Signal noise reduction method and system and storage medium

Abstract

The invention discloses a signal noise reduction method and system and a storage medium. The method comprises the following steps: acquiring a power line carrier signal; wherein the power line carrier signal is an OFDM signal; preprocessing the OFDM signal to obtain each subcarrier signal and the phase of each subcarrier signal; inputting each subcarrier signal into a preset chaos noise reduction system, so that the chaos noise reduction system measures the amplitude of each subcarrier signal according to the state transformation of a chaos oscillator in the system; and reconstructing the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain a denoised power line carrier signal. The noise reduction effect of the power line carrier signal can be improved, and the applicability is high.

Description

Technical Field

[0001] The present invention relates to the field of signal noise reduction, and in particular to a signal noise reduction method, system and storage medium. Background Art

[0002] Power line communication is a communication method that uses power lines as a transmission medium to transmit data. It has a wide transmission range, low cost, and continuous transmission capabilities, making it widely used in various communication scenarios. Power lines were originally designed for power transmission, not specifically for information and communication technology. Therefore, power lines have disadvantages such as poor communication channel environment, large noise interference, and a variety of types. In particular, as a high proportion of power electronic equipment is connected to low-voltage power lines, the channel environment is further deteriorated.

[0003] Existing noise reduction technologies essentially analyze the characteristics of noise signals in power lines. However, since the noise background of power line carrier signals is random and unpredictable, this greatly increases the complexity of signal processing, resulting in poor noise reduction effects. Therefore, it is crucial to explore a signal noise reduction method with good noise reduction effects and good applicability. Summary of the invention

[0004] The present invention provides a signal noise reduction method, system and storage medium to improve the noise reduction effect of a power line carrier signal, and the method has high applicability.

[0005] In a first aspect, the present application provides a signal noise reduction method, comprising:

[0006] Acquire a power line carrier signal; wherein the power line carrier signal is an OFDM signal;

[0007] Preprocessing the OFDM signal to obtain each subcarrier signal and the phase of each subcarrier signal;

[0008] Inputting each subcarrier signal into a preset chaotic noise reduction system, so that the chaotic noise reduction system measures the amplitude of each subcarrier signal according to the state change of the chaotic oscillator in the system;

[0009] Based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, the power line carrier signal is reconstructed to obtain the power line carrier signal after noise reduction.

[0010] The embodiment of the present application can firstly accurately obtain the noisy OFDM signal by obtaining the power line carrier signal; by preprocessing the OFDM signal, the OFDM signal can be decoupled into each subcarrier signal, and the phase of each subcarrier signal can be obtained; by utilizing the sensitivity of the chaotic oscillator in the chaotic noise reduction system to transform from a chaotic state to a large-scale periodic state, the amplitude of each subcarrier signal can be measured; based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, the power line carrier signal can be reconstructed, and the target power line carrier signal after noise reduction can be accurately obtained. Compared with the signal characteristic analysis of noise in the prior art, the present application analyzes the power line carrier signal, obtains the phase of each subcarrier signal using the cross-correlation function, and obtains the amplitude of each subcarrier signal using the chaotic noise reduction system, thereby reconstructing the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, thereby improving the noise reduction effect of the power line carrier signal, and has high applicability.

[0011] Further, the OFDM signal is preprocessed to obtain each subcarrier signal and the phase of each subcarrier signal, specifically:

[0012] Preprocessing the OFDM signal by using a cross-correlation function to obtain a cross-correlation function calculation result;

[0013] Each subcarrier signal and the phase of each subcarrier signal are obtained through the calculation result of the cross-correlation function, wherein each subcarrier signal is a single cosine wave signal decoupled from the OFDM signal.

[0014] In this way, by preprocessing the OFDM signal through the cross-correlation function, the OFDM signal can be decoupled into each subcarrier signal, and the phase of each subcarrier signal can be obtained.

[0015] Furthermore, the calculation formula of the cross-correlation function is:

[0016]

[0017] In the formula, R rx (τ) is the result of the cross-correlation function calculation, T is the period, τ is the delay, r(t) is the power line carrier signal containing noise, x(t) = cos(ω j t) is a reference signal with the same frequency as each subcarrier, and t represents time.

[0018] In this way, by preprocessing the OFDM signal through the cross-correlation function, the OFDM signal can be decoupled into each subcarrier signal, and the phase of each subcarrier signal can be obtained.

[0019] Further, the inputting of each subcarrier signal into a preset chaotic noise reduction system so that the chaotic noise reduction system measures the amplitude of each subcarrier signal according to the state change of the chaotic oscillator in the system, specifically:

[0020] Adjusting the external excitation amplitude of the chaotic noise reduction system so that the chaotic oscillator in the chaotic noise reduction system is in a critical chaotic state, and recording the first external excitation amplitude at the current moment;

[0021] Inputting each subcarrier signal into a preset chaotic noise reduction system, and adjusting the external excitation amplitude of the chaotic noise reduction system again, so that the chaotic oscillator in the chaotic noise reduction system returns to a critical chaotic state, and recording the second external excitation amplitude at the current moment;

[0022] The amplitude of each subcarrier signal is obtained based on the first external excitation amplitude and the second external excitation amplitude.

[0023] In this way, the amplitude of each subcarrier signal is measured by utilizing the sensitivity of the chaotic oscillator in the chaotic noise reduction system to transform from a chaotic state to a large-scale periodic state.

