A broadband beamforming device and method for fishing sonar

Abstract

The present invention discloses a broadband beamforming device and method for fishing sonar, wherein the broadband beamforming device comprises M samplers, a mixer, a low-pass filter, M time shifters, M phase shifters and N accumulators, wherein the M samplers are respectively connected to the transducers corresponding to each array, the mixer is respectively connected to the M samplers, the low-pass filter is connected to the mixer, the M time shifters are respectively connected to the low-pass filter, the M phase shifters are respectively connected to the M time shifters, and each accumulator is connected to the M phase shifters. The present invention serializes the time shifters and the phase shifters according to the beams, and adjusts the time shifter before the phase shifter, so that each array can serially complete the time shifting and phase shifting processing of N beams with only one time shifter and one phase shifter, significantly reducing the number of time shifters and phase shifters, and avoiding the substantial increase in resource consumption with the increase in the number of arrays and the number of beams.

Description

Technical Field

[0001] The present invention relates to the field of beamforming technology, and in particular to a broadband beamforming device and method for fishing sonar. Background Art

[0002] As a highly complex and technologically advanced fishing aid, multi-beam fishing sonar can achieve a longer spatial detection distance and higher angular resolution, and is widely used in the detection of fish schools in deep-sea trawling and purse seine fishing. Due to the narrow space inside fishing vessels, the power supply and heat dissipation capacity are also limited, which puts forward high requirements on the size, power consumption, and cost of fishing sonar.

[0003] Beamforming technology is the core technology of multi-beam fishing sonar, which is mainly used for the orientation of target fish schools. Beamforming algorithms include narrowband and broadband solutions. Compared with narrowband beamforming, the signal-to-noise ratio and anti-interference ability of broadband signal beamforming have been greatly improved.

[0004] In the prior art, a broadband beamforming device using a sideband beamforming algorithm processes each beam in each array in parallel, and therefore needs to set a number of time shifters and phase shifters that is the same as the product of the number of arrays and the number of beams. As the number of arrays and beams increases, the number of required time shifters and phase shifters also increases dramatically, resulting in the consumption of a large amount of hardware resources, or even making the process impossible to implement. Summary of the invention

[0005] The object of the present invention is to provide a broadband beamforming device and method for fishing sonar to reduce hardware resource consumption.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A broadband beamforming device for fishing sonar, the broadband beamforming device comprising:

[0008] M samplers, where M = 2 k , k is an integer greater than or equal to 0; the M samplers are respectively connected to the transducers corresponding to each array, and are used to convert the analog voltage signal provided by the transducer into a digital form according to the set sampling rate to obtain M sampling signals; each sampling signal includes a plurality of sampling values, and the number of the sampling values ​​is equal to the number of sampling times;

[0009] A mixer, connected to the M samplers respectively, for performing down-mixing processing on the M sampling values ​​obtained by each sampling to obtain M down-mixed signals; the down-mixed signals include a real part and an imaginary part corresponding to the real part;

[0010] A low-pass filter, connected to the mixer, for performing low-pass filtering on the M down-mixed signals respectively to obtain M low-pass filtered signals;

[0011] M time shifters are respectively connected to the low-pass filters, and are used to perform time shift processing on the M low-pass filter signals respectively to obtain M time-shifted signals, each of which includes N time-shifted results, where N represents the number of beams in each array;

[0012] M phase shifters are respectively connected to the M time shifters, and are used to perform phase shift processing on the M×N time shift results respectively to obtain phase shift results corresponding to each time shift result;

[0013] N accumulators; each of the accumulators is connected to the M phase shifters; the N accumulators are used to accumulate the M×N phase shift results by beam to obtain beamforming results of the N beams.

[0014] Optionally, the broadband beamforming device further includes:

[0015] The matched filters are connected to the N accumulators and the host computer respectively, and are used to perform matched filtering on the N beamforming results to obtain corresponding matched filtering results, so that the host computer can display the N matched filtering results according to the beam angle.

[0016] Optionally, the time shifter comprises:

[0017] A time-shift data storage unit, used for storing the low-pass filtered signal;

[0018] A time shift parameter storage unit, used for storing the time shift parameters of N beams;

[0019] A read-write control unit is respectively connected to the low-pass filter, the time-shift data storage unit, the time-shift parameter storage unit and the phase shifter, and is used to write the low-pass filter signal into the time-shift data storage unit according to a write address, and read the pre-stored low-pass filter signal from the time-shift data storage unit as the time-shift result of each beam according to the read address of each beam, and send it to the phase shifter; the read address of each beam is calculated based on the write address and the time-shift parameter of each beam.

