CN111505611A - Broadband sonar receiving beam forming method for fishing based on cylindrical transducer array - Google Patents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
- G01S15/96—Sonar systems specially adapted for specific applications for locating fish
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
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Abstract
The invention provides a broadband sonar receiving beam forming method based on a cylindrical transducer array, which is realized by utilizing the cylindrical transducer array. In the method, a cylindrical transducer array is adopted, a detection area is divided into a plurality of sectors, each sector corresponds to a partial arc array of the cylindrical transducer, the whole horizontal 360-degree detection is realized by horizontally and uniformly receiving beams at intervals for each sector, the operational capacity of the device is comprehensively considered, a plurality of arrays participate in a multi-channel receiver for processing, the processing program of each multi-channel receiver is the same, and the system maintainability is improved. The invention adopts the broadband beam forming method based on complex envelope, reduces the requirement of the sampling rate of the system, and realizes higher beam forming performance under the condition of lower sampling.
Description
Technical Field
The invention relates to the field of fishery equipment, in particular to a broadband sonar receiving beam forming method for fishery based on a cylindrical transducer array.
Background
The fishing sonar is taken as the most typical marine fishery fishing instrument, is an important means for acquiring the quantity and spatial distribution information of marine fish resources, and has an important role in improving the efficient, accurate and selective fishing of the marine fishery fishing. In order to obtain higher spatial detection resolution and fish species identification capability, marine fishery detection is rapidly developing towards the technical directions of bandwidth, multi-beam and the like. Particularly, with the development of microelectronic technology and artificial intelligence technology in recent years, a new technical development direction is brought to the development of fishing sonar, and a large-scale signal processor continuously provides hardware conditions for the use of more complex and higher-performance fish-finding signal processing technology, so that a chance is brought to the development of fishing sonar with higher performance.
The multi-beam sonar for fishing generally adopts a plane transducer array and a cylindrical transducer array, and the plane transducer array can only scan the sea area with a certain open angle (generally less than 90 degrees) of the course of the fishing boat; the cylindrical transducer array can realize horizontal 360-degree scanning centered on a fishing boat and vertical 60-degree scanning. As shown in figure 1, the working process of the multi-beam sonar for fishing is that a certain inclination angle is set according to the working environment, then the periodic repeated horizontal scanning is carried out, when a fish school is found, the vertical scanning is carried out in the horizontal direction of the found fish school, and therefore the multi-angle three-dimensional detection of the fish school is achieved.
The fishing sonar usually adopts signal forms including narrow-band signals and wide-band signals, narrow-band signal beam forming can be realized through phase shifting, but the anti-reverberation capability of the sonar is poor, particularly the interface reverberation capability brought by sea surface and seabed reflection, and the detection distance of a narrow-band signal system is limited. The fishing sonar adopts the broadband signal form, can effectual reduction interface reverberation's influence, improve fishing sonar's detection distance, but the broadband signal has phase modulation, so can not realize through simply must shifting phase, traditional approach sends the main control computer through multichannel signal is unified, carry out the method that adds up after the time delay in the main control computer and accomplish beam forming, it is higher to system's sampling phase deviation requirement, need higher sampling frequency, also bring great operand to follow-up signal processing, increase system complexity, bring the increase of overall cost.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a cylindrical transducer array-based broadband sonar receiving beam forming method for fishing, which adopts a complex envelope-based broadband beam forming method, reduces the requirement of the sampling rate of the system, realizes higher beam forming performance under the condition of lower sampling and solves the problem of complexity of a broadband signal sonar system in the prior art.
The technical scheme provided by the invention is as follows:
a broadband sonar receiving beam forming method for fishing based on a cylindrical transducer array is realized by using the cylindrical transducer array, wherein the cylindrical transducer array comprises a plurality of arrays distributed on a cylindrical surface, and the cylindrical transducer array is divided into a plurality of physical sectors along the axis direction; at least two adjacent physical sectors form a receiving sector for receiving beams, and the ratio of the arc length of the receiving sector to the perimeter of the cylindrical transducer array is 1:3 to 1: 6; at least one of the physical sectors is involved in a beamforming process for at least two of the receiving sectors, the receiving sectors being configured to simultaneously receive a plurality of beams, the beamforming process for each beam comprising the steps of:
(S1) calculating a sound path between each array in each of the receiving sectors and the origin of the cylindrical transducer array;
(S2) sampling signals received by each of the elements;
(S3) finding a complex envelope of the sampled signal;
(S4) performing phase compensation on the complex envelope of the received signal of each of the arrays;
(S5) performing delay compensation on the phase-compensated complex envelope;
(S6) carrying out weighted accumulation on the complex envelope after each array delay compensation in each physical sector to form partial wave beams;
(S7) performing weighted addition on the partial beams of each physical sector in the reception sector to obtain an output beam.
