CN104502904A - Torpedo homing beam sharpening method - Google Patents

Abstract

The invention relates to a torpedo homing beam sharpening method which can effectively improve resolving capability of a torpedo on a plurality of targets in different positions in space. The method is characterized by aiming at a torpedo homing acoustic base array. Through selecting different weighting coefficients for array element received signals of the base array to perform weighted summation, two wave beams are formed on the same direction in the space at the same time, and one beam is narrow in main lobe and high in side lobe, and the other beam is wide in main lobe and low in side lobe, respectively realizing to reduce beam main lobe and restrain beam side lobe. A combined processing of weighting corresponding products by using the two beam signals with different main lobe and side lobe characteristics and envelope, and the side lobe is recued while further sharpening the beam main lobe, so as to obtain a sharpened beam signal with low side lobe, thereby improving position resolving capability of the beam. The method is low in calculated amount, good in robustness, and good in adaptation capability. The method is especially suitable to be used in application environment where the number of space signal sources is unknown or each signal source has relatively strong correlation. The method has good engineering practicality, and can improve multi-target spatial position resolving capability of a torpedo.

Description

A kind of Torpedo Homing beam sharpening method

Technical field

The present invention relates to the Torpedo Homing beam sharpening method of a kind of effective raising torpedo target azimuth resolution characteristic, belong to torpedo sound self-conductance technical field, be applicable to Torpedo Homing target accurate pointing, multi-sources distinguishing and the identification of target fine-feature etc.

Background technology

Along with the fast development of modern naval battle underwateracoustic countermeasure techniques, the operational environment of torpedo is day by day complicated, on the one hand, may occur multiple target or bait simultaneously, make Torpedo Homing face target-rich environment in the work covering of the fan of torpedo acoustic homing system.On the other hand, torpedo not only needs to identify that target is true and false usually, and needs the many bright spots feature extracting the acoustic reflection of large scale target different parts, and the bright spot of effective resolution target different parts, analyzes each bright spot spatial distribution structure, realize precision target identification.Therefore, torpedo needs effectively to differentiate same sea area and is distributed in the multiple acoustic reflection bright spots multiple target in different spaces orientation or same objective body being distributed in different spaces orientation, in this case, just require that torpedo homing system must have very much higher object space azimuth discrimination ability.

Torpedo Homing and sonar system usually utilize acoustic array to receive acoustical signal and form wave beam thus effectively obtain object space azimuth information, and beam angle is the key factor affecting target Bearing Estimation precision.Usually, for the target being positioned at different directions wave beam, can according to beam direction determination target azimuth, but for being positioned at the different target of same wave beam, be difficult to effectively distinguish and accurate pointing.Therefore, torpedo homing system directly depends on the acuity of acoustic array wave beam to a great extent to effective resolution of the multiple target in space or target highlight and orientation estimated performance.But torpedo physical size is limited, beam feature is greatly limited by the impact of acoustic array physical pore size and frequency of operation.Under the condition that frequency of operation is certain, array beams width is subject to the physical pore size limit of array, and the normal restriction claiming " Rayleigh (Rayleigh) limit ", dimensional orientation resolution characteristic is limited.

