CN115053461B

CN115053461B - Apparatus, circuit and method for eliminating noise in power communication system

Info

Publication number: CN115053461B
Application number: CN202080095621.6A
Authority: CN
Inventors: 林泽锋; 潘稻; 黄亚东; 曾焱; 李亚奇; 钟威
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-03-12
Filing date: 2020-03-12
Publication date: 2023-09-22
Anticipated expiration: 2040-03-12
Also published as: CN115053461A; WO2021179235A1

Abstract

The application provides a device, a circuit and a method for eliminating noise in an electric power communication system, wherein the device is configured in a coupling circuit comprising a differential mode coupling circuit and a common mode coupling circuit, the device comprises a signal acquisition module and a noise elimination module, the signal acquisition module is used for acquiring a first differential mode signal from the differential mode coupling circuit and a first common mode signal from the common mode coupling circuit, and the noise elimination module is used for carrying out noise elimination processing on the acquired first differential mode signal according to the acquired first common mode signal. The device, the circuit and the method for eliminating the noise can reduce noise interference in the power communication system and improve the transmission rate and the transmission quality on the line.

Description

Apparatus, circuit and method for eliminating noise in power communication system

Technical Field

The present application relates to the field of communications, and more particularly, to an apparatus, circuit, and method for canceling noise in an electrical communication system.

Background

Power line communication (power line communication, PLC), also known as a power line network or power communication, refers to a technology that uses existing power lines to transmit data or information as digital signals. The PLC has the advantages that the power line is widely covered and naturally covers households, corridors and the like of residents, and the PLC has the disadvantages that the power line is not a line specially designed for communication after all, the load impedance on the line can change, noise interference exists in the line, the transmission rate on the line is restricted to a great extent, and the transmission quality is affected.

Disclosure of Invention

The application provides a device, a circuit and a method for eliminating noise in an electric power communication system, which can reduce noise interference in the electric power communication system and improve the transmission rate and the transmission quality of the electric power communication system.

In a first aspect, an apparatus for canceling noise is provided, the apparatus being configured in a coupling circuit including a differential mode coupling circuit and a common mode coupling circuit, the apparatus including a signal acquisition module for acquiring a first differential mode signal from the differential mode coupling circuit and a noise canceling module for performing noise canceling processing on the acquired first differential mode signal according to the acquired first common mode signal.

In the technical scheme of the application, the correlation between the differential mode noise and the common mode noise and the characteristic that the L/N/PE three-way common mode signal does not carry information are utilized, and the noise in the acquired differential mode signal is eliminated according to the acquired common mode signal, so that the noise in the differential mode signal is effectively reduced, the noise resistance of the power line communication system is effectively improved, the signal to noise ratio is improved, and the transmission rate of the system is improved.

The application relates to a silence phase and a transmission phase, wherein the transmission phase refers to a period of time when a transmitting end device transmits a frame carrying data or information, and correspondingly, the silence phase refers to a period of time when the transmitting end device transmits a frame not carrying any data or information. It will be appreciated that the above-described division of phases may not be performed. That is, frames carrying information and/or frames not carrying information may be transmitted at any time. When the receiving end equipment receives the frame carrying the information, the noise can be read from the frame carrying no information, the frame carrying the information is used for training the correlation coefficient or updating the correlation coefficient, and when the receiving end equipment receives the frame carrying the information, the noise in the differential mode signal can be counteracted by utilizing a noise counteraction method. However, in order to facilitate understanding of the technical solution of the present application, the following description will exemplify the manner of dividing the silence phase and the transmission phase.

Alternatively, the signal acquisition module may be connected to the differential mode coupling circuit and the common mode coupling circuit to acquire the differential mode signal and the common mode signal coupled by the differential mode coupling circuit and the common mode coupling circuit.

Alternatively, a differential mode coupling circuit and a common mode coupling circuit may be provided in the signal acquisition module, in which case the signal acquisition module is capable of self-coupling out differential mode signals and common mode signals. For example, one common mode signal and two differential mode signals may be coupled out, and for example, one differential mode signal and one common mode signal may be coupled out.

It should be understood that, assuming that the silence phase and the transmission phase are not divided, when the signal acquisition module acquires a differential mode signal from the differential mode coupling circuit and acquires a common mode signal from the common mode coupling circuit, the noise cancellation module may perform noise cancellation processing on the differential mode signal according to the common mode signal. When the differential mode signal and the common mode signal are information carrying (corresponding to the time when the differential mode signal and the common mode signal are the first differential mode signal and the first common mode signal, respectively), the obtained information can be more accurate after noise elimination processing. When the differential mode signal and the common mode signal do not carry information (corresponding to the case that the differential mode signal and the common mode signal are the second differential mode signal and the second common mode signal, respectively, and correspond to the frame which is transmitted by the transmitting end device and does not carry information), the device can still be used for noise elimination processing, and only after the noise elimination processing, the information can not be obtained.

It should also be understood that, in the present application, the first differential mode signal and the first common mode signal refer to corresponding signals that can be obtained when the transmitting end device transmits a frame carrying information; the second differential mode signal and the second common mode signal refer to corresponding signals that can be obtained when the transmitting end device transmits a frame that does not carry information.

With reference to the first aspect, in certain implementations of the first aspect, the signal acquisition module is further configured to acquire a second differential mode signal from the differential mode coupling circuit and acquire a second common mode signal from the common mode coupling circuit; and the noise cancellation module may be configured to perform noise cancellation processing on the first differential mode signal based on the first common mode signal and a first correlation coefficient, where the first correlation coefficient is obtained based on the second differential mode signal and the second common mode signal.

Alternatively, the second differential mode signal and the second common mode signal may be information-free signals acquired during a silence period, where the silence period refers to a period when the transmitting end device transmits information-free signals, as described above.

With reference to the first aspect, in some implementations of the first aspect, the noise cancellation module is specifically configured to determine a noise cancellation component according to the first common mode signal and the first correlation coefficient, and cancel noise in the first differential mode signal according to the noise cancellation component. The first correlation coefficient indicates the correlation between the noise in the differential mode signal and the noise in the common mode signal, and thus corresponds to the differential mode coupling circuit and the common mode coupling circuit to which it is connected.

The first correlation coefficient may correspond to a correlation coefficient between differential mode noise and common mode noise. In addition, the noise cancellation coefficient may be further determined according to the correlation coefficient between the differential mode noise and the common mode noise, and then the noise in the differential mode signal is cancelled according to the noise cancellation coefficient and the obtained common mode signal, where the noise cancellation coefficient may also be regarded as the first correlation coefficient. The first correlation coefficient may be obtained from other devices or apparatuses or modules, may be set manually, or may be obtained by setting a training module.

Alternatively, the obtained first common mode signal may be convolved with the first correlation coefficient or subjected to other operations to determine the noise cancellation component.

With reference to the first aspect, in certain implementations of the first aspect, the noise cancellation module may include a cancellation filter capable of receiving the first common mode signal, and obtaining a noise cancellation component corresponding to the first common mode signal according to coefficients of the cancellation filter, where the coefficients of the cancellation filter may be determined according to the first correlation coefficient.

With reference to the first aspect, in certain implementation manners of the first aspect, the apparatus may further include a training module, where the training module is configured to determine the first correlation coefficient according to the second differential mode signal and the second common mode signal. The second differential mode signal and the second common mode signal may be trained, for example, to obtain a correlation coefficient therebetween.

Alternatively, the correlation coefficient between the second differential mode signal and the second common mode signal may be calculated using the second common mode signal as a reference. That is, it is assumed that r is used for the second common mode signal _c The second differential mode signal is represented by r _d The relation between the two can be obtained by using the acquired second common mode signal and the second differential mode signal training: r is (r) _d ＝f(r _c ) Or calculating a correlation coefficient k between the two: r is (r) _d ＝r _c * k, wherein "×" denotes a convolution operation.

From the above, we can obtain the noise cancellation component corresponding to the common mode signal by using the cancellation filter, and can determine the coefficient of the noise filter according to the first correlation coefficient, so the method of obtaining the first correlation coefficient will be described below by taking the first correlation coefficient as the coefficient of the noise filter as an example.