[0024] Furthermore, the chaotic oscillator is a Duffing oscillator, and the state equation of the Duffing oscillator is:

[0025]

[0026] In the formula, and is the derivative of the state variable, x and y are the state variables, k is the equation coefficient, γ is the external excitation amplitude, ω is the scale conversion factor, and r(t) is the noisy power line carrier signal.

[0027] In this way, the amplitude of each subcarrier signal is measured by utilizing the sensitivity of the Duffing oscillator in transforming from a chaotic state to a large-scale periodic state.

[0028] Further, the power line carrier signal is reconstructed based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain the power line carrier signal after noise reduction, specifically:

[0029] Obtaining the frequency of each subcarrier signal;

[0030] Based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, the power line carrier signal is reconstructed to obtain a power line carrier signal after noise reduction; wherein the formula for reconstructing the power line carrier signal is:

[0031]

[0032] Where s(t) is the power line carrier signal, n is the number of subcarriers, ω i is the frequency of each subcarrier signal, A i is the amplitude of each subcarrier signal, is the phase of each subcarrier signal.

[0033] In this way, the power line carrier signal can be reconstructed based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, and the target power line carrier signal after noise reduction can be accurately obtained.

[0034] In a second aspect, the present application provides a signal noise reduction system, including an acquisition module, a preprocessing module, a detection module and an output module:

[0035] The acquisition module is used to acquire a power line carrier signal; wherein the power line carrier signal is an OFDM signal;

[0036] The preprocessing module is used to preprocess the OFDM signal to obtain each subcarrier signal and the phase of each subcarrier signal;

[0037] The detection module is used to input each subcarrier signal into a preset chaotic noise reduction system, so that the chaotic noise reduction system measures the amplitude of each subcarrier signal according to the state change of the chaotic oscillator in the system;

[0038] The output module is used to reconstruct the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain the power line carrier signal after noise reduction.

[0039] The embodiment of the present application can firstly accurately obtain the noisy OFDM signal by obtaining the power line carrier signal; by preprocessing the OFDM signal, the OFDM signal can be decoupled into each subcarrier signal, and the phase of each subcarrier signal can be obtained; by utilizing the sensitivity of the chaotic oscillator in the chaotic noise reduction system to transform from a chaotic state to a large-scale periodic state, the amplitude of each subcarrier signal can be measured; based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, the power line carrier signal can be reconstructed, and the target power line carrier signal after noise reduction can be accurately obtained. Compared with the signal characteristic analysis of noise in the prior art, the present application analyzes the power line carrier signal, obtains the phase of each subcarrier signal using the cross-correlation function, and obtains the amplitude of each subcarrier signal using the chaotic noise reduction system, thereby reconstructing the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, thereby improving the noise reduction effect of the power line carrier signal, and has high applicability.

[0040] Furthermore, the preprocessing module includes a preprocessing unit and a first computing unit:

[0041] The preprocessing unit is used to preprocess the OFDM signal by using a cross-correlation function to obtain a calculation result of the cross-correlation function;

[0042] The first calculation unit is used to obtain each subcarrier signal and the phase of each subcarrier signal through the calculation result of the cross-correlation function, wherein each subcarrier signal is a single cosine wave signal decoupled from the OFDM signal.

[0043] Furthermore, the calculation formula of the cross-correlation function in the preprocessing unit is:

[0044]

[0045] In the formula, R rx (τ) is the result of the cross-correlation function calculation, T is the period, τ is the delay, r(t) is the power line carrier signal containing noise, x(t) = cos(ω j t) is a reference signal with the same frequency as each subcarrier, and t represents time.

[0046] Further, the detection module includes a first adjustment unit, a second adjustment unit and a second calculation unit:

[0047] The first adjustment unit is used to adjust the external excitation amplitude of the chaotic noise reduction system so that the chaotic oscillator in the chaotic noise reduction system is in a critical chaotic state, and record the first external excitation amplitude at a current moment;

[0048] The second adjustment unit is used to input the subcarrier signals into a preset chaotic noise reduction system, and adjust the external excitation amplitude of the chaotic noise reduction system again to make the chaotic oscillator in the chaotic noise reduction system return to a critical chaotic state, and record the second external excitation amplitude at the current moment;

[0049] The second calculation unit is used to obtain the amplitude of each subcarrier signal based on the first external excitation amplitude and the second external excitation amplitude.

[0050] Furthermore, the chaotic oscillator is a Duffing oscillator, and the state equation of the Duffing oscillator is:

[0051]

[0052] In the formula, and is the derivative of the state variable, x and y are the state variables, k is the equation coefficient, γ is the external excitation amplitude, ω is the scale conversion factor, and r(t) is the noisy power line carrier signal.

[0053] Furthermore, the output module includes an acquisition unit and a third calculation unit:

[0054] The acquisition unit is used to acquire the frequency of each subcarrier signal;

[0055] The third calculation unit is used to reconstruct the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain a power line carrier signal after noise reduction; wherein the formula for reconstructing the power line carrier signal is:

[0056]

[0057] Where s(t) is the power line carrier signal, n is the number of subcarriers, ω i is the frequency of each subcarrier signal, A i is the amplitude of each subcarrier signal, is the phase of each subcarrier signal.

