A single-channel underwater ranging system and method based on independent element analysis

Abstract

This invention discloses a single-channel underwater ranging system and method based on independent element analysis, comprising a transmitter, a receiver, and a processing module; the transmitter, receiver, and processing module are connected sequentially; the transmitter generates a reference signal and modulates an initial laser based on the reference signal to obtain a modulated laser; the receiver receives target reflected light generated based on the modulated laser emission, filters the target reflected light, performs photoelectric conversion on the filtered target reflected light to generate an echo signal, and simultaneously receives the reference signal, transmitting both the reference signal and the echo signal to the processing module; the processing module performs correlation algorithms and single-channel blind source separation calculations on the reference signal and the echo signal to obtain the phase difference, and obtains distance information based on the phase difference. Through the above technical solution, this invention can overcome the influence of water scattering and improve detection accuracy.

Description

Technical Field

[0001] This invention relates to the field of ranging radar technology, and in particular to a single-channel underwater ranging system and method based on independent element analysis. Background Technology

[0002] In the field of underwater detection, lidar technology is a powerful detection method. Its emitted light waves have good directivity, low divergence, and high propagation speed. Compared with traditional acoustic detection, light wave detection offers significant improvements in imaging efficiency, resolution, and anti-interference capabilities. Currently, lidar technology is widely used in underwater target detection, identification, and seabed mapping.

[0003] LiDAR emits lasers to illuminate objects in the ocean and receives the echoes, thereby obtaining distance information about the objects.

[0004] Absorption and scattering of the detection beam by water are the main problems limiting the range and resolution of underwater lidar. Absorption causes attenuation of the detection laser signal, while scattering, in addition to signal attenuation, introduces strong noise into the detection system. In turbid waters or at long distances, strong backscattering can completely overwhelm the signal. Increasing the detection laser power only saturates the receiving system with the scattered signal, without improving system performance. Therefore, overcoming the absorption and scattering of laser light by water and its suspended matter has always been a difficult problem to be solved in underwater laser detection.

[0005] Independent source analysis (IBA) is a signal processing algorithm that can separate statistically independent source signals from observed mixed signals when the intrinsic source signals and the mixed system are unknown. Typically, observation data consists of the outputs of a set of sensors, each receiving different combinations of source signals. This requires multi-channel detection data for processing. To simplify the process and improve efficiency, single-channel blind source separation technology is of great significance. Summary of the Invention

[0006] To address the problems of laser absorption and scattering caused by water and suspended matter in the prior art, this invention provides a single-channel underwater ranging system and method based on independent element analysis, which can effectively overcome the influence of water and suspended matter on laser absorption and scattering.

[0007] To achieve the above-mentioned technical objectives, the present invention also provides a single-channel underwater ranging system based on independent element analysis, comprising:

[0008] Transmitter, receiver, and processing module;

[0009] The transmitting end and the receiving end are respectively connected to the processing module;

[0010] The transmitting end is used to generate a reference signal, modulate the initial laser based on the reference signal to obtain a modulated laser, and then emit the modulated laser.

[0011] The receiving end is used to receive target reflected light generated based on modulated laser emission, filter the target reflected light, perform photoelectric conversion on the filtered target reflected light to generate an echo signal, and simultaneously receive the reference signal and transmit the reference signal and the echo signal to the processing module.

[0012] The processing module is used to perform adaptive complete noise empirical mode decomposition on the source signal to obtain the intrinsic mode function, where the source signal is the echo signal detected in a single instance. Based on the intrinsic mode function, the source signal is denoised by correlation calculation, and based on the denoised source signal, the echo signal is filtered by fast independent element analysis to obtain the filtered echo signal. The phase difference between the reference signal and the filtered echo signal is calculated by cross-correlation, and the distance information is obtained based on the phase difference.