[0020] Optionally, the phase shifter comprises:

[0021] Phase shift parameter storage unit, used to store the phase shift parameters of N beams

[0022] A computing unit connected to the phase shift parameter storage unit, used for calculating the phase shift parameter according to the phase shift parameter Calculated The value of The value of

[0023] The first multiplication unit is connected to the operation unit and the time shifter, respectively, and is used to multiply the real part of the time shift result by Multiply them to get the real part phase shift result;

[0024] The second multiplication unit is connected to the operation unit and the time shifter, respectively, and is used to multiply the imaginary part of the time shift result by Multiply them to get the imaginary phase shift result;

[0025] The adding unit is connected to the first multiplication unit and the second multiplication unit respectively, and is used to subtract the real part phase shift result from the imaginary part phase shift result to obtain a corresponding phase shift result.

[0026] Optionally, the computing unit includes:

[0027] The sine data storage subunit is used to store sine values ​​within the range of 0 to 90 degrees with an interval of 0.1 degrees;

[0028] The operation subunit is connected to the phase shift parameter storage unit, the first multiplication unit, the second multiplication unit and the sine data storage subunit respectively, and is used to calculate the phase shift parameter according to the phase shift parameter. The symmetry and phase relationship of the trigonometric function are obtained from the sine data storage subunit. The value of is calculated based on the trigonometric function relationship. The value of .

[0029] The present invention also provides a broadband beamforming method for fishing sonar, the broadband beamforming method comprising:

[0030] Step S1: According to the set sampling rate, the analog voltage signals provided by the transducers corresponding to the M arrays are converted into digital form to obtain M sampling signals; each sampling signal includes multiple sampling values, and the number of sampling values ​​is equal to the number of sampling times; wherein M=2 k , k is an integer greater than or equal to 0;

[0031] Step S2: performing down-mixing processing on the M sampling values ​​obtained by each sampling to obtain M down-mixed signals; the down-mixed signals include a real part and an imaginary part corresponding to the real part;

[0032] Step S3: performing low-pass filtering on the M down-mixed signals respectively to obtain M low-pass filtered signals;

[0033] Step S4: performing time shift processing on the M low-pass filtered signals respectively to obtain M time-shifted signals, each of which includes N time-shifted results, where N represents the number of beams in each array;

[0034] Step S5: performing phase shift processing on the M×N time shift results respectively to obtain phase shift results corresponding to each time shift result;

[0035] Step S6: Accumulate the M×N phase shift results by beam to obtain beamforming results of N beams.

[0036] Optionally, after step S6, the method further includes:

[0037] Step S7: performing matched filtering processing on the N beamforming results to obtain corresponding matched filtering results, and sending the results to a host computer so that the host computer displays the N matched filtering results according to the beam angles.

[0038] Optionally, the step S4 specifically includes:

[0039] Step S41: storing the low-pass filtered signal in sequence into a time-shift data storage unit with a depth of H according to a write address, where H is a positive integer greater than or equal to N;

[0040] Step S42: according to the write address and the preset time shift parameters of each beam, the read address of each beam is calculated in sequence, and according to the read address, the pre-stored low-pass filter signal is read out in sequence from the time shift data storage unit as the time shift result of each beam;

[0041] Step S43: add 1 to the write address, and return to zero if the write address exceeds H-1.

[0042] Optionally, the step S5 specifically includes:

[0043] Step S51: Obtain the phase shift parameters of each beam respectively

[0044] Step S52: According to the phase shift parameter Calculated The value of The value of

[0045] Step S53: According to the time shift results of each beam, and The phase shift results of the N beams are calculated sequentially.

[0046] Optionally, the step S7 specifically includes:

[0047] The N beamforming results are processed by matched filtering using time division multiplexing technology to obtain N matched filtering results output in series and send them to a host computer, so that the host computer displays the N matched filtering results according to the angle of the beam.

[0048] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0049] The present invention provides a broadband beamforming device and method for fishing sonar, wherein the broadband beamforming device comprises M samplers, a mixer, a low-pass filter, M time shifters, M phase shifters and N accumulators, wherein the M samplers are respectively connected to transducers corresponding to each array, the mixer is respectively connected to the M samplers, the low-pass filter is connected to the mixer, the M time shifters are respectively connected to the low-pass filters, the M phase shifters are respectively connected to the M time shifters, and each accumulator is connected to the M phase shifters. Compared with a broadband beamforming device using a sideband beamforming algorithm, the present invention serializes the time shifter and the phase shifter according to the beam and adjusts the time shifter before the phase shifter, so that each array only needs one time shifter and one phase shifter to serially complete the time shifting and phase shifting processing of N beams, which significantly reduces the number of time shifters and phase shifters and avoids a substantial increase in resource consumption with the increase in the number of arrays and beams. In addition, the present invention further improves resource utilization by serializing the more complex mixers and low-pass filters according to the array. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0051] Figure 1 It is a schematic structural diagram of a broadband beamforming device of the present invention;

[0052] Figure 2 This is a diagram showing the effect of loading a broadband beamforming device according to the present invention;

