A Method for Improving the Signal Quality of Power Line Communication Based on Discrete Fourier Transform

Abstract

The present invention relates to the technical field of signal processing, and particularly to a method for improving the quality of power line communication signals based on discrete Fourier transform. The method includes: decomposing the time-domain signal corresponding to the target power line communication signal into n frequency components through discrete Fourier transform, and obtaining the frequency component sorting result; matching the frequency-domain signal corresponding to each frequency component with a plurality of pre-acquired interference signals to screen out the interference signal set corresponding to each frequency component; then obtaining a plurality of frequency component groups and the corresponding target matching degree of each frequency component group to screen out the target frequency group from the plurality of frequency component groups; calculating the frequency group score corresponding to each target frequency group, and filtering out some frequency components according to the frequency group score. The present invention can effectively filter out interference signals in a targeted manner, and realize a reliable and substantial improvement in the quality of power line communication signals.

Description

Technical Field

[0001] The present invention relates to the technical field of signal processing, and particularly to a method for improving the quality of power line communication signals based on discrete Fourier transform. Background Art

[0002] The discrete Fourier transform (DFT) is an important transform in the field of signal analysis. This transform is a mathematical method for converting a time-domain signal into a frequency-domain signal, and it can decompose a complex time-domain signal into several simple frequency components. Currently, with the help of computers, various signals can be processed efficiently. The signals processed by computers are all discrete and finite signals, and the analysis of discrete and finite signals is an important part of signal analysis. For example, in power line communication signals, the transmission principle is to load the high-frequency signal carrying information onto the current and then use the power line to transmit the high-frequency signal. The adapter at the receiving end then separates the high-frequency signal from the current and transmits it to a computer or a telephone to achieve information transmission. During transmission, multiple interference signals will be mixed in the high-frequency signal, and how to specifically filter out the interference signals is crucial for improving the quality of power line communication signals. Summary of the Invention

[0003] In view of the above technical problems, the present invention provides a method for improving the quality of power line communication signals based on discrete Fourier transform, which can effectively filter out interference signals specifically and achieve reliable and substantial improvement in the quality of power line communication signals.

[0004] The present invention provides a method for improving the quality of power line communication signals based on discrete Fourier transform, including the following steps:

[0005] Decompose the time-domain signal corresponding to the target power line communication signal into n frequency components through discrete Fourier transform, and sort the n frequency components from small to large to obtain the sorted result of the frequency components.

[0006] Match the frequency-domain signal corresponding to each frequency component with a plurality of pre-acquired interference signals, and screen out the interference signal set corresponding to each frequency component according to the matching degree.

[0007] Group the several frequency components with the number of components in each group being 1 to n to obtain several frequency component groups, and calculate the target matching degree corresponding to each frequency component group respectively according to the matching degree between each frequency component and each interference signal in the corresponding interference signal set.

[0008] Based on a preset signal quality improvement threshold and the normalized several target matching degrees, screen out the target frequency group from the several frequency component groups.

[0009] Calculate the frequency group score corresponding to each target frequency group according to the number of frequency components in each target frequency group and the position of the frequency component in the frequency component sorting result, and filter out the frequency components in the target frequency group corresponding to the smallest frequency group score from the n frequency components corresponding to the target power line communication signal, so as to obtain the final frequency domain signal corresponding to the target power line communication signal.

[0010] The present invention has at least the following beneficial effects:

[0011] The present invention provides a method for improving the quality of power line communication signals based on discrete Fourier transform. First, the time domain signal corresponding to the target power line communication signal is decomposed into a number of frequency components through discrete Fourier transform, and a frequency component sorting result is obtained. The frequency domain signal corresponding to each frequency component is matched with a number of pre-acquired interference signals to screen out the interference signal set corresponding to each frequency component, that is, to determine the interference signals that have a greater impact on each frequency component, and the influence of the interference signals under each frequency component can be grasped. Then, a number of frequency component groups and the target matching degree corresponding to each frequency component group are obtained based on a number of frequency components, so as to reflect the interference situation corresponding to each frequency component group, and the target frequency groups that meet the requirements are screened out from a number of frequency component groups. Finally, calculate the frequency group score corresponding to each target frequency group, and perform targeted frequency component filtering according to the frequency group score, so as to achieve reliable and substantial improvement in the quality of power line communication signals. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0013] Figure 1 It is a flowchart of the method for improving the quality of power line communication signals based on discrete Fourier transform provided by the embodiments of the present invention. Detailed Embodiments

[0014] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0015] The embodiments of the present invention provide a method for improving the quality of power line communication signals based on discrete Fourier transform, as Figure 1As shown, the method includes the following steps:

[0016] S100, decompose the time-domain signal corresponding to the target power line communication signal into n frequency components through discrete Fourier transform, and sort the n frequency components from small to large to obtain a sorted result of frequency components; it can be understood that: sort in ascending order according to the frequency magnitudes corresponding to the frequency components.

