CN110515065B - Radiation noise line spectrum source depth identification method - Google Patents
Radiation noise line spectrum source depth identification method Download PDFInfo
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- CN110515065B CN110515065B CN201910817051.6A CN201910817051A CN110515065B CN 110515065 B CN110515065 B CN 110515065B CN 201910817051 A CN201910817051 A CN 201910817051A CN 110515065 B CN110515065 B CN 110515065B
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- 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
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Abstract
The invention discloses a radiation noise line spectrum source depth identification method, which comprises the following steps: (1) initializing processing parameters; (2) reading in radiation noise line spectrum amplitude value and updatingA line spectrum amplitude sequence; (3) judging the time length corresponding to the radiation noise line spectrum amplitude sequenceTIf the requirements are met, performing the step 4, otherwise, returning to the step 2; (4) dividing the radiation noise line spectrum amplitude sequence into a plurality of subsequences, and respectively calculating the fluctuation index of the radiation noise line spectrum amplitude of each subsequence to obtain a line spectrum amplitude fluctuation index sequence; (5) counting the probability that the line spectrum amplitude fluctuation index exceeds a set threshold value in the line spectrum amplitude fluctuation index sequence obtained in the step 4, and if the probability is greater than 0.5, judging that the radiation noise line spectrum source is a water surface target; if the probability is less than 0.5, judging that the radiation noise line spectrum source is an underwater target; if the probability is equal to 0.5, the line spectrum source attribute cannot be judged.
Description
Technical Field
The invention relates to a radiation noise line spectrum source depth identification technology, and belongs to the technical field of extraction and identification of incident noise signal characteristics of underwater acoustic targets.
Background
Sonar underwater acoustic systems receive underwater acoustic signals by using a hydrophone array to realize functions of underwater target detection, positioning, identification and the like, wherein target identification and positioning are particularly important links and are related to correct judgment and decision of commanders. Because the depths of underwater vehicles such as submarines and the like and surface ships are obviously different when navigating, the identification of the target depth has an important support function for judging the type of the target.
The underwater acoustic target identification mainly distinguishes target type and type information by extracting target characteristic quantity. The object characteristic information is information contained or extractable in the object raw data and capable of accurately and simply indicating the state and identity of the object. The underwater acoustic targets mainly comprise characteristic information such as noise, motion, wake flow, geometric structures and the like, and the characteristic information of different underwater acoustic targets is different. Radiation noise is inevitably generated by underwater vehicles such as submarines and the like and surface ships during navigation, so that the radiation noise of underwater targets is a main information source for the work of the passive sonar at present, and the characteristics of the radiation noise are the main basis for the identification of the passive sonar targets.
The underwater target radiation noise line spectrum (line spectrum for short) refers to stable discrete frequency components in radiation noise power, particularly has long propagation distance and good stability of a low-frequency line spectrum, and is an important way for detecting and identifying low-noise and quiet underwater targets. Under the influence of sea surface waves, internal waves and the like, the depths of underwater vehicles such as submarines and water surface ships as radiation noise line spectrum sources often fluctuate, and the phenomenon is called the depth modulation effect of the ocean on ship targets. According to the underwater sound propagation theory, the fluctuation of the depth can cause the amplitude of a line spectrum in the radiation noise to fluctuate in the propagation process. Although line spectrum amplitude fluctuations are related to various factors such as distance, sea state, and scattering refraction, the current research results show that the second-order signal fluctuations are caused by the position fluctuations of the sound source in the vertical and horizontal directions. Therefore, the difference of the fluctuation of the line spectrum is utilized, and the method has important significance for effectively distinguishing whether the line spectrum source is positioned on the water surface or underwater.
The invention analyzes the line Spectrum Amplitude sequence output by passive sonar processing, calculates the Fluctuation index LSAFI (line Spectrum Amplitude Fluctuation index) of the line Spectrum Amplitude in the sequence, and realizes the discrimination of the line Spectrum source depth by counting the probability that the Fluctuation index of the line Spectrum Amplitude exceeds a set threshold value.
