A multi-beam fishing sonar signal processing method and system

Abstract

The present invention provides a multi-beam fishing sonar signal processing method and system. In this method, the process of receiving beams includes the following steps: (S1) Each signal processing board performs beamforming on each beam to be received according to the signals received by the arrays communicatively connected thereto, so as to obtain the signals of partial beams of each beam to be received; (S2) Each signal processing board sequentially performs matched filtering and decimation on the signals of the partial beams obtained by it; (S3) Each signal processing board transmits the decimated signals of the partial beams to the host through the switch; (S4) The host superimposes the partial beams of the beam to be received to obtain the signal of the beam to be received. In the present invention, by adding a matched filtering link in each signal processing board and performing decimation on the matched filtering link, the problem of excessive signal rate between the signal processing board and the host in the prior art is solved, and at the same time, the phase noise introduced in the decimation process is reduced.

Description

Technical Field

[0001] The present invention relates to the field of fishery equipment, and in particular, to a multi-beam fishery sonar signal processing method and system. Background Art

[0002] Fishery sonar (commonly known as "fish finder") is one of the most widely used and typical fishing aids in marine fishery, and is the main tool for detecting the quantity and spatial distribution information of marine fish resources by using hydroacoustic methods. The types of fish finders can be divided into vertical single-beam fish finders, horizontal fish finders, vertical dual-frequency fish finders, split-beam fish finders, multi-beam fish finders, etc. Among them, multi-beam fishery sonar can obtain a farther spatial detection distance and a higher angular resolution ability, and has a wide application in the detection of fish schools in pelagic fishery trawling and purse seine fishing, which can greatly improve the pelagic fishery fishing efficiency, and also provides a technical means for future accurate and selective fishing in marine fishery.

[0003] In order to achieve a farther detection distance and a higher angular resolution, fishery sonar hardware with more independent channels is designed and used. Typical commercial multi-beam fishery sonars include: SX90 of SIMRAD Company in Norway, FSV35 and FSV25 of Furuno Company in Japan, MAQ22, MAQ60 and MAQ90 of MAQ Company in Canada, etc. The number of channels can reach 256 channels, and can be as many as nearly a thousand channels at most. Each channel needs to perform separate signal processing, which poses a great challenge to a single-board signal processor.

[0004] To solve this problem, a solution of using multiple signal processing boards is often adopted to disperse the signal processing process and increase the maintainability of the system. However, at the same time, another problem is brought. Since the beamforming of multi-beam fishery sonar spans multiple signal processing boards, the amount of communication data between multiple signal processing boards or between the signal processing board and the host is extremely large. For example: for a 30MHz omnidirectional fishery sonar using a frequency band, if 160 beams are commonly used for scanning, each beamforming needs to span 3 boards, the data sampling rate is 1MHz, and the data bit width is 16 bits, then it is equivalent to having a 768MHz inter-board data transfer rate. Such a large amount of data transfer often needs to be completed by using optical fibers. When the fishery sonar is used at sea, the external environment such as vibration and salt spray is harsh during use, and the optical fiber is easily broken, which brings great complexity and unreliability to the system. At the same time, subsequent real-time matched filtering monitoring processing of 160 beams in the host also brings huge computing pressure to the host.

[0005] In some prior arts, the signal processing board will decimate the signal before transmitting it to the host. Although this method can reduce the signal rate, sampling too early will reduce the signal quality, introduce noise, and may also cause the loss of details in the signal. Summary of the Invention

[0006] Aiming at the defects in the prior art, the object of the present invention is to provide a multi-beam fishing sonar signal processing method and system. By adding a matched filtering link in each signal processing board and performing decimation on the matched filtering link, the problem of excessive signal rate between the signal processing board and the host in the prior art is solved.