Document " Wang Yongliang, Chen Hui, Peng Yingning; Wan Qun. the theoretical and algorithm of Estimation of Spatial Spectrum. publishing house of Tsing-Hua University; 2004,82 ~ 211 " describe the high-resolution Estimation of Spatial Spectrum method of Array Signal Processing, comprise Subspace Decomposition class algorithm sum of subspace matching class algorithm etc.Wherein, it is the noise subspace class algorithm of representative and the signal subspace class algorithm that is representative with invariable rotary subspace (ESPRIT) that Subspace Decomposition class algorithm can be divided into MUSIC, it receives the mathematic decomposition of data (as feature decomposition by pair array, svd, QR decomposes), be two mutually orthogonal subspaces by receiving Data Placement, namely consistent with the array manifold space of signal source signal subspace and the noise subspace orthogonal with it, then the orthogonal property of this two sub spaces is utilized to construct sharp-pointed spatial spectrum peak, realize orientation to estimate, improve estimated accuracy.Subspace fitting class algorithm comprises signal subspace fitting and noise subspace matching, and it is equivalent to receive the subspace of data and actual signal steering vector and forms matching between subspace, can be summed up as the optimization problem of multi-Dimensional parameters.Compared with Subspace Decomposition class algorithm, subspace fitting class algorithm estimated performance is better, and also can effectively estimate coherent source, but operand is larger.In a word, these high-resolution Estimation of Spatial Spectrum methods mainly utilize signal and the noise subspace characteristic of acoustic array each array element Received signal strength data covariance matrix, by the incident direction of the matrix operation solution room sound source of complexity, be characterized under certain basic matrix physical pore size condition, the dimensional orientation resolving power of breakthrough " Rayleigh limit " can be obtained, therefore, these methods effectively improve acoustic array to one of important channel of space different azimuth target resolution characteristic.But, the signal-to-noise ratio that these methods require is high, computing is complicated, more responsive to number of sources, correlativity etc., number of sources the unknown or these methods of information source correlativity strong all possibilities extreme influence carry out the validity of different target resolution, therefore, the robustness in practical engineering application is undesirable.Meanwhile, these method calculated amount are very large, are difficult to meet the real time handling requirement of torpedo to echo signal, are extremely restricted in Torpedo Homing practical engineering application.

Document " application number is the U.S. patent Nos Schlieter H of 6021096; Eigenbrod H.Method for theformation of radiated beams in direction finder systems.2000,2 " discloses a kind of super wave beam (Hyper beam) sharpening method.Acoustic array is divided into left and right half gust by the method, and utilize left and right half basic matrix to form the left and right split beam of the identical major axes orientation in space respectively, by left and right split beam signal and the nonlinear operation with difference, form the novel super wave beam of space major axes orientation identical with split beam, and by regulating the regulation and control of nonlinear factor realization to super beam shape leading indicator in the calculating of super wave beam.Therefore, the method feature realizes beam sharpening by the nonlinear operation process of the left and right half gust of split beam signal of acoustic array, and compared with traditional conventional beamformer method, it can effective sharpening beam main lobe, greatly can reduce beam side lobe simultaneously, improve target azimuth resolution characteristic.But the method is only applicable to single goal environment, for target-rich environment, its beam sharpening and target azimuth resolution characteristic do not have a clear superiority.That is, for the situation that only there is a target, the method can form sharp-pointed wave beam in direction, target place, the dimensional orientation of accurate indicating target; But for there is the situation of two or more target simultaneously, the method is difficult to the dimensional orientation differentiating each target.

Summary of the invention

Under the condition limited in basic matrix physical pore size in order to torpedo acoustic homing system, frequency of operation is not high, reduce beam angle, improve torpedo to the resolution characteristic of multiple targets being present in space different azimuth in self-conductance covering of the fan simultaneously, and to the resolution characteristic of large scale many bright spots target distribution in each acoustic reflection bright spot of space different azimuth, to carry out torpedo high-resolution intelligent target fine-feature to extract and image recognition, the invention provides a kind of Torpedo Homing beam sharpening method.The method, for Torpedo Homing acoustic array, calculates respectively and chooses two groups of different array element weighting coefficients, by the digital processing to each array element Received signal strength of basic matrix, realizes the function reducing beam main lobe and suppress beam side lobe respectively.In space, same direction forms two wave beams that main lobe is narrow, secondary lobe is high and main lobe is wide, secondary lobe is low simultaneously, and utilize these two beamformer output signals with different master, sidelobe performance, carry out the Combined Processing of wave beam envelope product weightings corresponding to beam signal respectively, realize the object of beam sharpening and suppressed sidelobes, finally obtain the sharpening wave beam that main lobe width is little, secondary lobe is low, improve beam positional resolution characteristic.

