A method and system for identifying and suppressing narrowband interference on power lines.

Abstract

This invention discloses a method and system for identifying and suppressing narrowband power line interference, belonging to the field of power line carrier communication technology. The method includes: segmenting the power line signal output by an ADC; performing time-frequency transformation on each segment; converting the amplitude of the frequency domain signal to obtain converted data and differential data; performing dual judgment to obtain multiple narrowband interference prediction frequency points; calculating the correlation ratio for each of the multiple narrowband interference prediction frequency points; identifying the narrowband interference prediction frequency point corresponding to the maximum correlation ratio as the narrowband interference frequency point when the maximum correlation ratio exceeds a correlation ratio threshold; performing single-frequency suppression on the power line signal based on the narrowband interference frequency point to obtain a suppressed power line signal; iteratively performing the above steps on the suppressed power line signal to obtain the final suppressed power line signal. This method and system solve the problems of signal distortion, high bit error rate, and decreased stability caused by narrowband interference to the transmission system, improving the reliability of the transmission system.

Description

Technical Field

[0001] This invention belongs to the field of power line carrier communication technology, and particularly relates to a method and system for identifying and suppressing narrowband interference from power lines. Background Technology

[0002] In power line carrier communication systems, power lines, designed for power transmission, have complex channel characteristics and are subject to persistent narrowband interference caused by harmonics from power equipment and switching noise. Furthermore, technologies like OFDM (Orthogonal Frequency Division Multiplexing) are particularly sensitive to narrowband interference, leading to a significant increase in the system's bit error rate. Existing commercial power line carrier equipment experiences a severe performance degradation in environments with strong narrowband interference. Therefore, narrowband interference suppression is an indispensable module for improving communication performance in power line carrier systems. In developing this invention, the inventors discovered at least the following problems in existing technologies: First, traditional methods struggle to accurately identify narrowband interference in low signal-to-noise ratio environments, especially when multiple narrowband interferences with significant energy differences coexist; second, notch filters typically have fixed parameters and cannot adapt to the dynamic changes in interference frequencies within the power line channel; third, power line communication is sensitive to processing delays, and many complex algorithms often fail to meet real-time processing requirements. Summary of the Invention

[0003] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method and system for identifying and suppressing narrowband interference on power lines, addressing the shortcomings of the prior art.

[0004] To address the aforementioned technical problems, in a first aspect, a method for identifying and suppressing narrowband interference on power lines is disclosed, comprising:

[0005] Step 1: Receive the power line signal output from the ADC (Analog-to-Digital Converter);

[0006] Step 2: Segment the power line signal, perform time-frequency transformation on each segment of the power line signal to obtain multiple sets of frequency domain signals, and then average them.

[0007] Step 3: Convert the amplitude of the averaged frequency domain signal to obtain converted data; perform first-order difference on the converted data to obtain differential data; perform dual judgment based on the converted data and differential data to obtain multiple narrowband interference prediction frequency points;

[0008] Step 4: Calculate the correlation ratio for each of the multiple narrowband interference prediction frequency points to obtain the maximum correlation ratio; when the maximum correlation ratio exceeds the correlation ratio threshold, identify the narrowband interference prediction frequency point corresponding to the maximum correlation ratio as the narrowband interference frequency point.

[0009] Step 5: Based on the narrowband interference frequency, the notch filter performs single-frequency suppression on the power line signal to obtain the suppressed power line signal;

[0010] Step 6: Iteratively execute steps 2 to 5 on the suppressed power line signal to obtain the final suppressed power line signal. Iterative processing ensures that no interference components are missed.

[0011] Furthermore, the method also includes: during or after the iteration in step 6, comparing and verifying the power line signal output by the ADC and the suppressed power line signal to determine whether the identified narrowband interference frequency point still exists. If the identified narrowband interference frequency point does not exist, the notch filter stops suppressing the identified narrowband interference frequency point on the power line signal output by the ADC. When the notch filter performs single-frequency suppression on the power line signal, there is a limit to the number of single-frequency points. Generally, the number of iterations is set according to the number of frequency points that the notch filter can suppress. After the notch filter stops suppressing the identified narrowband interference frequency point on the power line signal output by the ADC, step 6 can continue to be executed until a new narrowband interference frequency point is identified and suppressed. This comparison and verification can continue to identify new narrowband interference frequencies, improving the real-time performance and accuracy of narrowband identification, and avoiding the incomplete or excessive suppression caused by the fixed settings of the notch filter, which may affect the energy of the effective signal.

[0012] Furthermore, if the tolerance between the narrowband interference frequency points identified in subsequent iterations and those identified in previous iterations is within a preset threshold, then step 5 is skipped, and step 6 is executed directly. That is, the notch filter does not perform single-frequency suppression on the suppressed power line signal. If the tolerance between the narrowband interference frequency points identified in subsequent iterations and those identified in previous iterations is within a preset threshold, then the two narrowband interference frequency points are considered to belong to the same narrowband interference. Since the notch filter does not perform single-frequency suppression on the suppressed power line signal, this avoids repeated counting and suppression of the same interference source.