Disclosure of Invention
The invention aims to provide a method for identifying the depth of a radiation noise line spectrum source aiming at the problem of depth discrimination of the radiation noise line spectrum source. The method comprises the steps of firstly judging the time length of a given target radiation noise line spectrum amplitude sequence, dividing the radiation noise line spectrum amplitude sequence meeting a time length condition into a plurality of subsequences, respectively calculating a line spectrum amplitude fluctuation index LSAFI of each subsequence, then counting the probability that the line spectrum amplitude fluctuation index in the line spectrum amplitude sequence exceeds a set threshold value, and judging whether a line spectrum source is a water surface target or an underwater target according to the probability value.
In order to achieve the purpose, the method adopted by the invention is as follows: a radiation noise line spectrum source depth identification method comprises the following steps:
(1) initializing processing parameters;
(2) reading in a radiation noise line spectrum amplitude value, and updating a line spectrum amplitude sequence A (n);
(3) judging whether the time length T corresponding to the radiation noise line spectrum amplitude sequence meets the requirement, if so, performing the step 4, otherwise, returning to the step 2;
(4) dividing the radiation noise line spectrum amplitude sequence A (n) into Q subsequences, calculating the fluctuation index of the radiation noise line spectrum amplitude in each subsequence, and forming a line spectrum amplitude fluctuation index sequence LSAFI (Q);
(5) counting the probability p that each index in the line spectrum amplitude fluctuation index sequence LSAFI (q) obtained in the step 4 exceeds the threshold lambda, and if p is greater than 0.5, judging that the corresponding line spectrum source is a water surface target; if p is less than 0.5, judging the corresponding line spectrum source as an underwater target; when p is 0.5, the corresponding line spectrum source attribute cannot be determined.
As a further improvement of the present invention, step 1 initializes the following parameters:
(1.1) setting a sequence for storing radiation noise line spectrum amplitude values as a (N), wherein N is 1,2, …, N, and N is 1;
(1.2) setting the updating time interval of the radiation noise line spectrum amplitude value to be delta t;
(1.3) setting the updating accumulation time length gamma of the radiation noise line spectrum amplitude sequence;
and (1.4) setting the threshold value of the line spectrum amplitude fluctuation index to be lambda.
As a further improvement of the invention, the step 2 specifically comprises the following steps:
reading a radiation noise line spectrum amplitude value, giving the value to a variable a, and enabling A (N) to be a.
As a further improvement of the invention, the step 3 specifically comprises the following steps:
(3.1) calculating the time length T (NxDeltat) corresponding to the A (N) according to the radiation noise line spectrum amplitude sequence A (N) obtained in the step 2, wherein N is 1,2, … and N;
(3.2) if T is more than or equal to gamma, performing the step 4; otherwise, let N be N +1, and return to step 2.
As a further improvement of the invention, the step 4 specifically comprises the following steps:
(4.1) irradiatingThe noise line spectrum amplitude sequence A (n) is divided into Q subsequences (Q is more than or equal to 300), the length of each subsequence is L (L is more than or equal to 50), the overlapping length of two adjacent subsequence data is K (L/2 is more than or equal to K)<L), the qth subsequence is Aq(kq)，1+(L-K)(q-1)≤kq≤2L+(L-K)(q-1)，q＝1,2,…,Q。
(4.2) calculating the first-order power average function and the third-order power average function of each subsequence according to the formulas (1) and (2) to form a sequence PMF1(q)、PMF3(q)。
(4.3) PMF according to the sequence obtained1(q)、PMF3(q), calculating the line spectrum amplitude fluctuation index of each subsequence of the radiation noise line spectrum amplitude sequence, and forming a radiation noise line spectrum amplitude fluctuation index sequence LSAFI (q), which is shown in formula (3).
