JP2007295223A - Power line carrier communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power line carrier communication apparatus, capable of reducing the influence due to the noise superimposed on a power line shared by the transmission of a communication signal. <P>SOLUTION: The power line carrier communication apparatus is provided with: receiving filters BPF1, BPF2 for selectively passing a signal of communication frequency from signals K1, K2 generated in a second winding n12 and a third winding n23 of transformers T1, T2; and differential amplifiers AMP1, AMP2, AMP3 for outputting the difference of signals, passing respective receiving filters BPF1, BPF2 as a difference signal K3. Both the ends of a series circuit, obtained by connecting a first winding n21 and a second winding n22 in series in the identical polarity direction, are respectively connected to connecting terminals 2, 3 and the node between the first and second windings n21, n22 of the series circuit is connected to a connecting terminal 4. The winding ratio of a primary winding n11 to the secondary winding n12 is made equal to each of the winding ratio of the first winding n21 to the third winding n23, and the winding ratio of the second winding n22 to the third winding n23. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power line carrier communication device that performs communication using a pair of conductor wires shared by power supply and transmission of communication signals.

  In recent years, networking has progressed in various technical fields due to advances in communication technology, and various devices in a building are being connected to the network. Such devices are networked by organically linking these devices, and by connecting the network outside the building and the network inside the building to operate these devices from an external communication terminal. By instructing it, it is intended to provide a safe and comfortable life while responding to energy saving and remote control. There are various communication signal transmission methods, but the advantage that there is no need to lay a new transmission line because the existing wiring is used, and the initial cost associated with the introduction is accordingly low, From the advantage that the aesthetics of the building is not impaired, power line carrier communication using a power line for supplying power to these devices as a transmission path may be employed.

  In this power line carrier communication, for example, a high frequency communication signal is superimposed on a power waveform of a commercial frequency and transmitted, or the high frequency communication signal is separated from the power waveform and received. This is a communication method for transmitting and receiving via the Internet.

  FIG. 13 is a block diagram illustrating a configuration of a power line carrier communication apparatus according to the background art. A power line carrier communication apparatus 100 shown in FIG. 13 performs communication using a power line 101 to which a commercial power supply AC is connected, and includes a coupling circuit 102, a reception filter circuit 103, a reception amplifier 104, a reception signal processing unit 105, a modem. Unit 106, transmission signal processing unit 107, transmission filter 108, and transmission amplifier 109.

  In such a power line carrier communication apparatus 100, a signal superimposed on the commercial AC voltage is acquired from the power line 101 by the coupling circuit 102, and the commercial AC frequency is cut and a high frequency signal used for power line carrier communication is used. Passes through the coupling circuit 102 and is output to the reception filter circuit 103, and a desired power line carrier communication signal extracted by the reception filter circuit 103 is amplified by the reception amplifier 104. The signal output from the receiving amplifier 104 is converted into a signal form that can be processed by the modem unit 106 by the reception signal processing unit 105 and output to the modem unit 106, and the demodulated data is received by the modem unit 106. The

The data modulated by the modem unit 106 is converted into a signal for power line carrier communication by the transmission signal processing unit 107, and further subjected to signal processing such as waveform shaping by the transmission filter 108, and then the coupling circuit 102. Is superimposed on the commercial AC power supply voltage in the power line 101 via the power line 101, thereby enabling power line carrier communication between the power line carrier communication devices 100 via the power line 101 (see, for example, Patent Document 1). ).
JP 2005-236815 A

  By the way, the power line 101 used as a communication line is not shielded because it is not originally laid as a communication line, and there is a place where the end of the line is open, for example, an outlet, for distribution indoors. is there. For this reason, the power line 101 may function as an extremely efficient antenna for radio waves having a predetermined frequency (wavelength) propagating in the air. In such a case, the radio waves are used as common mode noise. 101 is superimposed. Furthermore, since the power line 101 is not originally laid as a communication line, the degree of balance is low. For example, as a switch for turning on / off an indoor lighting fixture, a single-cut switch is generally used, that is, a switch is interposed only in one phase of the power line 101. Then, since the power line 101 becomes an unbalanced line, the common mode noise generated by picking up the radio wave as described above is converted to the differential mode and propagates through the power line 101 as a disturbing signal. When the frequency, that is, the frequency of the radio wave propagating in the air is within the frequency band used for power line carrier communication, there is a disadvantage that the power line carrier communication is disturbed.