Assuming that the data length of the differential mode signal and the common mode signal for training is D, wherein D is a positive integer, the differential mode signal and the common mode signal can respectively use D-dimensional vector r _c And r _d A representation; assuming that the number of taps of the cancellation filter is represented by W, where W is a positive integer, the coefficients of the cancellation filter may be represented by a W-dimensional vector k. Let us assume an estimation of kRepresenting the coefficients of the cancellation filter obtained by training. An evaluation index for training results can be set to +.>That is, the smaller the value of J, the more accurate the training result. It should be understood that the evaluation index is not unique, and other performance evaluation indexes may be used, such as a norm or the like.

Alternatively, an estimate of k may be obtained using a linear least squares (linear least squares, LLS) estimation approachThe above +.>Determined as the coefficients of the cancellation filter, when in the transmit phase, the acquired common mode signal is assumed to be r' _c When the cancellation filter is used to determine the noise cancellation component, the determined noise cancellation component may satisfy the formula:wherein (1)>Representing the common mode signal r' _c A corresponding noise cancellation component.

When two paths of differential mode signals and one path of common mode signals exist, a first correlation coefficient corresponding to the first path of differential mode signals can be trained by using the first path of differential mode signals and the path of common mode signals, and a second correlation coefficient corresponding to the second path of differential mode signals can be trained by using the second path of differential mode signals and the path of common mode signals, wherein the second correlation coefficient can be obtained by adopting the same method as that for obtaining the first correlation coefficient. When determining the noise cancellation component, the noise cancellation components in the two paths of differential mode signals may be determined by using the first correlation coefficient corresponding to the first path of differential mode signal and the second correlation coefficient corresponding to the second path of differential mode signal, respectively.

Alternatively, when noise in the differential mode signal is processed, a noise cancellation component may be subtracted from the acquired differential mode signal. For example, the obtained common mode signal may be convolved with the first correlation coefficient to obtain a noise cancellation component, and then the noise cancellation component is subtracted from the obtained differential mode signal to obtain a cancelled differential mode signal.

In the transmitting stage, a first path of differential mode signal, a second path of differential mode signal and a first path of common mode signal are obtained, and a first correlation coefficient corresponding to the first path of differential mode signal and a second correlation coefficient corresponding to the second path of differential mode signal are determined, so that a first noise cancellation component corresponding to the first path of differential mode signal and a second noise cancellation component corresponding to the second path of differential mode signal are determined. The first noise cancellation component may be subtracted from the first differential mode signal and the second noise cancellation component may be subtracted from the second differential mode signal.

Further by way of example, let r be used for the first common mode signal _c Representing a first path of differential mode signal r _d1 The second path of differential mode signal is represented by r _d2 The correlation coefficients obtained during the silence phase are shown as: the first correlation coefficient corresponding to the first path of differential mode signal is The second correlation coefficient corresponding to the second path of differential mode signal is +.>The method shown in FIG. 5 can be used to obtain +.>And->Then in the transmission phase the noise cancellation component of the first differential mode signal is +.>The noise cancellation component of the second path differential mode signal isFurthermore, the first differential mode signal after cancellation can be obtained by the following equation>And obtaining the second path differential mode signal after cancellation by using the following formula +.>

In a second aspect, a method for removing noise is provided, where the method may be applied to a coupling circuit including a differential mode coupling circuit and a common mode coupling circuit, and the method may include obtaining a first differential mode signal from the differential mode coupling circuit, and obtaining a first common mode signal from the common mode coupling circuit, and performing noise removing processing on the first differential mode signal according to the first common mode signal.

The application relates to a silence phase and a transmission phase, wherein the transmission phase refers to a period of time when a transmitting end device transmits a frame carrying data or information, and the silence phase refers to a period of time when the transmitting end device transmits a frame not carrying any data or information.

With reference to the second aspect, in some implementations of the second aspect, the second differential mode signal may be further obtained from a differential mode coupling circuit and the second common mode signal may be obtained from a common mode coupling circuit, and when the first differential mode signal is noise processed, the first differential mode signal may be noise canceled according to a first common mode signal and a first correlation coefficient, where the first correlation coefficient is obtained according to the second differential mode signal and the second common mode signal.

With reference to the second aspect, in some implementations of the second aspect, when performing noise cancellation processing on the first differential mode signal according to the first common mode signal and the first correlation coefficient, a noise cancellation component may be determined according to the first common mode signal and the first correlation coefficient, and noise in the first differential mode signal may be cancelled according to the noise cancellation component.

With reference to the second aspect, in some implementations of the second aspect, in the determining the noise cancellation component according to the first common mode signal and the first correlation coefficient, a cancellation filter may be set, the first common mode signal is obtained by the cancellation filter, and the noise cancellation component corresponding to the first common mode signal is obtained according to a coefficient of the cancellation filter, where the coefficient of the cancellation filter may be determined according to the first correlation coefficient.

With reference to the second aspect, in some implementations of the second aspect, after the second differential mode signal and the second common mode signal are acquired, the second differential mode signal and the second common mode signal may be further trained to obtain the first correlation coefficient, where the first correlation coefficient corresponds to the differential mode coupling circuit and the common mode coupling circuit.

For example, in the silence phase, the coupling circuit and the signal acquisition module provided by the embodiment of the present application may be used to acquire the second differential mode signal and the second common mode signal, and then the training method provided by the embodiment of the present application is used to train to obtain the first correlation coefficient.

In a third aspect, a circuit for removing noise is provided, the circuit including a differential mode coupling circuit, a common mode coupling circuit, and a noise removing module, wherein the differential mode coupling circuit is configured to obtain a differential mode signal, the common mode coupling circuit is configured to obtain a common mode signal, and the noise removing module is configured to perform noise removing processing on a first differential mode signal from the differential mode coupling circuit according to the first common mode signal from the common mode coupling circuit.

As described in the first aspect, the present application relates to two phases, namely, a silence phase and a transmission phase, where the transmission phase refers to a period of time during which a transmitting end device transmits a frame carrying data or information, and the silence phase refers to a period of time during which the transmitting end device transmits a frame not carrying any data or information. It will be appreciated that the above-described division of phases may not be performed. That is, frames carrying information and/or frames not carrying information may be transmitted at any time. When the receiving end equipment receives the frame carrying the information, the noise can be read from the frame carrying no information, the frame carrying the information is used for training the correlation coefficient or updating the correlation coefficient, and when the receiving end equipment receives the frame carrying the information, the noise in the differential mode signal can be counteracted by utilizing a noise counteraction method. However, in order to facilitate understanding of the technical solution of the present application, the following description will exemplify the manner of dividing the silence phase and the transmission phase.

With reference to the third aspect, in some implementations of the third aspect, the noise cancellation module may be configured to perform noise cancellation processing on the first differential mode signal according to a first common mode signal and a first correlation coefficient, where the first correlation coefficient may be obtained according to a second differential mode signal and a second common mode signal.

Alternatively, the second differential mode signal may be a signal that is acquired by using a differential mode coupling circuit in the silence phase and does not carry information, and the second common mode signal may be a signal that is acquired by using a common mode coupling circuit in the silence phase, where the silence phase refers to a phase in which the transmitting end device transmits the signal that does not carry information, as described above.

With reference to the third aspect, in some implementations of the third aspect, the noise cancellation module may be configured to determine a noise cancellation component according to the first common mode signal and the first correlation coefficient, and cancel noise in the first differential mode signal according to the noise cancellation component.

With reference to the third aspect, in some implementations of the third aspect, the noise cancellation module may include a cancellation filter capable of receiving the first common mode signal, and obtaining a noise cancellation component corresponding to the first common mode signal according to coefficients of the cancellation filter, where the coefficients of the cancellation filter may be determined according to the first correlation coefficient.

With reference to the third aspect, in certain implementations of the third aspect, the apparatus may further include a training module for training the second differential mode signal and the second common mode signal to obtain a first correlation coefficient, the first correlation coefficient corresponding to the differential mode coupling circuit and the common mode coupling circuit,

in a fourth aspect, there is provided an apparatus for canceling noise, the apparatus comprising means in the first aspect or any possible implementation thereof, or the apparatus comprising circuitry in the third aspect or any possible implementation thereof.

In a fifth aspect, the present application provides a computer readable storage medium having stored therein computer instructions which, when run on a computer, cause the computer to perform the method of the second aspect or any possible implementation thereof.