[0053] Figure 3 It is a flow chart of the traditional shifted-sideband beamforming algorithm;

[0054] Figure 4 is a flow chart of a broadband beamforming method of the present invention;

[0055] Figure 5 It is a schematic diagram of the working principle of the time shifter of the broadband beamforming device of the present invention;

[0056] Figure 6 It is a schematic diagram of the working principle of the phase shifter of the broadband beamforming device of the present invention;

[0057] Figure 7 The figure is a comparison diagram of the beamforming measured results of the broadband beamforming method of the present invention and the sideband shifted beamforming algorithm;

[0058] Figure 8 A comparison diagram of the lookup table resources consumed by the broadband beamforming method of the present invention and the sideband shifted beamforming algorithm;

[0059] Fig. 9 A comparison diagram of register resources consumed by the broadband beamforming method of the present invention and the sideband shifted beamforming algorithm;

[0060] Fig.10 The figure is a comparison diagram of the storage block resources consumed by the broadband beamforming method of the present invention and the sideband shifted beamforming algorithm.

[0061] Explanation of symbols:

[0062] Sampler—1, analog-to-digital converter—101, sampling controller—102, mixer—2, low-pass filter—3, time shifter—4, phase shifter—5, accumulator—6, matching filter—7, host computer—8, transducer—9, transducer array—10, lifting mechanism—11, signal line—12, broadband beamforming device—13, data line—14, host computer—15, detection beam—16. DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] The object of the present invention is to provide a broadband beamforming device and method for fishing sonar to reduce hardware resource consumption.

[0065] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0066] Example 1 is a broadband beamforming device for fishing sonar provided by the present invention, Example 2 is a broadband beamforming method for fishing sonar provided by the present invention, and Example 3 is a comparison of the actual effects of a broadband beamforming method for fishing sonar provided by the present invention and a shifted edgeband beamforming algorithm.

[0067] Example 1

[0068] Figure 1 FIG. 1 is a schematic diagram of the structure of a broadband beamforming device according to the present invention. Figure 1 As shown, the broadband beamforming device includes M samplers 1, a mixer 2, a low-pass filter 3, M time shifters 4, M phase shifters 5 and N accumulators 6, where M=2 k , k is an integer greater than or equal to 0, and N represents the number of beams in each array.

[0069] Specifically, the M samplers 1 are respectively connected to the transducers 9 corresponding to each array, and are used to convert the analog voltage signal provided by the transducer 9 into a digital form according to the set sampling rate to obtain M sampling signals; each sampling signal includes multiple sampling values, and the number of the sampling values ​​is equal to the sampling times.

[0070] The mixer 2 is connected to the M samplers 1 respectively, and is used to perform down-mixing processing on the M sampling values ​​obtained by each sampling to obtain M down-mixed signals; the down-mixed signal includes a real part and an imaginary part corresponding to the real part.

[0071] The low-pass filter 3 is connected to the mixer 2 and is used to perform low-pass filtering on the M down-mixed signals respectively to obtain M low-pass filtered signals. The present invention can filter out the image signal generated after the down-mixing process by performing low-pass filtering on the signal obtained after the down-mixing process.

[0072] The M time shifters 4 are respectively connected to the low-pass filters 3 and are used to perform time shift processing on the M low-pass filtered signals respectively to obtain M time-shifted signals, each of which includes N time-shifted results.

[0073] The M phase shifters 5 are respectively connected to the M time shifters 4 to perform phase shift processing on the M×N time shift results to obtain phase shift results corresponding to each time shift result. The phase shifters 5 are connected to the time shifters 4 one-to-one.

[0074] Each of the accumulators 6 is connected to the M phase shifters 5; the N accumulators 6 are used to accumulate the M×N phase shift results by beam to obtain beamforming results of the N beams.

[0075] Furthermore, the broadband beamforming device also includes a matched filter 7; the matched filter 7 is respectively connected to the N accumulators 6 and the host computer 8, and is used to perform matched filtering processing on the N beamforming results to obtain corresponding matched filtering results, so that the host computer 8 displays the N matched filtering results according to the beam angle.

[0076] Furthermore, the sampler 1 includes an analog-to-digital converter 101 and a sampling controller 102 .

[0077] Specifically, the analog-to-digital converter 101 is connected to the transducer 9 of the corresponding array, and is used to convert the analog voltage signal provided by the transducer 9 into a digital sampling signal according to a set sampling rate.

[0078] The sampling controller 102 is connected to the analog-to-digital converter 101 and the mixer 2 respectively, and is used to provide a set sampling rate for the analog-to-digital converter.

[0079] Furthermore, the time shifter 4 includes a time shift data storage unit, a time shift parameter storage unit and a read-write control unit.