  For example, in the configuration of a general power line carrier communication modem such as the power line carrier communication apparatus 100 shown in FIG. 13, a reception amplifier 104 is provided to amplify a power line carrier communication signal having a low level. The amplifier 104 amplifies the interference signal other than the power line carrier communication signal, and when the reception level of the power line carrier communication signal is small and the level of the interference signal is large, the interference signal having a large level is further amplified. The received signal will be distorted. Since the reception signal distorted by the interference signal is transmitted to the reception signal processing unit 105 at the subsequent stage, there is a problem that signal identification becomes difficult and the communication performance of the power line carrier communication apparatus 100 is deteriorated.

  The present invention has been made in view of such a problem, and an object thereof is to provide a power line carrier communication device capable of reducing the influence of noise superimposed on a power line shared for transmission of communication signals. And

  In order to achieve the above object, a power line carrier communication device according to the first means of the present invention is connected to another power line carrier communication device via a pair of conductor lines shared for power supply and transmission of communication signals. A power line carrier communication device that performs communication between the first and second connection terminals for connection to the pair of conductor lines, a ground terminal used for grounding, and the first and second connection terminals, respectively. The first transformer to which the primary winding is connected, the second transformer having the first, second and third windings, and the first signal generated in the secondary winding of the first transformer to the communication. A first filter unit that selectively passes a signal having a frequency to be used; and a signal having a frequency that is used for the communication from a second signal generated in the third winding of the second transformer; Characteristic that allows signal to pass through the first filter section A second filter section that is substantially the same, a difference signal output section that outputs a difference between a signal passing through the first filter section and a signal passing through the second filter section as a difference signal, and the difference A differential signal output from the signal output unit, and a reception processing unit that acquires the differential signal as the communication signal, wherein both ends of the series circuit in which the first and second windings are connected in series in the same polarity direction And a connection point of the first and second windings in the series circuit is connected to the ground terminal, and a winding of a primary winding and a secondary winding in the first transformer. The line ratio is characterized by being equal to a winding ratio between the first winding and the third winding and a winding ratio between the second winding and the third winding.

  In the above power line carrier communication device, the differential signal output unit amplifies a signal passing through the first filter unit and a signal passing through the second filter unit and amplifies the signal. A difference between a second amplification unit whose rate is set substantially the same as that of the first amplification unit, a signal amplified by the first amplification unit, and a signal amplified by the second amplification unit; And a difference unit for outputting as a feature.

  Further, in the above power line carrier communication device, the difference unit is configured by using a three-winding third transformer including fourth, fifth, and sixth windings, and the fourth winding and the fourth winding. A series circuit in which a winding and a fifth winding having the same number of windings are connected in series in the same polarity direction is connected between the signal output terminal of the first amplification unit and the signal output terminal of the second amplification unit. The connection point of the fourth and fifth windings in the series circuit is connected to the ground, and a signal generated in the sixth winding is output as the differential signal.

  In the power line carrier communication device described above, the amplification factor of the second amplification unit is variable, and a communication signal transmitted from the other power line carrier communication device is erroneously received by the reception processing unit. An error rate calculation unit that calculates an error rate that is an error rate, and an amplification rate adjustment unit that adjusts the amplification rate of the second amplification unit so as to reduce the error rate calculated by the error rate calculation unit It is characterized by providing.

  In the power line carrier communication apparatus described above, the third winding is characterized in that a winding ratio with respect to the first and second windings is variable.

  Further, in the above power line carrier communication device, the third winding includes a plurality of intermediate taps, selects a signal generated in any of the plurality of intermediate taps, and uses the second filter as the second signal. It is further characterized by further comprising a changeover switch that makes the ratio of the number of turns of the third winding variable by outputting to the section.

  Further, in the above power line carrier communication device, an error rate calculation unit that calculates an error rate that is a rate at which a communication signal transmitted from the other power line carrier communication device is erroneously received by the reception processing unit; and It further includes a changeover switch control unit that switches a signal selected by the changeover switch so as to reduce the error rate calculated by the error rate calculation unit.

