display console displays sonar images, sonar operating parameters, and external sensor data in real time, and the display forms include digital form, one-dimensional curve, two-dimensional plane, and three-dimensional solid.

7. The method for using a multi-band three-dimensional buried object detection sonar according to claim 6, characterized in that: After the signal in S2 is transmitted in the water body, the signal returned to the receiver is first subjected to Fourier transformation and pulse compression in the frequency domain. After matched filtering, the signal processing result can be obtained, and finally a linear relationship graph between time and target distance is displayed.

8. The method for using a multi-band three-dimensional buried object detection sonar according to claim 7, characterized in that: The receiving array receives the reflected acoustic signals through the multiple receiving transducers, uses beamforming technology to enhance the conditions of the multiple receiving transducers, and makes full use of the array gain to improve the signal-to-noise of the target at a specific distance and orientation, and then obtains the beamforming result of the point, performs aperture synthesis formation processing on the basis of beamforming, further improves the array gain, and finally obtains the pixel amplitude value of the point for constructing two-dimensional and three-dimensional result maps.

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