The technical solution adopted for the present invention to solve the technical problems is: owing to can be equivalent to concentrating rate model when uniform planar acoustic array that Torpedo Homing is conventional forms wave beam in level or vertical plane, and for the Wave beam forming of concentrating rate, utilizing different array element signals to carry out amplitude weighting is a kind of effective wave beam master, sidelobe performance control method, namely to the Received signal strength of different array element, choose suitable weighting coefficient, the characteristic parameter such as the different main lobe width of received beam and main secondary lobe ratio can be obtained.Usually, when beam main lobe width reduces, then secondary lobe raises, and the main secondary lobe of wave beam is than reducing; Otherwise when beam side lobe reduces, main secondary lobe ratio increases, then main lobe width also increases.Therefore, beam main lobe width and main secondary lobe, than being a pair shifting parameter, in actual applications, usually needing to carry out between compromisely to consider, choosing suitable weighting coefficient.Therefore, the principle of the main sidelobe performance of array beamformer output can be regulated and controled based on the different amplitude weighting coefficient of this array element signals, this programme proposes a kind of Torpedo Homing acoustic array Received signal strength beam sharpening disposal route, the method utilizes two groups of different acoustic array array element signals weighting coefficients, obtain space equidirectional simultaneously but there are two wave beams that are different main, sidelobe performance, by the digital complex process of two beam signals, realize beam sharpening.Be characterized in being weighted summation by choosing different weights coefficient to each array element Received signal strength of Torpedo Homing acoustic array, form two wave beams that main lobe is narrow, secondary lobe is high and main lobe is wide, secondary lobe is low at space equidirectional simultaneously, on this basis, utilize the amplitude of the envelope of low sidelobe beam signal to narrow main lobe beam signal to carry out the Combined Processing of corresponding product weightings, obtain the sharpening beam signal of low sidelobe.

Based on a signal processing method for above-mentioned Torpedo Homing beam sharpening, be characterized in comprising the steps:

Step one: the plane acoustic array that each array element generally adopted for Torpedo Homing is evenly distributed, if need to carry out accurate pointing or resolution to horizontal direction target, then planar array vertical direction can be had the Received signal strength summation of every array unit of identical horizontal phase, and ask it average, make planar array be equivalent to horizontal homogeneous linear array, the array element columns in planar array with identical horizontal phase is equivalent array number; If need to carry out accurate pointing or resolution to vertical direction target, then horizontal direction can be had the Received signal strength summation of the often row array element of same vertical phase place, and ask it average, make planar array be equivalent to Vertical Uniform linear array, the line number in planar array with the array element of same vertical phase place is equivalent array number;

Step 2: for level or the Vertical Uniform linear array of equivalence, suppose that equivalent array number is N, to reduce beam main lobe width for target, the main secondary lobe of setting wave beam is than being B, and to get B be 0dB ~ 3dB, according to list of references " Tian Tan; Liu Guozhi; Sun Dajun. sonar technology. publishing house of Harbin Engineering University, 2000,3.67 ~ 73 " method introduced calculates one group of weighting coefficient A _i, i=1,2 ..., N, and the amplitude and the phase place complex weighting coefficient W that build Wave beam forming _i, i=1,2 ..., N, is weighted summation to each array element signals of equivalent linear array, obtains wave beam 1 and outputs signal.This step specifically comprises following sub-step:

Sub-step 1: according to list of references method, according to the main secondary lobe of wave beam of array number N and requirement than B, calculates the amplitude weighting coefficient A of each array element _i, i=1,2 ..., N, order

$x_0=\cosh \left[\frac{\ln (B+\sqrt{B^2-1})}{N-1}\right]---\left(1\right)$

In formula (1), cosh () is hyperbolic cosine function, and ln () is natural logarithm function.Make again

$\mathrm{\α}=1-\frac{1}{x_0^2}---\left(2\right)$

The then amplitude weighting coefficient A of i-th array element _i(i=1,2 ..., N) be respectively

$A_i=\frac{N-1}{N-k}\underset{s}{\mathrm{\Σ}}\left(\begin{array}{c}k-2\\ s\end{array}\right)\left(\begin{array}{c}N-k\\ s+1\end{array}\right){\mathrm{\α}}^{s+1}---\left(3\right)$

In formula (3)

1<i≤N,s＝0,1,...

$\left(\begin{array}{c}p\\ q\end{array}\right)=\frac{p!}{q!(p-q)!},(q\&le;p)$

And have $I_N^1=1.$

Sub-step 2: the level formed as required or the major axes orientation of vertical beam, utilize A _i, i=1,2 ..., N, builds amplitude and the phase place complex weighting coefficient W of each array element signals ₁, W ₂, W ₃..., W _n-1, W _n, namely

W _i＝A _ie ^{-j2πf(i-1)dsinθ/c}i＝1,2,...,N (4)

In formula (4), f is signal frequency, and unit is Hz; θ is the level or vertical beam major axes orientation that need to be formed, the array element distance of unit to be rad, d be equivalent uniform linear array, and the unit acoustic wave propagation velocity that to be m, c be in water, unit is m/s.