  Further, in the above power line carrier communication device, a power supply unit that supplies power for operation of the first and second amplification units based on power supply power received by the first and second connection terminals, and the second amplification unit An error that is a rate at which a communication signal transmitted from the other power line carrier communication device is erroneously received by the reception processing unit and a switch that turns on and off a signal path through which a signal amplified by the signal is output to the difference unit An error rate calculation unit for calculating a rate, and when the error rate calculated by the error rate calculation unit is less than a predetermined determination value, the switch is turned off and the power supply unit to the second amplification unit Power supply control for stopping the operation power supply and turning on the switch when a predetermined determination value is exceeded and supplying the operation power from the power supply unit to the second amplification unit. It is characterized by further comprising a section.

  Further, in the above power line carrier communication device, the power supply unit has a high impedance with respect to a signal having a frequency used for the communication and a filter having a low impedance with respect to a commercial power supply frequency. It is characterized by being connected to two connection terminals.

  In the power line carrier communication device having such a configuration, the signal received by the first and second connection terminals is set to a voltage according to the ratio of the number of turns of the primary winding and the secondary winding of the first transformer. A frequency component used for communication passes through the first filter unit and is input to the differential signal output unit. On the other hand, the common component of the signals received by the first and second connection terminals is the first winding and the third winding of the second transformer having the same winding number ratio as that of the first transformer. , And voltage conversion by the second and third windings, and a frequency component used for communication passes through the second filter unit and is input to the differential signal output unit. In addition, the differential component of the signals received by the first and second connection terminals depends on the turn ratio between the first winding and the second winding of the second transformer and the third winding. The frequency component used for communication passes through the second filter unit and is input to the differential signal output unit. Then, since the common component in the signal that has passed through the first filter unit, that is, the interference signal component, is equal to the common component in the signal that has passed through the second filter unit, the common component is subtracted in the differential signal output unit to remove the interference signal component. Is done. On the other hand, a differential component in the signal that has passed through the first filter unit, that is, a communication signal component, is a differential component in the signal that has passed through the second filter unit, which is the ratio of the number of turns of the first transformer to the second transformer. A voltage difference is generated according to the difference, and the difference signal output unit outputs the difference as a difference signal and is acquired as a communication signal by the reception processing unit. Therefore, noise superimposed on the power line shared for transmission of the communication signal Can be reduced.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a block diagram showing an example of the configuration of the power line carrier communication apparatus according to the first embodiment of the present invention. The power line carrier communication apparatus 1 shown in FIG. 1 is connected to another power line carrier communication apparatus 1 ′ connected to the conductor lines L and N using a pair of conductor lines L and N that supply a commercial AC power supply voltage AC of 100 V, for example. For example, the first connection terminal 2, the second connection terminal 3, the ground terminal 4, the coupling circuit 5, the reception filter BPF1 (first filter unit), the reception filter BPF2 (second filter unit), and the transmission filter BPF3. , Differential amplifier AMP1 (first amplification unit), differential amplifier AMP2 (second amplification unit), differential amplifier AMP3 (difference unit), power amplifier AMP4, transmission signal processing unit 6, reception signal processing unit 7, control unit 8, an impedance upper 9 (filter), and a power supply unit 10 are provided. In this case, the differential amplifier AMP1, the differential amplifier AMP2, and the differential amplifier AMP3 constitute a differential signal output unit.

  The first connection terminal 2 and the second connection terminal 3 are external connection terminals for connecting to a pair of conductor lines L and N, respectively. The ground terminal 4 is an external ground terminal used for grounding, and is connected to the ground line E to be grounded.

  The coupling circuit 5 includes capacitors C1 and C2, a transformer T1 (first transformer), and a three-winding transformer T2 (second transformer). Capacitors C1 and C2 are capacitors that cut the commercial power supply frequency (power supply component). Both ends of the primary winding n11 of the transformer T1 are connected to the first connection terminal 2 and the second connection terminal 3 via capacitors C1 and C2, respectively. The secondary winding n12 of the transformer T1 is connected to the input terminal of the differential amplifier AMP1 for reception via the reception filter BPF1, and is also connected to the output terminal of the power amplifier AMP4 for transmission.

  The transformer T2 includes a first winding n21, a second winding n22, and a third winding n23. One end of the series circuit in which the first winding n21 and the second winding n22 are connected in series in the same polarity direction is connected to the first connection terminal 2 via the capacitor C1, and the other end is connected via the capacitor C2. The connection point of the first winding n21 and the second winding n22 is connected to the ground terminal 4 and connected to the second connection terminal 3. Further, the third winding n23 is connected to the input terminal of the receiving differential amplifier AMP2 via the receiving filter BPF2.