The invention is further improved in that the cylindrical transducer array comprises 32 linear arrays distributed along the direction of the generatrix of the cylindrical surface; each linear array comprises 8 arrays, and the linear arrays are distributed on the cylindrical surface at equal intervals; each physical sector comprises 4 linear arrays, and each receiving sector is composed of two physical sectors; the ratio of the arc length of the receiving sector to the perimeter of the cylindrical transducer array is 1: 4.
The further improvement of the present invention is that the signal received by the receiving array of each physical sector is processed by a multi-channel receiver, after the partial beams are obtained, the multi-channel receiver sends partial beams to the main control computer, and the main control computer performs weighted addition on the partial beams to obtain output beams.
In the step S1, the invention further improves that the expression of the acoustic path between the array i and the origin of the cylindrical transducer array is calculated as follows:
wherein: [ x ] ofi，yi，zi]Is the rectangular coordinate of the array i in the cylindrical transducer array,
is the incident direction of the beam to be received.
In a further improvement of the present invention, in step S2, the sampling frequency is 1Mhz, and the signal expression obtained by sampling is:
si(n)＝cos(2πf0n-2πf0τi+γ(n-τi))+vi(n)
wherein: f. of0For the carrier frequency of the signal, gamma (t) is the phase modulation function, vi(n) noise superimposed on the received signal, τiIs the path difference.
A further improvement of the present invention resides in that, in the above-mentioned step S3:
the sampled signal si(n) and cos (2 π f)0n) multiplying and low-pass filtering the result of the multiplication to obtain the real part of the complex envelope:
Xeri(t)＝[cos(2πf0τi+γ(n-τi))]/2+wi(n)
the sampled signal si(n) and sin (2 π f)0n) multiplication and low-pass filtering the result of the multiplication to obtain the imaginary part of the complex envelope:
Ximi(t)＝[sin(2πf0τi+γ(n-τi))]/2+wi(n)
wherein, wiAnd (n) is a noise signal.
A further improvement of the invention is that the complex envelope of the received signal of the array i participates in the beamforming process of the multiple beams received by the receiving sector in which it is located.
A further improvement of the present invention resides in that, in the above-mentioned step S4: the complex envelope is subjected to phase shift operation by a trigonometric function formula to remove the corresponding direction as
Constant phase of beam
The expression is as follows:
the above expression is developed to obtain:
the present invention is further improved in that, in the delay compensation process in the above step S5, the orientation is set to be according to the lattice i
Relative path difference of wave beam
And carrying out time delay processing on the complex envelope, wherein the expression is as follows:
In a further improvement of the present invention, in the step S6, the array pairs in the physical sector are pointed to
The complex envelope of the beam is weighted, which is expressed as:
wherein weight _ totaliThe expression of the weight in the weighted accumulation process is as follows:
weight_total＝weight_line(:)*weight_column(1,:)
wherein, weight _ line (: is the weight of the first array i in the vertical linear array where the array is located, and weight _ column (1): is the weight of the linear array where the array is located in the physical sector.