[0058] In a third aspect, the present application provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the signal noise reduction method described in the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a flowchart of an embodiment of a signal noise reduction method provided by the present application;

[0060] Figure 2 is a time domain diagram of a noisy power line carrier signal provided by the present application;

[0061] Figure 3 It is the constellation diagram of the 16QAM modulation method provided by this application;

[0062] Figure 4 is the phase space diagram of the Duffing oscillator in the critical chaotic state provided by the present application;

[0063] Figure 5 It is the phase space diagram of the Duffing oscillator state at a large period scale provided by this application;

[0064] Figure 6 is a time domain diagram of the power line carrier signal after noise reduction provided by the present application;

[0065] Figure 7 It is a structural schematic diagram of an embodiment of a signal noise reduction system provided by the present application. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] It should be understood that the step numbers used in this article are only for the convenience of description and are not intended to limit the order in which the steps are executed.

[0068] It should be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0069] The terms “include” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0070] The term "and / or" means and includes any and all possible combinations of one or more of the associated listed items.

[0071] The power line carrier OFDM signal refers to the orthogonal frequency division multiplexing (OFDM) modulation method adopted by the power line carrier signal, which is a multi-carrier modulation form, and the time domain waveform is the superposition of multiple cosine waves.

[0072] Quadrature Amplitude Modulation (QAM) is a modulation method that performs amplitude modulation on two orthogonal carriers. The two carriers are usually sinusoidal waves with a phase difference of 90 degrees (π / 2). It can also be regarded as modulating the data into the amplitude and phase of a carrier at the same time.

[0073] Please refer to Figure 1 , Figure 1 This is a flow chart of an embodiment of a signal noise reduction method provided by the present application, including steps S1 to S4:

[0074] Step S1, obtaining a power line carrier signal; wherein the power line carrier signal is an OFDM signal;

[0075] Specifically, the formula of the OFDM signal is:

[0076]

[0077] Where r(t) is the noisy power line carrier signal, s(t) is the power line carrier signal, n(t) is the noise, n is the number of subcarriers, ω i is the frequency of each subcarrier signal, A i is the amplitude of each subcarrier signal, is the phase of each subcarrier signal.

[0078] It can be known that when the frequency ω of each subcarrier signal is determined i , the amplitude A of each subcarrier signal i , the phase of each subcarrier signal And the noise n(t), we can simulate the power line carrier signal r(t) under the noise background, where the time domain diagram of the noisy power line carrier signal is as follows Figure 2 shown.

[0079] It should be noted that the frequency ω of each subcarrier signal i It is a multiple of the base frequency, and the base frequency can be determined according to the "Power Line Carrier Standard" that complies with national standards and regional standards.

[0080] It should be noted that A i and Determined by the modulation technology of each subcarrier, when the modulation technology of each subcarrier is 16QAM, the amplitude to be measured based on the 16QAM modulated power line carrier signal is confirmed according to the constellation diagram as The phase to be measured is ±[0.1024, 0.25, 0.3976, 0.6024, 0.75, 0.8976]*π, so the amplitude of each randomly generated subcarrier signal The phase of each subcarrier signal is randomly generated The constellation diagram using the 16QAM modulation method is as follows Figure 3 It is worth noting that if other subcarrier modulation technologies, such as 4QAM, 64QAM, etc., are used, the amplitude A of each subcarrier signal can also be obtained. i and Phase That is, any QAM modulation method can obtain the amplitude A of each subcarrier signal. i and Phase That is, the modulation techniques of each subcarrier of the present invention are not limited to the 16QAM modulation method.

[0081] It should be noted that the noise n(t) can be any zero-mean noise, such as Gaussian white noise.

[0082] Step S2, preprocessing the OFDM signal to obtain each subcarrier signal and the phase of each subcarrier signal;

[0083] Specifically, the OFDM signal is preprocessed by a cross-correlation function to obtain a calculation result of the cross-correlation function;

[0084] The subcarrier signals and the phases of the subcarrier signals are obtained by calculating the cross-correlation function. Wherein, each subcarrier signal is a single cosine wave signal decoupled from the OFDM signal.

[0085] It should be noted that it is necessary to construct a reference signal x(t)=cos(ω j t), and perform cross-correlation calculation on the reference signal and the OFDM signal to obtain a cross-correlation function calculation result R rx (τ);

[0086] Among them, the cross-correlation function calculation result R rx The calculation formula of (τ) is:

[0087]

[0088] In the formula, R rx (τ) is the result of the cross-correlation function calculation, T is the period, τ is the delay, r(t) is the power line carrier signal containing noise, x(t) = cos(ω j t) is a reference signal with the same frequency as each subcarrier, and t represents time.

[0089] It should be noted that the cross-correlation function calculation result R rx (τ) can be divided into three parts, the first part The first cross-correlation function calculation result of the signal with the same frequency as the reference signal, the second part is the result of calculating the second cross-correlation function of the signal that is not in the same frequency as the reference signal. The third part N nx (τ) is the calculation result of the third cross-correlation function between the reference signal and the noise signal n(t);

[0090]

[0091] Among them, the calculation result of the first cross-correlation function is The calculation formula is:

[0092]

[0093] In the formula, is the result of the first cross-correlation function calculation, T is the period, A jis the amplitude of each subcarrier signal with the same frequency as the reference signal, ω j is the frequency of each subcarrier signal with the same frequency as the reference signal, is the phase of each subcarrier signal with the same frequency as the reference signal, and τ is the delay.

