Broadband power line carrier node frequency synchronization method

Abstract

The invention relates to a broadband power line carrier node ranging method, which is characterized in that transmission time is obtained based on each count value of a source node and the frequency of the source node, so that time deviation caused by reference time difference between the nodes is avoided; meanwhile, the destination node corrects the response delay count value through the frequency deviation coefficient, so that the fine difference of the frequency between the source node and the destination node is considered, and the duration corresponding to the response delay count value in the source node is equal to the duration corresponding to the corrected response delay count value in the destination node; therefore, the response signal can be sent at the accurate sending moment, and correspondingly, the source node can receive the signal at the accurate moment, so that the time error in the signal transmission process between the nodes is reduced, and the ranging accuracy is improved. The distance measurement method provided by the embodiment of the invention is simple and convenient, and can accurately obtain the distance between the nodes.

Description

Technical Field

[0001] The invention relates to the field of broadband power line carrier communications, and in particular to a broadband power line carrier node ranging method. Background Art

[0002] In the smart grid system, the measurement of the actual continuous distance between nodes plays an important role in power line carrier communication. It not only helps to determine the coverage range of power carrier signals, is responsible for network measurement, and improves communication efficiency, but also plays an important role in fault location and diagnosis. In the prior art, ranging is that the source node sends a ranging initiation frame to the target node, the target node receives the ranging initiation frame, and then the destination node calculates the transmission time of the ranging initiation frame based on the sending time and the local receiving time, so that the transmission distance between the source node and the target node can be determined based on the transmission time. In the prior art ranging process, on the one hand, the difference in node frequency is not considered, resulting in inaccurate sending time and local receiving time; on the other hand, the difference in reference time between nodes is not considered, resulting in inaccurate transmission time calculated based on the sending time of the source node and the local receiving time of the destination node. Therefore, how to accurately measure the distance of nodes in power lines is still a problem that needs to be solved urgently. Summary of the invention

[0003] In view of this, an embodiment of the present application provides a broadband power line carrier node ranging method to solve at least one problem existing in the background technology, and the method includes: The destination node performs frequency synchronization with the source node to obtain a frequency deviation coefficient; The source node sends a ranging signal to the destination node; wherein the source node obtains a first sending count value corresponding to a sending time, and the ranging signal includes a response delay count value; The destination node receives the ranging signal and performs synchronous demodulation processing to obtain a ranging synchronization count value and a response delay count value corresponding to a synchronous correlation peak; The destination node corrects the response delay count value according to the frequency deviation coefficient to obtain a corrected response delay count value; The destination node sends a response signal to the source node; wherein the count value corresponding to the time when the response signal is sent is equal to the sum of the ranging synchronization count value and the corrected response delay count value; The source node receives the response signal and performs synchronization to obtain a first receiving synchronization count value corresponding to a synchronization correlation peak; The source node calculates the distance between the source node and the destination node according to the first sending count value, the first receiving synchronization count value, and the response delay count value.

[0004] Optionally, the source node calculates the distance between the source node and the destination node according to the first sending count value, the first receiving synchronization count value, and the response delay count value, specifically as follows: s=v×[1 / f0×(NTB4'-NTB1-NTB delay )×1 / 2] Where s represents the distance between the source node and the destination node, v represents the transmission rate of the electrical signal in the power line, f0 represents the clock frequency of the source node, NTB4' represents the first receiving synchronization count value, NTB1 represents the first sending count value, and NTB delay Indicates the response delay count value.

[0005] Optionally, the destination node performs frequency synchronization with the source node to obtain a frequency deviation coefficient, including: The source node sends a first signal to the destination node; wherein the first signal includes a first signal sending count value corresponding to the first signal sending time; The destination node receives the first signal and performs synchronous demodulation processing to obtain a first signal synchronization count value and a first signal sending count value corresponding to a synchronous correlation peak; The destination node performs synchronization time compensation on the first signal synchronization count value to obtain a compensated first signal synchronization count value; The source node sends a second signal to the destination node; wherein the second signal includes a second signal sending count value corresponding to the second signal sending time; The destination node receives the second signal and performs synchronous demodulation processing to obtain a second signal synchronization count value and a second signal sending count value corresponding to a synchronous correlation peak; The destination node performs synchronization time compensation on the second signal synchronization count value to obtain a compensated second signal synchronization count value; The destination node obtains a frequency deviation coefficient according to the first signal sending count value, the compensated first signal synchronization count value, the second signal sending count value, and the compensated second signal synchronization count value.

