Active direct wave suppression method, apparatus, computer and storage medium

Abstract

The application discloses an active direct wave suppression method, device, computer and storage medium, which filters a received signal by using a time domain blocking matrix, suppresses an interference frequency component, and forms a new sampling sequence; and performs a discrete Fourier transform on the new sampling sequence generated after filtering to obtain a power spectrum signal after interference suppression. According to the active direct wave suppression method, device, computer and storage medium, the uniformity of a single-frequency signal in time domain sampling is utilized, alignment on a time domain waveform is realized through phase compensation, and a difference cancellation process is performed on a reference signal and an original signal, so that the frequency component is cancelled, and static reverberation is suppressed. The method is convenient to calculate, has good single-frequency direct wave interference and reverberation suppression capability, and can be used for active target detection in a single-frequency long pulse signal transmission mode, and the effective distance is improved.

Description

Technical Field

[0001] This invention relates to the field of acoustic signal processing and target detection, and particularly to an active direct wave suppression method, apparatus, computer, and storage medium. Background Technology

[0002] One of the key operating modes of sonar equipment is active detection, primarily used for detecting underwater schools of fish, moving targets, buried objects, and seabed facilities. Compared to passive detection, active detection is not limited by the magnitude of the target's radiated noise. Theoretically, as long as the transmitter level is increased infinitely, the target's echo will definitely be received, making it highly valued in the field of weak target detection.

[0003] However, when active sonar systems detect targets, in addition to the actual target, they also receive acoustic signals reflected from many other objects, such as marine life, the sea surface, seabed topography, and water bodies. These signals reflected from discrete, uninteresting target-like objects are collectively referred to as reverberation. Reverberation follows the transmitted signal, creating a large, undulating area on the sonar image, raising the background noise and reducing the sonar's detection capability. Therefore, reverberation has become one of the most significant factors limiting the performance of active sonar.

[0004] Single-frequency signals are often used to observe the Doppler velocity of underwater moving targets due to their excellent frequency resolution characteristics. However, the presence of strong reverberation causes the target's Doppler frequency shift to be affected by reverberation sidelobes, making it impossible to extract and detect. To solve this problem, the influence of reverberation is usually reduced by adjusting the transmitter level and the pulse width of the transmitted signal, but this also reduces detection performance. Therefore, there is an urgent need for a single-frequency reverberation suppression method without changing the transmission parameters. Summary of the Invention

[0005] The main objective of this invention is to provide an active direct wave suppression method, apparatus, computer, and storage medium, aiming to solve the problem that reducing the effect of reverberation by adjusting the emission source level and the pulse width of the emission signal in the case of strong reverberation will reduce the detection performance.

[0006] To achieve the above objectives, the present invention provides an active direct wave suppression method, comprising:

[0007] S1. Obtain the received signal, wherein the received signal includes direct wave, active reverberation, target echo and background noise;

[0008] S2. Construct the time-domain blocking matrix for phase compensation;

[0009] S3. The received signal is filtered using a time-domain blocking matrix to suppress interference frequency components and form a new sampling sequence.

[0010] S4. Perform a discrete Fourier transform on the newly sampled sequence generated after filtering to obtain the power spectrum signal after interference suppression.

[0011] S5. Use feature extraction methods to extract the target frequency features from the power spectrum signal and calculate the target radial velocity.

[0012] Further, step S1 includes:

[0013] Obtain the received signal and establish a received signal model:

[0014]

[0015] Where x(ω, t) is the time-domain waveform of the received signal, ω is the processing frequency, and t is the sampling time. To transmit a direct-wave sampling signal, ω L The frequency of the transmitted signal. For the direct wave phase, Active reverberation is formed by the collection of non-target echo signals generated by static scatterers, where M is the number of static scatterers, and the frequency of the scattered echo from each static scatterer is ω. L The phase varies due to different arrival times, so let's assume it's... The target echo is caused by a Doppler frequency shift ω due to the target's motion. Δ ω is extracted by detection Δ An estimate of the target's radial velocity can be obtained. The target echo phase.

[0016] Further, step S2 includes:

[0017] Construct the time-domain blocking matrix B N+1×N :

[0018]

[0019] Where Δt is the sampling interval between two time-domain sampling points, through It can achieve phase compensation for the next sampling point and align the two sampling points.