In a sixth aspect, the application provides a computer program product comprising computer program code which, when run on a computer, causes the computer to perform the method of the second aspect or any possible implementation thereof.

Drawings

Fig. 1 is a schematic diagram of several common coupling circuits.

Fig. 2 is a schematic diagram of a novel coupling circuit according to an embodiment of the present application.

Fig. 3 is a schematic diagram of an apparatus for removing noise according to an embodiment of the present application.

Fig. 4 is a schematic flow chart of a method for eliminating noise according to an embodiment of the present application.

Fig. 5 is a schematic flow chart of a method for obtaining a first correlation coefficient according to an embodiment of the present application.

Fig. 6 is a schematic flow chart of a method for eliminating noise according to an embodiment of the present application.

Fig. 7 is a schematic flow chart of silence phase training noise correlation coefficients provided by an embodiment of the present application.

Fig. 8 is a schematic flow chart of cancellation of noise at the transmit stage provided by an embodiment of the present application.

Fig. 9 is a schematic diagram of a possible structure of frames and silence frames provided by an embodiment of the present application.

Fig. 10 is a schematic diagram of connection of the novel coupling circuit according to the embodiment of the present application.

Fig. 11 is a schematic diagram of time domain variation of a received signal before and after noise cancellation according to an embodiment of the present application.

Fig. 12 is a schematic diagram showing a change of frequency domain characteristics of noise in a PLC before and after noise cancellation according to the embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

It should be appreciated that the power communication system of the embodiments of the present application may employ various wireless communication schemes for communication, such as: global system for mobile communications (global system of mobile communication, GSM), code division multiple access (code division multiple access, CDMA) system, wideband code division multiple access (wideband code division multiple access wireless, WCDMA) system, general packet radio service (general packet radio service, GPRS) system, long term evolution (long term evolution, LTE) system, wireless local area network (wireless local area networks, WLAN), LTE frequency division duplex (frequency division duplex, FDD) system, LTE time division duplex (time division duplex, TDD), universal mobile communication system (universal mobile telecommunication system, UMTS), worldwide interoperability for microwave access (worldwide interoperability for microwave access, wiMAX) communication system, fifth generation (5th generation,5G) mobile communication system, new radio access technology (new radio access technology, NR), and future communication systems, etc.

Although there are real-time changes in load and real-time changes in noise in the PLC, the PLC still has a certain periodic characteristic. Actual measurement and experiments show that the real-time change of the channel and the real-time change of noise in the PLC have the characteristic of a certain alternating current (alternate current, AC) period. That is, the channel response variation and the noise variation trend can be matched to some extent with the ac cycle (for example, the ac cycle is 50Hz, 60Hz, etc.), and have substantially the same cycle characteristics. The periodically changing channel characteristics eventually lead to that the capability of the channel actually carrying the transmitted data or information also presents the periodically changing, and if the transmitting end device keeps the same modulation coding parameters, such as carrier bit loading, forward error correction code (forward error correction, FEC) code rate, and the like, the channel capacity cannot be fully utilized, and the final transmission rate is smaller than the actual channel capacity.

Noise in the PLC is mainly derived from the electrical loads therein. The types and models of electric appliances in actual families and working environments are various, so that the diversity of noise characteristics in a system is caused, and in addition, the characteristics of noise generated by the same electric appliance are not consistent. Moreover, the electrical noise in the PLC is often characterized by large pulse amplitude, and even the signal may be almost submerged in the noise, which severely degrades the performance of the PLC system. The embodiment of the application provides a noise cancellation scheme, which utilizes the inherent characteristic of noise to reduce the noise in the PLC, thereby eliminating noise interference to a certain extent and improving the transmission quality and transmission rate of a PLC system.

The PLC has two signals, a differential mode signal (different mode signal) and a common mode signal (common mode signal), wherein the differential mode signal is a signal carrying information "wanted", and the common mode signal may be a signal carrying information "wanted", or may be a signal not carrying information "unwanted". That is, in the PLC, the differential mode signal is a signal carrying useful information, but there may be a useless signal (differential mode noise) in the differential mode signal. In the common mode signal, when information is carried, there may be a useless signal (common mode noise) therein, and when the common mode signal is a signal not containing any information, all of the common mode signal may be considered as noise (common mode noise) at this time.

It should be noted that, the noise in the embodiment of the present application refers to a useless electrical signal, and may be understood as an "unwanted" electrical signal. The noise includes differential mode noise and common mode noise, wherein the differential mode noise refers to noise in a differential mode signal, and a differential mode part (or referred to as a differential mode component) corresponding to the noise; the common mode noise refers to noise in the common mode signal, and corresponds to a common mode portion (or referred to as a common mode component) of the noise.

In the embodiment of the application, a certain correlation exists between the differential mode noise and the common mode noise in the PLC through research. The embodiment of the application aims to utilize the correlation to cancel noise, and in order to realize the method for canceling noise, the embodiment of the application provides a novel coupling circuit, and a coupling circuit of a common mode signal is added on the basis of the original coupling circuit, so that the novel coupling circuit can be used for coupling out differential mode signals and common mode signals. The novel coupling circuit is first described below.

For ease of understanding, the existing coupling circuit will first be described. In the existing coupling circuit, a differential mode coupling structure such as a T type coupling structure and a Delta type coupling structure is often adopted to couple out differential mode signals.

For example, in the coupling circuit shown in fig. 1 (a), a differential mode signal between a live (L) and a neutral (N) can be coupled out by using a T-type coupling circuit; and the common mode signal between L and N can be coupled out first, and then the differential mode signal between l+n and the guard conductors (protecting earthing, PE), PE being known as ground. As shown in fig. 1 (a), the coupling circuit is a T-type coupling circuit, a curved line in the drawing represents a coil, a coil is connected between L and N, and PE is connected to the middle of the coil between L and N through the coil, so that a structure similar to the letter "T" is formed, and thus the coupling circuit is also called a T-type coupling circuit. In use, three terminals indicated in L, N, PE are connected to the hot line L, neutral line N and ground line PE, respectively, in a power line communication system. The coupling circuit may be provided on the transmitting side of the signal or on the receiving side of the signal. When the coupling circuit shown in fig. 1 (a) is used as a coupling circuit on the transmitting side, T1 and T2 shown in fig. 1 (a) may be used as input terminals (may also be referred to as input nodes, input ports, etc.) of signals, that is, signals are input from T1 and T2, and coupled through coils, so that signals exist on power lines L, N and PE, it can be understood that two signals from T1 and T2 are converted into three signals on L, N and PE. When the coupling circuit shown in fig. 1 (a) is used as a coupling circuit on the transmitting side, the signals T1 and T2 shown in fig. 1 (a) can be used as output ends (also referred to as output nodes, output ports, etc.) of signals, that is, electric signals from the power line L, N and the PE, the signals are coupled out through the coil, and the coupled out signals are transmitted through the terminals T1 and T2, which can be understood as converting three-way signals from L, N and the PE into two-way signals on the terminals T1 and T2. It should be noted that, T1 and T2 are respectively connected to the coil, the other ends of the coils connected to the coil are connected to the ground, T1 and T2 are input ends or output ends of two signals, and only one of the two signals may be used to input or output signals, that is, the two signals input or output from T1 and T2 do not need to exist at the same time.