[0007] The technical solution provided by the present invention is as follows:

[0008] A multi-beam fishing sonar signal processing method, in which a plurality of arrays are divided into multiple groups; each group of arrays corresponds to a signal processing board, and each of the arrays is communicatively connected to the signal processing board corresponding to the group of arrays through a receiver, and each of the signal processing boards is communicatively connected to the host through a switch; the process of receiving a beam includes the following steps:

[0009] (S1) Each of the signal processing boards performs beamforming on each beam to be received according to the signals received by the arrays communicatively connected thereto, so as to obtain the signals of partial beams of each beam to be received;

[0010] (S2) Each of the signal processing boards sequentially performs matched filtering and decimation on the signals of the partial beams obtained by it, so as to reduce the data volume of the signals of the partial beams;

[0011] (S3) Each of the signal processing boards transmits the decimated signals of the partial beams to the host through the switch through the switch;

[0012] (S4) The host superimposes the partial beams of the beam to be received to obtain the signal of the beam to be received.

[0013] A further improvement of the present invention is that in the process of each signal processing board performing beamforming, according to the direction of the beam to be received, the received signals of each of the arrays are delayed or / and phase-shifted, and the weighted accumulation is performed on the phase-shifted or delayed result, and its expression is:

[0014]

[0015] Wherein, is the result of phase-shifting or time-delay of the i-th channel for the beam to be received with a directivity of ; weight_total i is the amplitude weighting value of the signal of the i-th channel, is the partial beam of the beam to be received with a directivity of .

[0016] A further improvement of the present invention is that in step S2, the expression for filtering and matching the signals of the partial beams is:

[0017]

[0018] Among them, is a partial beam of the to-be-received beam with a directivity of ; γ(n) is the phase modulation function of the to-be-received beam; S_output1 is the matched filtering result of the partial beam.

[0019] A further improvement of the present invention lies in that the matched filtering result of the partial beam is a discrete time series. During the decimation process, one value is selected every 10 sampling points to obtain the decimated time series, so as to reduce the signal rate.

[0020] A further improvement of the present invention lies in that when each to-be-received beam is received by two sets of antenna elements, the host adds the partial beams sent by the signal processing boards corresponding to the two sets of antenna elements;

[0021] When each to-be-received beam is received by more than three sets of antenna elements, the host weights and adds the partial beams sent by the signal processing boards corresponding to each set of antenna elements.

[0022] A further improvement of the present invention lies in that the host and the signal processing board are connected to each other by means of a network cable.

[0023] The present invention also relates to a multi-beam fishing sonar signal processing system, which includes:

[0024] A plurality of signal processing boards, each of the signal processing boards is communicatively connected to a plurality of the antenna elements through a receiver, and the antenna elements of each of the signal processing boards are arranged in an array;

[0025] A host, communicatively connected to the switch; the switch is communicatively connected to each of the signal processing boards by means of a network cable;

[0026] The signal processing board is configured to perform beamforming on each to-be-received beam according to the signals received by the antenna elements communicatively connected thereto, so as to obtain the signals of the partial beams of each to-be-received beam; perform matched filtering and decimation on the signals of the partial beams in sequence, and transmit the decimated signals of the partial beams to the host through the switch;

[0027] The host is configured to receive the signals of the partial beams sent by each of the signal processing boards, and superimpose the signals of the to-be-received partial beams to obtain the signals of the to-be-received beam.

[0028] A further improvement of the present invention lies in that the arrangement shape of each group of the antenna elements is a planar array, a cylindrical array or a linear array.

[0029] A further improvement of the present invention lies in that each of the signal processing boards has 32 channels, which are respectively used for receiving signals of 32 elements.

[0030] A further improvement of the present invention lies in that the signal processing board uses an FPGA as a signal processor.

[0031] Compared with the prior art, the present invention has the following beneficial effects: Each signal processing board first performs partial beamforming, places the matched filtering process on each signal processing board for distributed processing, and then performs sampling to reduce the signal transmission rate, and the host combines the low-rate distributed matched filtering results of each beam. The present invention completes the main signal processing process before reducing the signal rate, and can significantly reduce the data transmission rate between the board and the host without affecting the overall performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objects and advantages of the present invention will become more obvious:

[0033] Figure 1 is a hardware architecture diagram of a multi-beam fishing sonar signal processing system of the present invention;

[0034] Figure 2 is a flowchart of a multi-beam fishing sonar signal processing method of the present invention;

[0035] Figure 3 is a waveform diagram of a partial beam after matched filtering;

[0036] Figure 4 is a waveform diagram of a to-be-received beam after superposition of partial beams. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0038] As Figure 1 , 2 shown, the present invention provides a multi-beam fishing sonar signal processing method. In this method, a plurality of elements are divided into multiple groups; each group of elements corresponds to a signal processing board, each element is communicatively connected to the signal processing board corresponding to the group of elements through a receiver, and each signal processing board is communicatively connected to a host through a switch.