[0006] Optionally, the destination node obtains a frequency deviation coefficient according to the first signal sending count value, the compensated first signal synchronization count value, the second signal sending count value, and the compensated second signal synchronization count value, specifically: c=(NTB recv2 '-NTB recv1 ') / (NTB send2 -NTB send1 ) Where c represents the frequency deviation coefficient, NTB recv2' represents the second signal synchronization count value after compensation, NTB recv1 ' represents the first signal synchronization count value after compensation, NTB send2 Indicates the second signal sending count value, NTB send1 Indicates the first signal sending count value.

[0007] Optionally, after the source node receives the response signal sent by the destination node and performs synchronization to obtain a first reception synchronization count value corresponding to a synchronization correlation peak, the method further includes: The source node performs synchronization time compensation on the first receiving synchronization count value to obtain a compensated first receiving synchronization count value; Correspondingly, the source node obtains the distance between the source node and the destination node according to the first sending count value, the compensated first receiving synchronization count value, and the response delay count value.

[0008] Optionally, after the destination node receives the ranging signal and performs synchronous demodulation processing to obtain the ranging synchronization count value corresponding to the synchronous correlation peak and the response delay count value, the method further includes: The destination node performs synchronization time compensation on the ranging synchronization count value to obtain a compensated ranging synchronization count value; Correspondingly, the count value corresponding to the moment when the response signal is sent is equal to the sum of the compensated ranging synchronization count value and the corrected response delay count value.

[0009] Optionally, the synchronization time compensation includes: The receiving node obtains the leading synchronization symbol in the received signal according to the synchronization count value; wherein the synchronization count value is the count value corresponding to the synchronization correlation peak; the receiving node refers to the source node or the destination node corresponding to the received signal; Performing a fast Fourier transform on the leading synchronization symbol to obtain corresponding subcarrier phase values; Obtaining a phase difference value of each subcarrier according to the phase value of each subcarrier and a local subcarrier phase value of the receiving node; Calculate the phase difference within the effective subcarrier segment according to the phase difference values ​​of each subcarrier; A synchronization time difference is calculated according to the phase difference within the effective subcarrier band, and the synchronization count value is compensated according to the synchronization time difference to obtain a compensated synchronization count value.

[0010] Optionally, the synchronization time difference is calculated according to the phase difference within the effective subcarrier band, specifically: Δφ=2πbΔt Among them, Δφ is the phase difference within the effective subcarrier band, b is the bandwidth corresponding to the effective subcarrier band; Δt is the synchronization time difference.

[0011] Optionally, the synchronization count value is compensated according to the synchronization time difference to obtain the compensated synchronization count value, specifically: NTB' sync =NTB sync -Δt×f Among them, NTB' sync Indicates the compensated synchronization count value, NTB sync represents the synchronization count value, Δt represents the synchronization time difference, and f represents the clock frequency of the receiving node.

[0012] Optionally, calculating the phase difference within the effective subcarrier segment according to the subcarrier phase difference values ​​specifically includes: The phase difference within the effective subcarrier band is determined according to the effective subcarrier phase difference value of the minimum frequency and the effective subcarrier phase difference value of the maximum frequency.

[0013] The ranging method in the embodiment of the present application obtains the transmission time based on the various count values ​​of the source node and the frequency of the source node, thereby avoiding the time deviation between nodes caused by the reference time difference; on the other hand, the destination node corrects the response delay count value through the frequency deviation coefficient, thereby taking into account the slight difference in frequency between the source node and the destination node, so that the time length corresponding to the response delay count value in the source node is equal to the time length corresponding to the corrected response delay count value in the destination node, so that the response signal can be sent at the exact sending time, and correspondingly, the source node can receive the signal at the exact time, thereby reducing the time error in the signal transmission process between nodes and improving the accuracy of ranging.

[0014] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 A schematic diagram of a synchronization time compensation method provided in an embodiment of the present application; Figure 2 A schematic diagram of the phase difference of each subcarrier when there is no synchronization error provided by an embodiment of the present application; Figure 3 A schematic diagram of the phase difference of each subcarrier when there is a synchronization error provided by an embodiment of the present application; Figure 4 A schematic diagram of a frequency synchronization method between a destination node and a source node provided in an embodiment of the present application; Figure 5 A schematic diagram of frequency synchronization signal transmission between a source node and a destination node provided in an embodiment of the present application; Figure 6 A schematic diagram of a broadband power line carrier node ranging method flow chart provided in an embodiment of the present application; Figure 7 A schematic diagram of signal transmission during the ranging process between a source node and a destination node provided in one embodiment of the present application. DETAILED DESCRIPTION

[0016] In order to make the technical solutions and beneficial effects of the present invention more clearly understood, the following is a detailed description by listing specific embodiments. Unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical field to which this application belongs.