[0013] Further, step 3 includes: after removing zero values ​​from the amplitude of the averaged frequency domain signal, converting the amplitude into power spectral density to obtain the converted data;

[0014] Take the maximum value from the transformed data and mark it as... The position is denoted as P_top_idx1, and the frequency of the current point is denoted as... The current location is estimated to be the first narrowband interference frequency.

[0015] Furthermore, step 3 also includes: performing first-order differencing on the transformed data to obtain differencing data; taking the maximum value from the differencing data, and denoting the position point corresponding to the maximum value as P_diff_idx; taking the first N position point values ​​and the last N position point values ​​from the differencing data P_diff_idx; and taking the maximum value from the 2N+1 position point values, marking it as... The corresponding position is recorded as P_top_idx2, and the frequency of the current point is recorded as... The current location is estimated to be the second narrowband interference estimated frequency point; N is set according to the narrowband interference frequency band width.

[0016] The purpose of this operation is mainly because narrowband interference usually exhibits significant energy changes in the frequency domain signal. Therefore, the first-order difference method is considered to identify narrowband interference. However, in practical applications, considering the ADC sampling rate and the finite-length time-frequency transformation (FFT length) processing, the maximum value of the first-order difference may be a point near the maximum value of the narrowband interference. Therefore, considering the case, N points before and after are taken to determine the position of the actual maximum value to avoid frequency judgment deviation.

[0017] Furthermore, in step 4, the correlation ratio is calculated for each of the multiple narrowband interference prediction frequency points to obtain the maximum correlation ratio, including: designing the mean sampling length L, for the first narrowband interference prediction frequency point And position P_top_idx1, take the average of two data segments of length L before and after the first narrowband interference prediction frequency point from the transformed data, and denot it as ;

[0018] Frequency prediction for the second narrowband interference And position P_top_idx2, take the average of two data segments of length L before and after the second narrowband interference prediction frequency point from the transformed data, and denot it as ;

[0019] First narrowband interference predicted frequency correlation ratio ,

[0020] Second narrowband interference predicted frequency correlation ratio ,

[0021] like Then the maximum correlation ratio ;like Then the maximum correlation ratio .

[0022] Step 3 employs a dual detection strategy: absolute peak detection of the averaged frequency domain signal (directly finding the maximum power spectrum point) and first-order differential peak detection (identifying the edge points where power spectrum changes most drastically). Step 4 uses the correlation ratio between peak power and the average power of the neighborhood as the interference criterion, improving detection reliability. An adaptive threshold mechanism is set up for more accurate identification of narrowband interference frequencies. Introducing first-order differential features into narrowband interference detection solves the problem of insufficient sensitivity for weak interference detection in the context of OFDM signals using traditional methods.

[0023] Furthermore, during or after the iteration in step 6, the power line signal output by the ADC and the suppressed power line signal are compared and verified to determine whether the identified narrowband interference frequency points still exist, including:

[0024] The power line signal and the suppressed power line signal output by the ADC are subjected to time-frequency transformation to obtain the frequency domain signal before suppression and the frequency domain signal after suppression.

[0025] The frequency domain signals before and after suppression are compared. If a certain narrowband interference frequency point is found to have no difference in energy between the frequency domain signals before and after suppression, it is determined that the identified narrowband interference frequency point no longer exists.

[0026] Furthermore, step 2 involves segmenting the power line signal, including: according to each segment The length divides the power line signal into multiple segments. The time-frequency transformation is performed on each segment of the time-domain signal. Traditional methods usually perform FFT (Fast Fourier Transform) on the entire signal. This step can effectively suppress the random spikes caused by Gaussian white noise by segmenting the signal, thereby improving the reliability of subsequent detection.

[0027] Secondly, a system for identifying and suppressing narrowband interference on power lines is disclosed, comprising a narrowband interference identification module and a narrowband interference suppression module. The narrowband interference identification module includes a data acquisition unit, a time-frequency conversion unit, a narrowband interference prediction unit, and a narrowband interference identification unit.

[0028] The data acquisition unit is used to receive the power line signal output by the ADC;

[0029] The time-frequency conversion unit is used to segment the power line signal, perform time-frequency conversion on each segment of the power line signal, obtain multiple sets of frequency domain signals, and average them.

[0030] The narrowband interference prediction unit is used to convert the amplitude of the averaged frequency domain signal to obtain converted data; perform first-order difference on the converted data to obtain differential data; and perform dual judgment based on the converted data and differential data to obtain multiple narrowband interference prediction frequency points.

[0031] The narrowband interference identification unit is used to calculate the correlation ratio for multiple narrowband interference prediction frequency points respectively, and obtain the maximum correlation ratio; when the maximum correlation ratio exceeds the correlation ratio threshold, the narrowband interference prediction frequency point corresponding to the maximum correlation ratio is identified as the narrowband interference frequency point.

[0032] The narrowband interference suppression module is used to suppress the electric line signal output by the ADC at a single frequency point using a notch filter based on the narrowband interference frequency point, so as to obtain the suppressed electric line signal.