[0013] Optionally, the transmitting end includes a laser, a signal generator, and an electro-optic modulator;

[0014] The laser is used to generate the initial laser beam;

[0015] The signal generator is used to generate a reference signal and transmit the reference signal to the electro-optic modulator;

[0016] The electro-optic modulator is used to modulate the initial laser according to the reference signal to obtain the modulated laser, and to emit the modulated laser, wherein the modulated laser is an optical signal with a high frequency sine wave intensity.

[0017] Optionally, the receiving end includes a receiving lens, a filter, a photomultiplier tube, and an oscilloscope;

[0018] The receiving lens is used to receive the target reflected light generated based on the modulated laser reflection and to reduce the target reflected light.

[0019] The filter is used to perform band filtering on the target reflected light after beam contraction.

[0020] The photomultiplier tube is used to perform photoelectric conversion on the target reflected light filtered by the band to generate an echo signal, wherein the echo signal is an electrical signal.

[0021] The oscilloscope is used to receive the reference signal and transmit the reference signal and the echo signal to the processing module.

[0022] Optionally, the processing module includes a decomposition module, a noise reduction module, a filtering module, and a ranging module;

[0023] The decomposition module is used to decompose the source signal into several intrinsic mode functions through adaptive complete noise empirical modes, wherein the source signal is the echo signal detected in a single instance;

[0024] The denoising module is used to calculate the correlation between the intrinsic mode functions and the source signal, obtain the correlation coefficient corresponding to the intrinsic mode functions, perform threshold judgment on the correlation coefficient, remove the intrinsic mode functions of the correlation system that do not meet the threshold, and obtain the denoised source signal.

[0025] The filtering module is used to combine the intrinsic mode functions that meet the threshold with the denoised source signal to obtain a new probe signal matrix. Based on the probe signal matrix, the backscattered signal and echo signal in the source signal are separated by fast independent element analysis to obtain the filtered echo signal.

[0026] The ranging module is used to calculate the phase difference between the reference signal and the filtered echo signal through cross-correlation, calculate the time difference based on the phase difference, and calculate the distance information relative to the reference signal based on the time difference.

[0027] Optionally, the modulated laser is a 532nm chirped intensity laser; the filter in the receiver corresponding to the 532nm chirped intensity laser is a 532nm narrowband filter.

[0028] To better achieve the above technical objectives, this invention also provides a single-channel underwater ranging method based on independent element analysis, comprising:

[0029] A reference signal is generated, and the initial laser is modulated based on the reference signal to obtain a modulated laser, which is then emitted.

[0030] Receive the target reflected light generated based on modulated laser emission, filter the target reflected light, and perform photoelectric conversion on the filtered target reflected light to generate an echo signal;

[0031] Adaptive complete noise empirical mode decomposition is performed on the source signal to obtain the intrinsic mode function (EMF), where the source signal is the echo signal detected in a single instance. Based on the EMF, the source signal is denoised by correlation calculation. Based on the denoised source signal, the echo signal is filtered by fast independent element analysis to obtain the filtered echo signal. The phase difference between the reference signal and the filtered echo signal is calculated by cross-correlation, and the distance information is obtained based on the phase difference.

[0032] Optionally, the modulated laser is an optical signal with a high-frequency sine wave intensity.

[0033] Optionally, the process of generating the echo signal includes:

[0034] The system receives target reflected light generated based on modulated laser reflection and performs beam reduction on the target reflected light; it then performs band filtering on the beam-reduced target reflected light; finally, it performs photoelectric conversion on the band-filtered target reflected light to generate an echo signal, wherein the echo signal is an electrical signal.

[0035] Optionally, the process of obtaining the distance information includes:

[0036] The source signal is decomposed into several intrinsic mode functions by adaptive complete noise empirical mode, where the source signal is the echo signal detected in a single instance;

[0037] The correlation between the intrinsic mode functions and the source signal is calculated to obtain the correlation coefficients corresponding to the intrinsic mode functions. The correlation coefficients are then judged by a threshold, and the intrinsic mode functions in the source signal whose correlation coefficients do not meet the threshold are removed to obtain the denoised source signal.