[0020] Further, step S3 includes:

[0021] Using the time-domain blocking matrix B N+1×N Filter x(ω, t) to suppress interference frequency components ω L ,Right now

[0022] X1(ω, n) = B N+1×N X(ω,n) (3)

[0023] Where X(ω, n) is the sampling sequence of x(ω, t), X(ω, n) = [x(ω, n1), x(ω, n2), ..., x(ω, n)]. N+1 )] T If a sampling point is added to the previous snapshot, the new sampling sequence generated after filtering will be:

[0024] X1(ω,n)=[y(ω,n1),y(ω,n2),...,y(ω,n N )] T (4)

[0025]

[0026] in, The phase is the weighted sum, i = 1, 2, ..., N, s′ N (ω, t) represents the background noise sampled after cancellation.

[0027] Further, step S4 includes:

[0028] By performing a discrete Fourier transform on the new sampled sequence X1(ω,n), the power spectrum signal after interference suppression can be obtained.

[0029] X(ω) = |FFt(X1(ω, n))| 2 (6)

[0030] Where FFt is the Fourier transform.

[0031] The present invention also provides an apparatus for operating an active direct wave suppression method, comprising:

[0032] The acquisition unit is used to acquire the received signal, wherein the received signal includes direct wave, active reverberation, target echo and background noise;

[0033] Component units are used to construct the time-domain blocking matrix for phase compensation.

[0034] The suppression unit is used to filter the received signal using a time-domain blocking matrix, suppressing interference frequency components and forming a new sampling sequence.

[0035] The conversion unit is used to perform a discrete Fourier transform on the newly sampled sequence generated after filtering to obtain the power spectrum signal after interference suppression.

[0036] The extraction unit is used to extract the target frequency features from the power spectrum signal using a feature extraction method, and to calculate the target's radial velocity.

[0037] The present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described active direct wave suppression method.

[0038] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described active direct wave suppression method.

[0039] This invention provides an active direct-wave suppression method, apparatus, computer, and storage medium. Addressing the challenge of reverberation suppression in active sonar under single-frequency transmission signals, it utilizes the uniformity of the single-frequency signal's time-domain sampling. Phase compensation is used to align the time-domain waveform, and this is used as a reference signal to perform differential cancellation with the original signal, thus canceling out the frequency component and suppressing static reverberation. This method is computationally convenient, exhibits good suppression capabilities against single-frequency direct-wave interference and reverberation, and can be used for active target detection in single-frequency long-pulse signal transmission modes, extending the detection range. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the steps of the active direct wave suppression method in the first embodiment of the present invention;

[0041] Figure 2 This is a flowchart of the active direct wave suppression method of the present invention;

[0042] Figure 3 This is a comparison of lake test data processing results for the active direct wave suppression method of the first embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the apparatus for implementing the active direct wave suppression method of the present invention;

[0044] Figure 5 This is a schematic diagram of the computer device of the present invention.

[0045] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0046] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0047] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” “the,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, units, modules, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, units, modules, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connection or wireless coupling. The term “and / or” as used herein includes all or any of the units and all combinations of one or more associated listed items.

[0048] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0049] Reference Figure 1 and 2 In one embodiment of the present invention, an active direct wave suppression method includes:

[0050] S1. Obtain the received signal, wherein the received signal includes direct wave, active reverberation, target echo and background noise;

[0051] S2. Construct the time-domain blocking matrix for phase compensation;

[0052] S3. The received signal is filtered using a time-domain blocking matrix to suppress interference frequency components and form a new sampling sequence.

[0053] S4. Perform a discrete Fourier transform on the newly sampled sequence generated after filtering to obtain the power spectrum signal after interference suppression.

[0054] S5. Use feature extraction methods to extract the target frequency features from the power spectrum signal and calculate the target radial velocity.

[0055] The steps in S1 include:

[0056] Obtain the received signal and establish a received signal model:

[0057]

[0058] Where x(ω, t) is the time-domain waveform of the received signal, ω is the processing frequency, and t is the sampling time. To transmit a direct-wave sampling signal, ω L The frequency of the transmitted signal. For the direct wave phase, Active reverberation is formed by the collection of non-target echo signals generated by static scatterers, where M is the number of static scatterers, and the frequency of the scattered echo from each static scatterer is ω. L The phase varies due to different arrival times, so let's assume it's... The target echo is caused by a Doppler frequency shift ω due to the target's motion. Δ ω is extracted by detection Δ An estimate of the target's radial velocity can be obtained. The target echo phase.

