A method and apparatus for narrowband interference rejection based on an HPLC chip

Abstract

The present application relates to a kind of based on HPLC chip narrow-band interference filtering method and device, belong to power line carrier communication technical field.The present application is when carrying out pulse processing to signal, if narrow-band interference detection start signal is detected, then pause AGC / DAGC processing, narrow-band interference detection module uses the signal of pause AGC / DAGC processing to carry out the calculation of narrow-band interference frequency point, and filter coefficient used by narrow-band interference elimination module is determined based on narrow-band interference frequency point, and narrow-band interference elimination module carries out narrow-band interference elimination processing according to the filter coefficient determined.Therein, the signal participating in the calculation of narrow-band interference frequency point is paused AGC / DAGC processing when carrying out pulse processing, so that the signal fluctuation caused by AGC / DAGC processing is avoided, the accuracy of the calculation of narrow-band interference frequency point is improved, and the effect of narrow-band interference filtering is guaranteed.

Description

Technical Field

[0001] This invention relates to a method and apparatus for narrowband interference filtering based on an HPLC chip, belonging to the field of power line carrier communication technology. Background Technology

[0002] Broadband power line communication is an OFDM (Orthogonal Frequency Division Multiplexing) communication system. Due to the complex line connections, narrowband interference occurs intermittently. If the narrowband interference frequency happens to be located at the subcarrier position, the data of the corresponding subcarrier will be severely damaged, leading to an increase in the system's bit error rate. If the narrowband interference frequency is located between two subcarriers, it will increase FFT (Fast Fourier Transform) spectral leakage, causing the data of two adjacent subcarriers to be affected by the narrowband interference. If there are many narrowband interference frequencies and their intensity is high, it will directly affect the accuracy of timing synchronization and channel estimation, thereby reducing receiver performance. In severe cases, it will cause the receiver to fail to synchronize, making subsequent demodulation and decoding impossible. Therefore, it is essential to detect and suppress narrowband interference in a timely manner.

[0003] Only by accurately detecting narrowband interference can it be suppressed. For example, when using a notch filter for suppression, the filter coefficients of the notch filter need to be accurately determined. The filter coefficients of the notch filter need to be determined based on the interference frequency of the narrowband interference. Therefore, it is necessary to accurately determine the interference frequency of the narrowband interference. However, the determination of the interference frequency of narrowband interference is easily affected by the analog gain, which leads to inaccurate determination of the interference frequency and thus affects the narrowband interference filtering effect. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for narrowband interference filtration based on HPLC chips, so as to solve the problem of poor narrowband interference filtration effect in current methods.

[0005] To solve the above-mentioned technical problems, this invention provides a method for narrowband interference filtering based on an HPLC chip, the method comprising the following steps:

[0006] 1) Perform first-stage depulsation processing on the received power line carrier signal to filter out pulses in the signal, and perform AGC processing on the pulse-removed signal; if a narrowband interference detection start signal is detected during the first-stage depulsation processing, the AGC processing is paused.

[0007] 2) The narrowband interference cancellation module is used to perform narrowband interference cancellation processing on the data after the first stage of pulse de-pulse processing;

[0008] 3) Perform a second-stage depulsing process on the data after narrowband interference cancellation to filter out the remaining pulses in the signal, and perform DAGC processing on the pulse-cancelled signal; and if a narrowband interference detection start signal is detected during the second-stage depulsing process, DAGC processing will be suspended for the signal that was paused during the first-stage depulsing process.

[0009] 4) The narrowband interference detection module calculates the signal that the AGC processing is paused during the first-stage depulsation process and the signal that the DAGC processing is also paused during the second-stage depulsation process to determine the narrowband interference frequency. Based on the narrowband interference frequency, the filter coefficients used by the narrowband interference cancellation module are determined, and the narrowband interference cancellation module performs narrowband interference cancellation processing according to the determined filter coefficients.

[0010] Furthermore, in step 4), the narrowband interference detection module uses FFT to calculate the signal that pauses AGC processing during the first-stage depulsation process and the signal that pauses DAGC processing during the second-stage depulsation process to determine the narrowband interference frequency point. The narrowband interference frequency point refers to the frequency point corresponding to the current maximum power point, and the power of the maximum power point is greater than the set power.

[0011] Furthermore, when there are at least two identified narrowband interference frequencies, the corresponding filter coefficients are calculated for each narrowband interference frequency, and the narrowband interference cancellation module performs narrowband interference cancellation processing on each narrowband interference frequency according to the determined filter coefficients.