[0038] The intrinsic mode functions that meet the threshold are combined with the denoised source signal to obtain the probe signal matrix. Based on the probe signal matrix, the backscattered signal and echo signal in the source signal are separated by fast independent element analysis to obtain the filtered echo signal.

[0039] The phase difference between the reference signal and the filtered echo signal is calculated by cross-correlation. The time difference is then calculated based on the phase difference, and the distance information relative to the reference signal is obtained based on the time difference.

[0040] Optionally, the modulated laser is a 532nm chirped intensity laser.

[0041] The present invention has the following technical effects:

[0042] This invention processes the source signal through adaptive complete noise empirical mode decomposition, overcoming the requirement for a certain number of detection signals in traditional blind source separation, and proposes a single-channel blind source separation technique. By employing independent element analysis (IEA) technology, backscattering in the detection signal is separated from the target echo, overcoming the influence of water scattering, improving detection accuracy, and simultaneously simplifying the process and increasing efficiency. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the system provided in Embodiment 1 of the present invention;

[0045] Figure 2This is a flowchart of the method provided in Embodiment 2 of the present invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Example 1

[0048] To address the problems existing in the prior art, the present invention provides the following solution:

[0049] like Figure 1 The present invention provides a single-channel underwater ranging system based on independent element analysis, which is applied as a radar and includes:

[0050] Includes: transmitter, receiver, and processing module;

[0051] The transmitting end and the receiving end are respectively connected to the processing module;

[0052] The transmitting end is used to generate a reference signal, modulate the initial laser based on the reference signal to obtain a modulated laser, and then emit the modulated laser.

[0053] The receiving end is used to receive target reflected light generated based on modulated laser emission, filter the target reflected light, perform photoelectric conversion on the filtered target reflected light to generate an echo signal, and simultaneously receive the reference signal and transmit the reference signal and the echo signal to the processing module.

[0054] The processing module is used to perform adaptive complete noise empirical mode decomposition on the source signal to obtain the intrinsic mode function, where the source signal is the echo signal detected in a single instance. Based on the intrinsic mode function, the source signal is denoised by correlation calculation, and based on the denoised source signal, the echo signal is filtered by fast independent element analysis to obtain the filtered echo signal. The phase difference between the reference signal and the filtered echo signal is calculated by cross-correlation, and the distance information is obtained based on the phase difference.

[0055] The transmitting end includes a laser, a signal generator, and an electro-optic modulator. The laser is a 532nm chirped intensity modulated laser; the signal generator is used to generate a modulation signal and send it to the electro-optic modulator; the electro-optic modulator modulates the laser to obtain a modulated laser, which is an optical signal with a high-frequency sine wave intensity.

[0056] The receiving end includes a receiving lens, a 532nm filter, a photomultiplier tube, and an oscilloscope. The receiving lens is used to receive and narrow the reflected light from the target; the filter is a 532nm narrowband filter used to filter light outside the 532nm wavelength band; the photomultiplier tube acts as a detector, receiving light and converting it into an electrical signal, which is then amplified and sent to the oscilloscope as an echo signal. The oscilloscope receives the reference signal from the signal generator and the echo signal from the detector, and then sends the waveforms of the reference signal and the echo signal to a computer for calculation.

[0057] The processing module uses a computer to perform algorithm calculations:

[0058] First, the signal detected in a single instance is subjected to complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), which decomposes the source signal into a series of intrinsic mode functions.

[0059] CEEMDAN is an improved technique of Empirical Mode Decomposition (EMD). EMD is a classic adaptive signal time-frequency processing method. Its principle is to decompose the signal multiple times based on its own characteristics to obtain a set of Intrinsic Mode Function (IMF) components and a residual component. The IMF component contains local feature signals of the original signal at different time scales. The core of the CEEMDAN algorithm is to add adaptive white noise and calculate the unique residual component on the basis of the EMD algorithm to achieve a more accurate reconstruction of the IMF components.