[0080] Specifically, the time-shift data storage unit is used to store the low-pass filter signal; the time-shift parameter storage unit is used to store the time-shift parameters of N beams; the read-write control unit is respectively connected to the low-pass filter, the time-shift data storage unit, the time-shift parameter storage unit and the phase shifter 5, and is used to write the low-pass filter signal into the time-shift data storage unit according to the write address, and read the pre-stored low-pass filter signal from the time-shift data storage unit as the time-shift result of each beam according to the read address of each beam, and send it to the phase shifter 5; the read address of each beam is calculated based on the write address and the time-shift parameter of each beam.

[0081] Furthermore, the phase shifter 5 includes a phase shift parameter storage unit, an operation unit, a first multiplication unit, a second multiplication unit and an addition unit.

[0082] Specifically, the phase shift parameter storage unit is used to store the phase shift parameters of N beams. The operation unit is connected to the phase shift parameter storage unit and is used to store the phase shift parameters according to the phase shift parameters. Calculated The value of The first multiplication unit is connected to the operation unit and the time shifter 4, respectively, for the real part of the time shift result and The second multiplication unit is connected to the operation unit and the time shifter 4 respectively, and is used to multiply the imaginary part of the time shift result with The adding unit is connected to the first multiplication unit and the second multiplication unit respectively, and is used to subtract the real part phase shift result from the imaginary part phase shift result to obtain a corresponding phase shift result.

[0083] Preferably, the operation unit comprises a sinusoidal data storage subunit and an operation subunit.

[0084] Specifically, the sine data storage subunit is used to store sine values ​​within a range of 0 to 90 degrees and at intervals of 0.1 degrees; the operation subunit is respectively connected to the phase shift parameter storage unit, the first multiplication unit, the second multiplication unit and the sine data storage subunit, and is used to store the sine values ​​within a range of 0 to 90 degrees and at intervals of 0.1 degrees according to the phase shift parameter. The symmetry and phase relationship of the trigonometric function are obtained from the sine data storage subunit. The value of is calculated based on the trigonometric function relationship. The value of .

[0085] In this embodiment, the depth of the sine data storage subunit is 900. It only needs to store the sine value of 1 / 4 cycle. The sine value and cosine value of the complete cycle can be calculated in real time according to the symmetry and phase relationship of the trigonometric function. In this way, only 1 / 8 of the data is stored to obtain the sine value and cosine value accurate to 0.1°, which further saves resources while ensuring accuracy.

[0086] As a specific implementation, the value of M is 32, the value of N is 40, and the depth of the time-shift data storage unit is 256. The present invention is applicable to a fishing sonar with 32 arrays and 40 beams, but is not limited thereto. The number of arrays and the number of beams of the fishing sonar can be adjusted according to actual needs, and correspondingly, the values ​​of M and N can also be adjusted according to actual needs.

[0087] Figure 2 This is a diagram showing the effect of the broadband beamforming device of the present invention being installed on a ship. Taking the present invention applied to a fishing sonar with 32 arrays and 40 beams as an example, the 32-array transducer array 10 is located underwater and connected to a lifting mechanism 11 inside the hull located on the water surface. The water immersion depth of the transducer array 10 is adjusted by the lifting mechanism 11 connected thereto.

[0088] The broadband beamforming device 13 of the present invention is arranged in the sonar cabin inside the hull, and is connected to the transducer array 10 through a signal line 12 and is connected to the host computer 15 through a data line 14 .

[0089] In actual use, the transducer converts the acoustic signal into an analog voltage signal, and transmits it to the broadband beamforming device 13 through the signal line 12. The broadband beamforming device 13 sequentially samples, down-mixes, low-pass filters, time-shifts, phase-shifts, accumulates by beam, and performs matched filtering on the analog voltage signal to obtain the corresponding matched filtering result, and reports it to the background host computer 15. The host computer 15 displays the matched filtering result of each beam according to the angle of the beam, and marks the target fish school, thereby achieving the purpose of detecting and locating the fish school.

[0090] like Figure 2As shown, after being processed by the broadband beamforming device of the present invention, the beam received by the transducer array is finally processed into 40 detection beams 16, which point to different directions and angles, for example Figure 2 When the third detection beam 16 from the left detects a school of fish, a bright spot will appear at the corresponding position of beam 3 on the interface of the host computer 15, and the operator can go to this position to carry out fishing operations.

[0091] For the case of 32 arrays and 40 beams, the numbers of samplers, mixers, low-pass filters, time shifters, phase shifters, accumulators and matched filters required by the broadband beamforming device using the sideband beamforming algorithm in the prior art are 32, 32, 32, 1280, 1280, 40, and 40 respectively; while the numbers of components required by the broadband beamforming device provided by the present invention are 32, 1, 1, 32, 32, 40, and 1 respectively. Therefore, the broadband beamforming device of the present invention makes maximum use of the high-speed processing capability of the chip, significantly reduces the consumption of hardware resources while ensuring the detection performance of the fishing sonar, and the resource consumption will not increase significantly with the increase in the number of beams and the number of arrays, thereby significantly saving the hardware cost of the fishing sonar, while reducing the overall size of the sonar and reducing its power consumption, which is conducive to the installation and promotion of fishing sonar on fishing boats.