Compared with the prior art, the invention has the following beneficial effects:
(1) the fishing sonar adopts the cylindrical transducer array, divides a detection area into a plurality of sectors, each sector corresponds to a partial arc array of the cylindrical transducer, realizes the detection of the whole horizontal 360 degrees by carrying out horizontal uniform interval beam receiving on each sector, comprehensively considers the operational capacity of devices, participates a plurality of arrays into a multi-channel receiver for processing, realizes the same processing program of each multi-channel receiver, and improves the maintainability of the system;
(2) the invention adopts the broadband beam forming method based on complex envelope, reduces the requirement of the sampling rate of the system, and realizes higher beam forming performance under the condition of lower sampling.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic view of the working process of a multi-beam sonar for fishing in the prior art;
FIG. 2 is a hardware architecture diagram of the omnibearing broadband sonar system employed in the present invention;
FIG. 3 is a schematic diagram of a coordinate system of the cylindrical transducer array in this embodiment;
FIG. 4 is a schematic diagram of the physical sector division of the cylindrical transducer array in this embodiment;
FIG. 5 is a schematic diagram of a receiving sector;
FIG. 6 is a schematic diagram of a beam combining process between two multi-channel receivers;
fig. 7 is a schematic diagram of a beamforming process;
FIG. 8 is a waveform diagram of a 20kHz-30kHz chirp signal;
FIG. 9 is a schematic waveform of the real part of the complex envelope of a plurality of arrays;
FIG. 10 is a waveform diagram of the complex envelopes of three arrays after phase compensation;
FIG. 11 is a waveform diagram of a phase compensated complex envelope;
FIG. 12 shows the multi-element weighted accumulation output of the single-multi-channel receiver;
the receiving sector of fig. 13 performs beamforming on a certain receiving beam and finally outputs the result.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
The invention provides a broadband sonar receiving beam forming method based on a cylindrical transducer array, which is realized based on an omnibearing broadband sonar system shown in figure 2. The omnibearing broadband sonar for fishing comprises a 256-channel cylindrical transducer array, a signal processing host and a main control computer.
In the cylindrical transducer array, each array is distributed on the cylindrical surface of the cylindrical transducer array and works independently to complete the electro-acoustic conversion during the transmission of underwater acoustic signals and the acousto-electric conversion during the receiving.
The signal processing host consists of a plurality of multi-channel receivers (used for multi-channel receiving and transmitting, a signal processor, a receiving and transmitting transfer switch and the like), an exchanger, a back plate and the like, and is responsible for generating transmitting signals and driving a transmitting circuit during transmitting so as to realize high-power signal transmitting; in reception, signals received by the transducer are processed in analog and digital form, including filtering, amplification, down conversion, beamforming, etc.
The main control computer is responsible for the main control processes of setting the whole sonar operation parameters, setting the operation mode and the like and the processing process of the acoustic echo image; other peripheral modules comprise a display, a keyboard (including a mouse) and a signal processing host machine which are matched to finish the display of sonar detection images and the input and control of setting parameters and the like.
In order to transmit and receive a plurality of wave beams simultaneously, the array of the cylindrical transducer array adopts a multiplexing design according to the sector. Each array is distributed on the cylindrical surface, and the axis of the cylindrical surface is arranged along the vertical direction when the array is used. The sector is divided into a plurality of physical sectors along the axial direction of the transducer, and each physical sector comprises a plurality of arrays distributed on the surface of the arc sector.
The physical sectors are not divided uniquely. For example, physical sectors with smaller arc lengths may be used in the emphasis detection direction and more densely arranged arrays may be used, and sectors with larger arc lengths may be used in the non-emphasis direction and the arrays may be arranged more sparsely. The physical sectors may also be divided in the form of equally divided cylindrical surfaces, for example, the cylindrical transducer array may be divided equally along its axis into 12 physical sectors (30 ° per arc), 8 physical sectors (45 ° per arc), and 6 physical sectors (60 ° per arc).
In a cylindrical transducer array, at least two adjacent physical sectors form a receive sector for a receive beam. Each receive sector is used to receive multiple waveforms. Each physical sector participates in at least two receiving sectors, thereby realizing a multiplexing design. For the above-mentioned multiple physical sector division modes, the receiving sector may also adopt corresponding multiple division modes. For example, for a cylindrical transducer array divided into 12 physical sectors, any 2 or 3 adjacent physical sectors may be divided into one receiving sector, in which case the ratio of the arc length of a physical sector to the circumference of the cylindrical transducer array is 1:6 or 1: 4. For a cylindrical transducer array divided into 6 physical sectors, any 2 adjacent physical sectors can be divided into one receiving sector, and in this case, the ratio of the arc length of the physical sectors to the circumference of the cylindrical transducer array is 1: 3.
As shown in fig. 3 and 4, in a specific embodiment, the cylindrical transducer array is divided into 8 physical sectors along the axial direction, each physical sector has an arc length of 45 °, and each physical sector has 32 arrays. In the signal processing host, signals received by the array of each physical sector are processed by a 32 receiver/transmitter (hereinafter referred to as a multi-channel receiver). In each physical sector, 32 arrays are divided into four columns, and each column of arrays is parallel to the axial direction of the cylindrical transducer array.