[0012] Furthermore, in step 1), pausing AGC processing during the first-stage de-pulse processing refers to locking the analog gain value at the moment before the pause and outputting this gain value to the PGA in the AFE. The signals used for calculation by the narrowband interference detection module are all adjusted with the same analog gain value to avoid amplitude jumps in the signals involved in the calculation by the narrowband interference detection module.

[0013] Furthermore, in step 1), the signal length for pausing AGC processing during the first-stage de-pulse processing is the signal length required by the narrowband interference detection module to calculate the narrowband interference frequency.

[0014] Furthermore, the narrowband interference cancellation module in step 2) uses at least two cascaded second-order lattice IIR notch filters for narrowband interference cancellation.

[0015] Furthermore, the power line carrier signal undergoing the first stage of de-pulse processing is the signal after being processed by a bandpass filter.

[0016] Furthermore, the method also includes a receiver processing flow that performs RX buffer processing, synchronization processing, frequency offset compensation, cyclic prefix removal, FFT calculation, and channel decoding on the signal after the second-stage pulse processing when the narrowband interference detection module cannot detect the narrowband interference frequency.

[0017] The present invention also provides a narrowband interference filtration device based on an HPLC chip, including a processor, the processor being used to execute a computer program to implement the narrowband interference filtration method based on an HPLC chip described in the present invention.

[0018] The beneficial effects of this invention are as follows: As an improved invention, when pulse processing is performed on a signal, if a narrowband interference detection start signal is detected, the AGC / DAGC processing is paused. The narrowband interference detection module uses the signal indicating the pause of AGC / DAGC processing to calculate the narrowband interference frequency point, and determines the filter coefficients used by the narrowband interference cancellation module based on the narrowband interference frequency point. The narrowband interference cancellation module then performs narrowband interference cancellation processing according to the determined filter coefficients. The signal involved in calculating the narrowband interference frequency point is the signal indicating the pause of AGC / DAGC processing during pulse processing. This avoids signal fluctuations caused by AGC / DAGC processing, improves the accuracy of narrowband interference frequency point calculation, and ensures the effectiveness of narrowband interference filtering. Attached Figure Description

[0019] Figure 1 This is a flowchart of the narrowband interference filtering method based on HPLC chip of the present invention;

[0020] Figure 2 This is a schematic diagram of the narrowband interference filtering method based on an HPLC chip according to the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0022] This invention incorporates the signal from the pulse processing that pauses AGC / DAGC processing into the calculation of narrowband interference frequency points, thereby improving the accuracy of narrowband interference frequency point calculation and ensuring the effectiveness of narrowband interference filtering.

[0023] Implementation of a Narrowband Interference Filtering Method Based on HPLC Chips

[0024] In this invention, when pulse processing a signal, if a narrowband interference detection start signal is detected, the AGC / DAGC process is paused. The narrowband interference detection module uses the signal indicating the pause of AGC / DAGC processing to calculate the narrowband interference frequency point and determines the filter coefficients used by the narrowband interference cancellation module based on the narrowband interference frequency point. The narrowband interference cancellation module then performs narrowband interference cancellation processing according to the determined filter coefficients. This method can be used as part of a receiver in power line communication receivers. The specific implementation flow of this method is as follows: Figure 1 As shown, the implementation principle is as follows: Figure 2 As shown below, a detailed explanation will follow.

[0025] 1. Receive digital power signals after analog front-end processing.

[0026] HPLC (High-speed Power Line Communication) chips can perform narrowband interference detection on signals during power line carrier communication. The power signal sent to the receiver first passes through an analog front-end (AFE). Figure 2 As shown, the analog front-end (AFE) includes a PGA (Programmable Gain Amplifier) ​​and an ADC (Analog-Digital Converter). Therefore, the power signal is first amplified by the PGA, and then converted into a digital power signal by the ADC, which is then sent to the digital part of the receiver for further processing.

[0027] This invention utilizes a receiver to perform subsequent processing on the received signal, such as... Figure 2 As shown, the receiver includes a digital filtering module, a first-stage depulsation module, a narrowband interference cancellation module, a second-stage depulsation module, a narrowband interference detection module, and subsequent processing modules required for receiver reception, such as an RX buffer module, a synchronization module, a frequency offset compensation module, a cyclic prefix removal module, an FFT module, and channel estimation / equalization and signal decoding modules. The digital filtering module, the first-stage depulsation module, the narrowband interference cancellation module, the second-stage depulsation module, and the narrowband interference detection module are the modules used in the narrowband interference filtering method of this invention.