[0060] The main steps of CEEMDAN decomposition are:

[0061] (1) Let x(t) be the original signal, ω(t) be Gaussian white noise, and ω i (t) represents the noise added for the i-th time, where Gaussian white noise is added to the original signal to form a new signal x. i (t)=x(t)+σ0ω i (t), i=(1,···,N), σ0 is the standard deviation of the noise.

[0062] (2) Using the EMD decomposition method to analyze x i Decomposing (t) yields the first intrinsic mode function (IMF) of the CEEMDAN decomposition. M k [·] represents the Kth IMF obtained after EMD decomposition, σ kThis represents the amplitude of the noise added to the IMF. After the initial decomposition, the first IMF is removed from the original signal x(t), yielding the remainder r1:

[0063] r1=x(t)-IMF1

[0064] (3) Similarly, for Gaussian white noise ω i (t) is decomposed using EMD to obtain adaptive noise, and then a new signal to be decomposed, x(t)′, is reconstructed after adding the margin:

[0065] x(t)′=r k-1 +σ k-1 M k-1 [ω i (t)]

[0066] Repeat step (1) for the new signal to be decomposed, and step (2) yields the remaining IMF:

[0067]

[0068] r k =r k-1 -IMF k

[0069] When the final decomposition is complete, the number of extreme points of the remaining residual is less than 2. The CEEMDAN decomposition is complete, and the original signal is ultimately decomposed into the sum of several IMFs and the residual residual.

[0070]

[0071] The correlation between all the decomposed intrinsic mode functions and the source signal is calculated to obtain the correlation coefficients. The intrinsic mode functions with low correlation coefficients are removed from the source signal. The intrinsic mode functions with low correlation coefficients can be removed by manually setting a correlation threshold to perform preliminary noise reduction.

[0072] The eigenmode functions with high correlation coefficients are combined with the denoised source signal to form a new detection signal matrix. Fast independent element analysis is then performed to separate the backscattered signal from the target echo signal in the source signal, thus completing the entire filtering process.

[0073] Independent component analysis is a type of blind signal separation technique. The basic idea of ​​blind signal separation is based on the assumption of the independence of individual components of aliased signals. The directly measured observation matrix is ​​used as the result of aliasing of multiple source signals, and their statistical independence is used to estimate each independent signal component that makes up the overall signal.

[0074] The main steps are as follows:

[0075] (1) Whitening Preprocessing: X(n) is the observed signal, and the final unmixed signal is S(n). First, the data is whitened to remove impurities. Whitening also simplifies the process of extracting independent components before ICA iteration; in most cases, algorithms that use whitening before iteration have better convergence. In the current work, the principal component analysis (PCA) method in the BSS algorithm uses second-order statistics (variance) for dimensionality reduction, also known as whitening. Using whitening preprocessing for ICA data can effectively reduce the complexity of iterative separation, and the whitening process is simple and can be directly performed using PCA. The original mixing matrix will degenerate into an orthogonal matrix after PCA whitening; using orthogonal matrix separation can reduce the workload of ICA iteration. Furthermore, PCA itself can achieve data dimensionality reduction: when the number of observed signals is greater than the number of source signals, whitening can automatically reduce the observed signals to the same dimension as the source signals. The principle of this algorithm is Singular Value Decomposition (SVD). The steps of the SVD algorithm are as follows:

[0076] 1. Calculate matrix V: V column vectors (X T X)v i =λ i v i v i Let X be a matrix T The eigenvectors of X.

[0077] 2. Calculate matrix Σ: Let X be a matrix T The eigenvalues ​​of X correspond to the column vectors of V.

[0078] 3. Calculate matrix U: the column vectors of U (XX) T )u i =λ i u i , where u i For XX T eigenvectors.