As a further improvement of the invention, the step 5 specifically comprises the following steps:
(5.1) according to the LSAFI (q) obtained in the step 4, counting the probability p that each fluctuation index exceeds the threshold lambda, as shown in the formula (4):
wherein M {. DEG } represents the number of fluctuation index values which are greater than or equal to a threshold lambda in the radiation noise line spectrum amplitude fluctuation index sequence.
(5.2) if p is greater than 0.5, judging that the radiation noise line spectrum source is a water surface target; if p is less than 0.5, judging the radiation noise line spectrum source as an underwater target; if p is 0.5, it cannot be determined whether the radiation noise line spectrum source is a water surface target or an underwater target.
The invention discloses a radiation noise line spectrum source depth identification method. The method comprises the steps of firstly judging the time length of a given target radiation noise line spectrum amplitude sequence, dividing the radiation noise line spectrum amplitude sequence meeting a time length condition into a plurality of subsequences, respectively calculating a line spectrum amplitude fluctuation index LSAFI of each subsequence, then counting the probability that the line spectrum amplitude fluctuation index in the line spectrum amplitude sequence exceeds a set threshold value, and judging whether a line spectrum source is a water surface target or an underwater target according to the probability value.
Has the advantages that:
compared with the prior art, the method disclosed by the invention has the following advantages: the underwater acoustic target radiation noise time-frequency characteristic analysis method is combined with the underwater acoustic propagation characteristic analysis method, fluctuation characteristics of a radiation noise power spectrum line spectrum and monotonous characteristics of a power average function are fully utilized, prior information of target line spectrum frequency and marine environment parameter information are not needed, the algorithm is simple to implement, the physical significance is clear, and the identification efficiency is high.
Drawings
FIG. 1 is a flow chart of an embodiment of the method of the present invention.
Fig. 2 is a 240Hz line spectral amplitude curve of the sound source radiation noise in example 1.
Fig. 3 is a 240Hz line spectrum amplitude fluctuation index curve of the sound source radiation noise in example 1.
Fig. 4 is a 362Hz line spectrum amplitude curve of the sound source radiation noise in example 2.
FIG. 5 is a 362Hz line spectrum amplitude fluctuation index curve of the sound source radiation noise in example 2.
Detailed Description
The invention is described in further detail below with reference to the following figures and detailed description:
the invention analyzes the line spectrum amplitude sequence output by passive sonar processing, calculates the fluctuation index LSAFI of the line spectrum amplitude in the sequence, and realizes the discrimination of the line spectrum source depth by counting the probability that the fluctuation index of the line spectrum amplitude exceeds a set threshold value.
Example 1:
the invention is further elucidated with reference to the drawings and the detailed description.
A method for identifying the depth of a radiation noise line spectrum source, as shown in fig. 1, includes the following steps:
(1.1) setting a sequence for storing radiation noise line spectrum amplitude values as a (N), wherein N is 1,2, …, N, and N is 1;
(1.2) setting the updating time interval delta t of the radiation noise line spectrum amplitude value to be 1 second;
(1.3) setting the update accumulation time length gamma of the radiation noise line spectrum amplitude sequence to be 350 seconds;
(1.4) the threshold value λ of the line spectrum amplitude fluctuation index is 1.5.
The step 2 specifically comprises the following steps: reading an amplitude value of a line spectrum with the frequency of 240Hz in a actually measured water surface sound source radiation noise power spectrum, giving a variable a, and making A (N) be a.
The step 3 specifically comprises the following steps:
(3.1) calculating the time length T corresponding to a (N) ═ nxΔ T;
(3.2) if T is more than or equal to gamma, carrying out the next step; otherwise, let N be N +1, and return to step 2.
When N is 350, the time length T of sequence a (N) is 350 × 1, 350 seconds, the condition T ≧ Γ is satisfied, and step 4 is performed, where the obtained sequence a (N) is as shown in fig. 2.