[0017] After receiving the signal, the node must first synchronize to determine the accurate signal reception time. Therefore, the synchronization result will directly affect the accuracy of the ranging. In the actual signal transmission process, due to the presence of noise, large secondary peaks may appear on both sides of the synchronization correlation peak. In the case of poor channel quality, the synchronization correlation peak may be misjudged, resulting in inaccurate synchronization results, affecting the subsequent ranging results of the node. Figure 1 FIG. 1 is a flow chart of a synchronization time compensation method according to an embodiment of the present application. Figure 1 As shown, the synchronization time compensation method of the embodiment of the present application includes: S10. The receiving node obtains a leading synchronization symbol in a received signal according to a synchronization count value.

[0018] Among them, the synchronization count value is the count value corresponding to the synchronization correlation peak; the receiving node refers to the source node or destination node corresponding to the received signal. It should be noted that the node timing is realized by the node's own clock source and counter. The clock source generates a stable periodic clock signal, which is used as the reference for counting; the counter samples each cycle (or specified edge) of the clock signal and counts up. According to the current value of the counter and the known theoretical frequency of the clock signal, the elapsed time can be accurately calculated. It should be noted that there will be a slight deviation between the actual frequency of the node and the known theoretical frequency. The actual frequency during the signal transmission process is generally unknown. When calculating the actual time, it is generally calculated by the known theoretical frequency. For example, in an embodiment of the present application, the synchronization count value refers to the count value corresponding to the synchronization correlation peak (i.e., the synchronization moment), and the corresponding synchronization moment is equal to the synchronization count value multiplied by the theoretical clock frequency of the receiving node. It should be noted that in broadband power line carrier communication, the signal unit frame structure is composed of a preamble, frame control, and payload data, wherein the preamble has a total of multiple synchronization symbols, for example, 10.5 forward preamble synchronization symbols and 2.5 reverse preamble synchronization symbols, and each symbol is 1024 time domain sampling points in length. The preamble is used for synchronization at the receiving node. After receiving the preamble signal, the receiving node correlates with the local synchronization symbol. According to the correlation result, the final synchronization correlation peak will be located at the junction of the forward preamble synchronization symbol and the reverse preamble synchronization symbol. In an embodiment of the present application, the preamble synchronization symbol can be obtained by counting forward according to the synchronization count value. For example, a forward preamble synchronization symbol is obtained by counting forward 1024 time domain sampling points. Optionally, an embodiment of the present application obtains multiple forward preamble synchronization symbols according to the synchronization count value.

[0019] S11. Perform fast Fourier transform on the leading synchronization symbol to obtain corresponding phase values ​​of each subcarrier.

[0020] Specifically, a fast Fourier transform is performed on the leading synchronization symbol to convert the time domain signal into a frequency domain signal, and the phase value of each subcarrier can be obtained according to the frequency domain signal. Optionally, a fast Fourier transform is performed on multiple leading synchronization symbols, and then the average value of the transformed results is calculated to obtain the average spectrum of each subcarrier, thereby obtaining the phase value of each subcarrier. In the embodiment of the present application, by taking the average value of each subcarrier, the error caused by the influence of noise and the like can be eliminated.

[0021] S12. Obtain a phase difference value of each subcarrier according to a phase value of each subcarrier and a local subcarrier phase value of a receiving node.

[0022] Specifically, it is calculated by the following formula: φ diff (k)=φ fft_ave (k)-φ pream (k) Among them, φ pream (k) represents the subcarrier phase value, φ fft_ave (k) represents the local subcarrier phase value, φ diff (k) represents the phase difference value of the subcarrier, k represents the subcarrier number, where k=1,2,…512.

[0023] S13. Calculate the phase difference within the effective subcarrier segment according to the phase difference value of each subcarrier.

[0024] Specifically, it is calculated by the following formula: Δφ=φ diff (k1)-φ diff (k2) Among them, Δφ represents the phase difference within the effective subcarrier band, φ diff (k1) represents the phase difference of the effective subcarrier numbered k1, φ diff (k2) represents the phase difference value of the subcarrier numbered k2, and k1 and k2 are valid subcarrier numbers.