[0079] (2) Iterative Calculation: The goal of iterative calculation is to find a linear representation of the non-Gaussian data so that the components are statistically independent, thereby separating the components. This technique employs Fast Independent Component Analysis (Fast ICA) to find an iterative matrix W that maximizes the non-Gaussianity of each component. The main steps are as follows:

[0080] 1. Select a random initial weight matrix W0;

[0081] 2. Calculate the FastICA iteration: W +=E{X·g(W k-1 X)}-E{g′(W k-1 X)}W k-1 W + W is the iterative parameter matrix. k Let g(x) be the weight matrix after the k-th iteration, where k is the iteration number, and g(·) be an appropriate nonlinear function. In this paper, g(x) = x 3 , g′(·) is the derivative of g(·);

[0082] 3. Update the weight matrix:

[0083] 4. If <W k-1 W k If the result is greater than or equal to 1, then the algorithm has converged and the separation algorithm ends; otherwise, return to step 2) and repeat the subsequent steps until convergence is achieved, at which point the iteration process ends.

[0084] The phase difference between the reference signal and the filtered echo signal is calculated by cross-correlation, and the time difference is then calculated from the phase difference to obtain the distance information relative to the reference signal.

[0085] The process of cross-correlation calculation is as follows:

[0086] The modulation signal for emitting the laser is:

[0087]

[0088] In the formula, I1 represents the modulation signal strength at the transmitting end; A1 represents the modulation signal amplitude; f is the modulation signal frequency; t1, These represent the initial time and phase of the transmitted signal, respectively.

[0089] The modulated signal of the received echo signal is:

[0090]

[0091] In the formula, I2 represents the modulation signal strength at the transmitting end; A2 represents the modulation signal amplitude; f is the modulation signal frequency; t2, These represent the initial time and phase of the transmitted signal, respectively.

[0092] The phase offset between the receiver and the transmitter is:

[0093]

[0094] The time difference between the laser receiver and transmitter is:

[0095]

[0096] The distance to the target is:

[0097]

[0098] In the formula, N represents the complete number of wavelengths that differ between the echo signal and the transmitted signal. The phase difference between the echo signal and the transmitted signal can only be calculated for a single cycle. Let n be the length of the measuring scale in the phase ranging method, and n be the refractive index of the light wave in the medium. When the measured distance is greater than the measuring scale length, the distance measurement result needs to be increased by the complete number of wavelengths N.

[0099] To provide a more detailed technical description of the technology, the present invention provides the following: The laser is a chirped intensity modulated light source with a wavelength of 532 nm, which generates continuous light. The modulation frequency is generally set to above 100 MHz, because the cutoff frequency of backscattering in water is around 100 MHz. A carrier-modulated laser with a frequency higher than 100 MHz suppresses scattering in seawater and reduces backscattered signals in the received signal.

[0100] The signal generator uses the radio frequency sinusoidal intensity modulation signal as a reference signal and sends the reference signal to the oscilloscope for comparison in the phase-based ranging calculation.

[0101] The filter is a 532nm narrowband filter, which only retains the 532nm wavelength band. Light of other wavelengths is ambient stray light and is filtered out so that it cannot enter the detector.

[0102] The detector is a PMT photomultiplier tube, which can detect weak light signals, receive and amplify the echo, convert the echo light signal into an electrical signal by analog-to-digital conversion, obtain the curve of light intensity changing with time, and send it to the oscilloscope.

[0103] In distance measurement calculations, a reference point must first be established. The target is initially placed near the window of the water tank, and the phase difference and distance are calculated at this point to serve as the reference. Then, the target is placed inside the water tank, and the distance calculated is subtracted from the reference distance to obtain the target's actual position.

[0104] For the intrinsic mode functions (EMFs) after adaptive complete noise empirical mode decomposition, their correlation with the original signal is calculated. The correlation coefficient of each EMF with the source signal is obtained. The lower the correlation coefficient, the more likely the EMF has lost high-frequency components and belongs to low-frequency noise. Removing the EMFs with low correlation coefficients from the original signal yields the preliminary denoised signal. The remaining EMFs with higher correlation coefficients are then used together with this signal to form the observation matrix required for subsequent blind source separation. This allows for blind source separation with only a single detection signal, overcoming the limitation on the number of detection signals and achieving single-channel computation.