Sub-step 3: utilize this weighting coefficient Wi, i=1,2, N, by being weighted summation to each array element Received signal strength of equivalent concentrating rate 1 ~ N, the direction of space requirement forming the wave beam 1 that main lobe width is little, secondary lobe is relatively high, namely supposing that the Received signal strength of each array element of equivalent uniform linear array is respectively X _i, i=1,2 ..., N, then wave beam 1 exports and is

$Y_1=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{W}_i{X}_i,i=\mathrm{1,2},...,N---\left(5\right)$

Step 3: same is the level of N or Vertical Uniform linear array and each array element Received signal strength X thereof for above-mentioned equivalent array number _i, i=1,2 ..., N, to reduce beam side lobe for target, the main secondary lobe of setting wave beam is 30dB ~ 50dB than B, still according to the circular in above-mentioned steps two, utilizes formula (1) ~ (3) to calculate another group amplitude weighting coefficient A' respectively _i, i=1,2 ..., N.The major axes orientation θ of the level formed as required again or vertical beam, utilizes formula (4) to build its corresponding amplitude and phase place complex weighting coefficient W' _i, i=1,2 ..., N.Utilize this weighting coefficient, utilize formula (5) equally, by the weighted sum to each array element Received signal strength of acoustic array, with wave beam 1 equidirectional on form the low but wave beam 2 that main lobe is relatively wide of secondary lobe, namely

$Y_2=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{W}_i^{\&prime;}{X}_i,i=\mathrm{1,2},...,N---\left(6\right)$

Step 4: the complex envelope resolving wave beam 2 signal, concrete calculation method is as follows:

If torpedo homing system have employed the real signal method of sampling, then the wave beam 2 obtained according to above-mentioned steps is real signals.In this case, according to list of references " Hu Guangshu. digital signal processing: theoretical, algorithm and implementation. publishing house of Tsing-Hua University; 2003; 8.156 ~ 163 " method introduced, Hilbert conversion is carried out to the real signal of wave beam 2, first be transformed to complex signal, then resolved the complex envelope of wave beam 2 signal according to complex signal envelope method for solving below.

If torpedo homing system have employed the complex signal method of sampling, then the wave beam 2 obtained according to above-mentioned steps three is complex signals, can its complex envelope of directly calculation.Suppose wave beam 2 complex signal Y ₂sampled data length be L, the concrete data of each sampled point are y _2k=a _k+ b _k* i, k=1,2 ..., L, then the complex envelope of wave beam 2 signal is

${\tilde{y}}_{2k}=\sqrt{a_k^2+b_k^2},k=\mathrm{1,2},...,L---\left(7\right)$

Step 5: utilize the complex envelope of wave beam 2 signal to carry out corresponding product Combined Processing with wave beam 1 signal.Namely the sample data sequence of hypothesis wave beam 1 signal is y _1k=c _k+ d _k* i, k=1,2 ..., L, then utilize each sampling number certificate of wave beam 2 complex envelope with the sampling number of the corresponding synchronization of wave beam 1 signal according to y _1kcarry out product calculation process, can obtain the signal after product Combined Processing is:

$z_k={\tilde{y}}_{2k}{y}_{1k}=\sqrt{a_k^2+b_k^2}(c_k+d_k*i),k=\mathrm{1,2},...,L---\left(8\right)$

The signal z obtained like this _k, k=1,2 ..., L is the sample data sequence of compound wave beam output signal, and this compound wave beam main lobe width is narrow, secondary lobe is low, substantially increases the dimensional orientation resolution characteristic of wave beam.

