Signal Processing Method for Lightning Signals

Abstract

The present invention discloses a signal processing method for lightning signals, which relates to the field of lightning signal processing. It includes: S1 obtaining lightning signals; S2 identifying repeatedly occurring pulse signals as continuous steady-state pulse noise signals; S3 fitting the continuous steady-state pulse noise signals into standard noise; S4 performing sliding cross-correlation identification and denoising on the lightning signals with the standard noise as a reference; filtering out the baseline signals by separating the baseline signals and useful signals, which reduces low-frequency interference while maximizing the retention of the original lightning signal information; using the method of identifying the pulse noise waveform to fit the identified continuous steady-state pulse noise signals into standard noise, and performing identification and denoising on the lightning signals based on the standard noise signal waveform. Compared with the frequency-domain filtering method, it can more effectively filter out power harmonics and environmental noise interference.

Description

Technical Field

[0001] The present invention relates to the field of lightning signal processing, and in particular, to a signal processing method for lightning signals. Background Art

[0002] Lightning is one of the major natural disasters, which can cause forest and oil depot fires, and result in failures or damages to power supply and communication information systems, posing a major threat to aerospace, mines, and some important and sensitive high-tech equipment. Since the 1980s, the hazards caused by lightning have increased significantly. Especially in fields closely related to high-tech, such as aerospace, national defense, communication, power, computers, and the electronics industry, the probability of being struck by lightning has increased greatly due to the widespread application of large-scale and very large-scale integrated circuits that are extremely sensitive to lightning electromagnetic interference. It is conservatively estimated that the direct economic losses caused by lightning disasters in China exceed hundreds of millions of yuan every year, and the resulting indirect economic losses and impacts are difficult to estimate. Due to its rapid disaster formation, it has brought great difficulties to its research, prediction, and prevention. Utilizing lightning low-frequency signals can not only locate lightning in real time and achieve lightning activity early warning, thereby reducing the harmful effects caused by lightning, but also analyze the characteristics of lightning signals, deeply understand the lightning disaster-causing mechanism, and reduce the potential risks of lightning disasters. However, since lightning low-frequency signals are easily interfered, resulting in gross errors in the acquired lightning signals, it is an extremely urgent task at present to develop new lightning signal processing technologies and improve the quality of lightning signals.

[0003] Lightning low-frequency signals are usually mixed with low-frequency noise, which will bring "bulge" changes to signal recording. There is also some continuous steady-state noise, usually from the local electromagnetic environment or harmonic interference of some power supplies. The noise signals of different measurement stations may vary. These have a relatively large impact on the peak detection of lightning electric field signals, thereby affecting the accuracy of lightning location and signal characteristic analysis. The traditional signal preprocessing method is to use frequency-domain filtering to filter out relatively low-frequency noise signals. However, many noises, especially some continuous steady-state noises, are in the same frequency band as lightning signals, and it is very difficult to completely remove them simply through low-pass filtering. In addition, the traditional filtering method cannot accurately set the filtering range. If the frequency band set by the filter is narrow, the signal noise obtained is less, but the lightning signals outside the required frequency band are lost; if the set frequency band is wide, a lot of low-frequency noise will be introduced, reducing the signal quality. Summary of the Invention

[0004] The purpose of the present invention is to design a signal processing method for lightning signals to solve the above problems.

[0005] The present invention achieves the above purpose through the following technical solutions:

[0006] A signal processing method for lightning signals, comprising:

[0007] S1. Obtain lightning signals;

[0008] S2. Identify the repeatedly occurring pulse signals as continuous steady-state pulse noise signals, where the continuous steady-state pulse noise signals include power harmonics and environmental noise;

[0009] S3. Fit the continuous steady-state pulse noise signals into standard noise;

[0010] S4. Perform sliding cross-correlation identification and denoising on the lightning signals based on the standard noise to obtain the denoised lightning signals.

[0011] The beneficial effects of the present invention are as follows: By separating the baseline signal and the useful signal, the baseline signal is filtered out, reducing low-frequency interference while maximizing the retention of the original lightning signal information; By identifying the pulse noise waveform, the identified continuous steady-state pulse noise signals are fitted into standard noise, and based on the standard noise signal waveform, the lightning signals are identified and denoised. Compared with the frequency-domain filtering method, it can more effectively filter out the interference of power harmonics and environmental noise. Description of the Drawings

[0012] Figure 1 is a schematic flowchart of the signal processing method for lightning signals of the present invention;

[0013] Figure 2 is a schematic diagram of the separation of the baseline signal and the useful signal of the lightning electric field signal;

[0014] Figure 3 is a schematic diagram before and after the waveform recognition and filtering of the lightning electric field signal;

[0015] Wherein: Figure 3 In, a is the original lightning electric field signal, b is the electric field signal after signal processing, and FIGS. c and d are the waveforms of the standard noise signals respectively. Detailed Embodiments

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0017] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0018] It should be noted that like reference numerals and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

[0019] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0020] In addition, the terms "first", "second", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance.

[0021] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and defined, terms such as "arrangement", "connection", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] The following will describe in detail the specific embodiments of the present invention with reference to the drawings.

[0023] As Figure 1 , Figure 2 , Figure 3 shown, a signal processing method for lightning signals includes:

[0024] S1. Obtain lightning signals.