[0028] 2. Perform a first-stage de-pulse processing on the received digital power line signal to filter out pulse signals in the signal.

[0029] After receiving the AFE output data (i.e., digital power signal), the digital section of the receiver first inputs the received AFE output data to a bandpass filter for processing. The bandpass filter filters out out-of-band noise interference and DC bias, and outputs the filtered data. Then, the data processed by the bandpass filter is input to the first-stage depulsation module for further processing. The first-stage depulsation module has two functions: the first function is to perform pulse cancellation processing on the input data, filtering out pulse signals in the data; the second function is to perform AGC (analog gain adjustment) processing on the pulse-cancelled data, outputting the analog gain value to the PGA in the AFE. The PGA amplifies or reduces the analog signal to achieve the best quantization accuracy of the useful signal.

[0030] During the first-stage depulsation module's depulsation processing, its detection software determines whether a narrowband interference detection start signal has been sent. This signal is software-generated and can be sent at any time during reception. If a narrowband interference detection start signal is detected, the first-stage depulsation module pauses AGC processing on the pulse-eliminated data, locks the current analog gain value, and outputs it to the PGA in the AFE. This process ensures that the analog signal maintains the same analog gain adjustment, preventing amplitude jumps in the ADC data. In this invention, during the first-stage depulsation processing, if a narrowband interference detection start signal is detected, AGC processing is paused. The signal length for pausing AGC processing is the length required for the narrowband interference detection module to calculate the narrowband interference frequency. AGC processing resumes after this length is reached.

[0031] Since each narrowband interference detection in this embodiment requires 1024 data points, when the narrowband interference detection start signal is detected, the first-stage depulsation module needs to pause AGC processing for the next 1024 input data points, lock the current (before pausing) gain value and output it to the PGA in the AFE, and then resume AGC processing starting from the 1025th input data point, release the gain value lock, continue automatic gain adjustment, calculate the current gain value that needs to be adjusted and output it to the PGA in the AFE, and finally output the first-stage depulsation output data and the 1024 data points corresponding to the unchanged analog gain value to enable the output.

[0032] 3. Use a narrowband filter to perform narrowband interference cancellation processing on the data after the first stage of pulse de-pulse processing.

[0033] The data processed by the first-stage de-pulse module is input into a narrowband filter (also called a narrowband interference cancellation module) for further processing. Narrowband interference is suppressed using a time-domain notch filter. In this embodiment, multiple second-order lattice IIR (Infinite Impulse Response) notch filters are cascaded as the narrowband filter. Their parameters are obtained from the output data of the narrowband interference detection device and calculated by software. After processing by the narrowband interference cancellation module, the narrowband interference-cancelled output data is output. As one embodiment, the notch filter in this embodiment can be represented as:

[0034]

[0035] Where x(n) represents the current notch filter input, y(n) represents the current notch filter output, and A0, A1, and A2 are... B0, B1, and B2 are all filter coefficients of the current notch filter, which can be calculated by the subsequent narrowband interference detection module.

[0036] 4. Perform a second-stage depulsing process on the data after narrowband interference cancellation.

[0037] When there is narrowband in the signal, pulse processing is required before the narrowband interference frequency can be detected. Moreover, after pulse processing only once when there is narrowband in the signal, there will still be pulse residue. Narrowband interference cancellation is required before a second pulse processing is performed to completely eliminate the pulse.

[0038] The data after narrowband interference cancellation processing needs to be processed by a second-stage depulsation module. This second-stage module has two functions: first, it performs pulse cancellation processing on the input data again, filtering out residual pulse signals in the data after narrowband interference cancellation; second, it performs DAGC (Automatic Digital Gain Adjustment) processing on the pulse-cancelled data, effectively improving the receiver's adaptability and stability to signals, as well as its synchronization performance and decoding capabilities. Similar to the first-stage depulsation module, the second-stage module also needs its detection software to determine whether a narrowband interference detection start signal has been detected. If a narrowband interference detection start signal is detected, the second-stage depulsation module pauses DAGC processing on the signal that was paused during the first-stage depulsation process and whose DAGC processing was also paused. The length of the paused DAGC processing signal is the same as that during the first-stage pulse processing, and is not the signal length required for the narrowband interference detection module to calculate the narrowband interference frequency point. Once the length is reached, AGC processing continues. Pausing DAGC processing is similar to pausing AGC processing during the first-stage depulsation process; both involve locking the current digital gain value. This ensures that the data output by the second-stage depulsation module will not experience amplitude jumps.