For another example, in the coupling circuit shown in fig. 1 (b), a differential mode signal between L and N is coupled out by a Delta-type coupling circuit; and coupling out a differential mode signal between the L and PE by using a Delta type coupling circuit. As shown in fig. 1 (b), the coupling circuit is a Delta-type coupling circuit, the curved line in the figure represents a coil, and the coils are connected between L and N, between L and PE, and between N and PE, to form a triangle structure, similar to a uppercase "Delta" (i.e., delta), and thus the coupling circuit is also called a Delta-type coupling circuit. In use, the three terminals shown in figure L, N, PE are connected to the hot, neutral and ground lines, respectively, in a power line communication system. The coupling circuit may be provided on the transmitting side of the signal or on the receiving side of the signal. When the coupling circuit shown in fig. 1 (b) is used as a coupling circuit on the transmitting side, D1, D2, and D3 shown in fig. 1 (b) may be used as input terminals (may also be referred to as input nodes, input ports, etc.) of signals, that is, signals are input from any one or more of D1, D2, or D3, and coupled through coils, so that signals exist on the power lines L, N and the PEs, which may be understood as converting input signals from any one or more of D1, D2, or D3 into three signals on L, N and the PEs. For example, when D1 and D2 are used as inputs (D3 does not input signals), it is equivalent to converting input signals from two paths D1 and D2 into three paths L, N and PE. When the coupling circuit shown in fig. 1 (b) is used as the coupling circuit on the receiving side, D1, D2, and D3 shown in fig. 1 (b) may be used as the output terminals (may also be referred to as output nodes, output ports, etc.) of signals, that is, electric signals from the power lines L, N and PE, the signals are coupled out through the coils, and the coupled-out signals are obtained through any one or more of D1, D2, and D3. For example, when using D1 and D3 as outputs, it is equivalent to converting three signals from L, N and PE into two signals on D1 and D3. It should be noted that D1, D2, and D3 are respectively connected to the coils, the other ends of the coils connected to the coils are all connected to the ground, D1, D2, and D3 are input ends or output ends of three signals, and only one or more ends of the three signals may be used to input or output signals, that is, the three signals input or output from D1, D2, and D3 do not need to exist at the same time.

The common mode coupling circuit provided by the embodiment of the application is shown in (c) of fig. 1, and can be used for coupling out common mode signals among L, N, PE electrical signals, and is shown in (c) of fig. 1, and the common mode coupling circuit is in a coupling mode of L/N/PE three common modes. As shown in fig. 1 (c), the coupling circuit is a common mode coupling circuit, the curved line in the drawing represents a coil, and the point on the curved line is used to represent the same name end of the coil, and as can be seen from the drawing, the same name ends of four coils are all located on the same side, and thus the coupling circuit is called a common mode coupling circuit. Three coils are respectively connected in L, N and PE; the same-name end of the fourth coil is grounded, and the other end, namely the illustrated S4 end, is the input end or the output end of the signal. In use, the ends represented by L, N and PE are connected to the respective live, neutral and ground lines of the power line, respectively, the end represented by ground (the other end of the coil to which the diagram S4 is connected) is connected to ground, and the diagram S4 end is taken as the input or output end of the signal. It should be noted that, in the power line communication system, information or data is less likely to be transmitted by using the common mode signal, and in the embodiment of the present application, S4 is mainly used as the input terminal, that is, the common mode coupling circuit is disposed at the receiving terminal side, so as to obtain the common mode signal from the S4 terminal.

The novel coupling circuit provided by the embodiment of the application is described below.

Fig. 2 is a schematic diagram of a novel coupling circuit according to an embodiment of the present application. The coupling circuit comprises two paths of differential mode coupling circuits and one path of common mode coupling circuit, wherein the two paths of differential mode coupling circuits are used for coupling out differential mode signals, and the one path of common mode coupling circuit is used for coupling out common mode signals.

Alternatively, the two-way differential mode coupling circuit employs the same circuit as a conventional differential mode coupling circuit, such as the T-type coupling circuit or Delta-type coupling circuit shown in FIG. 1. As shown in fig. 2, the novel coupling circuit includes a differential mode coupling circuit 210, a differential mode coupling circuit 220, and a common mode coupling circuit 230.

The differential mode coupling circuit 210 may correspond to the Delta type coupling circuit shown in fig. 1 (b), and at this time, two coils at the left side of the differential mode coupling circuit 210 are used as coils of an input (RX) terminal RX0 and an output (TX) terminal TX0, respectively, and both ends of the coil of RX0 may correspond to D3 and ground shown in fig. 1 (b), respectively, and both ends of the coil of TX0 may correspond to D1 and ground shown in fig. 1 (b), respectively. It should be noted that, the two ends of the coil of RX0 may also correspond to D1 and ground shown in (b) of fig. 1, respectively, or may also correspond to D2 and ground shown in (b) of fig. 1, respectively; the coil both ends of TX0 may also correspond to D3 and ground shown in (b) of fig. 1, respectively, or may also correspond to D2 and ground shown in (b) of fig. 1, respectively. That is, the left two coils of the differential mode coupling circuit 210 may be any two coils of the three coils connected to D1, D2, or D3 in fig. 1 (b). It should be further understood that the two left coils of the differential mode coupling circuit 210 may be used as only the coils of the input terminal or only the coils of the output terminal, that is, the two left coils may be connected to only the input terminal or only the output terminal, which is not described herein.

In addition, the function of the differential mode coupling circuit 210 may also be implemented using a T-type coupling circuit, that is, the differential mode coupling circuit 210 may correspond to the T-type coupling circuit shown in fig. 1 (a). At this time, the two coils at the left side of the differential mode coupling circuit 210 are used as the coils of the input terminal RX0 and the output terminal TX0, respectively, the coil both ends of RX0 may correspond to T1 and ground shown in fig. 1 (a), respectively, and the coil both ends of TX0 may correspond to T2 and ground shown in fig. 1 (a), respectively. Note that, the coil ends of RX0 may correspond to T2 and ground shown in fig. 1 (a), and TX0 may correspond to T1 and ground shown in fig. 1 (a), respectively. It should be further understood that the two left coils of the differential mode coupling circuit 210 may be used as only the coils of the input terminal or only the coils of the output terminal, that is, the two left coils may be connected to only the input terminal or only the output terminal, which is not described herein.

The differential mode coupling circuit 220 may correspond to the Delta type coupling circuit shown in fig. 1 (b), in which case two coils at the left side of the differential mode coupling circuit 220 are used as coils of the input terminal RX1 and the output terminal TX1, respectively, the coil ends of RX1 may correspond to D3 and ground shown in fig. 1 (b), respectively, and the coil ends of TX1 may correspond to D1 and ground shown in fig. 1 (b), respectively. It should be noted that the two ends of the coil of RX1 may also correspond to D1 and the ground shown in (b) of fig. 1, respectively, or may also correspond to D2 and the ground shown in (b) of fig. 1, respectively; the coil both ends of TX1 may also correspond to D3 and ground shown in (b) of fig. 1, respectively, or may also correspond to D2 and ground shown in (b) of fig. 1, respectively. That is, the left two coils of the differential mode coupling circuit 220 may be any two coils of the three coils connected to D1, D2, or D3 in fig. 1 (b). It should be further understood that the two left coils of the differential mode coupling circuit 220 may be used as only the coils of the input terminal or only the coils of the output terminal, that is, the two left coils may be connected to only the input terminal or only the output terminal, which is not described herein.

In addition, the function of the differential mode coupling circuit 220 may also be implemented using a T-type coupling circuit, that is, the differential mode coupling circuit 220 may correspond to the T-type coupling circuit shown in fig. 1 (a). At this time, the two coils at the left side of the differential mode coupling circuit 220 may be used as the coils of the input terminal RX1 and the output terminal TX1, respectively, the coil ends of RX1 may correspond to T1 and the ground shown in (a) of fig. 1, respectively, and the coil ends of TX1 may correspond to T2 and the ground shown in (a) of fig. 1, respectively. Note that, the coil ends of RX1 may correspond to T2 and ground shown in fig. 1 (a), and TX1 may correspond to T1 and ground shown in fig. 1 (a), respectively. It should be further understood that the two left coils of the differential mode coupling circuit 220 may be used as only the coils of the input terminal or only the coils of the output terminal, that is, the two left coils may be connected to only the input terminal or only the output terminal, which is not described herein.

The common mode coupling circuit 230 may correspond to the common mode coupling circuit shown in fig. 1 (c). As shown in fig. 2, the three coils on the right side of the common mode coupling circuit 230 are respectively connected in series to the L, N and PE lines, the left side coil serves as a receiving terminal RX2, and the non-homonymous terminal of RX2 (the terminal without the dot if the homonymous terminal of the coil is indicated by the dot) may correspond to S4 shown in fig. 1 (c), and the homonymous terminal (the terminal with the dot if the homonymous terminal of the coil is indicated by the dot) may be connected to the ground. Note that in the power line communication system, information or data is not transmitted using a common mode signal, and therefore, in the embodiment of the present application, common mode noise in the power line communication system is mainly acquired using the common mode coupling circuit 230, and thus the common mode coupling circuit may be disposed only on the receiving side.