[0092] Example 2

[0093] Common broadband beamforming schemes include direct time delay method, frequency domain beamforming algorithm, and sideband beamforming algorithm. The direct time delay method first performs time compensation on the signals received by each array, and then superimposes each channel to form a beam directivity; since broadband signals have a higher center frequency, the delay accuracy of this algorithm is limited by the sampling rate, so the effect is poor. The frequency domain beamforming algorithm first decomposes the broadband signal into several sub-bands in the frequency domain, performs narrowband beamforming on the sub-band signals, and then obtains the broadband beam output through inverse Fourier transform; the accuracy of the frequency domain beamforming algorithm is limited by the number of decomposed sub-bands, and the amount of calculation is large, so it is not practical in fishing sonar. Figure 3 This is a flow chart of the traditional shifted-sideband beamforming algorithm. Figure 3 As shown in the figure, the sideband beamforming algorithm first mixes the higher carrier frequency signal down to a low frequency, and then performs phase and time compensation. Compared with the frequency domain beamforming algorithm, the accuracy of the sideband beamforming algorithm is improved, but when the number of arrays is large, the processing of phase shift and time shift will consume a lot of resources and needs further improvement.

[0094] The present invention improves the sideband beamforming algorithm and proposes a broadband beamforming method for fishing sonar. The principle is as follows:

[0095] The broadband echo signal received by the i-th phase is:

[0096] S i (t) = cos(2πf0(t-τ i )+γ(t-τ i ))+v i (t);

[0097] Where t is time, f0 is the signal carrier frequency, γ(t) is the phase modulation function, τ i is the delay caused by the acoustic path difference (its size is related to the beam direction), v i (t) is the noise signal.

[0098] The broadband beamforming method of the present invention uses a mixer, a time shifter, and a phase shifter to sequentially transform the broadband echo signal S i (t) = cos(2πf0(t-τ i )+γ(t-τ i ))+v i The 2πf0(t) term in (t), γ(-τ i ) term, 2πf0(τ i ) term is removed, and the image signal generated by the mixing is removed by using a low-pass filter, so that only the effective signal cos(γ(t)) and the noise signal v are retained in the broadband echo signal i (t) is used as the phase shift result, and the phase shift results of each beam are accumulated by an accumulator to obtain the beamforming results of each beam. Finally, the beamforming results are processed by a matched filter, and the final results are reported to the host computer so that the host computer can display the matched filtering results of each beam according to the angle of the beam.

[0099] Figure 4 is a flow chart of the broadband beamforming method of the present invention, as shown in Figure 4 As shown, the broadband beamforming method includes:

[0100] Step S1: According to the set sampling rate, the analog voltage signals provided by the transducers corresponding to the M arrays are converted into digital form to obtain M sampling signals; each sampling signal includes multiple sampling values, and the number of sampling values ​​is equal to the number of sampling times; wherein M=2 k , k is an integer greater than or equal to 0.

[0101] Step S2: Down-mix the M sampling values ​​obtained by each sampling to obtain M down-mixed signals; the down-mixed signals include a real part and an imaginary part corresponding to the real part. This step is used to convert the broadband echo signal S i (t) = cos(2πf0(t-τ i )+γ(t-τ i ))+v iThe term 2πf0(t) in (t) is removed.

[0102] Step S3: low-pass filter the M down-mixed signals respectively to obtain M low-pass filtered signals; the low-pass filtered signals include a real part and an imaginary part corresponding to the real part. This step is used to remove the image signal generated by the down-mixing process.

[0103] Step S4: Time-shift the M low-pass filtered signals respectively to obtain M time-shifted signals, each of which includes N time-shifted results, where N represents the number of beams in each array; the time-shifted results include a real part and an imaginary part corresponding to the real part. i (t) = cos(2πf0(t-τ i )+γ(t-τ i ))+v i (t) in γ(-τ i ) item is removed.

[0104] Step S5: Perform phase shift processing on the M×N time shift results respectively to obtain the phase shift results corresponding to each time shift result; the phase shift results include a real part and an imaginary part corresponding to the real part. This step is used to convert the broadband echo signal S i (t) = cos(2πf0(t-τ i )+γ(t-τ i ))+v i 2πf0(τ in (t) i ) is removed, so that only the effective signal cos(γ(t)) and the noise signal v are retained in the broadband echo signal i (t) as a phase shift result.

[0105] Step S6: Accumulate the M×N phase shift results by beam to obtain beamforming results of N beams.