The invention has the beneficial effects as follows: because the method is mainly based on the digital beam froming method of acoustic array array element Received signal strength weighted sum, utilize two wave beams of equidirectional and different main sidelobe performance, carry out the Combined Processing of corresponding product weightings, therefore, relative to other beam sharpening method and target azimuth high-resolution algorithm for estimating, its calculated amount is little, robustness is good, adaptable, particularly be applicable between space simultaneous number of sources the unknown or each information source and there is the even completely relevant application scenario of very strong correlativity, there is better practicality in practical engineering application.Meanwhile, this Torpedo Homing beam sharpening method, under the condition not changing the existing electro-acoustic hardware of Torpedo Homing and signal processing software system, effectively can improve torpedo dimensional orientation and multi-sources distinguishing ability.Like this, for the main passive homing system of torpedo, beam signal estimating target direction parameter more accurately can be utilized, also more fully can know the target azimuth distributed intelligence in self-conductance covering of the fan, thus utilize object space structure dimension distribution characteristics to carry out true and false target identification.Particularly, for large scale many bright spots target, torpedo effectively can distinguish each bright spot in different spaces orientation, extract each bright spot azimuth distribution feature, establishing target space structure size distribution acoustic image, realize the effective identification to the concrete position of target, thus select key position emphasis to attack, improve torpedo precision guidance capability.

Below in conjunction with the drawings and specific embodiments, the present invention is elaborated.

Accompanying drawing explanation

Fig. 1: concentrating rate Wave beam forming schematic diagram.

Fig. 2: sharpening compound wave beam forms schematic diagram.

Fig. 3: computer artificial result comparison diagram.

Fig. 4: experimental results comparison diagram.

In figure, 1-concentrating rate, 2-transducer array element, the weight coefficient vector of 3-weighted sum Wave beam forming.

Embodiment

With reference to Fig. 1, for general concentrating rate 1, comprise N number of transducer array element 2, its adjacent array element distance is d, and unit is m.Suppose that each array element Received signal strength is for being respectively X ₁, X ₂, X ₃..., X _n-1, X _n, needing to form the direction of wave beam is θ, and namely to the far field sound wave of θ direction incidence in space, array exports maximum, and requires that the master of wave beam, secondary lobe are than being B, then its Wave beam forming carries out as follows.

1. amplitude weighting coefficient is calculated according to the wave beam master of array number N and requirement, secondary lobe than B:

$x_0=\cosh \left[\frac{\ln (B+\sqrt{B^2-1})}{N-1}\right]---\left(9\right)$

In formula (9), cosh () is hyperbolic cosine function.

$\mathrm{\&alpha;}=1-\frac{1}{x_0^2}---\left(10\right)$

The then amplitude weighting coefficient A of i-th array element _ifor

$A_i=\frac{N-1}{N-k}\underset{s}{\mathrm{\&Sigma;}}\left(\begin{array}{c}k-2\\ s\end{array}\right)\left(\begin{array}{c}N-k\\ s+1\end{array}\right){\mathrm{\&alpha;}}^{s+1}---\left(11\right)$

In formula (11)

1<i≤N,s＝0,1,...

$\left(\begin{array}{c}p\\ q\end{array}\right)=\frac{p!}{q!(p-q)!}(q\&le;p)$

And have $I_N^1=1.$

2. each array element signals weighting coefficient W is calculated ₁, W ₂, W ₃..., W _n-1, W _n, form weight vector 3, wherein

W _i＝A _ie ^{-j2πf(i-1)dsinθ/c}i＝1,2,...,N (12)

In formula (12), f is signal frequency, and unit is Hz; C is the acoustic wave propagation velocity in water, and unit is m/s.

3. calculate the weighted sum of each array element signals, obtain beamformer output signal, namely

$Y_1=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{W}_i{X}_i,i=\mathrm{1,2},...,N---\left(13\right)$

With reference to Fig. 2, for the array element signals that Torpedo Homing acoustic array receives, according to the Beamforming Method shown in Fig. 1 and step, the main secondary lobe of wave beam of setting 0dB ~ 3dB compares parameter, calculate weight vector W1, carry out Wave beam forming process, obtain wave beam 1 signal that main lobe is narrow, secondary lobe is high.Meanwhile, still according to the Beamforming Method shown in Fig. 1 and step, but the main secondary lobe ratio of wave beam of setting 30dB ~ 50dB, calculate weight vector W2, carry out Wave beam forming process, obtain wave beam 2 signal that main lobe is wide, secondary lobe is low, and resolve this signal envelope.Finally, carry out corresponding product weightings process with the envelope of wave beam 2 signal with wave beam 1 signal, the output signal of compound sharpening low sidelobe wave beam can be obtained.