[0094] Among them, since all subcarriers of the OFDM signal have an integer number of cycles within one symbol signal time, and the subcarriers are orthogonal to each other, the calculation result of the second cross-correlation function is is zero, the second cross-correlation function calculation result The calculation formula is:

[0095]

[0096] Among them, since noise is a random process, the third cross-correlation function calculation result N nx (τ) is also a random variable, so it can only be subjected to statistical analysis. Assuming that the mean of n(t) is 0, the calculation result of the third cross-correlation function is N nx The mean value of (τ) is also zero, so as the step size decreases and the simulation time increases, the third cross-correlation function calculation result N nx (τ) will gradually approach 0.

[0097]

[0098] In summary, the cross-correlation function calculation result R rx (τ) is as follows:

[0099]

[0100] In the formula, R rx (τ) is the result of cross-correlation function calculation, A j is the amplitude of each subcarrier signal with the same frequency as the reference signal, ω j is the frequency of each subcarrier signal with the same frequency as the reference signal, is the phase of each subcarrier signal with the same frequency as the reference signal, and τ is the delay.

[0101] It is known that when When the cross-correlation function is calculated, the result R rx (τ) is the maximum value, at which point the phase of each subcarrier signal with the same frequency as the reference signal Since the frequency ω of the reference signal j The frequency ω of each subcarrier signal i The same, so at this time, we only need to know the delay τ to find the phase of each subcarrier signal with the same frequency as the reference signal. This also gives the phase of each subcarrier signal The delay τ is the extreme point of the cross-correlation function.

[0102] In this way, by preprocessing the OFDM signal through the cross-correlation function, the OFDM signal can be decoupled into each subcarrier signal, and the phase of each subcarrier signal can be obtained.

[0103] Step S3, inputting each subcarrier signal into a preset chaotic noise reduction system, so that the chaotic noise reduction system measures the amplitude of each subcarrier signal according to the state change of the chaotic oscillator in the system;

[0104] Specifically, the external excitation amplitude of the chaotic noise reduction system is adjusted so that the chaotic oscillator in the chaotic noise reduction system is in a critical chaotic state, and the first external excitation amplitude at the current moment is recorded; each subcarrier signal is input into a preset chaotic noise reduction system, and the external excitation amplitude of the chaotic noise reduction system is adjusted again so that the chaotic oscillator in the chaotic noise reduction system returns to the critical chaotic state, and the second external excitation amplitude at the current moment is recorded;

[0105] The amplitude of each subcarrier signal is obtained based on the first external excitation amplitude and the second external excitation amplitude.

[0106] The following takes the Duffing oscillator as an example to explain step S3 in detail. When the chaotic oscillator is a Duffing oscillator, the state equation of the Duffing oscillator is:

[0107]

[0108] In the formula, and is the derivative of the state variable, x and y are the state variables, k is the equation coefficient, γ is the external excitation amplitude, ω is the scale conversion factor, and r(t) is the noisy power line carrier signal.

[0109] It should be noted that the Duffing oscillator is an oscillator that describes forced vibrations, and has sensitivity from a chaotic state to a large-scale periodic state. It can exhibit a chaotic state under certain parameters, so this characteristic can be used to detect the amplitude of each subcarrier signal of an OFDM signal. It is worth noting that if other chaotic oscillators, such as the Vander Pol oscillator, the Chua oscillator, etc., are used, the amplitude of each subcarrier signal of an OFDM signal can also be detected, that is, any chaotic oscillator can detect the amplitude of each subcarrier signal of an OFDM signal, that is, the chaotic oscillator of the present invention is not limited to the Duffing oscillator.

[0110] It can be seen from this that when the amplitude of each subcarrier signal is desired to be obtained, different frequencies need to be adjusted according to the OFDM signal to be measured, that is, different scale factor sizes ω need to be adjusted.

[0111] According to the state equation of the Duffing oscillator, the external excitation amplitude γ is used as the horizontal coordinate and the state variable x is used as the vertical coordinate to observe the change state of the state variable x in the Duffing oscillator. When the state variable x changes from one point to multiple points, it proves that the chaotic oscillator is in a critical chaotic state. First, the external excitation amplitude γ of the chaotic noise reduction system is adjusted to make the Duffing oscillator in the chaotic noise reduction system in a critical chaotic state, and the first external excitation amplitude γ at the current moment is recorded. c , where the phase space diagram of the Duffing oscillator in the critical chaotic state is as follows: Figure 4 As shown; secondly, the subcarrier signals are input into the preset chaotic noise reduction system. At this time, the state of the Duffing oscillator in the chaotic noise reduction system changes, that is, it is converted from the critical chaotic state to the large-scale periodic state, wherein the phase space diagram of the Duffing oscillator in the large-scale periodic state is as shown in Figure 5 As shown, at this time, the external excitation amplitude γ of the chaotic noise reduction system needs to be adjusted again to make the Duffing oscillator in the chaotic noise reduction system return to the critical chaotic state, and record the second external excitation amplitude γ at the current moment d Finally, based on the first external excitation amplitude γ c With the second external excitation amplitude γ d The error is γ d -γ c , the amplitude of each subcarrier signal can be obtained, and by continuously adjusting the scale factor ω of the external excitation of the Duffing oscillator, the amplitude of each subcarrier signal can be obtained.