For the convenience of signal processing, a coordinate system needs to be established in the cylindrical transducer array in order to clarify the coordinate position of each array. In the above embodiments, the transducer coordinate system origin is the transducer center. The sailing direction of the ship is taken as the X-axis direction, the horizontal vertical direction of the course direction is taken as the Y-axis direction, the vertical direction of the course direction is taken as the Z-axis direction, and the origin of the Z axis is positioned in the middle of the height of the transducer.
In the above embodiment, the cylindrical transducer array has M rows and N columns, where M is 8 and N is 32. One row is an array arranged in a straight line to form a linear array. The linear arrays are arranged along the bus direction of the cylindrical transducer array, and the linear arrays are distributed on the cylindrical surface at equal intervals.
And adjacent linear arrays are distributed in a vertically staggered manner. The vertical staggered distribution means that among any three adjacent linear arrays, the linear arrays on two sides are equal in height, and the linear array in the middle is higher or lower than the other two linear arrays. In the cylindrical transducer array, one row of the array forms a circle with two adjacent arrays staggered up and down. The column numbers are numbered, 1, 2, 3 …..31, 32, counterclockwise from the right side of the X axis. The line numbers are 1, 2, 3 … … 7, and 8 from bottom to top. Corresponding to a spherical coordinate system, the counterclockwise direction from the X axis is 0 to 180 degrees, and the clockwise direction is 0 to-180 degrees. The vertical Z-axis positive half shaft is from-90 degrees to 90 degrees from top to bottom. As shown in fig. 4, eight multichannel receivers numbered 1# to 8# are responsible for signal reception of each array in one physical sector.
As shown in fig. 4 and 5, the cylindrical transducer has 8 receiving sectors. The physical sectors corresponding to the multichannel receiver 8# and the multichannel receiver 1# form a 1 st receiving sector; the physical sectors corresponding to the multichannel receiver 1# and the multichannel receiver 2# form a 2 nd receiving sector; the physical sectors corresponding to the multichannel receiver 2# and the multichannel receiver 3# form a 3 rd receiving sector; and so on. The eight physical sectors form eight receiving sectors with arc length of 90 degrees, and each physical sector has arc length of 45 degrees and participates in two receiving sectors.
For each receiving sector, which comprises a coordinate system in the same form, an independent coordinate system needs to be determined. For a receiving sector, the independent coordinate system takes the coordinate origin of the cylindrical transducer array as the coordinate origin of the receiving sector, the normal direction of a sector arc passing through the origin as an X axis, the horizontal vertical line passing through the origin as a Y axis, and the Z axis of the cylindrical transducer array as a Z axis. The vertical angle definition under the spherical coordinate system is consistent with that of the cylindrical transducer array, the horizontal angle definition is defined by the X axis of the transducer, and the anticlockwise direction from the X axis is 0-180 degrees, and the clockwise direction is 0-180 degrees. That is, the horizontal angle of the sector is the horizontal angle of the cylindrical transducer array minus the sector rotation angle.
In the above embodiment, the cylindrical transducer has 8 receive sectors, each of which completes 20 beams, covering a-22.5 ° to 22.5 ° area (in the independent coordinate system of the receive sectors) in front of the respective receive sector, with the beams spaced 2.25 ° apart. The horizontal angles of the 20 beams for each receive sector are: -21.375 °, -19.125 °, -16.875 °, -14.625 °, -12.375 °, -10.125 °, -7.875 °, -5.625 °, -3.375 °, -1.125 °, 3.375 °, 5.625 °, 7.875 °, 10.125 °, 12.375 °, 14.625 °, 16.875 °, 19.125 °, 21.375 °.
As shown in fig. 4 and 5, in the above embodiment, since there are 1 common physical sector between two receiving sectors, the multi-channel receiver corresponding to a single physical sector needs to participate in the 40-beam forming; for a multi-channel receiver of a single physical sector, the left half beam or the right half beam of a certain beam which participates in the reception can be obtained through each array connected with the multi-channel receiver. After the left/right half beams are obtained, the multichannel receiver sends the left/right half beams to the main control computer through the switch, and the main control computer can perform weighted superposition on the left half beams and the right half beams of the received beams to obtain the output beams.
As shown in fig. 6 and 7, specifically, the forming process of each beam includes the following steps:
(S1) calculating the sound path between each array in the receiving sector and the origin of the cylindrical transducer array; the calculation process is carried out under an independent coordinate system of the receiving sector; the rectangular coordinate of the array under the coordinate system is assumed to be [ xi，yi，zi]And then the expression of the acoustic path from the array i to the origin of the cylindrical transducer array is as follows:
wherein,
is ready to receiveThe incident direction of the received beam; for different beams to be received, the array i and the origin of the coordinate system have different acoustic path differences.