[0033] The narrowband interference identification module is also used to iteratively input the suppressed power line signal into the time-frequency conversion unit, the narrowband interference prediction unit, and the narrowband interference identification unit to obtain a new narrowband interference frequency point; the narrowband interference suppression module uses a notch filter to perform single-frequency suppression on the suppressed power line signal based on the new narrowband interference frequency point to obtain the final suppressed power line signal.

[0034] Furthermore, it also includes a comparison and verification module, which is used to compare and verify the power line signal output by the ADC and the suppressed power line signal during or after the iteration of the narrowband interference identification module, and to determine whether the identified narrowband interference frequency point still exists. If the identified narrowband interference frequency point does not exist, the notch filter stops suppressing the identified narrowband interference frequency point on the power line signal output by the ADC.

[0035] Furthermore, the narrowband interference identification module also includes a tolerance unit, which is used to determine whether the tolerance between the narrowband interference frequency point identified in the subsequent iteration and the narrowband interference frequency point identified in the previous iteration is within a preset threshold. If it is within the preset threshold, the narrowband interference frequency point identified in the subsequent iteration is not sent to the notch filter, and the iteration inside the narrowband interference identification module continues.

[0036] Beneficial effects: This invention sets a correlation ratio threshold to identify specific frequency points of multi-frequency narrowband interference with uneven energy intensity in the frequency domain, and uses a notch filter to suppress narrowband interference, thus solving the problems of signal distortion, high bit error rate, and decreased stability caused by narrowband interference to the signal transmission system, and improving the reliability of the signal transmission system. It does not require additional hardware overhead, significantly improving communication performance without substantially increasing costs. Attached Figure Description

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0038] Figure 1 A flowchart illustrating a method for identifying and suppressing narrowband interference on power lines, provided in an embodiment of this application.

[0039] Figure 2 This is a framework diagram of a power line narrowband interference identification and suppression system provided in an embodiment of this application.

[0040] Figure 3 This is a schematic diagram of the narrowband interference identification module in a power line narrowband interference identification and suppression system provided in an embodiment of this application.

[0041] Figure 4 This diagram illustrates the comparison before and after suppression of 1MHz, -20dBm narrowband interference using a method for identifying and suppressing narrowband power line interference provided in this application.

[0042] Figure 5 This diagram illustrates the comparison of the suppression of narrowband power line interference before and after using the identification and suppression method provided in this application for 1MHz (-20dBm), 3MHz (-30dBm), and 6MHz (-30dBm) narrowband interference.

[0043] Figure 6 This diagram illustrates the comparison before and after suppression of 1MHz narrowband interference (outside the low-frequency band) + OFDM effective signal using a method for identifying and suppressing narrowband power line interference provided in this application embodiment.

[0044] Figure 7 This diagram illustrates the comparison before and after suppression of 3MHz narrowband interference (in-band) + OFDM effective signal using a method for identifying and suppressing narrowband power line interference provided in this application embodiment.

[0045] Figure 8 This diagram illustrates the comparison before and after using the power line narrowband interference identification and suppression method provided in this application embodiment to suppress 6MHz narrowband interference (out-of-band high frequency) + OFDM effective signal.

[0046] Figure 9 This diagram illustrates the comparison before and after suppression of multiple narrowband interference + OFDM effective signals using a method for identifying and suppressing narrowband interference on power lines provided in this application. Detailed Implementation

[0047] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0048] The raw data processing can be categorized into the following schemes: 1. Directly perform time-frequency transformation on a single segment of the raw signal to obtain frequency domain information; 2. Perform two time-domain samplings on the raw signal, design delays for the two information streams, and apply different windowing methods, then superimpose them after time-frequency transformation to obtain the frequency domain signal; 3. Sample the raw signal multiple times, and accumulate the samples after time-frequency transformation to obtain the frequency domain signal. Methods for narrowband identification in power line carrier communication can be broadly categorized as follows: 1. Use subcarrier SINR (Signal-to-Interference-plus-Noise Ratio) to determine narrowband interference. SINR values ​​below a threshold are identified as narrowband. For similar SINR values, standard deviation is used for fine decomposition. The advantage of this method is accurate identification of narrowband interference in different subcarriers. However, its disadvantages include the need for extremely accurate channel estimation to obtain SINR values ​​and the inability to accurately determine the precise frequency of narrowband interference. If the narrowband frequency is between adjacent subcarriers, this method requires suppressing two subcarrier segments, wasting significant spectrum resources and impacting communication performance. 2. A method based on the highest amplitude of the frequency domain signal exceeding a threshold value is used, employing the difference between the highest value and the average of nearby spectra. This method can resolve most interference with obvious narrowband characteristics. However, under OFDM signals and in situations with uneven background noise, false alarms and misjudgments may occur with single amplitude detection. 3. A method that normalizes by dividing the entire frequency range by its magnitude and identifies narrowbands through a threshold value suffers from computational complexity and requires precise threshold setting; otherwise, false alarms and misjudgments will still occur.