Optionally, the one-path common mode coupling circuit is in a coupling mode of L/N/PE three-path common modes and is used for coupling common mode signals. It is noted that the effective signal coupled by the L/N/PE three-way common mode coupling circuit is very tiny no matter the first two-way differential mode coupling circuit selects the T-type coupling circuit or the Delta-type coupling circuit even in the signal transmitting stage.

It should be noted that, the coupling circuit relates to a coupling transformer, wherein the coupling transformer is called a differential mode transformer for coupling differential mode signals, and the coupling transformer is called a common mode transformer for coupling common mode signals.

It should be understood that fig. 2 is only an example of a coupling circuit provided in the embodiment of the present application, and other coupling circuit manners may be adopted, for example, coupling out more than two differential mode signals, for example, only one differential mode signal, for example, coupling out several common mode signals, etc., which are only required to include both differential mode coupling circuits and common mode coupling circuits, and will not be described herein again. In addition, the embodiment of the application also provides one possible connection situation of the circuit shown in fig. 2 to the PLC, as shown in fig. 10. Fig. 10 is a schematic connection diagram of a novel coupling circuit provided in an embodiment of the present application, taking a Delta-type differential mode coupling circuit and a common mode coupling circuit as an example, as shown in fig. 10, the corresponding ends of the differential mode coupling circuit and the corresponding ends of the common mode coupling circuit are respectively connected to a live wire, a ground wire and a neutral wire in a PLC. In fig. 10, the left side of the main transmission line (i.e., the live line L, the neutral line N, and the ground line PE in the drawing) of the power line system is a transmitting end side, the transmitting end side is provided with a differential mode coupling circuit 1010, the right side is a receiving end side, the receiving end side is provided with a differential mode coupling circuit 1020 and a common mode coupling circuit 1030, and the differential mode coupling circuit 1010, the differential mode coupling circuit 1020, and the common mode coupling circuit 1030 together form a novel coupling circuit 1000. Wherein, delta type differential mode coupling circuit 1010 is adopted at the transmitting end side, D1 of differential mode coupling circuit 1010 is connected to transmitting end TX0, D3 is connected to transmitting end TX1, common mode coupling circuit 1030 and Delta type differential mode coupling circuit 1020 are arranged at the receiving end side, D1 of differential mode coupling circuit 1020 is connected to receiving end RX0, D3 is connected to receiving end RX1, S4 of common mode coupling circuit 1030 is connected to receiving end RX2. When the circuit shown in fig. 10 works, two paths of signals are transmitted by using the transmitting ends TX0 and TX1, and converted into three paths of signals on L, N and PE through the differential mode coupling circuit 1010, when the three paths of signals reach the common mode coupling circuit 1030, the common mode coupling circuit 1030 is used for coupling out the common mode signals and obtaining the common mode signals through the receiving end RX2, and when the three paths of signals reach the differential mode coupling circuit 1020, the three paths of signals are converted into two paths of signals through the differential mode coupling circuit 1020 and obtained through the RX0 and the RX 1. RX0, RX1, RX2, TX0 and TX1 shown in FIG. 10 may correspond to RX0, RX1, RX2, TX0 and TX1, respectively, shown in FIG. 2.

From this, the novel coupling circuit shown in fig. 2 can acquire both differential mode signals and common mode signals, and can also acquire both differential mode noise and common mode noise (i.e., differential mode component and common mode component in noise). According to the above, there is a certain correlation between the differential mode noise and the common mode noise, specifically, there is a strong correlation between the differential mode noise and the common mode noise that exist simultaneously for the same time. Therefore, the simultaneous coupling of the common mode noise and the differential mode noise using the novel coupling circuit shown in fig. 2 has a strong correlation, specifically, the differential mode transformer in the novel coupling circuit couples the differential mode noise of the noise source (e.g., loads such as an electrical appliance in a PLC) out, the common mode transformer in the novel coupling circuit couples the common mode noise of the noise source out, and the coupling process is performed simultaneously or almost simultaneously, and the obtained differential mode noise and the common mode noise have a strong correlation therebetween.

Fig. 3 is a schematic diagram of an apparatus for removing noise according to an embodiment of the present application. As shown in fig. 3, the apparatus includes a signal acquisition module 310, a noise cancellation module 320, and may further include a training module 330.

The signal acquisition module 310 is configured to acquire a common mode signal and a differential mode signal, for example, the signal acquisition module 310 may be connected to the novel coupling circuit shown in fig. 2 to acquire the differential mode signal and/or the common mode signal that are coupled out by the novel coupling circuit.

It should be noted that a differential mode coupling circuit and a common mode coupling circuit may be provided in the signal acquisition module 310, and in this case, the signal acquisition module 310 may be capable of self-coupling out differential mode signals and/or common mode signals. For example, one common mode signal and two differential mode signals may be coupled out, and for example, one differential mode signal and one common mode signal may be coupled out.

The noise cancellation module 320 is configured to perform noise cancellation processing on the obtained differential mode signal according to the obtained common mode signal in a transmission stage (i.e., a stage of transmitting the signal).

The application relates to a silence phase and a transmission phase, wherein the transmission phase refers to a period of time when a transmitting end device transmits a frame carrying data or information, and correspondingly, the silence phase refers to a period of time when the transmitting end device transmits a frame not carrying any data or information. It will be appreciated that the above-described division of phases may not be performed. That is, frames carrying information and/or frames not carrying information may be transmitted at any time. When the receiving end equipment receives the frame carrying the information, the noise can be read from the frame carrying no information, the frame carrying the information is used for training the correlation coefficient or updating the correlation coefficient, and when the receiving end equipment receives the frame carrying the information, the noise in the differential mode signal can be counteracted by utilizing a noise counteraction method. However, in order to facilitate understanding of the technical solution of the present application, in the present application, a manner of dividing the silence period and the transmission period is mainly illustrated.

Assuming that the signal acquisition module 310 acquires a first differential mode signal from the differential mode coupling circuit and acquires a first common mode signal from the common mode coupling circuit in the transmission stage, the noise cancellation module 320 may perform noise cancellation processing on the first differential mode signal according to the first common mode signal.

It should be understood that, assuming that the silence phase and the transmission phase are not divided, when the signal acquisition module 310 acquires a differential mode signal from the differential mode coupling circuit and acquires a common mode signal from the common mode coupling circuit, the noise cancellation module 320 may perform noise cancellation processing on the differential mode signal according to the common mode signal. When the differential mode signal and the common mode signal are information carrying (corresponding to the time when the differential mode signal and the common mode signal are the first differential mode signal and the first common mode signal, respectively), the obtained information can be more accurate after noise elimination processing. When the differential mode signal and the common mode signal do not carry information (corresponding to the case that the differential mode signal and the common mode signal are the second differential mode signal and the second common mode signal, respectively, and correspond to the frame which is transmitted by the transmitting end device and does not carry information), the device can still be used for noise elimination processing, and only after the noise elimination processing, the information can not be obtained.

Alternatively, the noise cancellation module 320 may determine a noise cancellation component according to an acquired common mode signal (e.g., a first common mode signal) and a correlation coefficient (e.g., a first correlation coefficient) between the differential mode noise and the common mode noise, and subtract the noise cancellation component from the acquired differential mode signal (e.g., the first differential mode signal). That is, the noise cancellation component may be determined in the transmission stage based on the coupled common-mode signal and the first correlation coefficient, and the noise cancellation component may be determined by, for example, performing a convolution operation on the common-mode signal obtained in the transmission stage and the first correlation coefficient.

The first correlation coefficient indicates the correlation between the noise in the differential mode signal and the noise in the common mode signal, and thus corresponds to the differential mode coupling circuit and the common mode coupling circuit to which it is connected.

Optionally, the noise cancellation coefficient may be further determined according to a correlation coefficient between the differential mode noise and the common mode noise, and then noise in the differential mode signal is cancelled according to the noise cancellation coefficient and the obtained common mode signal, where the noise cancellation coefficient may also be used as the first correlation coefficient.

Alternatively, the noise cancellation module 320 may include a noise filter, and the coefficient of the noise filter is set according to the first correlation coefficient, so that the signal acquisition module 310 transmits the obtained common mode signal to the noise filter to obtain a corresponding noise cancellation component, and subtracts the noise cancellation component from the differential mode signal obtained by the signal acquisition module 310 in the transmission stage.