(S2) sampling the signals received by each array; under the condition that all multi-channel receivers are synchronous, digital sampling is carried out on underwater acoustic echo signals by adopting 1Mhz sampling frequency, and broadband signals to be received are as follows:
s(t)＝cos(2πf0t+γ(t))
wherein f is0Is the signal carrier frequency, gamma (t) phase modulation function. Fig. 8 shows a chirp signal with a carrier frequency of 20kHz and a bandwidth of 10kHz in this embodiment.
For the signal received by any array i, a certain delay tau exists due to the acoustic path differenceiThe magnitude of this delay is related to the beam direction. At the same time, the received signal is superimposed by noise vi(n) of (a). The expression for the received signal of the array i is:
si(n)＝cos(2πf0n-2πf0τi+γ(n-τi))+vi(n)
wherein: f. of0For the carrier frequency of the signal, gamma (t) is the phase modulation function, vi(n) noise superimposed on the received signal, τiIs the path difference. The above formula is unfolded to obtain
si(n)＝cos(2πf0n-2πf0τi+γ(n-τi))+vi(n)
Because the carrier frequency does not contain useful information of the signal, the beam forming can be carried out by solving the phase modulation function theta (n), and the output signal-to-noise ratio of the system is improved.
It is convenient to understand that the following description is made by a simple trigonometric function operation process, in the above formula, 2 pi f0n，-2πf0τi，-τiFor three characteristic quantities, the latter two terms are related to a given array and a given beam direction, we need to remove these three quantities through signal processing to obtain the complex envelope cos (θ (n)) of the received signal of each array, and finally, the complex envelopes of the received signals of all the arrays of the sector are summed to obtain the beam forming result. In the next step, IThey will remove 2 π f by means of a down-conversion + low-pass filtering0n, by phase-shifting to remove-2 π f0τiAnd by means of a time delay, -tau is removedi。
(S3) finding a complex envelope of the sampled signal; by finding the complex envelope, carrier frequencies that do not contain useful information can be removed. The envelope signal is used for beam forming, and the phase error influence of the sampling signal can be reduced. Specifically, the method for obtaining the complex envelope specifically comprises the following steps:
(S31) sampling the signal Si(n) and cos (2 π f)0n) multiplying and low-pass filtering the result of the multiplication to obtain the real part of the complex envelope: xeri(t)＝[cos(2πf0τi+γ(n-τi))]/2+wi(n)。
Sampled signal si(n) and cos (2 π f)0n) the expression after multiplication is:
si(n).*cos(2πf0n)＝cos(2πf0n-2πf0τi+γ(n-τi)).*cos(2πf0n)+vi(n)*cos(2πf0n)
from the trigonometric function formula, the above formula can be found as:
＝[cos(2πf0τi+γ(n-τi))+cos(2π*2f0n-2πf0τi+γ(n-τi))]/2+vi(n)*cos(2πf0n)
low-pass filtering to obtain real part of complex envelope of signal
Xeri(t)＝[cos(2πf0τi+γ(n-τi))]/2+wi(n)
(S32) sampling the signal Si(n) and sin (2 π f)0n) multiplication and low-pass filtering the result of the multiplication to obtain the imaginary part of the complex envelope:
Ximi(t)＝[sin(2πf0τi+γ(n-τi))]/2+wi(n)
wherein, wiAnd (n) is a noise signal.
The complex envelope determined in this step includes information of all beams that the array i needs to receive, and thus the complex envelope of the array i determined in step (S3) needs to participate in a plurality of beamforming processes. In the process of forming a plurality of beams by a certain receiving sector, the complex envelope of each array of the receiving sector only needs to be solved once. Fig. 9 is a waveform diagram showing the real part of the complex envelope of a plurality of arrays.
(S4) performing phase compensation on the complex envelope of the received signal of each of the arrays. Real part of complex envelope Xeri(n) and imaginary part Ximi(n) including variables in the expression
Which for each array point to
The phase constant value of the wave beam is removed by phase shift operation through a trigonometric function formula; the expression is as follows:
the above expression is developed to obtain:
fig. 10 is a waveform diagram of complex envelopes of three arrays after phase compensation, and after phase compensation, only fixed time delay is left between receiving signals of each array for any one receiving beam.