  The winding ratio between the primary winding n11 and the secondary winding n12 in the transformer T1 is, for example, 1: 1, and the windings of the first winding n21, the second winding n22, and the third winding n23. The ratio is, for example, 1: 1: 1.

  The reception filter BPF1 is a bandpass filter that selectively passes a signal of a frequency used for communication, for example, a signal of 2 MHz to 30 MHz, from the first signal K1 generated in the secondary winding n12 of the transformer T1. The reception filter BPF2 is a bandpass filter having substantially the same characteristics as the reception filter BPF1 and allows signals to pass through. The reception filter BPF2 has a frequency signal used for communication from the second signal K2 generated in the third winding n23 of the transformer T2, for example, A signal of 2 MHz to 30 MHz is selectively passed. Note that “substantially the same” means that the same range includes a range of manufacturing variations and errors. Further, the reception filters BPF1 and BPF2 are not limited to passing signals of 2 MHz to 30 MHz, and may pass other frequencies used in power line carrier communication.

  The signal that has passed through the reception filter BPF1 is amplified by the differential amplifier AMP1 and output to the differential amplifier AMP3. The signal that has passed through the reception filter BPF2 is amplified by the differential amplifier AMP2 having a signal amplification factor substantially the same as that of the differential amplifier AMP1, and is output to the differential amplifier AMP3. The signal amplification factor of the differential amplifier AMP2 is made variable according to the control signal AGC from the control unit 8. The differential amplifier AMP3 outputs the difference between the signal amplified by the differential amplifier AMP1 and the signal amplified by the differential amplifier AMP2 to the reception signal processing unit 7 as a difference signal K3.

  The reception signal processing unit 7 is a communication interface circuit that converts the differential signal K3 into a signal form that can be processed by the control unit 8 and outputs the signal form to the control unit 8 as a reception signal Rx. The transmission signal processing unit 6 is a communication interface circuit that converts the transmission signal Tx output from the control unit 8 into a signal form for power line carrier communication and outputs the signal form to the power amplifier AMP4 via the transmission filter BPF3.

  The power amplifier AMP4 amplifies the signal output from the transmission filter BPF3 and outputs the amplified signal to the secondary winding n12 of the transformer T1. Then, a signal induced in the primary winding n11 of the transformer T1 is output to the conductor lines L and N via the capacitors C1 and C2, and a communication signal is superimposed on the commercial AC power supply voltage AC to be applied to the conductor lines L and N. Communication with other connected power line carrier communication apparatuses 1 ′ is enabled.

  The power supply unit 10 is connected to the connection terminals 2 and 3 via an impedance upper 9 having a high impedance with respect to a signal having a frequency used for communication, for example, a signal of 2 MHz to 30 MHz. Then, the power supply voltage supplied from the commercial AC power supply to the connection terminals 2 and 3 via the conductor lines L and N is acquired via the impedance upper 9, and to each part in the power line carrier communication device 1 based on this power supply voltage. Supply power for operation. In this case, the impedance upper 9 increases the input impedance of the power supply unit 10 with respect to a signal having a frequency used for communication, so that the impedance of the conductor lines L and N with respect to the communication signal is lowered by the power supply unit 10 to generate a communication signal. Attenuation is reduced.

  The control unit 8 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a ROM (Read Only Memory) that stores a predetermined control program, and a RAM (Random Access Memory) that temporarily stores data. And a serial communication interface circuit such as USART (Universal Synchronous and Asynchronous Receiver-Transmitter), and peripheral circuits thereof, and the like, and by executing a control program stored in the ROM, a transmission processing unit 81, It functions as a reception processing unit 82, an error rate calculation unit 83, and an amplification factor adjustment unit 84.

  The reception processing unit 82 includes, for example, the conductor lines L and N, the coupling circuit 5, the reception filter BPF1, the differential amplifiers AMP1 and AMP3, and the reception signal from the other power line carrier communication device 1 ′ connected to the conductor lines L and N. A reception signal Rx received via the processing unit 7 is acquired, and a control signal is output to an electric device such as a discharge lamp (not shown) according to the reception data to control its operation.