[0025] It should be noted that an effective subcarrier refers to a useful subcarrier for transmitting data according to a communication protocol, and an effective subcarrier band refers to a band between two effective subcarriers.

[0026] As an optional specific implementation, the phase difference within the effective subcarrier band is determined according to the effective subcarrier phase difference value of the minimum frequency and the effective subcarrier phase difference value of the maximum frequency, that is, φ diff (k2) is the effective subcarrier phase difference of the maximum frequency, φ diff (k1) represents the effective subcarrier phase difference value of the minimum frequency; correspondingly, the phase difference within the effective subcarrier band at this time is the maximum phase difference.

[0027] S14. Calculate the synchronization time difference according to the phase difference in the effective subcarrier band, and compensate the synchronization count value according to the synchronization time difference to obtain the compensated synchronization count value.

[0028] The synchronization time difference is calculated based on the phase difference within the effective subcarrier band, and is specifically calculated using the following formula: Δφ=2πbΔt Wherein, Δφ is the phase difference within the effective subcarrier band, b is the bandwidth of the effective subcarrier band, and Δt is the synchronization time difference. It should be noted that bandwidth refers to the frequency difference between two effective subcarriers corresponding to the effective subcarrier band.

[0029] Due to the influence of noise and calculation accuracy, the phase difference of the effective subcarrier has different degrees of jitter. Compared with obtaining the synchronization time difference by averaging the effective subcarrier phase difference, in the embodiment of the present application, the synchronization time difference is obtained by calculating the phase difference within the effective subcarrier band and the bandwidth of the effective subcarrier band, thereby reducing the influence caused by phase difference jitter, especially abnormal jitter, so that the synchronization time difference can be obtained more accurately. For example, if the effective subcarrier of a certain frequency is affected by noise, causing its phase difference to deviate seriously from the normal value, the error of the averaging method will be greater, and this situation can be reduced by the method of the embodiment of the present application. Furthermore, the embodiment of the present application determines the phase difference within the effective subcarrier band by the effective subcarrier phase difference value of the minimum frequency and the effective subcarrier phase difference value of the maximum frequency, which is equivalent to linear fitting of the effective subcarrier phase difference value, taking into account the overall situation of the phase difference value within the effective subcarrier band, thereby reducing the error and obtaining a more accurate synchronization time difference.

[0030] In the embodiment of the present application, the synchronization count value is compensated according to the synchronization time difference to obtain the compensated synchronization count value, which is specifically: NTB' sync =NTB sync -Δt×f Among them, NTB' sync Indicates the compensated synchronization count value, NTB sync represents the synchronization count value, Δt represents the synchronization time difference, and f represents the clock frequency of the receiving node.

[0031] In the embodiment of the present application, by receiving the phase value of each subcarrier corresponding to the leading synchronization symbol in the signal, and then obtaining the phase difference value of each subcarrier according to the phase value of each subcarrier and the local subcarrier, and finally calculating the synchronization time difference based on the phase difference value of each subcarrier, the synchronization moment can be compensated to obtain accurate synchronization time. The synchronization time compensation method of the embodiment of the present application is simple and convenient, so as to avoid the problem of inaccurate ranging caused by inaccurate synchronization results, and ensure the accuracy of ranging.

[0032] In order to better illustrate the beneficial effects of the embodiments of the present application, simulations were performed to verify the results of synchronization without error and with error (the synchronization moment is one sampling point earlier than the true value), wherein the theoretical value of the sampling frequency is 25 MHz. Figure 2 A schematic diagram of the phase difference of each subcarrier when there is no synchronization error provided by an embodiment of the present application, Figure 3 A schematic diagram of the phase difference of each subcarrier when there is a synchronization error provided by an embodiment of the present application. Figure 2As shown, the number corresponding to the effective subcarrier band is 80-490, and the corresponding maximum bandwidth is b=10.007MHz. The phase difference Δφ=0 is obtained by calculation. Therefore, the calculated compensated synchronization count value is equal to the synchronization calculation value corresponding to the synchronization moment, that is, NTB' sync =NTB sync .like Figure 3 As shown in the figure, due to the inaccurate synchronization time, the phase difference value in the effective subcarrier band changes roughly linearly. By calculating the phase difference Δφ=-2.5868, the bandwidth b=10.007MHz, so the synchronization time difference Δt=-4.11×10 -8 s, converted into a count value of -1.03, rounded to -1, which corresponds to exactly one sampling point. It should be noted that in actual communication situations, the phase difference curve within the effective subcarrier band is affected by factors such as noise, and may also have abnormal points or nonlinear changes.