The step 4 specifically comprises the following steps:
(4.1) dividing the radiation noise line spectrum amplitude sequence A (n) into sub-sequences with Q being 301, wherein the length of each sub-sequence is L being 50, the overlapping length of two adjacent sub-sequence data is K being 49, and the Q-th sub-sequence is Aq(kq)，q≤kq≤q+49，q＝1,2,…,301。
(4.2) calculating the first-order power average function and the third-order power average function of each subsequence according to the formulas (1) and (2) to form a sequence PMF1(q)、PMF3(q)。
(4.3) According to the obtained sequence PMF1(q)、PMF3(q), calculating the line spectrum amplitude fluctuation index of each subsequence of the radiation noise line spectrum amplitude sequence according to the formula (3), and forming a radiation noise line spectrum amplitude fluctuation index sequence LSAFI (q), as shown in FIG. 3.
(5.1) obtaining lsafi (q) according to step 4, wherein the number of subsequences with each fluctuation index exceeding the threshold λ is 290, and the probability p that each fluctuation index exceeds the threshold λ is calculated according to formula (4) as 0.9435:
(5.2) judging that the radiation noise source corresponding to the 240Hz line spectrum is a water surface sound source as p is greater than 0.5, and the result is consistent with the actual situation.
Example 2:
a method for identifying the depth of a radiation noise line spectrum source, as shown in fig. 1, includes the following steps:
(1.1) setting a sequence for storing radiation noise line spectrum amplitude values as a (N), wherein N is 1,2, …, N, and N is 1;
(1.2) setting the updating time interval delta t of the radiation noise line spectrum amplitude value to be 1 second;
(1.3) setting the update accumulation time length gamma of the radiation noise line spectrum amplitude sequence to be 350 seconds;
(1.4) the threshold value λ of the line spectrum amplitude fluctuation index is 1.5.
The step 2 specifically comprises the following steps: reading an amplitude value of a line spectrum with the frequency of 362Hz in a measured underwater sound source radiation noise power spectrum, giving the amplitude value to a variable a, and making A (N) a.
The step 3 specifically comprises the following steps:
(3.1) calculating the time length T corresponding to a (N) ═ nxΔ T;
(3.2) if T is more than or equal to gamma, carrying out the next step; otherwise, let N be N +1, and return to step 2.
When N is 350, the time length T of sequence a (N) is 350 × 1, 350 seconds, the condition T ≧ Γ is satisfied, and step 4 is performed, where the obtained sequence a (N) is as shown in fig. 4.
The step 4 specifically comprises the following steps:
(4.1) dividing the radiation noise line spectrum amplitude sequence A (n) into sub-sequences with Q being 301, wherein the length of each sub-sequence is L being 50, the overlapping length of two adjacent sub-sequence data is K being 49, and the Q-th sub-sequence is Aq(kq)，q≤kq≤q+49，q＝1,2,…,301。
(4.2) calculating the first-order power average function and the third-order power average function of each subsequence according to the formulas (1) and (2) to form a sequence PMF1(q)、PMF3(q)。
(4.3) PMF according to the sequence obtained1(q)、PMF3(q), calculating the line spectrum amplitude fluctuation index of each subsequence of the radiation noise line spectrum amplitude sequence according to the formula (3), and forming a radiation noise line spectrum amplitude fluctuation index sequence LSAFI (q), as shown in FIG. 5.
(5.1) obtaining lsafi (q) according to step 4, wherein the number of subsequences with each fluctuation index exceeding the threshold λ is 25, and the probability p of each fluctuation index exceeding the threshold λ is counted as 0.0831 according to equation (4):
(5.2) if p is less than 0.5, judging that the radiation noise source corresponding to the 362Hz line spectrum is an underwater sound source, and the situation is consistent with the actual situation.
The embodiment shows that the amplitude fluctuation index of the radiation noise line spectrum of the water surface and underwater targets calculated by the method has better discrimination, and the depth identification of the radiation noise line spectrum source can be effectively realized.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, but any modifications or equivalent variations made according to the technical spirit of the present invention are within the scope of the present invention as claimed.