[0049] This application embodiment is based on the frequency domain signal obtained after segmented time-frequency transformation processing of the received ADC raw data information. It performs accurate identification of narrowband interference and achieves effective identification and suppression of narrowband interference through a three-level thickening of "dual detection - precise positioning - adaptive filtering". It can be applied to power line carrier communication SOC (System on Chip) in various environments, and is particularly suitable for power line communication application scenarios with high requirements for communication reliability, such as smart grids and industrial automation.

[0050] The first embodiment of this application discloses a method for identifying and suppressing narrowband interference on power lines, such as... Figure 1 As shown, it includes:

[0051] Step 1: Receive the power line signal output by the ADC;

[0052] Step 2: Segment the power line signal, perform time-frequency transformation on each segment of the power line signal to obtain multiple sets of frequency domain signals, and then average them.

[0053] Segmenting the power line signal, including: according to each segment The length divides the power line signal into multiple segments. .

[0054] Step 3: Convert the amplitude of the averaged frequency domain signal to obtain converted data; perform first-order difference on the converted data to obtain differential data; perform dual judgment based on the converted data and differential data to obtain multiple narrowband interference prediction frequency points; specifically, this includes:

[0055] After removing zero values ​​from the amplitude of the averaged frequency domain signal, the amplitude is converted into power spectral density to obtain the converted data.

[0056] Let X be the averaged frequency domain signal, and Y be the transformed data. Then the transformation formula is as follows:

[0057]

[0058] The unit of the converted data Y obtained by the above formula is dBm / Hz, and the impedance of the communication module is 50 ohms. The communication module refers to the chip plus peripherals and the PCB (Printed Circuit Board) as a whole. The method and system provided in this embodiment are integrated into the chip.

[0059] Take the maximum value from the transformed data and mark it as... The position is denoted as P_top_idx1, and the frequency of the current point is denoted as... The current location is estimated to be the first narrowband interference frequency.

[0060] In practical signal transmission systems, narrowband interference with a power spectral density greater than the out-of-band weak energy of the OFDM effective signal can occur. This interference still affects the transmission system, leading to a decrease in transmission rate and stability. Considering that the above methods cannot identify this type of narrowband interference, a first-order difference is performed on the converted data to obtain differential data. The maximum value of the differential data is taken, and the position point corresponding to the maximum value is denoted as P_diff_idx. The first N position point values ​​and the last N position point values ​​of position point P_diff_idx are taken from the differential data, and the maximum value is taken from 2N+1 position point values ​​and marked as... The corresponding position is recorded as P_top_idx2, and the frequency of the current point is recorded as... The current location is estimated to be the second narrowband interference estimated frequency point; N is set according to the narrowband interference frequency band width. For example, if the narrowband interference has a strong energy bandwidth of 250KHz and the width of each subcarrier is 24KHz, then N is set to 5.

[0061] Step 4: Calculate the correlation ratio for each of the multiple narrowband interference prediction frequency points to obtain the maximum correlation ratio; when the maximum correlation ratio exceeds the correlation ratio threshold, identify the narrowband interference prediction frequency point corresponding to the maximum correlation ratio as the narrowband interference frequency point and continue to step 5; when the maximum correlation ratio is lower than the correlation ratio threshold, execute step 1.

[0062] The correlation ratio is calculated for multiple narrowband interference prediction frequency points to obtain the maximum correlation ratio, including: designing the mean sampling length L, for the first narrowband interference prediction frequency point. And position P_top_idx1, take the average of two data segments of length L before and after the first narrowband interference prediction frequency point from the transformed data, and denot it as ;

[0063]

[0064] in, i This represents the position index of two segments of length L before and after the estimated frequency point of the first narrowband interference. Indicates position i The converted data at the location.

[0065] Frequency prediction for the second narrowband interference And position P_top_idx2, take the average of two data segments of length L before and after the second narrowband interference prediction frequency point from the transformed data, and denot it as ;

[0066]

[0067] in, j This indicates the position index of the two segments of length L before and after the estimated frequency point of the second narrowband interference. Indicates position j The converted data at the location.

[0068] First narrowband interference predicted frequency correlation ratio ,

[0069] Second narrowband interference predicted frequency correlation ratio ,

[0070] like Then the maximum correlation ratio Narrowband interference frequency ;like Then the maximum correlation ratio Narrowband interference frequency .

[0071] When the maximum correlation ratio When the frequency point is identified as a narrowband interference frequency point, the corresponding frequency point is identified as such.

[0072] Extensive laboratory testing in this embodiment has shown that when the narrowband interference energy exceeds the energy value in adjacent frequency bands by more than 20 dB, the system's bit error rate increases significantly and its stability decreases sharply. Therefore, this embodiment sets the correlation ratio threshold value to be... .

[0073] After sampling and time-frequency transformation, the energy of narrowband interference is usually not a jump at a single frequency point, but gradually decreases from the center of that frequency point to both sides. Its influence ranges from 500kHz to 1MHz. For example, if the bandwidth of the power line signal is 12.5MHz and the number of subcarriers is 512, then 1MHz bandwidth covers 41 subcarriers. Therefore, taking L as 20 can more accurately obtain the average energy within the range.