[0106] Furthermore, after step S6, the method further includes:

[0107] Step S7: performing matched filtering processing on the N beamforming results to obtain corresponding matched filtering results, and sending the results to a host computer so that the host computer displays the N matched filtering results according to the beam angles.

[0108] The following is a detailed discussion of each step:

[0109] Preferably, step S4 specifically includes:

[0110] Step S41: storing the low-pass filtered signal in sequence into a time-shifted data storage unit with a depth of H according to a write address, where H is a positive integer greater than or equal to N.

[0111] Step S42: Calculate the read address of each beam in turn according to the write address and the preset time shift parameters of each beam, and read out the pre-stored low-pass filtered signal from the time shift data storage unit in turn according to the read address as the time shift result of each beam.

[0112] Step S43: add 1 to the write address, and return to zero if the write address exceeds H-1.

[0113] Figure 5 FIG. 1 is a schematic diagram showing the working principle of the time shifter of the broadband beamforming device of the present invention. Figure 5 As shown, taking the value of H as 256 (i.e., the depth of the time-shift data storage unit is 256) as an example, assuming that the time-shift parameter of beam 1 is 3, the time-shift parameter of beam N is 1, and the write address corresponding to the current sampling is 3, firstly, the low-pass filter signal including the real part and the imaginary part transmitted by the low-pass filter is stored in the position corresponding to the write address in the time-shift data storage unit; then, according to the write address and the preset time-shift parameter of beam 1, the read address of beam 1 is calculated to be 0 (i.e., write address 3-time-shift parameter 3 of beam 1=read address 0), therefore, the pre-stored low-pass filtered signal data is read at address 0 of the time-shift parameter storage unit as the time-shift result of beam 1; by analogy, according to the write address and the pre-set time-shift parameter of beam N, the read address of beam N is calculated to be 2 (i.e., write address 3 - time-shift parameter 1 of beam N = read address 2), therefore, the pre-stored low-pass filtered signal data is read at address 2 of the time-shift parameter storage unit as the time-shift result of beam N; finally, the write address is increased by 1, and the above operation is repeated at the next sampling.

[0114] Preferably, step S5 specifically includes:

[0115] Step S51: Obtain the phase shift parameters of each beam respectively

[0116] Step S52: According to the phase shift parameter Calculated The value of The value of .

[0117] Step S53: According to the time shift results of each beam, and The phase shift results of the N beams are calculated sequentially.

[0118] In the broadband beamforming method of the present invention, the mathematical principle used for phase shifting the time shift results of each beam is as follows:

[0119]

[0120] Among them, Y ijrepresents the phase shift result of the jth beam in the i-th array, X ij represents the time shift result of the jth beam in the i-th array, X ij re represents the real part of the time shift result of the jth beam in the i-th array, X ij im represents the imaginary part of the time shift result of the jth beam in the i-th array, is the phase shift parameter of the jth beam in the i-th array, f0 represents the signal carrier frequency, τ ij Represents the delay caused by the sound path difference; where i is a positive integer from 1 to M, and j is a positive integer from 1 to N.

[0121] Figure 6 FIG. 1 is a schematic diagram showing the working principle of the phase shifter of the broadband beamforming device of the present invention. Figure 6 As shown, the phase shift module uses a sine data storage subunit with a depth of 900 to store sine values ​​of 0 to 90° with an interval of 0.1°. For each beam, first obtain its corresponding phase shift parameter according to Lookup from the sine data storage subunit The value of is then calculated based on the trigonometric relationship. The value of , and finally use the formula Two multipliers and one adder are used to calculate and obtain the corresponding phase shift result Y.

[0122] In this embodiment, the time shift parameter and the phase shift parameter are data obtained in advance through simulation tests and stored in the broadband beamforming device of the present invention, wherein the time shift parameter is an integer and the phase shift parameter is an angle.

[0123] Preferably, step S7 specifically includes: using time division multiplexing technology to perform matched filtering processing on the N beamforming results, obtaining N matched filtering results output in series and sending them to a host computer, so that the host computer displays the N matched filtering results according to the beam angle.

[0124] Preferably, step S2 specifically includes: using time division multiplexing technology to perform down-mixing processing on the M sampling values ​​respectively to obtain M down-mixed signals output in series.

[0125] Preferably, step S3 specifically includes: using time division multiplexing technology to perform low-pass filtering on the M down-mixed signals respectively to obtain M low-pass filtered signals output in series.

[0126] Example 3

[0127] Taking 32 arrays and 40 beams as an example, the comparison results of the number of modules between the shifted edgeband beamforming algorithm and the improved broadband beamforming method of the present invention are shown in Table 1.