[0112] In this way, the amplitude of each subcarrier signal is measured by utilizing the sensitivity of the chaotic oscillator in the chaotic noise reduction system to transform from a chaotic state to a large-scale periodic state.

[0113] Step S4: reconstruct the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain a power line carrier signal after noise reduction.

[0114] Specifically, obtaining the frequency of each subcarrier signal;

[0115] It should be noted that the frequency ω of each subcarrier signal i It is a multiple of the base frequency, and the base frequency can be determined according to the "Power Line Carrier Standard" that complies with national standards and regional standards.

[0116] Based on the phase of each subcarrier signal and the amplitude A of each subcarrier signal i , reconstruct the power line carrier signal to obtain the power line carrier signal s(t) after noise reduction; wherein the time domain diagram of the power line carrier signal after noise reduction is as follows Figure 6shown.

[0117] Wherein, the formula for reconstructing the power line carrier signal is:

[0118]

[0119] Where s(t) is the power line carrier signal, n is the number of subcarriers, ω i is the frequency of each subcarrier signal, A i is the amplitude of each subcarrier signal, is the phase of each subcarrier signal.

[0120] In this way, the power line carrier signal can be reconstructed based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, and the target power line carrier signal after noise reduction can be accurately obtained.

[0121] The embodiment of the present application can firstly accurately obtain the noisy OFDM signal by obtaining the power line carrier signal; by preprocessing the OFDM signal, the OFDM signal can be decoupled into each subcarrier signal, and the phase of each subcarrier signal can be obtained; by utilizing the sensitivity of the chaotic oscillator in the chaotic noise reduction system to transform from a chaotic state to a large-scale periodic state, the amplitude of each subcarrier signal can be measured; based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, the power line carrier signal can be reconstructed, and the target power line carrier signal after noise reduction can be accurately obtained. Compared with the signal characteristic analysis of noise in the prior art, the present application analyzes the power line carrier signal, obtains the phase of each subcarrier signal using the cross-correlation function, and obtains the amplitude of each subcarrier signal using the chaotic noise reduction system, thereby reconstructing the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, thereby improving the noise reduction effect of the power line carrier signal, and has high applicability.

[0122] Please refer to Figure 7 , Figure 7 It is a structural diagram of an embodiment of a signal noise reduction system provided in the present application, including an acquisition module 01, a preprocessing module 02, a detection module 03 and an output module 04.

[0123] Specifically, the acquisition module 01 is used to acquire a power line carrier signal; wherein the power line carrier signal is an OFDM signal;

[0124] Specifically, the formula of the OFDM signal is:

[0125]

[0126] Where r(t) is the noisy power line carrier signal, s(t) is the power line carrier signal, n(t) is the noise, n is the number of subcarriers, ω iis the frequency of each subcarrier signal, A i is the amplitude of each subcarrier signal, is the phase of each subcarrier signal.

[0127] It can be known that when the frequency ω of each subcarrier signal is determined i , the amplitude A of each subcarrier signal i , the phase of each subcarrier signal And the noise n(t), we can simulate the power line carrier signal r(t) under the noise background, where the time domain diagram of the noisy power line carrier signal is as follows Figure 2 shown.

[0128] It should be noted that the frequency ω of each subcarrier signal i It is a multiple of the base frequency, and the base frequency can be determined according to the "Power Line Carrier Standard" that complies with national standards and regional standards.

[0129] It should be noted that A i and Determined by the modulation technology of each subcarrier, when the modulation technology of each subcarrier is 16QAM, the amplitude to be measured based on the 16QAM modulated power line carrier signal is confirmed according to the constellation diagram as The phase to be measured is ±[0.1024, 0.25, 0.3976, 0.6024, 0.75, 0.8976]*π, so the amplitude of each randomly generated subcarrier signal The phase of each subcarrier signal is randomly generated The constellation diagram using the 16QAM modulation method is as follows Figure 3 It is worth noting that if other subcarrier modulation technologies, such as 4QAM, 64QAM, etc., are used, the amplitude A of each subcarrier signal can also be obtained. i and Phase That is, any QAM modulation method can obtain the amplitude A of each subcarrier signal. i and Phase That is, the modulation techniques of each subcarrier of the present invention are not limited to the 16QAM modulation method.

[0130] It should be noted that the noise n(t) can be any zero-mean noise, such as Gaussian white noise.

[0131] The preprocessing module 02 is used to preprocess the OFDM signal to obtain each subcarrier signal and the phase of each subcarrier signal; the preprocessing module 02 includes a preprocessing unit and a first calculation unit:

[0132] Specifically, the preprocessing unit is used to preprocess the OFDM signal by using a cross-correlation function to obtain a calculation result of the cross-correlation function;

[0133] The first calculation unit is used to obtain each subcarrier signal and the phase of each subcarrier signal through the calculation result of the cross-correlation function, wherein each subcarrier signal is a single cosine wave signal decoupled from the OFDM signal.