[0074] Step 5: Based on the narrowband interference frequency, the notch filter performs single-frequency suppression on the power line signal to obtain the suppressed power line signal;

[0075] Step 6: Iteratively execute steps 2 to 5 on the suppressed power line signal to obtain the final suppressed power line signal. The iteration period is set according to the configuration of the notch filter, specifically, according to the number of narrowband interference frequency points that the notch filter can suppress.

[0076] During or after the iteration in step 6, the electric field signal output by the ADC and the suppressed electric field signal are compared and verified to determine whether the identified narrowband interference frequency still exists. If the identified narrowband interference frequency does not exist, the notch filter stops suppressing the identified narrowband interference frequency on the electric field signal output by the ADC. The comparison and verification of the electric field signal output by the ADC and the suppressed electric field signal to determine whether the identified narrowband interference frequency still exists includes:

[0077] The power line signal and the suppressed power line signal output by the ADC are subjected to time-frequency transformation to obtain the frequency domain signal before suppression and the frequency domain signal after suppression.

[0078] The energy of the identified narrowband interference frequency points of the pre-suppression and post-suppression frequency domain signals is compared. If there is no energy difference, it is determined that the identified narrowband interference frequency point no longer exists. The notch filter then resets the parameters for that narrowband interference frequency point in preparation for setting parameters for subsequent new narrowband interference frequency points. The energy refers to the value obtained by converting the amplitude of the identified narrowband interference frequency point in the frequency domain signal into power spectral density.

[0079] When executing step 6, if the tolerance between the narrowband interference frequency point identified in subsequent iterations and the narrowband interference frequency point identified in previous iterations is within a preset threshold, then step 5 is skipped, and step 6 is executed directly. That is, the notch filter does not perform single-frequency suppression on the suppressed power line signal. In specific implementation, the preset threshold can be set to 100kHz. It is generally considered that interference within 100kHz originates from a single narrowband frequency point. If another narrowband interference is identified within 100kHz, it is highly likely that the data processing is abnormal, requiring re-receiving and processing of data, or indicating a hardware malfunction.

[0080] The first embodiment of this application accurately identifies narrowband interference by setting a threshold value after processing the frequency domain signal using an algorithm and by employing a dual comparison method. Furthermore, it adjusts the narrowband suppression frequency in real time through dynamic notch filter parameter tuning, thereby solving the problems of signal distortion, high bit error rate, and decreased stability caused by narrowband interference to the signal transmission system and improving the reliability of the signal transmission system.

[0081] The second embodiment of this application discloses a system for identifying and suppressing narrowband interference on power lines, such as... Figure 2 As shown, it includes a narrowband interference identification module and a narrowband interference suppression module (notch filter). Figure 3 As shown, the narrowband interference identification module includes a data acquisition unit, a time-frequency conversion unit, a narrowband interference prediction unit, and a narrowband interference identification unit. The data acquisition unit is used to receive the power line signal output by the ADC or the power line signal output by the narrowband interference suppression module.

[0082] The time-frequency conversion unit is used to segment the power line signal, perform time-frequency conversion on each segment of the power line signal, obtain multiple sets of frequency domain signals, and average them.

[0083] The narrowband interference prediction unit is used to convert the amplitude of the averaged frequency domain signal to obtain converted data; perform first-order difference on the converted data to obtain differential data; and perform dual judgment based on the converted data and differential data to obtain multiple narrowband interference prediction frequency points.

[0084] The narrowband interference identification unit is used to calculate the correlation ratio for multiple narrowband interference prediction frequency points respectively, and obtain the maximum correlation ratio; when the maximum correlation ratio exceeds the correlation ratio threshold, the narrowband interference prediction frequency point corresponding to the maximum correlation ratio is identified as the narrowband interference frequency point.

[0085] The narrowband interference suppression module is used to suppress the electric line signal output by the ADC at a single frequency point using a notch filter based on the narrowband interference frequency point, so as to obtain the suppressed electric line signal.

[0086] The narrowband interference identification module is also used to iteratively input the suppressed power line signal into the time-frequency conversion unit, the narrowband interference prediction unit, and the narrowband interference identification unit to obtain a new narrowband interference frequency point; the narrowband interference suppression module uses a notch filter to perform single-frequency suppression on the suppressed power line signal based on the new narrowband interference frequency point to obtain the final suppressed power line signal.

[0087] The identification and suppression system for narrowband power line interference further includes a comparison and verification module. The comparison and verification module is used to compare and verify the power line signal output by the ADC and the suppressed power line signal during or after the iteration of the narrowband interference identification module, and to determine whether the identified narrowband interference frequency point still exists. If the identified narrowband interference frequency point does not exist, the notch filter stops suppressing the identified narrowband interference frequency point on the power line signal output by the ADC.

[0088] The narrowband interference identification module also includes a tolerance unit. This tolerance unit determines whether the tolerance between the narrowband interference frequency point identified in the subsequent iteration and the narrowband interference frequency point identified in the previous iteration is within a preset threshold. If it is within the preset threshold, the narrowband interference frequency point identified in the subsequent iteration is not sent to the notch filter, and the iteration within the narrowband interference identification module continues. The iteration period is set according to the configuration of the notch filter.