  The transmission processing unit 81 receives predetermined data from an electrical device (not shown) connected to the control unit 8, and receives the received data as a transmission signal processing unit 6, a transmission filter BPF3, a power amplifier AMP4, a coupling circuit 5, And transmitted to another power line carrier communication device 1 ′ via the conductor lines L and N.

  In this case, the electrical device connected to the control unit 8 is a device that operates using electricity as an energy source. For example, a device that adjusts an office environment or a dwelling unit environment such as a lighting fixture or an air conditioner, an elevator, an escalator, or the like. Mobility assistance equipment that assists the movement of people, measuring devices such as power meters, gas meters and water meters, smoke sensors, sensors such as temperature sensors, humidity sensors, and illuminance sensors, dwelling equipment such as electronic lock devices, televisions, Home appliances such as video tape recorders, DVD recorders and washing machines, information processing equipment such as computers, communication equipment such as telephones and facsimile machines, and medical equipment such as pulse meters, thermometers, blood oximeters and electrocardiographs, etc. It is.

  The error rate calculation unit 83 calculates the error rate (error rate) of the reception signal Rx received by the reception processing unit 82. For example, when the reception processing unit 82 receives the reception signal Rx in which the data content and the data amount are set in advance, the error rate calculation unit 83 sets the preset data in the received data. The ratio containing different data is calculated as the error rate.

  Note that the error rate calculation unit 83 only needs to be able to calculate the error rate with an accuracy that can roughly determine whether the communication quality is good or bad. For example, the error rate calculation unit 83 can determine that the communication signal transmitted through the conductor lines L and N is When receiving a disturbance such as a waveform being distorted by an interference wave, the reception signal processing unit 7 cannot recognize the signal and cannot receive the signal. A value obtained by subtracting the amount of data actually received as the received signal Rx from the amount, that is, the ratio of the amount of data that could not be received may be calculated as the error rate.

  The amplification factor adjustment unit 84 adjusts the signal amplification factor of the differential amplifier AMP2 by outputting a control signal AGC so as to reduce the error rate calculated by the error rate calculation unit 83. Specifically, the amplification factor adjustment unit 84, for example, changes the signal amplification factor of the differential amplifier AMP2 using the control signal AGC, and then repeats the operation of calculating the error rate by the error rate calculation unit 83, thereby causing an error. The signal amplification factor of the differential amplifier AMP2 that minimizes the rate is searched and adjusted to the searched signal amplification factor.

  Next, the operation of the power line carrier communication apparatus 1 shown in FIG. 1 will be described. First, a communication signal for power line carrier communication is output to the conductor lines L and N from another power line carrier communication device 1 ′ connected to the conductor lines L and N, and is superimposed on the commercial AC power supply voltage AC in the conductor lines L and N. Is transmitted and received at the connection terminals 2 and 3 in the power line carrier communication apparatus 1. The capacitors C1 and C2 cut the power supply component of the signals received at the connection terminals 2 and 3, and the frequency component including the remaining communication signal is output to the reception filter BPF1 via the transformer T1, and further the communication signal Frequency component passes through the reception filter BPF1 and is input to the input terminal of the differential amplifier AMP1.

  Here, when the conductor lines L and N become antennas and radio waves propagating in the air are superimposed on the conductor lines L and N, if the conductor lines L and N are balanced with respect to the ground, the conductor A common mode interference signal component of the same level appears in each of the lines L and N, and no interference signal component appears between the lines. However, when the conductor lines L and N are unbalanced with respect to the ground as in the case of home wiring, the magnitude of the disturbing signal component appearing on each line is different. As a result, a difference in the magnitude of the common mode interference signal component appearing on each line appears between the lines.

  When this interference signal component is within the power line carrier communication band, the interference signal component passes through the capacitors C1 and C2 and the transformer T1 together with the communication signal and is input to the reception filter BPF1. The reception filter BPF1 passes only the signal of the power line carrier communication band, but the interference signal component cannot be removed because the interference signal component is also in the band, and the interference signal component is also included in the differential amplifier AMP1 together with the communication signal. The voltage is input to the input terminal, amplified by the differential amplifier AMP1, and output to the differential amplifier AMP3.

  On the other hand, of the signals received at the connection terminals 2 and 3, the signal component that has passed through the capacitor C1 flows to the ground via the first winding n21, the ground terminal 4 and the ground line E in the transformer T2, and passes through the capacitor C2. The signal component that has passed through the second winding n22 in the transformer T2 flows to the ground through the ground terminal 4 and the ground line E.