[0017] Specifically, decompose the time-domain signal corresponding to the target power line communication signal into several frequency components, for example:

[0018] For a discrete-time sequence x[m] of length M, m = 0, 1, …… M - 1, after discrete Fourier transform, it is X[k]=∑ M-1 m=1 x[m]e -jkm×2π / M , where j is the imaginary unit, k = 0, 1, …… M - 1. Since converting the time-domain signal to the frequency-domain signal through discrete Fourier transform is a prior art, it will not be elaborated here.

[0019] S200, match the frequency-domain signal corresponding to each frequency component with several pre-acquired interference signals, and screen to obtain an interference signal set corresponding to each frequency component according to the matching degree.

[0020] Specifically, the interference signal refers to any signal that is pre-extracted from the initial power line communication signal and causes interference to the target power line communication signal.

[0021] In a specific embodiment, step S200 includes the following steps:

[0022] S201, calculate the matching degree between the frequency-domain signal corresponding to each frequency component and several pre-acquired interference signals to obtain the matching degree between the frequency-domain signal corresponding to each frequency component and each interference signal.

[0023] Further, the matching degree between the frequency-domain signal corresponding to the frequency component and the interference signal meets the following conditions:

[0024] S = w1×d1 + w2×d2 + w3×d3, where S represents the matching degree between the frequency-domain signal corresponding to any frequency component and any interference signal, w1, w2, and w3 are the first preset weight, the second preset weight, and the third preset weight respectively, d1 is the Euclidean distance between the frequencies of the frequency-domain signal and the interference signal, d2 is the Euclidean distance between the phase spectra of the frequency-domain signal and the interference signal, and d3 is the Euclidean distance between the amplitude spectra of the frequency-domain signal and the interference signal. Among them, obtaining the Euclidean distance between two parameters is known to those skilled in the art and will not be elaborated here.

[0025] As described above, by comprehensively considering the frequency proximity between the frequency-domain signal and the interference signal, as well as the similarity between their phase spectra and amplitude spectra, the similarity between the frequency-domain signal and the interference signal is compared, and the interference signals similar to each frequency component and having a greater impact can be determined, which is beneficial to the processing and improvement of signal quality.

[0026] S202. When the matching degree between the frequency-domain signal corresponding to the frequency component and the interference signal is greater than the matching degree threshold, it is determined that the frequency component and the interference signal have a matching relationship.

[0027] S203. For any frequency component, several interference signals having a matching relationship with the frequency component are screened out and form an interference signal set corresponding to the frequency component.

[0028] As described above, by calculating the matching degree between each interference signal and the frequency component, the interference signals similar to the frequency component can be screened out. Since the interference signal with a higher matching degree has a greater impact on the power line communication signal, determining the interference signals having a greater impact on each frequency component can master the influence of the interference signals under each frequency component, which is beneficial to the targeted and effective filtering of the interference signals and enables the improvement degree of the signal quality to meet the required requirements.

[0029] S300. The several frequency components are grouped with the group size being 1 to n respectively to obtain several frequency component groups, and according to the matching degree between each frequency component and each interference signal in the corresponding interference signal set, the target matching degree corresponding to each frequency component group is calculated respectively.

[0030] Furthermore, the method obtains several frequency component groups through the following steps:

[0031] S301. When the group size is i and i = 1, after grouping the several frequency components, n first frequency component groups are obtained, where each first frequency component group contains one frequency component.

[0032] S302. When the group size is i and 1 < i ≤ n, after grouping the several frequency components, n - i + 1 second frequency component groups are obtained, where each second frequency component group includes i frequency components and the i frequency components are consecutive in the frequency component sorting result. For example, when there are 5 frequency components and i = 3, a total of 3 second frequency component groups are obtained, namely (frequency component 1, frequency component 2, frequency component 3), (frequency component 2, frequency component 3, frequency component 4), (frequency component 3, frequency component 4, frequency component 5).

[0033] In another implementation manner, when the second frequency component group includes i frequency components, the i frequency components can also be randomly obtained i frequency components from the frequency component sorting result.