[0089] The signal transmission system, in addition to the aforementioned power line narrowband interference identification and suppression system, also includes a PGA (Programmable Gain Amplifier), an ADC, and an AGC (Auto-Gain Control). The signal to be transmitted enters the ADC under the PGA gain. The power line signal output by the ADC is identified and suppressed by the narrowband interference identification module and the narrowband interference suppression module. The suppressed signal is then sent to the subsequent digital system for signal processing. After narrowband interference suppression, the signal undergoes another gain value calculation via the AGC to correct for the gain deviation caused by excessive narrowband interference energy, and this correction is fed back to the PGA for proper gain adjustment. The PGA, ADC, and AGC, as well as their interconnections, are existing technologies and are not limited to this embodiment of the invention.

[0090] Example:

[0091] Step 1: Receive the power line signal output by the ADC. The ADC has a sampling rate of 50MHz, a power line signal bandwidth of 12.5MHz, and 16384 time-domain signal sampling points.

[0092] Step 2: Segment the power line signal, with each segment being [length missing]. It is divided into 4 sections.

[0093] Perform time-frequency transformation on each power line signal segment to obtain multiple sets of frequency domain signals, and average them to obtain the averaged frequency domain signal X.

[0094] Step 3: Remove zero values ​​from the current frequency domain signal X and convert it to PSD, denoted as Y.

[0095]

[0096] The PSD unit derived from the above formula is dBm / Hz, and the impedance of the communication module is 50 ohms.

[0097] We will process Y in two ways:

[0098] 1. Take the maximum PSD of the current frequency domain signal Y and mark it as... The position is denoted as P_top_idx1, and the frequency of the current point is denoted as... The current location is estimated to be a narrowband interference frequency point;

[0099] 2. In practical signal transmission systems, the PSD of the effective OFDM signal may exceed that of weak out-of-band interference. However, this interference still affects the transmission system, leading to a decrease in transmission rate and stability. Considering that the first processing method cannot identify this type of narrowband interference, we consider performing a first-order difference on the frequency domain signal Y, taking the position point corresponding to the maximum PSD after the difference, denoted as P_diff_idx. We then compare the maximum PSD among the eleven points (five points before and five points after this point) to find the maximum PSD, marking it as... The position is denoted as P_top_idx2, and the frequency of the current point is denoted as... The purpose of this operation is mainly because narrowband interference usually exhibits significant energy changes in the frequency domain signal. Therefore, a one-stage differential method is considered to identify narrowband interference. However, in practical applications, considering the ADC sampling rate and the finite length of the time-frequency transform (FFT length), the maximum value of the first-order differential may be a point near the maximum value of the narrowband interference. Therefore, considering the example, five points before and after are taken to determine the actual location of the maximum PSD (50MHz sampling rate, FFT length 4096, 11 points cover an area of ​​approximately 100KHz, which can basically cover most of the narrowband interference frequency band width) to avoid frequency judgment deviation.

[0100] Step 4: Calculate the correlation ratio for each of the multiple narrowband interference prediction frequency points to obtain the maximum correlation ratio; when the maximum correlation ratio exceeds the correlation ratio threshold, identify the narrowband interference prediction frequency point corresponding to the maximum correlation ratio as the narrowband interference frequency point.

[0101] For the two known sets of narrowband interference prediction markers P_top_idx1, as well as P_top_idx2, The design sampling length is L=20. The average of two data segments of length L before and after the narrowband interference prediction frequency point is taken as the standard for judging the mean. The narrowband interference prediction frequency point is then calculated. correlation ratio and narrowband interference prediction frequency points correlation ratio .

[0102] like Then the maximum correlation ratio Narrowband interference frequency ;like Then the maximum correlation ratio Narrowband interference frequency .

[0103] When the maximum correlation ratio When the frequency point is identified as a narrowband interference frequency point, the corresponding frequency point is identified as such.

[0104] Step 5: Based on the narrowband interference frequency, the notch filter performs single-frequency suppression on the power line signal to obtain the suppressed power line signal;

[0105] Step 6: Iteratively execute steps 2 to 5 on the suppressed power line signal to obtain the final suppressed power line signal. In this embodiment, the hardware configuration based on the notch filter suppresses a maximum of five different frequency points. Therefore, the iteration period can be set to 5. If a frequency point is subsequently deleted through comparison and verification, step 6 can be continued to identify and suppress a new frequency point.

[0106] The narrowband interference frequency points identified in subsequent iterations are evaluated against those identified in previous iterations, with a tolerance within 100kHz. This avoids duplicate counting of the same interference source while allowing adjustment of some filter parameters to deepen the notch depth and enhance suppression of narrowband energy. This avoids the problem of incomplete or excessive suppression of narrowband signals due to fixed notch filter settings that result in suppressing different energies with the same energy, thus affecting the energy of the effective signal. Furthermore, the system does not stop detecting after five iterations; the detection mechanism remains continuously active throughout the system's operation. At this time, the system simultaneously monitors and compares the frequency domain signals of the ADC data and the data after the notch filter, providing real-time feedback on the changing narrowband interference frequency points in the circuit. If a detected narrowband interference frequency point shows no significant difference in energy between the ADC data and the data after the notch filter, it indicates that the narrowband interference corresponding to that frequency point no longer exists. The suppression function for that narrowband interference frequency point can then be disabled, and step 6 can continue until a new narrowband interference frequency point is identified and suppressed. Improve the real-time performance and accuracy of narrowband recognition in the system.