[0039] In a specific embodiment, the multi-beam fishing sonar transducer has a total of M*N elements. The N elements correspond to N independent receivers and are connected to a certain channel of a signal processing board. Typically, N is 8, 16, or 32. Such M signal processing boards complete the access of all channels. Typically, M is 8 or 16. Each signal processing board transmits partial beam generation results to the host through a data transmission device, and the host processes the data across multiple boards.

[0040] Each group of elements is used to receive multiple beams to be received, and each beam to be received is received by at least two groups of elements. The signal processing board corresponding to each group of elements can obtain partial beams of each beam to be received. After the signal processing board processes each partial beam, it is transmitted to the host, and the host accumulates each partial beam to form a complete beam to be received. Specifically, the process of receiving a beam includes the following steps:

[0041] (S1) Each signal processing board performs beamforming on each beam to be received according to the signals received by the elements communicatively connected to it, so as to obtain the signals of the partial beams of each beam to be received; during the process of each signal processing board performing beamforming, according to the direction of the beam to be received, the received signals of each element are delayed or / and phase-shifted, and the phase-shifted or delayed results are weighted and accumulated. Its expression is:

[0042]

[0043] Among them, is the result of phase-shifting or time-delay of the i-th channel for the beam to be received with a directivity of ; weight_total i is the amplitude weighting value of the signal of the i-th channel, is the partial beam of the beam to be received with a directivity of .

[0044] The signals received by each element contain the signals of multiple beams. In order to highlight the beam to be received, according to the positions of each element and the directivity of the beam to be received, the signals received by the elements are correspondingly delayed or / and phase-shifted, so that the components of the wave-divided beams in the signals of each element can be highlighted in the subsequent weighted accumulation, while other signals will cancel each other out during the weighted accumulation process because their phases are randomly distributed. In addition, the weighted accumulation process can suppress side lobes and obtain better beamforming directivity.

[0045] (S2) Each signal processing board sequentially performs matched filtering and decimation on the signals of the partial beams it obtains to reduce the data volume of the signals of the partial beams. The expression for filtering and matching the signals of the partial beams is:

[0046]

[0047] Among them, is a partial beam of the received beam with a directivity of , γ(n) is the phase modulation function of the received beam, which is determined by the beam emitted by the fishing sonar; S_output1 is the matched filtering result of the partial beam. Figure 3 The waveform diagram of the partial beam after matched filtering in this embodiment is shown as follows.

[0048] The matched filtering result of the partial beam is a discrete time series. During the decimation process, one value is selected every 10 sampling points to obtain the decimated time series. In this embodiment, combining matched filtering and decimation can reduce the signal rate (one-tenth) while avoiding the introduction of phase noise due to premature downsampling, which affects the subsequent processing performance. At the same time, this method utilizes the principle that the matched filtering process conforms to the distributive law, disperses the matched filtering process to each signal processing board, and can give full play to the role of the real-time signal processor on the signal processing board (usually having a large number of parallel hardware multipliers, which can efficiently complete the matched filtering process). By reducing the communication rate between the signal processing board and the host, the communication cost between the host and the signal processing board can be reduced, and conditions can be created for more independent channels to participate in beamforming under the specified hardware architecture.

[0049] (S3) Each signal processing board transmits the signal of the decimated partial beam to the host through the switch.

[0050] (S4) The host superimposes the partial beams of the received beam to obtain the signal of the received beam. When each received beam is received by two sets of antenna elements, the host adds the partial beams sent by the signal processing boards corresponding to the two sets of antenna elements; when each received beam is received by more than three sets of antenna elements, the host weights and adds the partial beams sent by the signal processing boards corresponding to each set of antenna elements to obtain the signal of the received beam.