  Here, when the conductor lines L and N are balanced and the disturbance signal component superimposed on the conductor line L and the disturbance signal component superimposed on the conductor line N are equal, the first winding n21 and the second winding Since the magnitudes of the currents flowing through n22 are equal and opposite in polarity, the interference signal is canceled by the first winding n21 and the second winding n22, and no voltage is generated in the third winding n23.

  However, when the conductor lines L and N are unbalanced, the magnitudes of currents flowing through the first winding n21 and the second winding n22 of the transformer T2 are different, and the voltage difference signal K3 corresponding to this difference is the third winding. It will occur on line n23. The differential signal K3 passes through the reception filter BPF2 and is amplified by the differential amplifier AMP2. Since the amplified interference signal component is equal to the interference signal component included in the output signal of the differential amplifier AMP1, the output voltage of the differential amplifier AMP1 and the output voltage of the differential amplifier AMP2 are differentiated by the differential amplifier AMP3. By performing dynamic amplification, it becomes possible to remove the interference signal component, and it is possible to input only a desired power line carrier communication signal to the reception signal processing unit 7.

  Specifically, the winding ratio of the primary winding n11 and the secondary winding n12 in the transformer T1 is 1: 1, and the first winding n21, the second winding n22, and the third winding n23 are wound. Under the condition that the line ratio is 1: 1: 1, the differential voltage between the connection terminals 2 and 3 is Vd, the common voltage between the connection terminal 2 and the ground terminal 4 is Vc1, and between the connection terminal 3 and the ground terminal 4 Is Vc2, the signal K1 output from the secondary winding n12 of the transformer T1 is Vd + Vc1-Vc2. On the other hand, in the transformer T2, since the differential voltage Vd is applied to the series circuit of the first winding n21 and the second winding n22, the relationship of the winding ratio of the transformer T2 to the differential voltage Vd is (n21 + n22): As a result of n23 = 2: 1, the differential voltage Vd is halved by the transformer T2 and output from the third winding n23. Therefore, the signal K2 output from the third winding n23 of the transformer T2 is Vd / 2 + Vc1-Vc2.

  Here, when the amplification factor of the differential amplifiers AMP1 and AMP2 is α and the amplification factor of the differential amplifier AMP3 is β, the differential signal K3 of the differential amplifier AMP3 is β (αK1−αK2) = βVd / 2, Common voltages Vc1 and Vc2, which are common mode voltage components generated by superimposing propagating radio waves on conductor lines L and N, are removed, and βVd / 2 which is a communication signal component is obtained.

  Based on the difference signal K3 from which the common voltages Vc1 and Vc2 are removed in this way, the reception signal processing unit 7 generates the reception signal Rx and the reception processing unit 82 acquires the reception signal Rx. The influence of noise superimposed on N can be reduced, and the communication reliability can be improved.

  In the transformer T1, the winding ratio of the primary winding n11 and the secondary winding n12 is 1: 1, and the winding ratio of the first winding n21, the second winding n22, and the third winding n23 is In the case of 1: 1: 1, the winding ratio between the primary winding n11 and the secondary winding n12, the winding ratio between the first winding n21 and the third winding n23, and the second winding are described. The winding ratio between the line n22 and the third winding n23 may be equal, and the winding ratio between the first winding n21 and the second winding n22 may be 1: 1. If the winding ratio with the next winding n12 is 1: 2, the winding ratio of the first winding n21, the second winding n22, and the third winding n23 is 1: 1: 2. Also good.

  Incidentally, as described above, the winding ratio of the primary winding n11 and the secondary winding n12 in the transformer T1 is 1: 1, and the first winding n21, the second winding n22, and the third winding n23. If the winding ratio of the differential amplifiers AMP1 and AMP2 is equal, the differential signal K3 of the differential amplifier AMP3 is a communication signal component from which the common voltages Vc1 and Vc2 are removed. A certain βVd / 2 can be obtained. For example, when the voltage magnification according to the winding ratio cannot be obtained due to variations in characteristics of the transformers T1 and T2, or when the amplification factors of the differential amplifiers AMP1 and AMP2 vary and are not equal. The common voltages Vc1 and Vc2 are not removed, and the interference signal component is still included in the differential signal K3, making it difficult for the reception signal processing unit 7 to correctly receive the communication signal. I fear there is.