Claims (5)
1. A radiation noise line spectrum source depth identification method is characterized by comprising the following steps:
(1) initializing processing parameters;
(2) reading in a radiation noise line spectrum amplitude value, and updating a line spectrum amplitude sequence A (n);
(3) judging whether the time length T corresponding to the radiation noise line spectrum amplitude sequence meets the requirement, if so, performing the step (4), otherwise, returning to the step (2);
(4) dividing the radiation noise line spectrum amplitude sequence A (n) into Q subsequences, calculating the fluctuation index of the radiation noise line spectrum amplitude in each subsequence, and forming a line spectrum amplitude fluctuation index sequence LSAFI (Q);
(5) counting the probability p that each index in the line spectrum amplitude fluctuation index sequence LSAFI (q) obtained in the step (4) exceeds the threshold lambda, and if p is greater than 0.5, judging that the corresponding line spectrum source is a water surface target; if p is less than 0.5, judging the corresponding line spectrum source as an underwater target; when p is 0.5, the corresponding line spectrum source attribute cannot be judged;
wherein, the step (4) comprises the following steps:
(4.1) dividing the radiation noise line spectrum amplitude sequence A (n) into Q subsequences, wherein Q is more than or equal to 300, the length of each subsequence is L, L is more than or equal to 50, the overlapping length of two adjacent subsequences is K, and L/2 is more than or equal to K<L, the qth subsequence is Aq(kq)，1+(L-K)(q-1)≤kq≤2L+(L-K)(q-1)，q＝1,2,…,Q；
(4.2) calculating the first-order power average function and the third-order power average function of each subsequence according to the formulas (1) and (2) to form a sequence PMF1(q)、PMF3(q)；
(4.3) PMF according to the sequence obtained1(q)、PMF3(q), calculating the line spectrum amplitude fluctuation index of each subsequence of the radiation noise line spectrum amplitude sequence, and forming a radiation noise line spectrum amplitude fluctuation index sequence LSAFI (q), wherein the formula (3) is as follows:
2. the method for identifying the depth of a radiation noise line spectrum source according to claim 1, wherein the step (1) initializes the following parameters:
(1.1) setting a sequence for storing radiation noise line spectrum amplitude values as a (N), wherein N is 1,2, …, N, and N is 1;
(1.2) setting the updating time interval of the radiation noise line spectrum amplitude value to be delta t;
(1.3) setting the updating accumulation time length gamma of the radiation noise line spectrum amplitude sequence;
and (1.4) setting the threshold value of the line spectrum amplitude fluctuation index to be lambda.
3. The method for identifying the depth of a radiation noise line spectral source according to claim 1, wherein the step (2) specifically comprises the following steps: reading a radiation noise line spectrum amplitude value, giving the value to a variable a, and enabling A (N) to be a.
4. The method for identifying the depth of a radiation noise line spectral source according to claim 2, wherein the step (3) specifically comprises the following steps:
(3.1) calculating the time length T of a (N) corresponding to the radiation noise line spectrum amplitude sequence a (N) obtained in the step (2), wherein N is 1,2, …, N;
(3.2) if T is more than or equal to gamma, performing the step (4); otherwise, let N be N +1, and return to step (2).
5. The method for identifying the depth of a radiation noise line spectral source according to claim 1, wherein the step (5) specifically comprises the following steps:
(5.1) according to the LSAFI (q) obtained in the step (4), counting the probability p that each fluctuation index exceeds the threshold lambda, as shown in the formula (4):
wherein M {. is } represents the number of fluctuation index values which are greater than or equal to a threshold lambda in the radiation noise line spectrum amplitude fluctuation index sequence;
(5.2) if p is greater than 0.5, judging that the radiation noise line spectrum source is a water surface target; if p is less than 0.5, judging the radiation noise line spectrum source as an underwater target; if p is 0.5, it cannot be determined whether the radiation noise line spectrum source is a water surface target or an underwater target.
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