The first correlation coefficient may be obtained from other devices or apparatuses or modules, or may be manually set, or may be obtained by setting a training module, where the device includes a training module, and the case where the first correlation coefficient can be obtained or updated in real time is described below.

Optionally, the apparatus may further comprise a training module 330 for obtaining the first correlation coefficient. In the transmitting phase, the first correlation coefficient may be used to determine a noise cancellation component corresponding to the obtained common mode signal. The transmitting phase refers to a period of time when the transmitting end device transmits a frame carrying data or information, and the silence phase refers to a period of time when the transmitting end device transmits a frame not carrying any data or information.

It should be understood that the training module 330 may be included in the apparatus shown in fig. 3, but may also be an independent apparatus or module, and the function of obtaining the correlation coefficient may also be implemented by using the method provided in the embodiment of the present application.

Alternatively, the training module 330 may determine the first correlation coefficient using the differential mode signal and the common mode signal acquired during the silence period by the following method.

For example, during the silence phase, the signal acquisition module 310 obtains a differential mode signal and a common mode signal (e.g., a second differential mode signal and a second common mode signal), and the training module 330 trains the correlation coefficients of the differential mode signal and the common mode signal, or determines the corresponding noise cancellation coefficients according to the correlation coefficients. As can be seen from the above, the silence period refers to a period of time in which the transmitting end device does not transmit a signal carrying data or information, and during this period of time, the transmitting end device transmits only silence frames (i.e., frames carrying no data or information) carrying no information. Therefore, neither the differential mode signal nor the common mode signal acquired by the signal acquisition module 310 carries data or information, and is noise. Thus, the training module 330 may obtain a correlation coefficient between the differential mode signal (all differential mode noise) and the common mode signal (all common mode noise) obtained during the silence period, or further obtain a noise cancellation coefficient.

It should be appreciated that when the silence phase and the transmission phase are not divided, the second differential mode signal and the second common mode signal may be transmitted to the training module 330 when the signal acquisition module 310 obtains the second differential mode signal and the second common mode signal, and the training module 330 may obtain a correlation coefficient (for example, the first correlation coefficient) of the second differential mode signal and the second common mode signal, or further determine the corresponding noise cancellation coefficient according to the correlation coefficient. In addition, when the signal acquisition module 310 obtains the second differential mode signal and the second common mode signal that do not carry information, the second differential mode signal and the second common mode signal may be further transmitted to the noise cancellation module 320 for noise cancellation, where the second differential mode signal and the second common mode signal are not transmitted or sent to the noise cancellation module 320, because no more accurate information is obtained by canceling the noise due to the cancellation, and thus the noise cancellation process may not be performed.

It should also be understood that when the silence phase and the transmission phase are not divided, the signal acquisition module 310 may also transmit the first differential mode signal and the first common mode signal to the training module 330 when they are obtained, but because there is both noise and information in the first differential mode signal and the first common mode signal, the first correlation coefficient established according to this may be poor in practical use, so that the determination of the first correlation coefficient may not be performed when the first differential mode signal and the first common mode signal are obtained, and the connection mode of this case is not shown in fig. 3, that is, the case that the signal acquisition module 310 transmits or transmits the first differential mode signal and the first common mode signal to the training module 330 is not shown.

The device shown in fig. 3 can realize the processing of noise elimination of the simultaneously acquired differential mode signals by using the acquired common mode signals, reduce noise in the differential mode signals, and effectively improve the noise immunity of the power line communication system, improve the signal to noise ratio and improve the transmission rate of the system by using the device shown in fig. 3 for noise cancellation.

Fig. 4 is a schematic flow chart of a method for eliminating noise according to an embodiment of the present application. The steps are described below in connection with fig. 4.

401. A differential mode signal from a differential mode coupling circuit and a common mode signal from a common mode coupling circuit are acquired.

Alternatively, the differential mode coupling circuit and the common mode coupling circuit may constitute the coupling circuit shown in fig. 2.

Alternatively, the signal acquisition module shown in fig. 3 may be used to acquire the differential mode signal coupled by the differential mode coupling circuit and the common mode signal coupled by the common mode coupling circuit.

It will be appreciated that in one case, the differential mode signal obtained may be a first differential mode signal and the common mode signal may be a first common mode signal. In this case, the frame carrying data or information is transmitted by the transmitting device, and the coupling circuit couples the first differential mode signal and the first common mode signal when the frame passes through the coupling circuit. In another case, however, the differential mode signal obtained is a second differential mode signal and the common mode signal is a second common mode signal. In this case, the coupling circuit couples the second differential mode signal and the second common mode signal when the coupling circuit passes through, which corresponds to the transmission end device transmitting the silence frame without data or information, and the same procedure as when the first differential mode signal and the first common mode signal are obtained may be performed.

When step 401 is performed in the transmission phase, the obtained differential mode signal carries information, but since the common mode signal does not carry information almost in both the silence phase and the transmission phase, the common mode signal can be considered as common mode noise.

402. And performing noise elimination processing on the acquired differential mode signal according to the acquired common mode signal.

Alternatively, a noise cancellation component may be determined according to the obtained common mode signal and the first correlation coefficient, and noise in the obtained differential mode signal may be cancelled according to the noise cancellation component.

It should be noted that the first correlation coefficient may be a first correlation coefficient obtained by using the training module 330 shown in fig. 3, and the obtaining method has been described above correspondingly, and is not repeated here for brevity.

Alternatively, the coefficient of the noise filter may be determined according to the first correlation coefficient, and the obtained common mode signal may be transmitted to the noise filter, thereby obtaining the noise cancellation component corresponding to the obtained common mode signal.

Alternatively, the first correlation coefficient may be obtained using the training module 330 shown in FIG. 3. The method of obtaining the first correlation coefficient is illustrated below in conjunction with fig. 5.

Fig. 5 is a schematic flow chart of a method for obtaining a first correlation coefficient according to an embodiment of the present application. The steps are described below in conjunction with fig. 5.

501. The transmitting end device transmits a silence frame to the receiving end device during the silence phase.

During the silence phase, the transmitting end device transmits silence frames to the receiving end device for collecting noise (e.g., differential mode noise and common mode noise) in the PLC system. Silence frames are frames of data that do not carry any data. Because the silence frame does not carry information, the silence frame can collect noise in the line in the process of reaching the receiving end equipment through the novel coupling circuit, so that the receiving end equipment can acquire the collected noise in the line when receiving the silence frame. Noise in the PLC includes differential mode noise and common mode noise.

When the silence phase and the transmission phase are not divided, the steps correspond to the transmission of a frame carrying no information to the reception side device.

502. The receiving end device acquires a second differential mode signal and a second common mode signal.

Alternatively, the second differential mode signal and the second common mode signal may be coupled out using the novel coupling circuit described above.

Alternatively, the second differential mode signal from the differential mode coupling circuit and the second common mode signal from the common mode coupling circuit may be acquired using the signal acquisition module described above.

It should be understood that the transmitting end device does not transmit the signal carrying information in the silence phase, and thus both the second differential mode signal and the second common mode signal are signals carrying no information, that is, only differential mode noise and common mode noise, respectively, in the second differential mode signal and the second common mode signal.

Alternatively, the novel coupling circuit shown in fig. 2 may be used to obtain two differential mode signals and one common mode signal during the silence phase. Alternatively, the differential mode signal and the common mode signal of the silence phase may be acquired using the signal acquisition module 310 shown in fig. 3.

503. The receiving end equipment obtains a first correlation coefficient according to the second differential mode signal and the second common mode signal.

In step 503, the differential mode noise is the whole of the differential mode signal, and the common mode noise is the whole of the common mode signal, and thus the correlation coefficient between the differential mode noise and the common mode noise is obtained. It should also be understood that the correlation coefficient between the differential mode noise and the common mode noise may be taken as the first correlation coefficient, or the noise cancellation coefficient may be further determined according to the correlation coefficient, and taken as the first correlation coefficient.

Alternatively, the first correlation coefficient may be obtained using the training module 330 shown in FIG. 3.