[0134] It should be noted that it is necessary to construct a reference signal x(t)=cos(ω j t), and perform cross-correlation calculation on the reference signal and the OFDM signal to obtain a cross-correlation function calculation result R rx (τ);

[0135] The calculation formula of the cross-correlation function in the pre-processing unit is:

[0136]

[0137] In the formula, R rx (τ) is the result of the cross-correlation function calculation, T is the period, τ is the delay, r(t) is the power line carrier signal containing noise, x(t) = cos(ω j t) is a reference signal with the same frequency as each subcarrier, and t represents time.

[0138] It should be noted that the cross-correlation function calculation result R rx (τ) can be divided into three parts, the first part The first cross-correlation function calculation result of the signal with the same frequency as the reference signal, the second part is the result of calculating the second cross-correlation function of the signal that is not in the same frequency as the reference signal. The third part N nx (τ) is the calculation result of the third cross-correlation function between the reference signal and the noise signal n(t);

[0139]

[0140] Among them, the calculation result of the first cross-correlation function is The calculation formula is:

[0141]

[0142] In the formula, is the result of the first cross-correlation function calculation, T is the period, A j is the amplitude of each subcarrier signal with the same frequency as the reference signal, ω j is the frequency of each subcarrier signal with the same frequency as the reference signal, is the phase of each subcarrier signal with the same frequency as the reference signal, and τ is the delay.

[0143] Among them, since all subcarriers of the OFDM signal have an integer number of cycles within one symbol signal time, and the subcarriers are orthogonal to each other, the calculation result of the second cross-correlation function is is zero, the second cross-correlation function calculation result The calculation formula is:

[0144]

[0145] Among them, since noise is a random process, the third cross-correlation function calculation result N nx (τ) is also a random variable, so it can only be subjected to statistical analysis. Assuming that the mean of n(t) is 0, the calculation result of the third cross-correlation function is N nx The mean value of (τ) is also zero, so as the step size decreases and the simulation time increases, the third cross-correlation function calculation result N nx (τ) will gradually approach 0.

[0146]

[0147] In summary, the cross-correlation function calculation result R rx (τ) is as follows:

[0148]

[0149] In the formula, R rx (τ) is the result of cross-correlation function calculation, A j is the amplitude of each subcarrier signal with the same frequency as the reference signal, ω j is the frequency of each subcarrier signal with the same frequency as the reference signal, is the phase of each subcarrier signal with the same frequency as the reference signal, and τ is the delay.

[0150] It is known that when When the cross-correlation function is calculated, the result R rx (τ) is the maximum value, at which point the phase of each subcarrier signal with the same frequency as the reference signal Since the frequency ω of the reference signal j The frequency ω of each subcarrier signal i The same, so at this time, we only need to know the delay τ to find the phase of each subcarrier signal with the same frequency as the reference signal. This also gives the phase of each subcarrier signal The delay τ is the extreme point of the cross-correlation function.

[0151] Therefore, according to the above results, the phase to be measured of each subcarrier can be obtained, and the multi-carrier signal can be decoupled into a single cosine wave signal.

[0152] In this way, by preprocessing the OFDM signal through the cross-correlation function, the OFDM signal can be decoupled into each subcarrier signal, and the phase of each subcarrier signal can be obtained.

[0153] The detection module 03 is used to input each subcarrier signal into a preset chaotic noise reduction system, so that the chaotic noise reduction system measures the amplitude of each subcarrier signal according to the state change of the chaotic oscillator in the system; the detection module 03 includes a first adjustment unit, a second adjustment unit and a second calculation unit:

[0154] Specifically, the first adjustment unit is used to adjust the external excitation amplitude of the chaotic noise reduction system so that the chaotic oscillator in the chaotic noise reduction system is in a critical chaotic state, and record the first external excitation amplitude at the current moment;

[0155] The second adjustment unit is used to input the subcarrier signals into a preset chaotic noise reduction system, and adjust the external excitation amplitude of the chaotic noise reduction system again to make the chaotic oscillator in the chaotic noise reduction system return to a critical chaotic state, and record the second external excitation amplitude at the current moment;

[0156] The second calculation unit is used to obtain the amplitude of each subcarrier signal based on the first external excitation amplitude and the second external excitation amplitude.

[0157] When the chaotic oscillator is a Duffing oscillator, the state equation of the Duffing oscillator is:

[0158]

[0159] In the formula, and is the derivative of the state variable, x and y are the state variables, k is the equation coefficient, γ is the external excitation amplitude, ω is the scale conversion factor, and r(t) is the noisy power line carrier signal.

[0160] It should be noted that the Duffing oscillator is an oscillator that describes forced vibrations, and has sensitivity from a chaotic state to a large-scale periodic state. It can exhibit a chaotic state under certain parameters, so this characteristic can be used to detect the amplitude of each subcarrier signal of an OFDM signal. It is worth noting that if other chaotic oscillators, such as the Vander Pol oscillator, the Chua oscillator, etc., are used, the amplitude of each subcarrier signal of an OFDM signal can also be detected, that is, any chaotic oscillator can detect the amplitude of each subcarrier signal of an OFDM signal, that is, the chaotic oscillator of the present invention is not limited to the Duffing oscillator.

[0161] It can be seen from this that when the amplitude of each subcarrier signal is desired to be obtained, different frequencies need to be adjusted according to the OFDM signal to be measured, that is, different scale factor sizes ω need to be adjusted.