[0059] The combined effect of direct wave and active reverberation creates blind zones of varying sizes within the detection range, depending on the level and length of the transmitted signal source, thus affecting the performance of active detection.

[0060] Step S2 includes:

[0061] Construct the time-domain blocking matrix B N+1×N :

[0062]

[0063] Where Δt is the sampling interval between two time-domain sampling points, through It can achieve phase compensation for the next sampling point and align the two sampling points.

[0064] To avoid and Component pairs Considering the significant frequency difference between the former two signals and the target echo, interference suppression in the frequency dimension can be achieved. Since single-frequency signals have uniform sampling properties in phase, frequency cancellation can be performed through phase compensation. Because cancellation requires consuming one degree of freedom, the time-domain blocking matrix B... N+1×N It is set to N+1×N dimensions.

[0065] The steps in S3 include:

[0066] Using the time-domain blocking matrix B N+1×N Filter x(ω, t) to suppress interference frequency components ω L ,Right now

[0067] X1(ω, n) = B N+1×NX(ω,n) (3)

[0068] Where X(ω, n) is the sampling sequence of x(ω, t), X(ω, n) = [x(ω, n1), x(ω, n2), ..., x(ω, n)]. N+1 )] T If a sampling point is added to the previous snapshot, the new sampling sequence generated after filtering will be:

[0069] X1(ω,n)=[y(ω,n1),y(ω,n2),...,y(ω,n N )] T (4)

[0070]

[0071] in, The phase is the weighted sum, i = 1, 2, ..., N, s′ N (ω, t) represents the background noise sampled after cancellation.

[0072] Considering the loss of degrees of freedom, a sampling point needs to be added in the previous snapshot, hence equation (4) is introduced. As can be seen from equation (5), ω is removed from the new sampling sequence. L Interference from frequency components is eliminated, and only the target echo signal component is retained. Due to phase inconsistency, amplitude fluctuations occur, requiring a sampling number much greater than ω for subsequent processing. L +ω Δ Periodic sampling at a given frequency.

[0073] The steps in S4 include:

[0074] By performing a discrete Fourier transform on the new sampled sequence X1(ω,n), the power spectrum signal after interference suppression can be obtained.

[0075] X(ω) = |FFt(X1(ω, n))| 2 (6)

[0076] Where FFt is the Fourier transform.

[0077] In this invention, the direct wave and active reverberation work together to create blind zones of varying sizes within the detection range, depending on the source level and length of the transmitted signal, thus affecting active detection performance. To address the challenge of reverberation suppression in active sonar under single-frequency transmitted signals, this invention utilizes the uniformity of the single-frequency signal's time-domain sampling. Phase compensation is used to align the time-domain waveform, and this is used as a reference signal to perform differential cancellation with the original signal, thus canceling out the frequency component and suppressing static reverberation. This method is computationally convenient, exhibits good suppression capabilities against single-frequency direct wave interference and reverberation, and can be used for active target detection in single-frequency long-pulse signal transmission modes, thereby increasing the detection range.

[0078] Reference Figure 3 In one embodiment, the target's Doppler frequency shift is approximately 4.6 Hz. The dashed line represents the signal power spectrum after conventional processing. Because the direct wave interference intensity far exceeds the signal, the target's feature spectrum is completely masked and cannot be extracted. The solid line represents the power spectrum after differential cancellation processing. It can be seen that the interference background at the target's azimuth is suppressed, and the signal-to-noise ratio is enhanced, providing high-quality input for subsequent feature extraction.

[0079] Reference Figure 4 The present invention also provides an apparatus for operating an active direct wave suppression method, comprising:

[0080] The acquisition unit 10 is used to acquire the received signal, wherein the received signal includes direct wave, active reverberation, target echo and background noise;

[0081] Component unit 20 is used to construct the time-domain blocking matrix for phase compensation;

[0082] The suppression unit 30 is used to filter the received signal using a time-domain blocking matrix to suppress interference frequency components and form a new sampling sequence.