[0128] Table 1 Comparison of the number of modules of the sideband beamforming algorithm and the broadband beamforming method of the present invention

[0129]

[0130] As shown in Table 1, after the above improvements in the broadband beamforming method of the present invention, each array only needs one time shifter and one phase shifter to serially complete the time shift and phase shift processing of 40 beams, thereby significantly reducing the number of modules, and the resource consumption will not increase with the increase in the number of beams. At the same time, by serializing the modules with higher complexity (mixer, low-pass filter, matching filter), the resource utilization rate is further improved.

[0131] Figure 7 The broadband beamforming method of the present invention (ie Figure 7 The comparison of the measured beamforming results of the improved algorithm in () and the sideband shift beamforming algorithm is shown in the figure. Figure 7 As shown, both schemes can perform beamforming on the data of each array after down-mixing and low-pass filtering, and the simulation results are basically consistent, with no performance difference.

[0132] In order to compare the resource consumption of the two algorithms under different array numbers, the beamforming devices were implemented using FPGA respectively. Table 2 is a comparison table of FPGA resources consumed by the shifted edgeband beamforming algorithm and the broadband beamforming method of the present invention.

[0133] Table 2 Comparison of FPGA resources consumed by the shifted-sideband beamforming algorithm and the broadband beamforming method of the present invention

[0134]

[0135] As shown in Table 2, under different array numbers, the main logic resources (lookup table, register, storage block) consumed by the broadband beamforming method of the present invention are lower than those of the sideband beamforming algorithm.

[0136] Figure 8 The broadband beamforming method of the present invention (ie Figure 8 The comparison of the lookup table resources consumed by the improved algorithm in () and the sideband beamforming algorithm is shown in the figure. Figure 8 As shown in (a), as the number of arrays increases, the number of lookup tables consumed by the broadband beamforming method of the present invention is slightly reduced compared to the sideband beamforming algorithm; Figure 8 As shown in (b), as the number of arrays increases, the proportion of lookup tables saved by the broadband beamforming method of the present invention increases slightly compared to the sideband beamforming algorithm.

[0137] Fig. 9 The broadband beamforming method of the present invention (ie Fig. 9The comparison of register resources consumed by the improved algorithm in () and the shifted sideband beamforming algorithm is shown in the figure. Fig. 9 As shown in (a), as the number of arrays increases, the number of registers consumed by the broadband beamforming method of the present invention is slightly reduced compared to the sideband beamforming algorithm; Fig. 9 As shown in (b), as the number of arrays increases, the proportion of registers saved by the broadband beamforming method of the present invention increases slightly compared to the sideband beamforming algorithm, and the change trend is similar to the lookup table resources.

[0138] Fig.10 The broadband beamforming method of the present invention (ie Fig.10 The comparison of storage block resources consumed by the improved algorithm in () and the sideband beamforming algorithm is shown in the figure. Fig.10 As shown in (a), as the number of arrays increases, the number of storage blocks consumed by the broadband beamforming method of the present invention is significantly reduced compared to the sideband beamforming algorithm; Fig.10 As shown in (b), as the number of arrays increases, the proportion of storage blocks saved by the improved algorithm increases significantly compared to the sideband beamforming algorithm, and 90.6% of the storage blocks are saved when 64 arrays are used.

[0139] The present invention serially time-division multiplexes modules such as time shift, phase shift, and matched filtering according to beams, and adjusts the time shift processing to before the phase shift processing, thereby making maximum use of the high-speed processing capability of the chip. By applying the present invention in fishing sonar, the consumption of hardware resources can be reduced while ensuring the detection performance, thereby significantly saving the hardware cost of the fishing sonar, while reducing the size of the whole sonar machine and its power consumption, which is conducive to the installation and promotion of fishing sonar on fishing boats.