[0034] S303. Based on the obtained first frequency component groups and all the second frequency component groups, obtain several frequency component groups.

[0035] Specifically, the method obtains the target matching degree corresponding to each frequency component group through the following steps:

[0036] S310. For any frequency component in any frequency component group, determine the sum of the matching degrees between the frequency component and each interference signal in the corresponding interference signal set as the total matching degree corresponding to the frequency component.

[0037] S320. Perform normalization processing on the total matching degree corresponding to each frequency component, and for any frequency component group, determine the sum of the normalized total matching degrees corresponding to each frequency component in the frequency component group as the target matching degree corresponding to the frequency component group.

[0038] As described above, by obtaining the target matching degree corresponding to each frequency component group according to the matching degree between the frequency component and each interference signal in the corresponding interference signal set, it can reflect the amount of interference corresponding to each frequency component group, so as to achieve targeted frequency component filtering according to the signal quality improvement requirements.

[0039] S400. Based on the preset signal quality improvement threshold and the normalized several target matching degrees, screen out the target frequency groups from the several frequency component groups; it can be understood that when the normalized target matching degree is greater than the preset signal quality improvement threshold, the frequency component group corresponding to the target matching degree is screened out and used as the target frequency group.

[0040] S500. According to the number of frequency components in each target frequency group and the position of the frequency component in the frequency component sorting result, calculate the frequency group score corresponding to each target frequency group, and filter out the frequency components in the target frequency group corresponding to the smallest frequency group score from the n frequency components corresponding to the target power line communication signal, so as to obtain the final frequency domain signal corresponding to the target power line communication signal.

[0041] Specifically, the frequency group score corresponding to the target frequency group meets the following conditions:

[0042] P c = ξ1×Q c1 + ξ2×Q c2 where, P c represents the frequency group score corresponding to the c-th target frequency group, ξ1 is the preset frequency component quantity weight, Q c1 is the number of frequency components in the c-th target frequency group, ξ2 is the preset distance weight, Q c2is the minimum distance between the c-th target frequency group and both ends of the frequency component sorting result.

[0043] Preferably, ξ1 > ξ2. Considering the position relative to the frequency components, fewer frequency components should be filtered out first. Therefore, the above settings are adopted. In a specific implementation, ξ1 can be set to 0.8 and ξ2 to 0.2.

[0044] Furthermore, the distances between the target frequency group and both ends of the frequency component sorting result respectively refer to the difference in the order numbers corresponding to the first frequency component in the target frequency group and the last frequency component in the frequency component sorting result, and the difference in the order numbers between the last frequency component in the target frequency group and the first frequency component in the frequency component sorting result.

[0045] As mentioned above, when filtering out interference signals, in order to effectively reduce the impact on the power line communication signal quality during filtering, fewer frequency components and frequency components with too large or too small frequencies should be filtered out first. Therefore, when calculating the frequency group score, considering the number of frequency components and the magnitude of the frequencies comprehensively, the frequency components with relatively fewer numbers and those closer to the edges of the sorting result are filtered out, ensuring that the final frequency domain signal obtained has a high quality and realizing the improvement of the power line communication signal quality.

[0046] In summary, the present invention provides a method for improving the quality of power line communication signals based on discrete Fourier transform. First, the time domain signal corresponding to the target power line communication signal is decomposed into several frequency components through discrete Fourier transform, and a frequency component sorting result is obtained. Each frequency domain signal corresponding to a frequency component is matched with several pre-acquired interference signals to screen out the interference signal set corresponding to each frequency component, that is, to determine the interference signals that have a greater impact on each frequency component, and the influence of the interference signals under each frequency component can be grasped. Then, several frequency component groups and the corresponding target matching degree of each frequency component group are obtained based on several frequency components, so as to reflect the interference situation corresponding to each frequency component group, and the target frequency group that meets the requirements is screened out from several frequency component groups. Finally, the frequency group score corresponding to each target frequency group is calculated, and targeted frequency component filtering is realized according to the frequency group score, thereby realizing the reliable and substantial improvement of the power line communication signal quality.

[0047] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should also understand that various modifications can be made to the embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended technical solutions.