[0107] Figures 4 to 9 The upper part of the diagrams represents the original frequency domain signal, while the lower part represents the frequency domain signal after narrowband suppression. Figure 4The results of single narrowband suppression are shown. freq_nbi represents the identified narrowband interference frequency, and R_nbi represents the correlation ratio calculated for that frequency. Due to the inherent characteristics of the ADC, the system introduces some harmonics of the 1MHz main frequency. In this embodiment, the 3rd and 5th harmonics have relatively significant energy, but compared to the fundamental frequency, their energy is still very low. Traditional identification methods would find it difficult to identify such low-energy harmonics. However, the results of this embodiment show that these two harmonics can still be identified and suppressed, significantly improving communication performance. Figure 5 The results demonstrate the ability to accurately identify and suppress narrowband interference of different energies and frequencies. Figure 6 , Figure 7 and Figure 8 The identification and suppression of low-frequency out-of-band narrowband, in-band narrowband, and high-frequency out-of-band narrowband with effective OFDM signals are demonstrated respectively. It can be clearly seen that the out-of-band narrowband interference is completely suppressed and has no effect on the effective OFDM spectrum. The in-band narrowband is also significantly suppressed, with an affected frequency band width of about 200kHz, which has almost no impact on the effective information frequency band of this embodiment. Figure 9 The results of multi-narrowband suppression with OFDM effective signals are shown. It can be seen that while completely suppressing the narrowband at each frequency point, it has almost no impact on the effective information frequency band, which is comparable to the performance of single-frequency narrowband suppression.

[0108] In its specific implementation, this application provides a computer storage medium and a corresponding data processing unit. The computer storage medium is capable of storing a computer program, which, when executed by the data processing unit, can run the invention's content regarding the identification and suppression method for narrowband power line interference, as well as some or all of the steps in various embodiments. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0109] Those skilled in the art will clearly understand that the technical solutions in the embodiments of the present invention can be implemented using computer programs and their corresponding general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of computer programs, i.e., software products. These computer program software products can be stored in a storage medium and include several instructions to cause a device containing a data processing unit (which may be a personal computer, server, microcontroller, MUU, or network device, etc.) to execute the methods described in various embodiments or certain parts of the embodiments of the present invention.

[0110] This invention provides a method and system for identifying and suppressing narrowband interference on power lines. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for identifying and suppressing narrowband interference on power lines, characterized in that, include: Step 1: Receive the power line signal output by the ADC; Step 2: Segment the power line signal, perform time-frequency transformation on each segment of the power line signal to obtain multiple sets of frequency domain signals, and then average them. Step 3: Convert the amplitude of the averaged frequency domain signal to obtain the converted data; Perform first-order differencing on the transformed data to obtain the differencing data; Based on a dual assessment using both the transformed data and the differential data, multiple narrowband interference prediction frequency points are obtained, including: Take the maximum value from the transformed data and mark it as... The position is denoted as P_top_idx1, and the frequency of the current point is denoted as... The current location is estimated to be the first narrowband interference frequency point; Take the maximum value from the difference data, and denote the position point corresponding to the maximum value as P_diff_idx. Then, take the N preceding and N following position point values ​​of position point P_diff_idx from the difference data, and finally, take the maximum value from the 2N+1 position point values, marking it as... The corresponding position is recorded as P_top_idx2, and the frequency of the current point is recorded as... The current location is estimated to be the second narrowband interference estimated frequency point; N is set according to the narrowband interference frequency band width; Step 4: Calculate the correlation ratio for each of the multiple narrowband interference prediction frequency points to obtain the maximum correlation ratio, including: The average sampling length L is designed to predict the frequency point for the first narrowband interference. And position P_top_idx1, take the average of two data segments of length L before and after the first narrowband interference prediction frequency point from the transformed data, and denot it as ; Frequency prediction for the second narrowband interference And position P_top_idx2, take the average of two data segments of length L before and after the second narrowband interference prediction frequency point from the transformed data, and denot it as ; First narrowband interference predicted frequency correlation ratio , Second narrowband interference predicted frequency correlation ratio , like Then the maximum correlation ratio ;like Then the maximum correlation ratio ; When the maximum correlation ratio exceeds the correlation ratio threshold, the narrowband interference prediction frequency corresponding to the maximum correlation ratio is identified as the narrowband interference frequency. Step 5: Based on the narrowband interference frequency, the notch filter performs single-frequency suppression on the power line signal to obtain the suppressed power line signal; Step 6: Iteratively execute steps 2 to 5 on the suppressed electric field signal to obtain the final suppressed electric field signal.