[0140] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0141] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A broadband beamforming device for fishing sonar, characterized in that: The broadband beamforming device comprises: M samplers, where M = 2 k , k is an integer greater than or equal to 0; the M samplers are respectively connected to the transducers corresponding to each array, and are used to convert the analog voltage signal provided by the transducer into a digital form according to the set sampling rate to obtain M sampling signals; each sampling signal includes a plurality of sampling values, and the number of the sampling values ​​is equal to the number of sampling times; A mixer, connected to the M samplers respectively, for performing down-mixing processing on the M sampling values ​​obtained by each sampling to obtain M down-mixed signals; the down-mixed signals include a real part and an imaginary part corresponding to the real part; A low-pass filter, connected to the mixer, for performing low-pass filtering on the M down-mixed signals respectively to obtain M low-pass filtered signals; M time shifters are respectively connected to the low-pass filters, and are used to perform time shift processing on the M low-pass filter signals respectively to obtain M time-shifted signals, each of which includes N time-shifted results, where N represents the number of beams in each array; M phase shifters are respectively connected to the M time shifters, and are used to perform phase shift processing on the M×N time shift results respectively to obtain phase shift results corresponding to each time shift result; N accumulators; each of the accumulators is connected to the M phase shifters; the N accumulators are used to accumulate the M×N phase shift results by beam to obtain beamforming results of the N beams; The time shifter comprises: A time-shift data storage unit, used for storing the low-pass filtered signal; A time shift parameter storage unit, used for storing the time shift parameters of N beams; A read-write control unit, connected to the low-pass filter, the time-shift data storage unit, the time-shift parameter storage unit and the phase shifter, respectively, for writing the low-pass filter signal into the time-shift data storage unit according to a write address, and reading the pre-stored low-pass filter signal from the time-shift data storage unit as the time-shift result of each beam according to the read address of each beam, and sending it to the phase shifter; the read address of each beam is calculated based on the write address and the time-shift parameter of each beam; The phase shifter comprises: Phase shift parameter storage unit, used to store the phase shift parameters of N beams A computing unit connected to the phase shift parameter storage unit for calculating the phase shift parameter according to the phase shift parameter Calculated The value of The value of The first multiplication unit is connected to the operation unit and the time shifter, respectively, and is used to multiply the real part of the time shift result by Multiply them to get the real part phase shift result; The second multiplication unit is connected to the operation unit and the time shifter, respectively, and is used to multiply the imaginary part of the time shift result by Multiply them to get the imaginary phase shift result; The adding unit is connected to the first multiplication unit and the second multiplication unit respectively, and is used to subtract the real part phase shift result from the imaginary part phase shift result to obtain a corresponding phase shift result.

2. The broadband beamforming device according to claim 1, characterized in that: The broadband beamforming device further comprises: The matched filters are connected to the N accumulators and the host computer respectively, and are used to perform matched filtering on the N beamforming results to obtain corresponding matched filtering results, so that the host computer can display the N matched filtering results according to the beam angle.

3. The broadband beamforming device according to claim 1, characterized in that: The computing unit comprises: The sine data storage subunit is used to store sine values ​​within the range of 0 to 90 degrees with an interval of 0.1 degrees; The operation subunit is connected to the phase shift parameter storage unit, the first multiplication unit, the second multiplication unit and the sine data storage subunit respectively, and is used to calculate the phase shift parameter according to the phase shift parameter. The symmetry and phase relationship of the trigonometric function are obtained from the sine data storage subunit. The value of is calculated based on the trigonometric function relationship. The value of .

4. A broadband beamforming method for fishing sonar, applied to the broadband beamforming device for fishing sonar as claimed in claim 1, characterized in that: The broadband beamforming method comprises: Step S1: According to the set sampling rate, the analog voltage signals provided by the transducers corresponding to the M arrays are converted into digital form to obtain M sampling signals; each sampling signal includes multiple sampling values, and the number of sampling values ​​is equal to the number of sampling times; wherein M=2 k , k is an integer greater than or equal to 0; Step S2: performing down-mixing processing on the M sampling values ​​obtained by each sampling respectively to obtain M down-mixed signals; the down-mixed signals include a real part and an imaginary part corresponding to the real part; Step S3: performing low-pass filtering on the M down-mixed signals respectively to obtain M low-pass filtered signals; Step S4: performing time shift processing on the M low-pass filtered signals respectively to obtain M time-shifted signals, each of which includes N time-shifted results, where N represents the number of beams in each array; Step S5: performing phase shift processing on the M×N time shift results respectively to obtain phase shift results corresponding to each time shift result; Step S6: Accumulate the M×N phase shift results by beam to obtain beamforming results of N beams.

5. The broadband beamforming method according to claim 4, characterized in that: After step S6, the method further includes: Step S7: performing matched filtering processing on the N beamforming results to obtain corresponding matched filtering results, and sending the results to a host computer so that the host computer displays the N matched filtering results according to the beam angles.

6. The broadband beamforming method according to claim 4, characterized in that: The step S4 specifically includes: Step S41: storing the low-pass filtered signal in sequence into a time-shift data storage unit with a depth of H according to a write address, where H is a positive integer greater than or equal to N; Step S42: according to the write address and the preset time shift parameters of each beam, the read address of each beam is calculated in sequence, and according to the read address, the pre-stored low-pass filter signal is read out in sequence from the time shift data storage unit as the time shift result of each beam; Step S43: add 1 to the write address, and return to zero if the write address exceeds H-1.

7. The broadband beamforming method according to claim 4, characterized in that: The step S5 specifically includes: Step S51: Obtain the phase shift parameters of each beam respectively Step S52: According to the phase shift parameter Calculated The value of The value of Step S53: According to the time shift results of each beam, and The phase shift results of the N beams are calculated sequentially.

8. The broadband beamforming method according to claim 5, characterized in that: The step S7 specifically includes: The N beamforming results are processed by matched filtering using time division multiplexing technology to obtain N matched filtering results output in series and send them to a host computer, so that the host computer displays the N matched filtering results according to the angle of the beam.

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