[0039] In this embodiment, 1024 data points are required for narrowband interference detection. Therefore, when the start signal is detected, the second-stage depulsation module needs to pause DAGC processing on the 1024 input data points whose analog gain value is locked by the first-stage depulsation output, lock the current digital gain value, and resume DAGC processing starting from the 1025th input data point, releasing the lock on the digital gain value and continuing automatic digital gain adjustment. Finally, the output of the second-stage depulsation output data after DAGC digital amplification and the 1024 data points corresponding to the unchanged analog and digital gain values ​​are effectively enabled.

[0040] Therefore, the second-stage depulsation module of the present invention can perform second-stage depulsation processing on the data after narrowband interference cancellation to filter out pulse signals in the signal, and perform AGC processing on the pulse-cancelled signal to obtain the corresponding analog gain value and output it to the PGA in the AFE.

[0041] 5. The narrowband interference detection module calculates the signal that pauses AGC processing during the first-stage depulsation process and also pauses DAGC processing during the second-stage depulsation process to determine the narrowband interference frequency. Based on the narrowband interference frequency, the filter coefficients used by the narrowband interference cancellation module are determined, and the narrowband interference cancellation module performs narrowband interference cancellation processing according to the determined filter coefficients.

[0042] The data processed by the second-stage depulsation module undergoes synchronous processing and signal decoding, and is simultaneously output to the narrowband interference detection module. The narrowband interference detection module detects the valid enable signal for 1024 data points where both the analog and digital gain values ​​of the second-stage depulsation remain unchanged. When this signal is valid, the data is buffered. Once the buffer reaches 1024 data points, a start calculation signal is sent to the FFT module. When the FFT module detects the FFT start calculation signal, it begins reading the buffered data and performing FFT calculations. After the FFT calculation is completed, the narrowband interference detection module buffers the FFT calculation results. The module then reads the FFT calculation results and performs further analysis, calculating the power and average power at each point, finding the latest maximum power and its corresponding location, and calculating the corresponding narrowband interference frequency point f0. The f0 narrowband interference frequency point refers to the frequency point corresponding to the current maximum power point, where the power at this maximum power point is greater than a set power.

[0043] The narrowband interference detection module calculates the filter coefficients of the notch filter based on the obtained narrowband interference frequency point f0, and outputs the calculated filter coefficients of the notch filter to the narrowband interference cancellation module. The narrowband interference cancellation module uses the received filter coefficients of the notch filter as the notch filter coefficients used by the narrowband interference cancellation module for the next round of narrowband interference cancellation processing.

[0044] When calculating the filter coefficients of the narrowband interference detection module, the notch bandwidth of the notch filter is assumed to be 1 / 2 of the subcarrier spacing, i.e., normalized. Notch filter normalized frequency point Where N is the number of points in the FFT transform, F S It is the data sampling rate.

[0045] The filter coefficient factors α, β, and Gain of the three IIR filter coefficients are calculated using the following formulas:

[0046]

[0047]

[0048]

[0049] The coefficients A0, A1, and A2 of the notch filter (IIR in this embodiment) are calculated based on the above three factors. The specific calculation formulas for B0, B1, and B2 are as follows:

[0050]

[0051]

[0052] The coefficients A0, A1, and A2 of the filter obtained above, B0, B1, and B2 are fed back to the narrowband interference cancellation module, which uses the determined filter coefficients to perform a single-tone interference cancellation filter on the input signal x(n) in its corresponding formula. At this point, the process of detecting, analyzing, and eliminating narrowband interference is completed.

[0053] If M narrowband interferences are detected, meaning there are M instances of the latest maximum power (in this embodiment, there are M instances), then the narrowband interference detection module will also determine M narrowband interference frequency points f0. In this way, the above filter coefficient calculation formula can be used to determine M sets of filter coefficients. The obtained M sets of filter coefficients are then input into the narrowband interference detection module, which performs filtering processing based on the determined filter coefficients for each set, performing M single-tone interference cancellation filtering on the input signal x(n) to eliminate single-tone interference one by one.

[0054] The narrowband interference detection module is used to detect the filtered signal. If narrowband interference frequencies still exist, the above process is repeated until no narrowband interference frequencies are detected in the narrowband interference detection module (Schowyl anomaly detection, which judges anomalies by comparing the deviation of data points from the mean to whether they exceed a specific threshold). At this point, it means that the data after being eliminated by the current narrowband interference cancellation module no longer has narrowband interference frequencies. Then, subsequent reception processing can be performed, which is the receiver processing flow of processing the signal after the second-stage pulse processing, including RX buffer processing, synchronization processing, frequency offset compensation, removal of cyclic prefix, FFT calculation, and channel decoding.