2. The method for identifying and suppressing narrowband interference on power lines according to claim 1, characterized in that, Also includes: During or after the iteration in step 6, the power line signal output by the ADC and the suppressed power line signal are compared and verified to determine whether the identified narrowband interference frequency point still exists. If the identified narrowband interference frequency point does not exist, the notch filter stops suppressing the identified narrowband interference frequency point on the power line signal output by the ADC.

3. The method for identifying and suppressing narrowband interference on power lines according to claim 2, characterized in that, If the tolerance between the narrowband interference frequency points identified in subsequent iterations and those identified in previous iterations is within a preset threshold when performing step 6, then step 5 is skipped and step 6 is executed directly.

4. The method for identifying and suppressing narrowband interference on power lines according to claim 3, characterized in that, Step 3 involves converting the amplitude of the averaged frequency domain signal to obtain the converted data. This includes removing zero values ​​from the amplitude of the averaged frequency domain signal and converting the amplitude into power spectral density to obtain the converted data.

5. The method for identifying and suppressing narrowband interference on power lines according to claim 4, characterized in that, During or at the end of step 6, the power line signal output by the ADC and the suppressed power line signal are compared and verified to determine whether the identified narrowband interference frequency points still exist, including: The power line signal and the suppressed power line signal output by the ADC are subjected to time-frequency transformation to obtain the frequency domain signal before suppression and the frequency domain signal after suppression. Energy comparison is performed on the identified narrowband interference frequency points of the pre-suppression frequency domain signal and the post-suppression frequency domain signal. If there is no energy difference, it is determined that the identified narrowband interference frequency points no longer exist.

6. The method for identifying and suppressing narrowband interference on power lines according to claim 5, characterized in that, Step 2 involves segmenting the power line signal, including: dividing it into segments. The length divides the power line signal into multiple segments. .

7. A system for identifying and suppressing narrowband interference on power lines, characterized in that, It includes a narrowband interference identification module and a narrowband interference suppression module. The narrowband interference identification module includes a data acquisition unit, a time-frequency conversion unit, a narrowband interference prediction unit, and a narrowband interference identification unit. The data acquisition unit is used to receive the power line signal output by the ADC. The time-frequency conversion unit is used to segment the power line signal, perform time-frequency conversion on each segment of the power line signal, obtain multiple sets of frequency domain signals, and average them. The narrowband interference prediction unit is used to convert the amplitude of the averaged frequency domain signal to obtain the converted data. Perform first-order differencing on the transformed data to obtain the differencing data; Based on a dual assessment using both the transformed data and the differential data, multiple narrowband interference prediction frequency points are obtained; including: Take the maximum value from the transformed data and mark it as... The position is denoted as P_top_idx1, and the frequency of the current point is denoted as... The current location is estimated to be the first narrowband interference frequency point; Take the maximum value from the difference data, and denote the position point corresponding to the maximum value as P_diff_idx. Then, take the N preceding and N following position point values ​​of position point P_diff_idx from the difference data, and finally, take the maximum value from the 2N+1 position point values, marking it as... The corresponding position is recorded as P_top_idx2, and the frequency of the current point is recorded as... The current location is estimated to be the second narrowband interference estimated frequency point; N is set according to the narrowband interference frequency band width; The narrowband interference identification unit is used to calculate the correlation ratio for multiple narrowband interference prediction frequency points respectively, and obtain the maximum correlation ratio; when the maximum correlation ratio exceeds the correlation ratio threshold, the narrowband interference prediction frequency point corresponding to the maximum correlation ratio is identified as the narrowband interference frequency point. The step of calculating the correlation ratio for multiple narrowband interference prediction frequency points to obtain the maximum correlation ratio includes: The average sampling length L is designed to predict the frequency point for the first narrowband interference. And position P_top_idx1, take the average of two data segments of length L before and after the first narrowband interference prediction frequency point from the transformed data, and denot it as ; Frequency prediction for the second narrowband interference And position P_top_idx2, take the average of two data segments of length L before and after the second narrowband interference prediction frequency point from the transformed data, and denot it as ; First narrowband interference predicted frequency correlation ratio , Second narrowband interference predicted frequency correlation ratio , like Then the maximum correlation ratio ;like Then the maximum correlation ratio ; The narrowband interference suppression module is used to suppress the electric line signal output by the ADC at a single frequency point using a notch filter based on the narrowband interference frequency point, so as to obtain the suppressed electric line signal. The narrowband interference identification module is also used to iteratively input the suppressed power line signal into the time-frequency conversion unit, the narrowband interference prediction unit, and the narrowband interference identification unit to obtain a new narrowband interference frequency point; the narrowband interference suppression module uses a notch filter to perform single-frequency suppression on the suppressed power line signal based on the new narrowband interference frequency point to obtain the final suppressed power line signal.

8. The identification and suppression system for narrowband interference on power lines according to claim 7, characterized in that, It also includes a comparison and verification module, which is used to compare and verify the power line signal output by the ADC and the suppressed power line signal during or after the iteration of the narrowband interference identification module, and to determine whether the identified narrowband interference frequency point still exists. If the identified narrowband interference frequency point does not exist, the notch filter stops suppressing the identified narrowband interference frequency point on the power line signal output by the ADC.

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