[0105] Example 2

[0106] like Figure 2 As shown, to better achieve the above technical objectives, the present invention also provides a single-channel underwater ranging method based on independent element analysis, comprising:

[0107] A reference signal is generated, and the initial laser is modulated based on the reference signal to obtain a modulated laser, which is then emitted.

[0108] Receive the target reflected light generated based on modulated laser emission, filter the target reflected light, and perform photoelectric conversion on the filtered target reflected light to generate an echo signal;

[0109] An adaptive complete noise empirical mode decomposition (EMD) is performed on the source signal to obtain the intrinsic mode function (EMF), where the source signal is the echo signal detected in a single instance. Based on the EMF, the source signal is denoised through correlation calculation. Then, based on the denoised source signal, the echo signal is filtered through fast independent element analysis (LIMA) to obtain the filtered echo signal. The phase difference between the reference signal and the filtered echo signal is calculated through cross-correlation, and distance information is obtained based on the phase difference. The system and method content of this invention correspond to each other and will not be repeated here.

[0110] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A single-channel underwater ranging system based on independent component analysis, characterized in that, include: Transmitter, receiver, and processing module; The transmitter, the receiver, and the processing module are connected in sequence. The transmitting end is used to generate a reference signal, modulate the initial laser based on the reference signal to obtain a modulated laser, and then emit the modulated laser. The receiving end is used to receive target reflected light generated based on modulated laser emission, filter the target reflected light, perform photoelectric conversion on the filtered target reflected light to generate an echo signal, and simultaneously receive the reference signal and transmit the reference signal and the echo signal to the processing module. The processing module is used to take the echo signal detected in a single detection as the source signal, perform adaptive complete noise empirical mode decomposition on the source signal to obtain the intrinsic mode function, denoise the source signal by correlation calculation based on the intrinsic mode function, and filter the echo signal by fast independent element analysis based on the denoised source signal to obtain the filtered echo signal. The phase difference between the reference signal and the filtered echo signal is calculated by cross-correlation, and the distance information is obtained based on the phase difference. The processing module includes a decomposition module, a noise reduction module, a filtering module, and a ranging module; The decomposition module is used to take the echo signal detected in a single detection as the source signal and decompose the source signal into several intrinsic mode functions through adaptive complete noise empirical mode. The denoising module is used to calculate the correlation between the intrinsic mode functions and the source signal, obtain the correlation coefficient corresponding to the intrinsic mode functions, perform threshold judgment on the correlation coefficient, remove the intrinsic mode functions of the correlation system that do not meet the threshold, and obtain the denoised source signal. The filtering module is used to combine the intrinsic mode functions that meet the threshold with the denoised source signal to obtain a new probe signal matrix. Based on the probe signal matrix, the backscattered signal and echo signal in the source signal are separated by fast independent element analysis to obtain the filtered echo signal. The ranging module is used to calculate the phase difference between the reference signal and the filtered echo signal through cross-correlation, calculate the time difference based on the phase difference, and calculate the distance information relative to the reference signal based on the time difference. The phase difference between the reference signal and the filtered echo signal is calculated by cross-correlation, and the time difference is then calculated from the phase difference to obtain the distance information relative to the reference signal. The process of cross-correlation calculation is as follows: The modulation signal for emitting the laser is: In the formula, I1 represents the modulation signal strength at the transmitting end; A1 represents the modulation signal amplitude; f is the modulation signal frequency; t1, These represent the initial time and phase of the transmitted signal, respectively. The modulated signal of the received echo signal is: In the formula, I2 represents the modulation signal strength at the transmitting end; A2 represents the modulation signal amplitude; f is the modulation signal frequency; t2, These represent the initial time and phase of the transmitted signal, respectively. The phase offset between the receiver and the transmitter is: The time difference between the laser receiver and transmitter is: The distance to the target is: In the formula, N represents the number of complete wavelengths that differ between the echo signal and the transmitted signal; the phase difference between the echo signal and the transmitted signal can only be calculated for a single cycle. Where n is the length of the measuring scale in the phase ranging method, and n is the refractive index of the light wave in the medium; when the measured distance is greater than the length of the measuring scale, the distance measurement result needs to be added to the complete number of wavelengths N.