With reference to Fig. 3, build 12 yuan of concentrating rate models, array element distance 30mm, frequency of operation 20kHz, be respectively-5 ° and 1 ° of two Coherent Targets to surface level interior orientation, the simulation result that beam target detects and differentiates as shown in Figure 3.Give sharpening wave beam described in conventional wave beam and this programme is respectively two Coherent Targets of-5 ° and 1 ° distinguishing results to orientation in Fig. 3 simultaneously.As seen from Figure 3, for two targets laying respectively at dimensional orientation-5 ° and 1 °, conventional wave beam cannot be differentiated, and described in this programme, sharpening wave beam can effectively be differentiated, and sharpening beam side lobe is very low.Therefore, the method is sharpening wave beam greatly, improves the resolution characteristic to different spaces orientation target.

With reference to Fig. 4, build the principle sample battle array of 12 yuan of concentrating rate, array element distance 30mm, frequency of operation 25kHz, to two Coherent Targets laying respectively at-5 °, surface level interior orientation and 5 °, carry out the pond testing experiment of beam target detection and resolution.The experimental test result that beam target detects and differentiates as shown in Figure 4.Give sharpening wave beam described in conventional wave beam and this programme to the distinguishing results of these two different azimuth Coherent Targets in Fig. 4 equally simultaneously.Test findings is as shown in Figure 4 visible, and for these two targets laying respectively at-5 ° and 5 ° in surface level, conventional wave beam cannot be differentiated, and the sharpening beam forming method described in this programme can realize effective resolution.Therefore, test findings demonstrates the validity that method described in this programme is carried out beam sharpening and improved dimensional orientation resolution characteristic further, also demonstrates its feasibility in practical engineering application.

Claims (3)

1. a Torpedo Homing beam sharpening method, it is characterized in that, utilize the acoustic array array element signals weighting coefficient that two groups different, obtain space equidirectional simultaneously but there are two wave beams that are different main, sidelobe performance, by the digital complex process of two beam signals, realize beam sharpening.

2. a Torpedo Homing beam sharpening method as claimed in claim 1, its feature is, specifically comprises the steps:

Step one: the plane acoustic array that each array element generally adopted for Torpedo Homing is evenly distributed, if need to carry out accurate pointing or resolution to horizontal direction target, then planar array vertical direction had the Received signal strength summation of every array unit of identical horizontal phase, and ask it average, make planar array be equivalent to horizontal homogeneous linear array, the array element columns in planar array with identical horizontal phase is equivalent array number; If need to carry out accurate pointing or resolution to vertical direction target, then horizontal direction can be had the Received signal strength summation of the often row array element of same vertical phase place, and ask it average, make planar array be equivalent to Vertical Uniform linear array, the line number in planar array with the array element of same vertical phase place is equivalent array number;

Step 2: for level or the Vertical Uniform linear array of equivalence, supposes that equivalent array number is N, and to reduce beam main lobe width for target, the main secondary lobe of setting wave beam is than being B, and to get B be 0dB ~ 3dB, calculates one group of weighting coefficient A _i, i=1,2 ..., N, and the amplitude and the phase place complex weighting coefficient W that build Wave beam forming _i, i=1,2 ..., N, is weighted summation to each array element signals of equivalent linear array, obtains wave beam 1 and outputs signal;

Step 3: same is the level of N or Vertical Uniform linear array and each array element Received signal strength X thereof for above-mentioned equivalent array number _i, i=1,2 ..., N, to reduce beam side lobe for target, the main secondary lobe of setting wave beam is 30dB ~ 50dB than B, calculates another group amplitude weighting coefficient A ' _i, i=1,2 ..., N; The major axes orientation θ of the level formed as required again or vertical beam, builds its corresponding amplitude and phase place complex weighting coefficient W ' _i, i=1,2 ..., N; Utilize this weighting coefficient, by the weighted sum to each array element Received signal strength of acoustic array, with wave beam 1 equidirectional on form the low but wave beam 2 that main lobe is relatively wide of secondary lobe, namely

$Y_2=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{W}_i^{\&prime;}{X}_i,i=\mathrm{1,2},\&CenterDot;\&CenterDot;\&CenterDot;,N---\left(6\right)$

Step 4: the complex envelope resolving wave beam 2 signal, concrete calculation method is as follows:

If torpedo homing system have employed the real signal method of sampling, the wave beam 2 then obtained according to above-mentioned steps is real signals, Hilbert conversion is carried out to the real signal of wave beam 2, is first transformed to complex signal, then resolve the complex envelope of wave beam 2 signal according to complex signal envelope method for solving below;

If torpedo homing system have employed the complex signal method of sampling, then the wave beam 2 obtained according to above-mentioned steps three is complex signals, can its complex envelope of directly calculation; Suppose wave beam 2 complex signal Y ₂sampled data length be L, the concrete data of each sampled point are y _2k=a _k+ b _k* i, k=1,2 ..., L, then the complex envelope of wave beam 2 signal is

${\tilde{y}}_{2k}=\sqrt{a_k^2+b_k^2},k=\mathrm{1,2},\&CenterDot;\&CenterDot;\&CenterDot;,L---\left(7\right)$

Step 5: utilize the complex envelope of wave beam 2 signal to carry out corresponding product Combined Processing with wave beam 1 signal.Namely the sample data sequence of hypothesis wave beam 1 signal is y _1k=c _k+ d _k* i, k=1,2 ..., L, then utilize each sampling number certificate of wave beam 2 complex envelope with the sampling number of the corresponding synchronization of wave beam 1 signal according to y _1kcarry out product calculation process, obtaining the signal after product Combined Processing is:

$z_k={\tilde{y}}_{2k}{y}_{1k}=\sqrt{a_k^2+b_k^2}(c_k+d_k*i),k=\mathrm{1,2},\&CenterDot;\&CenterDot;\&CenterDot;,L---\left(8\right)$

The signal z obtained like this _k, k=1,2 ..., L is the sample data sequence of compound wave beam output signal.

3. a Torpedo Homing beam sharpening method as claimed in claim 2, its feature is, described step 2 specifically comprises following sub-step:

Sub-step 1: according to list of references method, according to the main secondary lobe of wave beam of array number N and requirement than B, calculates the amplitude weighting coefficient A of each array element _i, i=1,2 ..., N, order

$x_0=\cosh \left[\frac{\ln (B+\sqrt{B^2-1})}{N-1}\right]---\left(1\right)$

In formula (1), cosh () is hyperbolic cosine function, and ln () is natural logarithm function.Make again

$\mathrm{\&alpha;}=1-\frac{1}{x_0^2}---\left(2\right)$

The then amplitude weighting coefficient A of i-th array element _i(i=1,2 ..., N) be respectively

$A_i=\frac{N-1}{N-k}\underset{s}{\mathrm{\&Sigma;}}\left(\begin{array}{c}k-2\\ s\end{array}\right)\left(\begin{array}{c}N-k\\ s+1\end{array}\right){\mathrm{\&alpha;}}^{s+1}---\left(3\right)$

In formula (3)

1<i≤N,s＝0,1,…

$\left(\begin{array}{c}p\\ q\end{array}\right)=\frac{p!}{q!(p-q)!},(q\&le;p)$

And have $I_N^1=1.$

Sub-step 2: the level formed as required or the major axes orientation of vertical beam, utilize A _i, i=1,2 ..., N, builds amplitude and the phase place complex weighting coefficient W of each array element signals ₁, W ₂, W ₃..., W _n-1, W _n, namely

$W_i=A_i{e}^{-j2\mathrm{\&pi;f}(i-1)d\sin \mathrm{\&theta;}/c},i=\mathrm{1,2},\&CenterDot;\&CenterDot;\&CenterDot;,N---\left(4\right)$

In formula (4), f is signal frequency, and unit is Hz; θ is the level or vertical beam major axes orientation that need to be formed, the array element distance of unit to be rad, d be equivalent uniform linear array, and the unit acoustic wave propagation velocity that to be m, c be in water, unit is m/s.

Sub-step 3: utilize this weighting coefficient Wi, i=1,2, N, by being weighted summation to each array element Received signal strength of equivalent concentrating rate 1 ~ N, the direction of space requirement forming the wave beam 1 that main lobe width is little, secondary lobe is relatively high, namely supposing that the Received signal strength of each array element of equivalent uniform linear array is respectively X _i, i=1,2 ..., N, then wave beam 1 exports and is

$Y_1=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{W}_i{X}_i,i=\mathrm{1,2},\&CenterDot;\&CenterDot;\&CenterDot;,N---\left(5\right)$