Alternatively, the second common mode signal may be used as a reference to calculate the second differential mode signal and the second differential mode signalCorrelation coefficients between two common mode signals. That is, it is assumed that r is used for the second common mode signal _c The second differential mode signal is represented by r _d The relation between the two can be obtained by using the acquired second common mode signal and the second differential mode signal training: r is (r) _d ＝f(r _c ) Or calculating a correlation coefficient k between the two: r is (r) _d ＝r _c * k, wherein "×" denotes a convolution operation.

Assuming that the data length of the differential mode signal and the common mode signal for training is D, wherein D is a positive integer, the differential mode signal and the common mode signal can respectively use D-dimensional vector r _c And r _d A representation; assuming that the number of taps of the cancellation filter is represented by W, where W is a positive integer, the coefficients of the cancellation filter may be represented by a W-dimensional vector k. Let us assume an estimation of k Representing the coefficients of the cancellation filter obtained by training. An evaluation index for training results can be set to +.>That is, the smaller the value of J, the more accurate the training result. It should be understood that the evaluation index is not unique, and other performance evaluation indexes may be used, such as a norm or the like.

Alternatively, an estimate of k may be obtained using a linear least squares (linear least squares, LLS) estimation approachMake->The following formula is satisfied:

H ^≈-1 (r _c )＝[H ^T (r _c )H(r _c )] ^-1 H ^T (r _c )，

wherein r is _c Representing the acquired D-dimensional common-mode signal vector, r _d Representing the acquired D-dimensional differential mode signal vector,represents an estimate of the W-dimensional correlation coefficient vector k, H (r _c ) Representing the sum of the D-dimensional common-mode signal vector r _c Toeplitz matrix of D rows and W columns, H ^T (r _c ) Represents H (r) _c ) Transposed matrix of (H) ^≈-1 (r _c ) Represents H (r) _c ) Pseudo-inverse matrix of (H) ^T (r _c ) And H ^≈-1 (r _c ) Are all matrices of W rows and D columns.

The above can be appliedDetermined as the coefficients of the cancellation filter, when in the transmit phase, the acquired common mode signal is assumed to be r' _c When the cancellation filter is used to determine the noise cancellation component, the determined noise cancellation component may satisfy the formula:wherein (1)>Representing the common mode signal r' _c A corresponding noise cancellation component.

When the novel coupling circuit shown in fig. 2 is used for coupling, two paths of differential mode signals and one path of common mode signals can be obtained, then a first correlation coefficient corresponding to the first path of differential mode signals can be trained by using the first path of differential mode signals and the path of common mode signals, and a second correlation coefficient corresponding to the second path of differential mode signals can be trained by using the second path of differential mode signals and the path of common mode signals, and the second correlation coefficient can be obtained by adopting the same method as that for obtaining the first correlation coefficient. When determining the noise cancellation component, the noise cancellation components in the two paths of differential mode signals may be determined by using the first correlation coefficient corresponding to the first path of differential mode signal and the second correlation coefficient corresponding to the second path of differential mode signal, respectively.

Alternatively, the noise cancellation component may be subtracted from the acquired differential mode signal as the noise in the differential mode signal is processed at step 402. For example, the obtained common mode signal may be convolved with the first correlation coefficient to obtain a noise cancellation component, and then the noise cancellation component is subtracted from the obtained differential mode signal to obtain a cancelled differential mode signal.

It is assumed that, in the transmission stage, the first differential mode signal, the second differential mode signal and the first common mode signal are coupled by using the novel coupling circuit shown in fig. 2, and a first correlation coefficient corresponding to the first differential mode signal and a second correlation coefficient corresponding to the second differential mode signal are determined, so that a first noise cancellation component corresponding to the first differential mode signal and a second noise cancellation component corresponding to the second differential mode signal are determined. The first noise cancellation component may be subtracted from the first differential mode signal and the second noise cancellation component may be subtracted from the second differential mode signal.

It can be seen that embodiments of the present application relate to a silence phase where correlation coefficients between noise are trained and a transmit phase where noise is cancelled. The respective execution of the two phases is described below in connection with fig. 6 to 8.

It should be noted that the method shown in fig. 5 may be used to obtain noise correlation coefficients other than the first correlation coefficient. For example, when the obtained differential mode signal has two paths, a first correlation coefficient between the first path differential mode signal and the common mode signal may be obtained using the method shown in fig. 5, and a second correlation coefficient between the second path differential mode signal and the common mode signal may also be obtained using the method shown in fig. 5.

Fig. 6 is a schematic flow chart of a method for eliminating noise according to an embodiment of the present application. The steps are described below in connection with fig. 6.

601. The second differential mode signal and the second common mode signal are acquired during the silence phase.

Optionally, the transmitting end device may be used to transmit a silence frame without information and data, and the receiving end device may be used to receive the silence frame and read the data collected in the silence frame, where the silence frame is not shoelace information and data during transmission, so that the data read by the receiving end is noise collected from the power line communication system during transmission. The execution of step 601 may refer to the relevant steps 701 and 702 shown in fig. 7.

602. The first correlation coefficient is determined from the second differential mode signal and the second common mode signal.

Alternatively, the method shown in fig. 5 may be employed, with the second differential mode signal and the second common mode signal being used for training, to obtain a first correlation coefficient, which is used to represent the correlation between the differential mode signal and the common mode signal. Execution of step 603 may refer to the correlation step 703 shown in fig. 7.

603. The first differential mode signal and the first common mode signal are acquired in a transmission phase.

In the transmitting stage, the transmitting end device transmits a signal carrying data and/or information, and after transmitting to the receiving end device, the receiving end device can acquire the corresponding signal and read the data and/or information from the corresponding signal. However, noise exists in the power line communication system, so that noise components are doped in the first differential mode signal and the first common mode signal acquired by the receiving end device. Execution of step 603 may refer to the relevant step 801 shown in fig. 8.

604. And performing noise elimination processing on the first differential mode signal according to the first common mode signal and the first correlation coefficient.

Alternatively, the noise cancellation component may be determined from the first common mode signal and the first correlation coefficient and then subtracted from the first differential mode signal. Execution of step 604 may refer to the correlation step 802 shown in fig. 8.

In the method shown in fig. 6, the correlation coefficient is obtained by training the differential mode signal and the common mode signal in the silence stage, and then the differential mode signal in the transmission stage is subjected to noise elimination processing by using the correlation coefficient and the common mode signal in the transmission stage, so that noise is effectively reduced, and the transmission quality and the transmission rate of data and signals can be effectively improved.

701. The transmitting end device transmits the silence frame to the receiving end device.

As known from the above, a silence frame (silence probe) is a data frame that is transmitted by a transmitting end device to a receiving end device during a silence period, without carrying any data. Fig. 9 is a schematic diagram of a possible structure of frames and silence frames provided by an embodiment of the present application. As shown in fig. 9, one frame includes a preamble (preamble), a header (header), and N payloads (payload), where N may be a positive integer, and a silence frame differs from a normal frame in that no information or data is carried in the payload portion of the silence frame (silence is maintained).

It should be noted that step 701 is a step performed in the silence period, that is, the transmitting end device transmits the silence frame to the receiving end device in the silence period. It should be appreciated that silence frames may also be transmitted to collect noise in the power line system when no division of silence and transmit phases is made, that is, the transmission of silence frames may be performed at intervals of transmitting data frames carrying data.

702. The receiving end equipment acquires differential mode noise and common mode noise according to the received silence frames.

The receiving end device can detect the frame through the preamble, and can judge that the frame is a silence frame through demodulating the frame header part, and then extract the differential mode signal and the common mode signal from the load part of the silence frame, and because no data exists in the load of the silence frame, the signals extracted from the load of the received silence frame are all noise, that is, the differential mode signal and the common mode signal at the moment are noise without information, namely, the differential mode noise and the common mode noise.

It should be noted that, step 702 is a step performed in the silence period, and thus, all the receiving end devices receive the silence frames. It should be understood that the receiving end device determines whether it is a silence frame or a data frame by the preamble when it receives the frame, and thus, it is possible for the receiving end device to distinguish and read out the first differential mode signal and the first common mode signal and to read out and distinguish the second differential mode signal and the second common mode signal, whether or not the silence phase and the transmission phase are divided.

703. The receiving end device determines a correlation coefficient between the differential mode noise and the common mode noise.