[0033] It should be noted that the transmission speed of electrical signals is close to the speed of light, which is about 3×10 8 m / s. In the broadband power carrier communication standard protocol, the theoretical values ​​of the sampling frequency and the clock frequency are both 25MHz, that is, the sampling interval and the clock counting interval are both 40ns. Therefore, even if the count value corresponding to the synchronization moment is one sampling point wrong, it will cause a ranging error of 12 meters. The embodiment of the present application can accurately calculate the synchronization time difference based on the phase difference within the effective subcarrier band, thereby compensating for the synchronization count value, reducing the time deviation introduced by the synchronization process, and greatly improving the accuracy of ranging.

[0034] In the broadband carrier communication protocol, the clock frequency of each node is specified to be 25MHz, but in actual scenarios, there will be slight deviations in the clock frequency of each node. For inter-node ranging, slight deviations in frequency will cause deviations in the time corresponding to the count values ​​between nodes, which will also cause inaccurate ranging results.

[0035] In order to solve the problem of the influence of clock frequency deviation between nodes on ranging, an embodiment of the present application also provides a frequency synchronization method between nodes. Figure 4 A flow chart of a method for synchronizing a frequency between a destination node and a source node provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, the method includes: S20. The source node sends a first signal to the destination node.

[0036] The first signal includes a first signal sending count value corresponding to the first signal sending moment.

[0037] S21. The destination node receives the first signal and performs synchronous demodulation processing to obtain a first signal synchronization count value and a first signal sending count value corresponding to a synchronous correlation peak.

[0038] S22. The destination node performs synchronization time compensation on the first signal synchronization count value to obtain a compensated first signal synchronization count value.

[0039] Specifically, the method of synchronization time compensation can be implemented by the above-mentioned synchronization time compensation embodiment, and the corresponding destination node is the receiving node, and the specific process is not repeated. In the embodiment of the present application, the destination node can obtain the accurate count value corresponding to the synchronization moment in the first signal through synchronization time compensation, thereby reducing the error of frequency synchronization and improving the accuracy of frequency synchronization.

[0040] S23. The source node sends a second signal to the destination node.

[0041] The second signal includes a second signal sending count value corresponding to the second signal sending moment.

[0042] S24. The destination node receives the second signal and performs synchronous demodulation processing to obtain a second signal synchronization count value and a second signal sending count value corresponding to a synchronous correlation peak.

[0043] S25. The destination node performs synchronization time compensation on the second signal synchronization count value to obtain a compensated second signal synchronization count value.

[0044] Specifically, the method of synchronization time compensation can be implemented by the above-mentioned synchronization time compensation method embodiment, and the corresponding destination node is the receiving node, and the specific process is not repeated. In the embodiment of the present application, the destination node can obtain the accurate count value corresponding to the synchronization moment in the second signal through synchronization time compensation, thereby reducing the synchronization error and improving the accuracy of frequency synchronization.

[0045] S26. The destination node obtains a frequency deviation coefficient according to the first signal sending count value, the compensated first signal synchronization count value, the second signal sending count value, and the compensated second signal synchronization count value.

[0046] In the embodiment of the present application, the accurate count values ​​corresponding to the synchronization moments of the first signal and the second signal can be obtained respectively through synchronization time compensation, so that the accurate frequency deviation coefficient can be obtained. Specifically, it is calculated by the following formula: c=(NTB recv2 '-NTB recv1 ') / (NTB send2 -NTB send1 ) Where c represents the frequency deviation coefficient, NTB recv2 ' represents the second signal synchronization count value after compensation, NTB recv1 ' represents the first signal synchronization count value after compensation, NTBsend2 Indicates the second signal sending count value, NTB send1 Indicates the first signal sending count value.

[0047] It should be noted that the frequency deviation coefficient represents the deviation of the clock frequency between the source node and the destination node. If c=1, it indicates that the clock frequencies of the source node and the destination node are equal; if c<1, it indicates that the clock frequency of the source node is less than the clock frequency of the destination node; if c>1, it indicates that the clock frequency of the source node is greater than the clock frequency of the destination node.

[0048] In the embodiment of the present application, the destination node performs synchronization time compensation on the synchronization count values ​​of the first signal and the second signal respectively, so that the count values ​​corresponding to the accurate synchronization moments can be obtained respectively, thereby reducing the synchronization error and improving the accuracy of frequency synchronization. It should be noted that the duration between two transmitted signals is generally equal to the duration between two received signals, and the count value reflects the size of the duration, so the frequency deviation coefficient can be obtained by the ratio of the count values.