(S5) delay time compensating the phase compensated complex envelope. The purpose of the delay compensation is to eliminate the fixed delay mentioned above. In the delay compensation process, the direction is determined according to the array i
Relative path difference of wave beam
For complex envelopeLine delay processing, the expression of which is:
(S6) carrying out weighted accumulation on the complex envelope after each array delay compensation in each physical sector to form partial wave beams; for any receiving beam, the two physical sectors carry out weighted accumulation on the complex envelope, and a left half beam and a right half beam can be obtained respectively.
In this embodiment, an expression of the weighted accumulation process of the complex envelopes of the arrays in a certain physical sector of the receive beam is as follows:
wherein weight _ totaliThe expression of the weight in the weighted accumulation process is as follows:
weight_total＝weight_line(:)*weight_column(1,:)
wherein, weight _ line (: is the weight of the first array i in the vertical linear array where the array is located, and weight _ column (1): is the weight of the linear array where the array is located in the physical sector.
The above-mentioned weighting and accumulating process can be understood as a linear array and an arc combined weighting. The above process can suppress side lobes and obtain better beamforming directivity. The same phase modulation signal can be obtained through step S5, but in practice, because the signal has difference due to the influence of noise, the incoherent characteristic of noise is utilized to accumulate multiple sub-signals, the noise can be partially cancelled, and the received signal is weighted and enhanced to obtain better directional gain.
In the above process, the complex envelope of each array includes signals of a plurality of beams to be received, but after performing phase compensation and delay compensation on a specific beam to be received, the signal phases of the specific beam to be received in the complex envelope of each array are consistent, and the phases of other beams are randomly distributed, similar to noise, so that the amplitude of the specific beam to be received with consistent phases in the weighted accumulation process is highlighted, and the beams of other signals are cancelled out due to the random distribution of phases in the weighted accumulation process. Therefore, in the present embodiment, a specific beam to be received is extracted from a plurality of beams to be received by performing phase compensation and delay compensation for the specific beam to be received.
As can be seen from fig. 12, for a certain receive beam, the amplitude of the signal after accumulation of the complex envelopes of the elements in a single physical sector increases significantly.
(S7) performing weighted addition on the partial beams of each physical sector in the reception sector to obtain an output beam. In this embodiment, one receiving sector includes two physical sectors, and after a multi-channel receiver corresponding to a physical sector obtains a partial beam, the partial beam is sent to the main control machine through the switch, and each partial beam of each receiving beam is subjected to weighted addition in the main control machine to obtain a signal of each receiving beam. The expression is as follows:
fig. 13 is a signal waveform diagram showing the weighted summation of the beam portions of a certain reception beam. In the embodiment, each multi-channel receiver independently generates part of beams, so that the transmission of the received signals of each array to the main control computer is avoided, the distributed processing mode can fully utilize the computing resources of the system, and the communication bandwidth of the system is reduced.
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (10)
1. A broadband sonar receiving beam forming method for fishing based on a cylindrical transducer array is realized by using the cylindrical transducer array, wherein the cylindrical transducer array comprises a plurality of arrays distributed on a cylindrical surface, and the cylindrical transducer array is divided into a plurality of physical sectors along the axis direction; at least two adjacent physical sectors form a receiving sector for receiving beams, and the ratio of the arc length of the receiving sector to the perimeter of the cylindrical transducer array is 1:3 to 1: 6; at least one of the physical sectors is involved in a beamforming process for at least two of the receiving sectors, the receiving sectors being configured to simultaneously receive a plurality of beams, the beamforming process for each beam comprising the steps of:
(S1) calculating a sound path between each array and the origin of the cylindrical transducer array;
(S2) sampling signals received by each of the elements;
(S3) finding a complex envelope of the sampled signal;
(S4) performing phase compensation on the complex envelope of the received signal of each of the arrays;
(S5) performing delay compensation on the phase-compensated complex envelope;
(S6) carrying out weighted accumulation on the complex envelope after each array delay compensation in each physical sector to form partial wave beams;
(S7) performing weighted addition on the partial beams of each physical sector in the reception sector to obtain an output beam.