Alternatively, the correlation coefficient (e.g., the first correlation coefficient) may be obtained using the method shown in fig. 5.

If the differential mode signals are multiple paths, the correlation coefficients corresponding to the multiple paths of differential mode signals are needed to be obtained. And all can be obtained by the method shown in fig. 5, and are not described in detail herein.

801. The receiving end device acquires a differential mode signal and a common mode signal.

The receiving end device can detect the frame through the preamble, and can judge that the frame is a frame carrying information (i.e. not a silence frame) through demodulating the frame header part, so as to extract the differential mode signal and the common mode signal from the load part of the frame. At this time, the differential mode signal includes both information transmitted by the transmitting end device and differential mode noise introduced during transmission, and the effective signal component in the common mode signal is extremely small, so that only the common mode noise can be considered.

802. The receiving end device performs noise elimination processing on the differential mode signal according to the common mode signal.

Alternatively, the noise cancellation component corresponding to the common mode signal may be determined according to the common mode signal and the noise correlation coefficient, and then the noise in the differential mode signal may be cancelled according to the noise cancellation component.

Alternatively, the noise correlation coefficient may be determined in the silence phase from the acquired differential mode noise and common mode noise. If the differential mode signals are multiple paths, the correlation coefficients corresponding to the multiple paths of differential mode signals are needed.

By utilizing the technical scheme for canceling noise provided by the embodiment of the application, the anti-noise capability of the power line communication system can be effectively improved, the signal-to-noise ratio can be improved, and the transmission rate of the system can be improved. Taking the example that there is a shot interference in the PLC, fig. 11 and fig. 12 respectively show the technical scheme of noise cancellation provided by the embodiment of the present application, where the time domain variation of the signal received by the receiving end device before and after cancellation, and the frequency domain feature variation of the noise before and after cancellation. Fig. 11 is a schematic diagram of time domain variation of a received signal before and after noise cancellation according to the embodiment of the present application, and fig. 12 is a schematic diagram of frequency domain characteristic variation of noise in PLC before and after noise cancellation according to the embodiment of the present application.

As can be seen from fig. 11 and 12, the noise portion is significantly reduced after the received signal is subjected to noise cancellation under the interference of the spot light. In addition, the frequency domain characteristics before and after noise cancellation can also show that the noise has optimization close to 10 decibels (dB) in a low frequency band, so that the signal to noise ratio of the system is effectively improved. In this example, the system transmission rate only reaches 116 megabits per second (million bits per second, mbps) under the interference of the spot light before the technical scheme of the application is not utilized, and the system rate is obviously improved to 195Mbps after the cancellation is performed by the technical scheme of the application, and the gain reaches 68%.

By using the technical scheme provided by the embodiment of the application to perform noise cancellation, the noise immunity of the power line communication system can be effectively improved, the signal to noise ratio can be improved, and the transmission rate of the system can be improved. For example, table 1 shows a comparison of the parameters of the transmission performance of the PLC when no cancellation is performed in the case where there are interference of the humidifier, the halogen lamp, and the deluxe spotlight electrical appliance in the PLC, with the parameters of the transmission performance of the PLC when cancellation is performed using the technical solution of the embodiment of the present application. As can be seen from table 1, the technical solution of the embodiment of the present application has an obvious noise cancellation effect, and can effectively improve the transmission rate of the system. In addition, the noise proportion in the signal transmission process can be reduced through noise cancellation, namely the signal to noise ratio is improved, so that the transmission quality of the signal transmission is improved.

TABLE 1

Those of ordinary skill in the art will appreciate that the elements and algorithm steps described in connection with the embodiments disclosed herein may be embodied in electronic hardware, in computer software, or in a combination of the two, and that the elements and steps of the examples have been generally described in terms of function in the foregoing description to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.

In the several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices, or elements, or may be an electrical, mechanical, or other form of connection.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment of the present invention.

In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention is essentially or a part contributing to the prior art, or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a read-only memory (ROM), a random access memory (random access memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims

1. A device for eliminating noise is characterized in that the device is configured in a coupling circuit comprising a differential mode coupling circuit and a common mode coupling circuit,

the device comprises:

the signal acquisition module is used for acquiring a first differential mode signal from the differential mode coupling circuit and acquiring a first common mode signal from the common mode coupling circuit;

the noise elimination module is used for carrying out noise elimination processing on the first differential mode signal according to the first common mode signal;

the signal acquisition module is further configured to acquire a second differential mode signal from the differential mode coupling circuit and acquire a second common mode signal from the common mode coupling circuit, where the second differential mode signal and the second common mode signal are signals that are acquired in a silence phase and do not carry information, and the silence phase is a phase in which a transmitting end device transmits the signals that do not carry information;

The noise cancellation module is specifically configured to perform noise cancellation processing on the first differential mode signal according to the first common mode signal and a first correlation coefficient, where the first correlation coefficient is obtained according to the second differential mode signal and the second common mode signal.

2. The apparatus of claim 1, wherein the apparatus further comprises:

and the training module is used for training the second differential mode signal and the second common mode signal to obtain the first correlation coefficient, and the first correlation coefficient corresponds to the differential mode coupling circuit and the common mode coupling circuit.

3. The apparatus according to claim 1 or 2, wherein the noise cancellation module is configured to determine a noise cancellation component based in particular on the first common mode signal and the first correlation coefficient;

and canceling noise in the first differential mode signal according to the noise cancellation component.

4. A method of removing noise, the method being applied to a coupling circuit comprising a differential mode coupling circuit and a common mode coupling circuit, comprising:

acquiring a first differential mode signal from the differential mode coupling circuit, and acquiring a first common mode signal from the common mode coupling circuit;

Performing noise elimination processing on the first differential mode signal according to the first common mode signal;

the method further comprises the steps of:

acquiring a second differential mode signal from the differential mode coupling circuit and acquiring a second common mode signal from the common mode coupling circuit, wherein the second differential mode signal and the second common mode signal are signals which are acquired in a silence phase and do not carry information, and the silence phase is a phase in which a transmitting end device transmits the signals which do not carry information;

the noise cancellation processing for the first differential mode signal according to the first common mode signal includes:

and performing noise elimination processing on the first differential mode signal according to the first common mode signal and a first correlation coefficient, wherein the first correlation coefficient is obtained according to the second differential mode signal and the second common mode signal.

5. The method of claim 4, wherein after acquiring the second differential mode signal and the second common mode signal, the method further comprises:

training the second differential mode signal and the second common mode signal to obtain the first correlation coefficient, wherein the first correlation coefficient corresponds to the differential mode coupling circuit and the common mode coupling circuit.

6. The method according to claim 4 or 5, wherein said noise canceling the first differential mode signal based on the first common mode signal and a first correlation coefficient comprises:

determining a noise cancellation component from the first common mode signal and the first correlation coefficient;

7. A circuit for canceling noise, the circuit comprising:

the differential mode coupling circuit is used for acquiring differential mode signals;

the common mode coupling circuit is used for acquiring a common mode signal;

the noise elimination module is used for carrying out noise elimination processing on the first differential mode signal from the differential mode coupling circuit according to the first common mode signal from the common mode coupling circuit;

the noise elimination module is specifically configured to perform noise elimination processing on the first differential mode signal according to the first common mode signal and a first correlation coefficient, where the first correlation coefficient is obtained according to a second differential mode signal and a second common mode signal; the second differential mode signal is a signal which is acquired by using the differential mode coupling circuit in a silence phase and does not carry information, the second common mode signal is a signal which is acquired by using the common mode coupling circuit in the silence phase and does not carry information, and the silence phase is a phase in which a transmitting end device transmits the signal which does not carry information.

8. The circuit of claim 7, wherein the circuit further comprises:

9. The circuit according to claim 7 or 8, wherein the noise cancellation module is configured to determine a noise cancellation component based in particular on the first common mode signal and the first correlation coefficient;

10. A device for canceling noise, characterized in that it comprises an apparatus according to any one of claims 1 to 3.

11. An apparatus for canceling noise, characterized in that the apparatus comprises a circuit as claimed in any one of claims 7 to 9.

12. A computer readable storage medium storing computer instructions which, when executed, implement the method of any one of claims 4 to 6.