[0049] Figure 5 A schematic diagram of frequency synchronization signal transmission between a source node and a destination node provided in an embodiment of the present application is shown in FIG. Figure 5 As shown, NTB recv2 'With NTB recv1 The time interval between ' and NTB send2 With NTB send1 The time intervals between them are equal. Since the time is determined by the count value and the frequency of the clock signal, NTB recv2 'With NTB recv1 'The count difference between send2 With NTB send1 The ratio of the count differences between them is equal to the ratio of the source node clock frequency to the destination node clock frequency, that is, the frequency deviation coefficient is equal to the ratio of the source node clock frequency to the destination node clock frequency.

[0050] Based on the synchronization time compensation method and frequency synchronization method of the above-mentioned embodiments, the embodiments of the present application also provide a broadband power line carrier node ranging method. Figure 6 A schematic diagram of a broadband power line carrier node ranging method flow chart provided in an embodiment of the present application is as follows: Figure 6 As shown, the method includes: S1. The destination node performs frequency synchronization with the source node to obtain a frequency deviation coefficient.

[0051] Specifically, the frequency synchronization between the destination node and the source node can be implemented by the above-mentioned frequency synchronization method embodiment, which will not be described in detail here.

[0052] S2. The source node sends a ranging signal to the destination node.

[0053] The source node obtains a first transmission count value corresponding to the transmission time, and the ranging signal includes a response delay count value. The response delay count value represents the count value between the time when the destination node synchronously receives the signal and the time when the response signal is sent. It should be noted that the response delay count value refers to the count value corresponding to the clock frequency of the source node.

[0054] S3. The destination node receives the ranging signal and performs synchronous demodulation processing to obtain a ranging synchronization count value and a response delay count value corresponding to a synchronous correlation peak.

[0055] In the embodiment of the present application, the ranging synchronization count value refers to the count value at the synchronization moment, that is, the moment when the destination node receives the ranging signal. In the embodiment of the present application, the time information between the source node and the destination node is transmitted in the form of their respective count values, so as to conform to the timing form of the corresponding node itself, without the need for conversion between time-count values, thereby speeding up the signal processing speed. For example, if the ranging signal directly includes the response delay time corresponding to the response delay count value, the destination node needs to convert the response delay time into the count value corresponding to the destination node after receiving the response delay time, thereby increasing the processing time.

[0056] S4. The destination node corrects the response delay count value according to the frequency deviation coefficient to obtain a corrected response delay count value.

[0057] Since the clock frequencies of the source node and the destination node may have a slight deviation, the duration corresponding to the response delay count value in the source node is not equal to the duration corresponding to the response delay count value in the destination node. The embodiment of the present application corrects the response delay count value by the frequency deviation coefficient, thereby correcting the deviation caused by the frequency, so that the duration corresponding to the response delay count value in the source node is equal to the duration corresponding to the corrected response delay count value in the destination node, thereby avoiding the time deviation caused by the frequency deviation, thereby improving the accuracy of the ranging. Specifically, it is calculated by the following formula: NTB delay ' = c × NTB delay Among them, NTB delay ' represents the response delay count value after compensation, c represents the frequency deviation coefficient, NTB delay Indicates the response delay count value.

[0058] S5. The destination node sends a response signal to the source node.

[0059] The count value corresponding to the time when the response signal is sent is equal to the sum of the ranging synchronization count value and the corrected response delay count value. In the embodiment of the present application, the destination node can send the response signal at an accurate time point after receiving the ranging signal through the accurate corrected response delay count value, so that the source node can obtain the accurate time point of receiving the signal, providing a basis for the subsequent accurate calculation of the signal transmission time.

[0060] S6. The source node receives the response signal and performs synchronization to obtain a first receiving synchronization count value corresponding to the synchronization correlation peak.

[0061] In the embodiment of the present application, the first receiving synchronization count value reflects the time corresponding to the source node receiving the signal, so that the source node can calculate the specific signal transmission duration through the signal sending time, response delay time and signal receiving time.

[0062] S7. The source node calculates the distance between the source node and the destination node according to the first sending count value, the first receiving synchronization count value, and the response delay count value.