[0162] According to the state equation of the Duffing oscillator, the external excitation amplitude γ is used as the horizontal coordinate and the state variable x is used as the vertical coordinate to observe the change state of the state variable x in the Duffing oscillator. When the state variable x changes from one point to multiple points, it proves that the chaotic oscillator is in a critical chaotic state. First, the external excitation amplitude γ of the chaotic noise reduction system is adjusted to make the Duffing oscillator in the chaotic noise reduction system in a critical chaotic state, and the first external excitation amplitude γ at the current moment is recorded. c , where the phase space diagram of the Duffing oscillator in the critical chaotic state is as follows: Figure 4 As shown; secondly, the subcarrier signals are input into the preset chaotic noise reduction system. At this time, the state of the Duffing oscillator in the chaotic noise reduction system changes, that is, it is converted from the critical chaotic state to the large-scale periodic state, wherein the phase space diagram of the Duffing oscillator in the large-scale periodic state is as shown in Figure 5 As shown, at this time, the external excitation amplitude γ of the chaotic noise reduction system needs to be adjusted again to make the Duffing oscillator in the chaotic noise reduction system return to the critical chaotic state, and record the second external excitation amplitude γ at the current moment d Finally, based on the first external excitation amplitude γ c With the second external excitation amplitude γ d The error is γ d -γ c , the amplitude of each subcarrier signal can be obtained, and by continuously adjusting the scale factor ω of the external excitation of the Duffing oscillator, the amplitude of each subcarrier signal can be obtained.

[0163] In this way, the amplitude of each subcarrier signal is measured by utilizing the sensitivity of the chaotic oscillator in the chaotic noise reduction system to transform from a chaotic state to a large-scale periodic state.

[0164] The output module 04 is used to reconstruct the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain the power line carrier signal after noise reduction. The output module 04 includes an acquisition unit and a third calculation unit:

[0165] Specifically, the acquisition unit is used to acquire the frequency of each subcarrier signal;

[0166] It should be noted that the frequency ω of each subcarrier signal i It is a multiple of the base frequency, and the base frequency can be determined according to the "Power Line Carrier Standard" that complies with national standards and regional standards.

[0167] The third calculation unit is used to reconstruct the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain a power line carrier signal after noise reduction; wherein the time domain diagram of the power line carrier signal after noise reduction is as follows Figure 6 shown.

[0168] Wherein, the formula for reconstructing the power line carrier signal is:

[0169]

[0170] Where s(t) is the power line carrier signal, n is the number of subcarriers, ω i is the frequency of each subcarrier signal, A i is the amplitude of each subcarrier signal, is the phase of each subcarrier signal.

[0171] In this way, the power line carrier signal can be reconstructed based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, and the target power line carrier signal after noise reduction can be accurately obtained.

[0172] The embodiment of the present application can firstly accurately obtain the noisy OFDM signal by obtaining the power line carrier signal; by preprocessing the OFDM signal, the OFDM signal can be decoupled into each subcarrier signal, and the phase of each subcarrier signal can be obtained; by utilizing the sensitivity of the chaotic oscillator in the chaotic noise reduction system to transform from a chaotic state to a large-scale periodic state, the amplitude of each subcarrier signal can be measured; based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, the power line carrier signal can be reconstructed, and the target power line carrier signal after noise reduction can be accurately obtained. Compared with the signal characteristic analysis of noise in the prior art, the present application analyzes the power line carrier signal, obtains the phase of each subcarrier signal using the cross-correlation function, and obtains the amplitude of each subcarrier signal using the chaotic noise reduction system, thereby reconstructing the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, thereby improving the noise reduction effect of the power line carrier signal, and has high applicability.

[0173] An embodiment of the present application further provides a computer-readable storage medium, in which processor-executable instructions are stored. The processor-executable instructions are used to implement the above-mentioned signal noise reduction method when executed by the processor.

[0174] The contents of the above-mentioned signal noise reduction method embodiment are all applicable to the present storage medium embodiment. The functions specifically implemented by the present storage medium embodiment are the same as those of the above-mentioned signal noise reduction method embodiment, and the beneficial effects achieved are also the same as those achieved by the above-mentioned signal noise reduction method embodiment. Therefore, this embodiment can also improve the noise reduction effect of the power line carrier signal and has high applicability.

[0175] Those skilled in the art can understand that all or part of the processes in the above embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes in the above embodiments. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0176] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A signal noise reduction method, characterized in that: include: Acquire a power line carrier signal; wherein the power line carrier signal is an OFDM signal; Preprocessing the OFDM signal to obtain each subcarrier signal and the phase of each subcarrier signal; Inputting each subcarrier signal into a preset chaotic noise reduction system, so that the chaotic noise reduction system measures the amplitude of each subcarrier signal according to the state change of the chaotic oscillator in the system; Based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, the power line carrier signal is reconstructed to obtain the power line carrier signal after noise reduction.

2. The signal noise reduction method according to claim 1, characterized in that: The OFDM signal is preprocessed to obtain each subcarrier signal and the phase of each subcarrier signal, specifically: Preprocessing the OFDM signal by using a cross-correlation function to obtain a cross-correlation function calculation result; Each subcarrier signal and the phase of each subcarrier signal are obtained through the calculation result of the cross-correlation function, wherein each subcarrier signal is a single cosine wave signal decoupled from the OFDM signal.