Claims

1. A method for improving the signal quality of power line communication based on discrete Fourier transform, characterized in that, The method includes the following steps: Decompose the time-domain signal corresponding to the target power line communication signal into n frequency components by discrete Fourier transform, and sort the n frequency components from small to large to obtain the sorted result of frequency components; Match the frequency-domain signal corresponding to each frequency component with a plurality of pre-acquired interference signals, and screen to obtain the interference signal set corresponding to each frequency component according to the matching degree; Group the several frequency components with the number of components in each group being 1 to n to obtain several frequency component groups, and calculate the target matching degree corresponding to each frequency component group respectively according to the matching degree between each frequency component and each interference signal in the corresponding interference signal set; Based on the preset signal quality improvement threshold and the normalized several target matching degrees, screen out the target frequency group from the several frequency component groups; Calculate the frequency group score corresponding to each target frequency group according to the number of frequency components in each target frequency group and the position of the frequency components in the sorted result of frequency components, and filter out the frequency components in the target frequency group corresponding to the smallest frequency group score from the n frequency components corresponding to the target power line communication signal to obtain the final frequency-domain signal corresponding to the target power line communication signal; The frequency group score corresponding to the target frequency group meets the following conditions: P c = ξ1 × Q c1 + ξ2 × Q c2 where P c represents the frequency group score corresponding to the c-th target frequency group, ξ1 is the preset frequency component quantity weight, Q c1 is the quantity of frequency components in the c-th target frequency group, ξ2 is the preset distance weight, Q c2 is the minimum distance between the c-th target frequency group and the two ends of the frequency component sorting result, ξ1 > ξ2; The distances between the target frequency group and both ends of the sorted result of frequency components respectively refer to the difference in the order quantity between the first frequency component in the target frequency group and the last frequency component in the sorted result of frequency components and the difference in the order quantity between the last frequency component in the target frequency group and the first frequency component in the sorted result of frequency components.

2. The method for improving the power line communication signal quality based on discrete Fourier transform according to claim 1, wherein The interference signal refers to any signal that causes interference to the target power line communication signal and is pre-extracted from the initial power line communication signal.

3. The method for improving the power line communication signal quality based on discrete Fourier transform according to claim 1, characterized in that The interference signal set corresponding to each frequency component is screened through the following steps: Calculate the matching degree between the frequency-domain signal corresponding to each frequency component and a plurality of pre-acquired interference signals to obtain the matching degree between the frequency-domain signal corresponding to each frequency component and each interference signal respectively; When the matching degree between the frequency-domain signal corresponding to the frequency component and the interference signal is greater than the matching degree threshold, it is determined that the frequency component and the interference signal have a matching relationship; For any frequency component, screen out the several interference signals having a matching relationship with the frequency component and form the interference signal set corresponding to the frequency component.

4. The method for improving the power line communication signal quality based on discrete Fourier transform according to claim 3, wherein The matching degree between the frequency-domain signal corresponding to the frequency component and the interference signal meets the following conditions: S = w1×d1 + w2×d2 + w3×d3, where S represents the matching degree between the frequency-domain signal corresponding to any frequency component and any interference signal, w1, w2, and w3 are the first preset weight, the second preset weight, and the third preset weight respectively, d1 is the Euclidean distance between the frequencies of the frequency-domain signal and the interference signal, d2 is the Euclidean distance between the phase spectra of the frequency-domain signal and the interference signal, and d3 is the Euclidean distance between the amplitude spectra of the frequency-domain signal and the interference signal.

5. The method for improving the power line communication signal quality based on discrete Fourier transform according to claim 1, wherein The several frequency component groups are obtained through the following steps: When the number within the group is \(i\) and \(i = 1\), after grouping a number of frequency components, \(n\) first frequency component groups are obtained, where each first frequency component group contains one frequency component; When the number within the group is \(i\) and \(1\lt i\leq n\), after grouping a number of frequency components, \(n - i + 1\) second frequency component groups are obtained, where each second frequency component group includes \(i\) frequency components and the \(i\) frequency components are consecutive in the frequency component sorting result; Based on the obtained first frequency component groups and all the second frequency component groups, a number of frequency component groups are obtained.

6. The method for improving the power line communication signal quality based on discrete Fourier transform according to claim 1, wherein The target matching degree corresponding to each frequency component group is obtained through the following steps: For any frequency component in any frequency component group, the sum of the matching degrees between the frequency component and each interference signal in the corresponding interference signal set is determined as the total matching degree corresponding to the frequency component; The total matching degree corresponding to each frequency component is normalized, and for any frequency component group, the sum of the normalized total matching degrees corresponding to each frequency component in the frequency component group is determined as the target matching degree corresponding to the frequency component group.

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