  Therefore, in the power line carrier communication device 1, the noise component is reduced by adjusting the amplification factor of the differential amplifier AMP2. FIG. 2 is a sequence diagram for explaining the adjustment process of the amplification factor of the differential amplifier AMP2. FIG. 3 is a flowchart for explaining the adjustment process of the amplification factor of the differential amplifier AMP2. In the following description, in order to simplify the description, the coupling circuit 5 in the transmission / reception operation, the transmission signal processing unit 6, the reception signal processing unit 7, the transmission processing unit 81, the reception processing unit 82, the differential amplifiers AMP1, AMP2, and the like. Description of the operations of the AMP3, the power amplifier AMP4, the reception filters BPF1, BPF2, and the transmission filter BPF3 is omitted. In addition, the same step number is assigned to the same operation, and the description thereof is omitted.

  First, when data is transmitted from the power line carrier communication device 1 ′ to the power line carrier communication device 1, a transmission permission request command for requesting permission for transmission is transmitted from the power line carrier communication device 1 ′ to the power line carrier communication device 1 ( # 1). Then, whether or not the received data is a transmission permission request command is confirmed by the amplification factor adjustment unit 84 in the power line carrier communication apparatus 1 (step S1), and is a transmission permission request command (YES in step S1). The signal AGC is set to an initial value (step S2).

  FIG. 4 is an explanatory diagram showing an example of the relationship between the level of the control signal AGC and the amplification factor G of the differential amplifier AMP2. As shown in FIG. 4, the amplification factor G increases or decreases according to the increase or decrease of the level of the control signal AGC. The initial value of the control signal AGC is set in advance to, for example, zero in order to make the gain G smaller than the gain of the differential amplifier AMP1. It is desirable that the initial value of the control signal AGC is smaller than the gain of the differential amplifier AMP1 and the difference is smaller, and the value of the control signal AGC satisfying such conditions is set as the initial value. You may do it.

  Next, 100% is set to the variable ERR by the amplification factor adjustment unit 84 (step S3), and a transmission request response is transmitted from the power line carrier communication device 1 to the power line carrier communication device 1 '(step S4). Then, a control information command is transmitted from the power line carrier communication device 1 'to the power line carrier communication device 1 (# 2). The control information command is set to, for example, a preset data amount, for example, a 1 kB data amount.

  Then, the amplification factor adjusting unit 84 in the power line carrier communication device 1 confirms whether or not the received data is a transmission permission request command (step S1), and is not a transmission permission request command (NO in step S1). It is confirmed whether or not the data is a control information command (step S5), and since it is a control information command (YES in step S5), the current error rate is calculated by the error rate calculation unit 83 (step S6). Specifically, the error rate calculation unit 83 can receive a value obtained by subtracting the data amount actually received as the reception signal Rx from the set reception data amount with respect to a preset data amount, for example, 1 kB. The ratio of the missing data amount is calculated as the actual error rate EX.

  Next, whether or not the error rate EX is a preset minimum value is confirmed by the amplification factor adjusting unit 84 (step S7). In this case, the minimum value of the error rate EX is, for example, the minimum value of the error rate that can be expected in the modulation method of the power line carrier communication employed in the power line carrier communication device 1, that is, when it is not affected by noise. The obtained error rate is set as the minimum value of the error rate EX.

  If the error rate EX is the minimum value, it is considered that the error rate EX is not affected by noise. Therefore, from the power line carrier communication device 1 to the power line carrier communication device 1 ′ to start data transmission from the power line carrier communication device 1 ′. If the error rate EX is not the minimum value (NO in step S7), the amplification rate adjusting unit 84 compares the error rate EX with the variable ERR (step S8). If the error rate EX is smaller than the variable ERR (YES in step S8), the control signal AGC is increased by a preset ΔAGC to increase the amplification factor G of the differential amplifier AMP2 (step S9), and the error rate is set in the variable ERR. EX is substituted (step S10), and the power line carrier communication apparatus 1 again calculates the error rate EX. Control information transmission request is transmitted to the Luo power line communication apparatus 1 '(step S11). Then, a control information command is transmitted from the power line carrier communication apparatus 1 'to the power line carrier communication apparatus 1 (# 3). If ΔAGC is reduced, the adjustment time is increased instead of improving the adjustment accuracy of the amplification factor G, and if ΔAGC is increased, the adjustment time is shortened instead of the adjustment accuracy of the amplification factor G being decreased. It may be set as appropriate according to the required specifications.