[0055] Implementation of a Narrowband Interference Filtering Device Based on HPLC Chip

[0056] The narrowband interference filtering device based on an HPLC chip of the present invention includes a processor, wherein the processor is used to execute a computer program to implement the above-described narrowband interference filtering method based on an HPLC chip. The specific implementation process of the filtering method has been described in detail in the embodiments of the narrowband interference filtering method based on an HPLC chip, and will not be repeated here. The narrowband interference filtering device based on an HPLC chip of the present invention can be used as part of a receiver for narrowband interference filtering of power line carrier signals received by the receiver.

Claims

1. A method for filtering narrowband interference based on an HPLC chip, characterized in that, The method includes the following steps: 1) Perform first-stage depulsation processing on the received power line carrier signal to filter out pulses in the signal, and perform AGC processing on the pulse-removed signal; if a narrowband interference detection start signal is detected during the first-stage depulsation processing, the AGC processing is paused. 2) The narrowband interference cancellation module is used to perform narrowband interference cancellation processing on the data after the first stage of pulse de-pulse processing; 3) Perform a second-stage depulsing process on the data after narrowband interference cancellation to filter out the remaining pulses in the signal, and perform DAGC processing on the pulse-cancelled signal; and if a narrowband interference detection start signal is detected during the second-stage depulsing process, DAGC processing will be suspended for the signal that was paused during the first-stage depulsing process. 4) The narrowband interference detection module calculates the signal that the AGC processing is paused during the first-stage depulsation process and the signal that the DAGC processing is also paused during the second-stage depulsation process to determine the narrowband interference frequency. Based on the narrowband interference frequency, the filter coefficients used by the narrowband interference cancellation module are determined, and the narrowband interference cancellation module performs narrowband interference cancellation processing according to the determined filter coefficients.

2. The narrowband interference filtering method based on HPLC chip according to claim 1, characterized in that, In step 4), the narrowband interference detection module uses FFT to calculate the signal that pauses AGC processing during the first-stage depulsation process and the signal that pauses DAGC processing during the second-stage depulsation process to determine the narrowband interference frequency point. The narrowband interference frequency point refers to the frequency point corresponding to the current maximum power point, and the power of the maximum power point is greater than the set power.

3. The narrowband interference filtering method based on HPLC chip according to claim 1, characterized in that, When there are at least two identified narrowband interference frequencies, the corresponding filter coefficients are calculated for each narrowband interference frequency. The narrowband interference cancellation module then performs narrowband interference cancellation processing on each narrowband interference frequency according to the identified filter coefficients.

4. The narrowband interference filtering method based on HPLC chip according to claim 1, characterized in that, In step 1), the pause AGC process during the first-stage de-pulse processing refers to locking the analog gain value at the moment before the pause and outputting this gain value to the PGA in the AFE. The signals used for calculation by the narrowband interference detection module are all adjusted with the same analog gain value to avoid abrupt changes in the signal amplitude participating in the calculation by the narrowband interference detection module.

5. The narrowband interference filtering method based on HPLC chip according to claim 1, characterized in that, In step 1), the signal length for pausing AGC processing during the first-stage de-pulse processing is the signal length required by the narrowband interference detection module to calculate the narrowband interference frequency.

6. The narrowband interference filtering method based on HPLC chip according to claim 1, characterized in that, The narrowband interference cancellation module in step 2) uses at least two cascaded second-order lattice IIR notch filters to perform narrowband interference cancellation.

7. The narrowband interference filtering method based on HPLC chip according to claim 1, characterized in that, The power line carrier signal undergoing the first stage of pulse de-pulsation processing is the signal after being processed by a bandpass filter.

8. The narrowband interference filtering method based on HPLC chip according to claim 1, characterized in that, The method also includes a receiver processing flow that performs RXBuffer processing, synchronization processing, frequency offset compensation, cyclic prefix removal, FFT calculation, and channel decoding on the signal after the second-stage pulse processing when the narrowband interference detection module cannot detect the narrowband interference frequency.

9. A narrowband interference filtering device based on an HPLC chip, comprising a processor, characterized in that, The processor is used to execute a computer program to implement the narrowband interference filtration method based on an HPLC chip as described in any one of claims 1-8.

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