3. The signal noise reduction method according to claim 2, characterized in that: The calculation formula of the cross-correlation function is: In the formula, R rx (τ) is the result of the cross-correlation function calculation, T is the period, τ is the delay, r(t) is the power line carrier signal containing noise, x(t) = cos(ω j t) is a reference signal with the same frequency as each subcarrier, and t represents time.

4. The signal noise reduction method according to claim 1, characterized in that: The inputting of each subcarrier signal into a preset chaotic noise reduction system so that the chaotic noise reduction system measures the amplitude of each subcarrier signal according to the state change of the chaotic oscillator in the system is specifically as follows: Adjusting the external excitation amplitude of the chaotic noise reduction system so that the chaotic oscillator in the chaotic noise reduction system is in a critical chaotic state, and recording the first external excitation amplitude at the current moment; inputting each subcarrier signal into a preset chaotic noise reduction system, and adjusting the external excitation amplitude of the chaotic noise reduction system again so that the chaotic oscillator in the chaotic noise reduction system returns to the critical chaotic state, and recording the second external excitation amplitude at the current moment; The amplitude of each subcarrier signal is obtained based on the first external excitation amplitude and the second external excitation amplitude.

5. The signal noise reduction method according to claim 4, characterized in that: The chaotic oscillator is a Duffing oscillator, and the state equation of the Duffing oscillator is: In the formula, and is the derivative of the state variable, x and y are the state variables, k is the equation coefficient, γ is the external excitation amplitude, ω is the scale conversion factor, and r(t) is the noisy power line carrier signal.

6. The signal noise reduction method according to claim 1, characterized in that: The reconstructing the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain the power line carrier signal after noise reduction is specifically as follows: Obtaining the frequency of each subcarrier signal; Based on the phase of each subcarrier signal and the amplitude of each subcarrier signal, the power line carrier signal is reconstructed to obtain a power line carrier signal after noise reduction; wherein the formula for reconstructing the power line carrier signal is: Where s(t) is the power line carrier signal, n is the number of subcarriers, ω i is the frequency of each subcarrier signal, A i is the amplitude of each subcarrier signal, is the phase of each subcarrier signal.

7. A signal noise reduction system, characterized in that: Including acquisition module, preprocessing module, detection module and output module: The acquisition module is used to acquire a power line carrier signal; wherein the power line carrier signal is an OFDM signal; The preprocessing module is used to preprocess the OFDM signal to obtain each subcarrier signal and the phase of each subcarrier signal; The detection module is used to input each subcarrier signal into a preset chaotic noise reduction system, so that the chaotic noise reduction system measures the amplitude of each subcarrier signal according to the state change of the chaotic oscillator in the system; The output module is used to reconstruct the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain the power line carrier signal after noise reduction.

8. The signal noise reduction system according to claim 7, characterized in that: The preprocessing module includes a preprocessing unit and a first computing unit: The preprocessing unit is used to preprocess the OFDM signal by using a cross-correlation function to obtain a calculation result of the cross-correlation function; The first calculation unit is used to obtain each subcarrier signal and the phase of each subcarrier signal through the calculation result of the cross-correlation function, wherein each subcarrier signal is a single cosine wave signal decoupled from the OFDM signal.

9. The signal noise reduction system according to claim 8, characterized in that: The calculation formula of the cross-correlation function in the pre-processing unit is: In the formula, R rx (τ) is the result of the cross-correlation function calculation, T is the period, τ is the delay, r(t) is the power line carrier signal containing noise, x(t) = cos(ω j t) is a reference signal with the same frequency as each subcarrier, and t represents time.

10. The signal noise reduction system according to claim 7, characterized in that: The detection module includes a first adjustment unit, a second adjustment unit and a second calculation unit: The first adjustment unit is used to adjust the external excitation amplitude of the chaotic noise reduction system so that the chaotic oscillator in the chaotic noise reduction system is in a critical chaotic state, and record the first external excitation amplitude at a current moment; The second adjustment unit is used to input the subcarrier signals into a preset chaotic noise reduction system, and adjust the external excitation amplitude of the chaotic noise reduction system again to make the chaotic oscillator in the chaotic noise reduction system return to a critical chaotic state, and record the second external excitation amplitude at the current moment; The second calculation unit is used to obtain the amplitude of each subcarrier signal based on the first external excitation amplitude and the second external excitation amplitude.

11. The signal noise reduction system according to claim 10, characterized in that: The chaotic oscillator is a Duffing oscillator, and the state equation of the Duffing oscillator is: In the formula, and is the derivative of the state variable, x and y are the state variables, k is the equation coefficient, γ is the external excitation amplitude, ω is the scale conversion factor, and r(t) is the noisy power line carrier signal.

12. The signal noise reduction system according to claim 7, characterized in that: The output module includes an acquisition unit and a third calculation unit: The acquisition unit is used to acquire the frequency of each subcarrier signal; The third calculation unit is used to reconstruct the power line carrier signal based on the phase of each subcarrier signal and the amplitude of each subcarrier signal to obtain a power line carrier signal after noise reduction; wherein the formula for reconstructing the power line carrier signal is: Where s(t) is the power line carrier signal, n is the number of subcarriers, ω i is the frequency of each subcarrier signal, A i is the amplitude of each subcarrier signal, is the phase of each subcarrier signal.

13. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the signal noise reduction method according to any one of claims 1 to 6.

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