[0051] The waveform diagram after superimposing the partial beams is as shown in Figure 4 . After obtaining the received beam, the host can perform subsequent processing such as envelope detection and interpolation on it in the subsequent process, which will not be described here.

[0052] An embodiment of the present invention further includes a multi-beam fishing sonar signal processing system, which is used to implement the above multi-beam fishing sonar signal processing method. The system includes:

[0053] A plurality of signal processing boards, each signal processing board is communicatively connected to a plurality of antenna elements through a receiver, and the antenna elements of each signal processing board are arranged in an array;

[0054] A host, communicatively connected to the switch; the switch is communicatively connected to each signal processing board by means of a network cable;

[0055] The signal processing board is configured to perform beamforming on each beam to be received according to the signals received by the arrays communicatively connected thereto, so as to obtain the signals of partial beams of each beam to be received; sequentially perform matched filtering and decimation on the signals of the partial beams, and transmit the decimated signals of the partial beams to the host through the switch;

[0056] The host is configured to receive the signals of the partial beams sent by each of the signal processing boards, and superimpose the signals of the partial beams to be received to obtain the signals of the beams to be received.

[0057] In this embodiment, the arrangement shape of each group of the arrays is a planar array, a cylindrical array or a linear array. Each signal processing board has 32 channels, which are respectively used to receive the signals of 32 arrays. The signal processing board uses an FPGA as the signal processor. The signal processing modules (floating-point operations, logical operations) are implemented in the FPGA in the form of soft cores or hard cores, and the signal processing modules can perform parallel operations, so that the FPGA has extremely high signal processing capabilities.

[0058] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying 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 construed as a limitation to the present application.

[0059] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A multi-beam fishing sonar signal processing method, characterized in that, In this method, a plurality of antenna elements are divided into multiple groups; each group of antenna elements corresponds to a signal processing board. Each of the antenna elements is communicatively connected to the signal processing board corresponding to this group of antenna elements through a receiver, and each of the signal processing boards is communicatively connected to a host through a switch; the process of receiving a beam includes the following steps: (S1) Each of the signal processing boards performs beamforming on each beam to be received according to the signals received by the antenna elements communicatively connected thereto, so as to obtain the signals of partial beams of each beam to be received; (S2) Each of the signal processing boards sequentially performs matched filtering and decimation on the signals of the partial beams it obtains, so as to reduce the data volume of the signals of the partial beams; (S3) Each of the signal processing boards transmits the decimated signals of the partial beams to the host through the switch through the switch; (S4) The host superimposes the partial beams of the beam to be received to obtain the signal of the beam to be received; In step S2, the expression for filtering and matching the signals of the partial beams is: Among them, is the partial beam of the received beam to be received with a directivity of , γ(n) is the phase modulation function of the received beam to be received; S_output1 is the matched filtering result of the partial beam; The matched filtering result of the partial beam is a discrete time series. During the decimation process, one value is selected every 10 sampling points to obtain the decimated time series, so as to reduce the signal rate.

2. The multi-beam fishing sonar signal processing method according to claim 1, characterized in that During the process of each of the signal processing boards performing beamforming, according to the direction of the beam to be received, the received signals of each of the antenna elements are delayed and / or phase-shifted, and the phase-shifted or delayed results are weighted and accumulated, and its expression is: Among them, is the result of phase shift or time delay of the i-th channel pair for the received beam with a directivity of ; weight_total i is the amplitude weighting value of the i-th channel signal, is a partial beam of the received beam with a directivity of ​ 3. A multi-beam fishing sonar signal processing method according to claim 1, wherein When each beam to be received is received by using two groups of antenna elements, the host adds the partial beams sent by the signal processing boards corresponding to the two groups of antenna elements; When each beam to be received is received by using more than three groups of antenna elements, the host performs weighted addition on the partial beams sent by the signal processing boards corresponding to each group of antenna elements.

4. A multi-beam fishing sonar signal processing method according to claim 1, characterized in that The host and the signal processing board are connected to the host by means of a network cable.

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