2. The broadband sonar receiving beam forming method based on the cylindrical transducer array for the fishing is characterized by comprising 32 linear arrays distributed along the generatrix direction of a cylindrical surface; each linear array comprises 8 arrays, and the linear arrays are distributed on the cylindrical surface at equal intervals; each physical sector comprises 4 linear arrays, and each receiving sector comprises two physical sectors; the ratio of the arc length of the receiving sector to the perimeter of the cylindrical transducer array is 1: 4.
3. The broadband sonar receiving beam forming method based on the cylindrical transducer array for the fishing is characterized in that signals received by a receiving array of each physical sector are processed by a multi-channel receiver, after the partial beams are obtained, the multi-channel receiver sends the partial beams to a main control computer, and the main control computer performs weighted addition on the partial beams to obtain output beams.
4. The method according to claim 1, wherein in step S1, the expression for calculating the acoustic path from the array i to the origin of the cylindrical transducer array is:
wherein: [ x ] ofi，yi，zi]Is the rectangular coordinate of the array i in the cylindrical transducer array,
is the incident direction of the beam to be received.
5. The broadband sonar receiving beam forming method based on the cylindrical transducer array for the fishing use according to claim 4, wherein in step S2, the sampling frequency is 1Mhz, and the signal expression obtained by sampling is as follows:
si(n)＝cos(2πf0n-2πf0τi+γ(n-τi))+vi(n)
wherein: f. of0For the carrier frequency of the signal, gamma (t) is the phase modulation function, vi(n) noise superimposed on the received signal, τiIs the path difference.
6. The method according to claim 5, wherein in step S3:
the sampled signal si(n) and cos (2 π f)0n) multiplying and low-pass filtering the result of the multiplication to obtain the real part of the complex envelope:
Xeri(t)＝[cos(2πf0τi+γ(n-τi))]/2+wi(n)
the sampled signal si(n) and sin (2 π f)0n) multiplication and low-pass filtering the result of the multiplication to obtain the imaginary part of the complex envelope:
Ximi(t)＝[sin(2πf0τi+γ(n-τi))]/2+wi(n)
wherein, wiAnd (n) is a noise signal.
7. The cylindrical transducer array-based broadband sonar receiving beam forming method for fishing is characterized in that the complex envelope of the received signal of the array i participates in the beam forming process of a plurality of beams received by the receiving sector where the array i is located.
8. According to claim 6, the broadband sonar receiving beam forming based on the cylindrical transducer arrayThe method of type i, wherein in step S4: the complex envelope is subjected to phase shift operation by a trigonometric function formula to remove the corresponding direction as
Constant phase of beam
The expression is as follows:
the above expression is developed to obtain:
9. the method according to claim 8, wherein the delay compensation is performed in step S5 according to the orientation of the array i
Relative path difference of wave beam
And carrying out time delay processing on the complex envelope, wherein the expression is as follows:
10. The method according to claim 9, wherein in step S6, each array pair in the physical sector is pointed to
The complex envelope of the beam is weighted, which is expressed as:
wherein weight _ totaliThe expression of the weight in the weighted accumulation process is as follows:
weight_total＝weight_line(：)*weight_column(1，：)
wherein, weight _ line (: is the weight of the first array i in the vertical linear array where the array is located, and weight _ column (1): is the weight of the linear array where the array is located in the physical sector.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113866748A (en) * | 2021-09-26 | 2021-12-31 | 中国水产科学研究院渔业机械仪器研究所 | Scanning and transmitting method and system for transmitting detection signals by omnidirectional multi-beam fish detector |
| CN113866776A (en) * | 2021-09-26 | 2021-12-31 | 中国水产科学研究院渔业机械仪器研究所 | Digital fishing sonar sea-sweeping receiving method and system |
| CN115103003A (en) * | 2022-06-21 | 2022-09-23 | 中山大学 | Point-to-multipoint underwater sound instant messaging system |
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| CN113866748A (en) * | 2021-09-26 | 2021-12-31 | 中国水产科学研究院渔业机械仪器研究所 | Scanning and transmitting method and system for transmitting detection signals by omnidirectional multi-beam fish detector |
| CN113866776A (en) * | 2021-09-26 | 2021-12-31 | 中国水产科学研究院渔业机械仪器研究所 | Digital fishing sonar sea-sweeping receiving method and system |
| CN113866748B (en) * | 2021-09-26 | 2022-07-01 | 中国水产科学研究院渔业机械仪器研究所 | Scanning and transmitting method and system for transmitting detection signals by omnidirectional multi-beam fish detector |
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