[0063] Specifically, the source node calculates the signal transmission time between the source node and the destination node according to the first sending count value, the first receiving synchronization count value, and the response delay count value, which can be calculated by the following formula: t = 1 / f0 × (NTB4'-NTB1-NTB delay )×1 / 2 Wherein, t represents the signal transmission time, f0 represents the source node clock frequency, NTB4' represents the first receiving synchronization count value, NTB1 represents the first sending count value, and NTB delay Indicates the response delay count value.

[0064] In the embodiment of the present application, the signal transmission time is obtained through the various counting values ​​of the source node and the frequency of the source node. On the one hand, it avoids the time deviation between the source node and the destination node due to the frequency deviation. On the other hand, it also avoids the time deviation caused by the reference time difference between the source node and the destination node, thereby more accurately obtaining the transmission time between the source node and the destination node.

[0065] The source node calculates the distance based on the signal transmission time and the transmission rate of the electrical signal in the power line, which is calculated by the following formula: s=v×t Among them, s represents the distance between the source node and the destination node, v represents the transmission rate of the electrical signal in the power line, and t represents the signal transmission time.

[0066] That is, the distance between the source node and the destination node is s=v×[1 / f0×(NTB4'-NTB1-NTB delay)×1 / 2].

[0067] The ranging method in the embodiment of the present application obtains the transmission time based on the various count values ​​of the source node and the frequency of the source node, thereby avoiding the time deviation between nodes caused by the reference time difference; on the other hand, the destination node corrects the response delay count value through the frequency deviation coefficient, thereby taking into account the slight difference in frequency between the source node and the destination node, so that the time length corresponding to the response delay count value in the source node is equal to the time length corresponding to the corrected response delay count value in the destination node, so that the response signal can be sent at the exact sending time, and correspondingly, the source node can receive the signal at the exact time, thereby reducing the time error in the signal transmission process between nodes and improving the accuracy of ranging.

[0068] As an optional specific implementation, after step S3, the method further includes: The destination node performs synchronization time compensation on the ranging synchronization count value to obtain the compensated ranging synchronization count value; Correspondingly, in step S5, the count value corresponding to the time when the response signal is sent is equal to the sum of the compensated ranging synchronization count value and the corrected response delay count value.

[0069] Specifically, the method of synchronization time compensation can be implemented by the above-mentioned synchronization time compensation method embodiment, which will not be repeated here. In the embodiment of the present application, through synchronization time compensation, the destination node can obtain a more accurate synchronization moment, reduce the time error caused by synchronization, and improve the accuracy of the ranging result.

[0070] As an optional specific implementation, after step S6, the method further includes: The source node performs synchronization time compensation on the first receiving synchronization count value to obtain the compensated first receiving synchronization count value; Correspondingly, in step S7, the source node obtains the distance between the source node and the destination node according to the first sending count value, the compensated first receiving synchronization count value and the response delay count value. Correspondingly, NTB4' in the above calculation formula represents the compensated first receiving synchronization count value.

[0071] Specifically, the method of synchronization time compensation can be implemented by the above-mentioned synchronization time compensation method embodiment, which will not be repeated here. In the embodiment of the present application, through synchronization time compensation, the source node can obtain a more accurate synchronization moment, reduce the time error caused by synchronization, and improve the accuracy of the ranging result.

[0072] Figure 7A schematic diagram of signal transmission during the ranging process between the source node and the destination node provided in an embodiment of the present application. As shown in the figure, the count value corresponding to the sending moment of the source node is NTB1; the destination node receives the ranging signal, and then obtains the count value NTB2' of the precise synchronization moment through synchronization time compensation, and then sends a response signal after the count value reaches NTB3, wherein the response delay count value NTB2' after compensation between NTB3 is delay 'The corresponding duration will be equal to the response delay count value NTB delay The source node receives the response signal, and then obtains the count value NTB4' corresponding to the precise synchronization time through synchronization time compensation; finally, the source node calculates the count value NTB4' according to NTB1 and NTB delay And NTB4' obtains the transmission time, and determines the distance between the source node and the destination node according to the transmission time.

[0073] It should be understood that the above embodiments are exemplary and are not intended to include all possible implementations included in the claims. Various modifications and changes may be made on the basis of the above embodiments without departing from the scope of the present disclosure. Similarly, the various technical features of the above embodiments may be arbitrarily combined to form other embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only express several implementations of the present invention and do not limit the scope of protection of the patent of the present invention.