2. The single-channel underwater ranging system based on independent component analysis according to claim 1, characterized in that: The transmitting end includes a laser, a signal generator, and an electro-optic modulator; The laser is used to generate the initial laser beam; The signal generator is used to generate a reference signal and transmit the reference signal to the electro-optic modulator; The electro-optic modulator is used to modulate the initial laser according to the reference signal to obtain the modulated laser, and to emit the modulated laser, wherein the modulated laser is an optical signal with a high frequency sine wave intensity.

3. The single-channel underwater ranging system based on independent component analysis according to claim 1, characterized in that: The receiving end includes a receiving lens, a filter, a photomultiplier tube, and an oscilloscope; The receiving lens is used to receive the target reflected light generated based on the modulated laser reflection and to reduce the target reflected light. The filter is used to perform band filtering on the target reflected light after beam contraction. The photomultiplier tube is used to perform photoelectric conversion on the target reflected light filtered by the band to generate an echo signal, wherein the echo signal is an electrical signal. The oscilloscope is used to receive the reference signal and transmit the reference signal and the echo signal to the processing module.

4. The single-channel underwater ranging system based on independent component analysis according to claim 3, characterized in that: The initial laser is a 532nm chirped intensity laser; the filter in the receiving end corresponding to the 532nm chirped intensity laser is a 532nm narrowband filter.

5. A single-channel underwater ranging method based on independent component analysis, characterized in that, The method achieves underwater ranging based on the system described in any one of claims 1-4, and the method includes: A reference signal is generated, and the initial laser is modulated based on the reference signal to obtain a modulated laser, which is then emitted. Receive the target reflected light generated based on modulated laser emission, filter the target reflected light, and perform photoelectric conversion on the filtered target reflected light to generate an echo signal; The echo signal detected in a single detection is used as the source signal. Adaptive complete noise empirical mode decomposition is performed on the source signal to obtain the intrinsic mode function. Based on the intrinsic mode function, the source signal is denoised by correlation calculation. Based on the denoised source signal, the echo signal is filtered by fast independent element analysis to obtain the filtered echo signal. The phase difference between the reference signal and the filtered echo signal is calculated by cross-correlation, and the distance information is obtained based on the phase difference.

6. The single-channel underwater ranging method based on independent component analysis according to claim 5, characterized in that: The modulated laser is a light signal with a high-frequency sine wave intensity.

7. The single-channel underwater ranging method based on independent component analysis according to claim 5, characterized in that: The process of generating the echo signal includes: The system receives target reflected light generated based on modulated laser reflection and performs beam reduction on the target reflected light; it then performs band filtering on the beam-reduced target reflected light; finally, it performs photoelectric conversion on the band-filtered target reflected light to generate an echo signal, wherein the echo signal is an electrical signal.

8. The single-channel underwater ranging method based on independent component analysis according to claim 5, characterized in that: The process of obtaining the distance information includes: The echo signal detected in a single detection is used as the source signal, and the source signal is decomposed into several intrinsic mode functions through adaptive complete noise empirical mode. The correlation between the intrinsic mode functions and the source signal is calculated to obtain the correlation coefficients corresponding to the intrinsic mode functions. The correlation coefficients are then judged by a threshold, and the intrinsic mode functions in the source signal whose correlation coefficients do not meet the threshold are removed to obtain the denoised source signal. The intrinsic mode functions that meet the threshold are combined with the denoised source signal to obtain the probe signal matrix. Based on the probe signal matrix, the backscattered signal and echo signal in the source signal are separated by fast independent element analysis to obtain the filtered echo signal. The phase difference between the reference signal and the filtered echo signal is calculated by cross-correlation. The time difference is then calculated based on the phase difference, and the distance information relative to the reference signal is obtained based on the time difference.

9. The single-channel underwater ranging method based on independent component analysis according to claim 5, characterized in that: The initial laser is a 532nm chirped intensity laser.

Images