[0025] S0. Remove the baseline signal of the lightning signal;

[0026] S01. Let the lightning signal be Y, the useful signal be X1, the baseline signal be X2, and the noise signal be X3, Y = X1 + X2 + X3;

[0027] S02. When the lightning signal passes through a low-pass filter, if F≈L(X2 + X3), then the estimated value of Y - X1 is where L is a zero-order uncorrelated recursive filter, is the estimated value of the useful signal;

[0028] S03, Add the estimated value X1 of the useful signal to both the left and right sides of the equation as where H is a zero-order uncorrelated recursive filter;

[0029] S04. Introduce a quadratic data fidelity term and substitute it into

[0030] Suppose the loss function corresponding to the useful signal is F(X1), and the corresponding optimization function is G(X1, V). For the same useful signal, G(X1, V) ≥ G(X1, V), and only when X1 = V, G(X1, V) = G(X1, X1) = F(X1). Then the estimated value X1 of the useful signal satisfies where s is the penalty function term, In the formula, D i X1 is the i-th order difference operation of the useful signal X1, N i is the length of the i-th order difference of X1, λ i is the control signal D i of the sparsity of X1;

[0031] S06. Introduce an asymmetric penalty function θ(x n ; r),

[0032]

[0033] , where r is a constant and r > 0, ε is an infinitesimal constant and ε > 0. Then where Γ(V) is a diagonal matrix, b T is the transpose matrix of matrix b, c(V)) satisfies

[0034] S07. Iteratively solve the useful signal X1, and the iteration equation is X1 (k+1) = A(Q (k) ) -1 (B -1 BA -1 y) - λ0A T b, where Q is a band matrix that satisfies Q (k) = B T B + A T M (k) A, where M (k) satisfies A and B are band matrices, and A and B satisfy H = BA -1 .

[0035] S2. Identify the pulse signals that appear repeatedly no less than 20 times in the lightning signals after removing the signal basis as continuous steady-state pulse noise signals.

[0036] S3. Fit the continuous steady-state pulse noise signals into standard noise.

[0037] S4. Perform sliding cross-correlation denoising on the lightning signals with the standard noise as the reference to obtain the denoised lightning signals. The sliding window is 2 - 3 times the time width of the standard noise. When the correlation between the lightning signal and the standard noise exceeds 95%, zero the signal amplitude of this lightning signal to eliminate the influence of noise on the peak pulse.

[0038] When preprocessing the lightning pulses in this patent, the lightning signal is split into signal, baseline, and noise components. An asymmetric function is used to handle the convex optimization problem and establish an objective function to obtain the estimated value of the lightning pulse signal, and then the estimated value of the baseline signal is deduced. Thus, the baseline can be filtered out, the original pulse signal can be retained, and at the same time, the low-frequency interference of the "bulge" superimposed on the electric field waveform is removed, improving the quality of the acquired lightning signal. In addition, there is environmental noise interference at some stations, and the power supply generates common-mode noise interference at high frequencies. These noise interference pulses are usually regular and appear repeatedly at a certain frequency. Conventional frequency-domain filters cannot eliminate this noise. Therefore, the method of identifying the pulse noise waveform is adopted to batch extract and superimpose and fit this kind of noise waveform to form standard noise, and then denoise the lightning signal, which can effectively improve the accuracy of lightning location and lightning signal feature analysis.

[0039] The technical solution of the present invention is not limited to the restrictions of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention falls within the protection scope of the present invention.

Claims

1. A signal processing method for lightning signals, characterized in that, Including: S1. Obtain lightning signals; S0. Remove the baseline signal of the lightning signal in the target frequency band; Specifically including: S01. Let the lightning signal be Y, the useful signal be X1, the baseline signal be X2, and the noise signal be X3. ; When the lightning signal passes through the low-pass filter, there is , then the estimated value of Y - X1 is , where L is a zero-order uncorrelated recursive filter, is the estimated value of the useful signal; S03, Add the estimated value of the useful signal to both the left and right sides of the equation which is , where H is a zero-order uncorrelated recursive filter; S04. Introduce a secondary data fidelity term , and substitute it into ; S05. Let the loss function corresponding to the useful signal be , and the corresponding optimization function be . For the same useful signal,[[]] , and only when , , then the estimated value X1 of the useful signal satisfies , where s is the penalty function term,[[]] , in the formula D i X1 is the i-th order difference operation of the useful signal X1, N i is the length of the i-th order difference of X1, λ i is to control the sparsity of the signal D i X1; S06. Introduce the asymmetric penalty function θ(x n ; r), where \(r\) is a constant and \(r > 0\), and \(\varepsilon\) is an infinitesimal constant and \(\varepsilon>0\), then , where is a diagonal matrix, , \(b\) T is the transpose matrix of matrix \(b\), , \(c(V)\) satisfies ; S07. Iteratively solve the useful signal X1, and the iterative equation is , where Q is a banded matrix satisfying Q (k) =B T B + A T M (k) A, where M (k) satisfies , A and B are banded matrices, and A and B satisfy H = BA -1 ; S2. Identify repeatedly occurring pulse signals as continuous steady-state pulse noise signals; S3. Fit the continuous steady-state pulse noise signals into standard noise; S4. Perform sliding cross-correlation identification and denoising on the lightning signals based on the standard noise to obtain the denoised lightning signals.

2. The signal processing method for lightning signals according to claim 1, wherein, In S2, the number of times the pulse noise signal appears repeatedly is not less than 20 times.

3. The signal processing method for lightning signals according to claim 1, characterized in that, In S4, the sliding window is 2 - 3 times the time width of the standard noise.

4. The signal processing method for lightning signals according to claim 3, characterized in that, In S4, when the correlation between the lightning signal and the standard noise exceeds 95%, zero the signal amplitude of the lightning signal.

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