Claims

1. A broadband power line carrier node frequency synchronization method, characterized in that: The method comprises: The source node sends a first signal to the destination node; wherein the first signal includes a first signal sending count value corresponding to the first signal sending time; The destination node receives the first signal and performs synchronous demodulation processing to obtain a first signal synchronization count value and a first signal sending count value corresponding to a synchronous correlation peak; The destination node performs synchronization time compensation on the first signal synchronization count value to obtain a compensated first signal synchronization count value; The source node sends a second signal to the destination node; wherein the second signal includes a second signal sending count value corresponding to the second signal sending time; The destination node receives the second signal and performs synchronous demodulation processing to obtain a second signal synchronization count value and a second signal sending count value corresponding to a synchronous correlation peak; The destination node performs synchronization time compensation on the second signal synchronization count value to obtain a compensated second signal synchronization count value; The destination node obtains a frequency deviation coefficient according to the first signal sending count value, the compensated first signal synchronization count value, the second signal sending count value, and the compensated second signal synchronization count value.

2. The broadband power line carrier node frequency synchronization method according to claim 1, characterized in that: The destination node obtains a frequency deviation coefficient according to the first signal sending count value, the compensated first signal synchronization count value, the second signal sending count value, and the compensated second signal synchronization count value, specifically: c=(NTB recv2 '-NTB recv1 ') / (NTB send2 -NTB send1 ) Where c represents the frequency deviation coefficient, NTB recv2 ' represents the second signal synchronization count value after compensation, NTB recv1 ' represents the first signal synchronization count value after compensation, NTB send2 Indicates the second signal sending count value, NTB send1 Indicates the first signal sending count value.

3. The broadband power line carrier node frequency synchronization method according to claim 1, characterized in that: The synchronization time compensation includes: The receiving node obtains the leading synchronization symbol in the received signal according to the synchronization count value; wherein the synchronization count value is the count value corresponding to the synchronization correlation peak; the receiving node refers to the source node or the destination node corresponding to the received signal; Performing a fast Fourier transform on the leading synchronization symbol to obtain corresponding subcarrier phase values; Obtaining a phase difference value of each subcarrier according to the phase value of each subcarrier and a local subcarrier phase value of the receiving node; Calculate the phase difference within the effective subcarrier segment according to the phase difference values ​​of each subcarrier; A synchronization time difference is calculated according to the phase difference within the effective subcarrier band, and the synchronization count value is compensated according to the synchronization time difference to obtain a compensated synchronization count value.

4. The broadband power line carrier node frequency synchronization method according to claim 3, characterized in that: The phase difference value of each subcarrier is obtained according to the phase value of each subcarrier and the local subcarrier phase value of the receiving node, specifically: f diff (k)=φ fft_ave (k)-φ pream (k) Among them, φ pream (k) represents the subcarrier phase value, φ fft_ave (k) represents the local subcarrier phase value, φ diff (k) represents the phase difference value of the subcarrier, k represents the subcarrier number, where k=1,2,…512.

5. The broadband power line carrier node frequency synchronization method according to claim 3, characterized in that: The phase difference within the effective subcarrier segment is calculated according to the phase difference values ​​of each subcarrier, specifically: Δφ=φ diff (k1)-φ diff (k2) Among them, Δφ represents the phase difference within the effective subcarrier band, φ diff (k1) represents the phase difference of the effective subcarrier numbered k1, φ diff (k2) represents the phase difference value of the subcarrier numbered k2, and k1 and k2 are valid subcarrier numbers.

6. The broadband power line carrier node frequency synchronization method according to claim 5, characterized in that: Calculating the phase difference within the effective subcarrier segment according to the subcarrier phase difference values ​​specifically includes: The phase difference within the effective subcarrier band is determined according to the effective subcarrier phase difference value of the minimum frequency and the effective subcarrier phase difference value of the maximum frequency.

7. The broadband power line carrier node frequency synchronization method according to claim 3, characterized in that: The synchronization time difference is calculated according to the phase difference within the effective subcarrier band, specifically: Δφ=2πbΔt Among them, Δφ is the phase difference within the effective subcarrier band, b is the bandwidth of the effective subcarrier band; Δt is the synchronization time difference.

8. The broadband power line carrier node frequency synchronization method according to claim 3, characterized in that: The synchronization count value is compensated according to the synchronization time difference to obtain the compensated synchronization count value, specifically: NTB' sync =NTB sync -Δt×f Among them, NTB' sync Indicates the compensated synchronization count value, NTB sync represents the synchronization count value, Δt represents the synchronization time difference, and f represents the clock frequency of the receiving node.

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