[0083] The conversion unit 40 is used to perform a discrete Fourier transform on the newly sampled sequence generated after filtering to obtain the power spectrum signal after interference suppression.

[0084] Extraction unit 50 is used to extract the target frequency features in the power spectrum signal using a feature extraction method and calculate the target radial velocity.

[0085] The working modes of the acquisition unit 10, component unit 20, suppression unit 30, conversion unit 40 and extraction unit 50 are the same as those in the aforementioned method embodiments, and will not be repeated here.

[0086] Reference Figure 5 The present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described active direct wave suppression method.

[0087] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described active direct wave suppression method.

[0088] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media provided in this application and in the embodiments may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be obtained in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual-speed SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAM bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0089] In summary, the active direct-wave suppression method, apparatus, computer, and storage medium of this invention address the challenge of suppressing reverberation in active sonar under single-frequency transmission signals. By utilizing the uniformity of the single-frequency signal in the time-domain sampling, phase compensation is used to align the time-domain waveform. This waveform is then used as a reference signal to perform differential cancellation with the original signal, thus canceling out the frequency component and suppressing static reverberation. This method is computationally convenient, exhibits good suppression capabilities against single-frequency direct-wave interference and reverberation, and can be used for active target detection in single-frequency long-pulse signal transmission modes, thereby increasing the effective range.

[0090] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An active direct wave suppression method, characterized in that, include: S1. Obtain the received signal, wherein the received signal includes direct wave, active reverberation, target echo and background noise; S2. Construct the time-domain blocking matrix for phase compensation; S3. The received signal is filtered using a time-domain blocking matrix to suppress interference frequency components and form a new sampling sequence. S4. Perform a discrete Fourier transform on the newly sampled sequence generated after filtering to obtain the power spectrum signal after interference suppression. S5. Use feature extraction methods to extract the target frequency features from the power spectrum signal and calculate the target radial velocity. Step S1 includes: obtaining the received signal and establishing a received signal model. Where x(ω,t) is the time-domain waveform of the received signal, ω is the processing frequency, and t is the sampling time. To transmit direct wave sampling signals, The frequency of the transmitted signal. For the direct wave phase, Active reverberation is formed by the collection of non-target echo signals generated by static scatterers, where M is the number of static scatterers, and the frequency of the scattered echo from each static scatterer is... The phase varies due to different arrival times, so let's assume it's... The target echo is caused by a Doppler frequency shift due to the target's motion. Extracted through detection Obtain an estimate of the target's radial velocity. For the target echo phase; Step S2 includes: constructing a time-domain blocking matrix. : Where Δt is the sampling interval between two time-domain sampling points, through Phase compensation is performed on the next sampling point to align the two sampling points.

2. The active direct wave suppression method according to claim 1, characterized in that, Step S3 includes: utilizing a time-domain blocking matrix Filter x(ω,t) to suppress interference frequency components. ,Right now Where X(ω,n) is the sampling sequence of x(ω,t), If a sampling point is added to the previous snapshot, the new sampling sequence generated after filtering will be: in, The phase is the weighted value. This is a sample of the background noise after cancellation.

3. The active direct wave suppression method according to claim 2, characterized in that, Step S4 includes: by sampling the new sequence Perform a discrete Fourier transform to obtain the power spectrum signal after interference suppression. Where FFt is the Fourier transform.

4. An apparatus employing the active direct wave suppression method according to any one of claims 1 to 3, characterized in that, include: The acquisition unit is used to acquire the received signal, wherein the received signal includes direct wave, active reverberation, target echo and background noise; Component units are used to construct the time-domain blocking matrix for phase compensation. The suppression unit is used to filter the received signal using a time-domain blocking matrix, suppressing interference frequency components and forming a new sampling sequence. The conversion unit is used to perform a discrete Fourier transform on the newly sampled sequence generated after filtering to obtain the power spectrum signal after interference suppression. The extraction unit is used to extract the target frequency features from the power spectrum signal using a feature extraction method, and to calculate the target's radial velocity.

5. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes a computer program, it implements the steps of the active direct wave suppression method according to any one of claims 1 to 3.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When a computer program is executed by a processor, it implements the steps of the active direct wave suppression method according to any one of claims 1 to 3.

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