  Then, the amplification factor adjusting unit 84 in the power line carrier communication device 1 confirms whether or not the received data is a transmission permission request command (step S1), and is not a transmission permission request command (NO in step S1). It is confirmed whether or not the data is a control information command (step S5), and since it is a control information command (YES in step S5), the current error rate is newly calculated by the error rate calculation unit 83 (step S6). .

  Next, the gain adjustment unit 84 checks whether or not the error rate EX is a preset minimum value (step S7). If the error rate EX is not the minimum value (NO in step S7), the gain adjustment is performed. The error rate EX is compared with the variable ERR by the unit 84 (step S8). If the error rate EX is smaller than the variable ERR again (YES in step S8), the control signal AGC is increased by a preset ΔAGC, and the differential amplifier The amplification factor G of AMP2 is increased (step S9), the error rate EX is substituted into the variable ERR (step S10), and control information is transmitted from the power line carrier communication device 1 to the power line carrier communication device 1 ′ to calculate the error rate EX again. A transmission request is transmitted (step S11). Then, a control information command is transmitted from the power line carrier communication device 1 'to the power line carrier communication device 1 (# 4).

  The processes in steps S1 to S11 are repeated until the error rate EX becomes larger than the variable ERR, and the value of the control signal AGC that minimizes the error rate EX is searched.

  Then, the amplification factor adjusting unit 84 in the power line carrier communication device 1 confirms whether or not the received data is a transmission permission request command (step S1), and is not a transmission permission request command (NO in step S1). It is confirmed whether or not the data is a control information command (step S5), and since it is a control information command (YES in step S5), the current error rate is newly calculated by the error rate calculation unit 83 (step S6). .

  Next, the gain adjustment unit 84 checks whether or not the error rate EX is a preset minimum value (step S7). If the error rate EX is not the minimum value (NO in step S7), the gain adjustment is performed. The error rate EX is compared with the variable ERR by the unit 84 (step S8). If the error rate EX is equal to or greater than the variable ERR (NO in step S8), the control signal AGC is set too large, so that the control signal AGC is ΔAGC. And the gain G of the differential amplifier AMP2 is decreased (step S12), and a transmission permission command is sent from the power line carrier communication device 1 to the power line carrier communication device 1 ′ to start data transmission from the power line carrier communication device 1 ′. Is transmitted (step S13). Then, data transmission from the power line carrier communication device 1 'to the power line carrier communication device 1 is started (# 5).

  Then, the amplification factor adjusting unit 84 in the power line carrier communication device 1 confirms whether or not the received data is a transmission permission request command (step S1), and is not a transmission permission request command (NO in step S1). It is confirmed whether or not the data is a control information command (step S5). Since it is not a control information command (NO in step S5), the reception processing unit 82 executes a data reception process (step S14).

  Thereby, since the amplification factor G of the differential amplifier AMP2 is automatically set so as to reduce the error rate EX in the power line carrier communication apparatus 1, the reliability of the power line carrier communication can be improved.

  Further, the power line carrier communication apparatus 1 and the power line carrier communication apparatus 1 ′ are switched and the processes of steps S1 to S15 are executed again, so that the error rate EX in the power line carrier communication apparatus 1 ′ is reduced. Since the amplification factor G of the differential amplifier AMP2 of the device 1 ′ is automatically set, the reliability of power line carrier communication can be improved.

  As shown in FIG. 5, a three-winding transformer T3 (third transformer) may be used as the difference unit instead of the differential amplifier AMP3. In the power line carrier communication apparatus 1 shown in FIG. 5, the transformer T3 includes a first winding n31 (fourth winding), a second winding n32 (fifth winding), and a third winding n33 (sixth winding). ). One end of the series circuit in which the first winding n31 and the second winding n32 are connected in series in the same polarity direction is connected to the output terminal of the differential amplifier AMP1, and the other end is connected to the output terminal of the differential amplifier AMP2. The connection point between the first winding n31 and the second winding n32 is connected to the circuit ground. Further, one end of the third winding n33 is connected to the input terminal of the reception signal processing unit 7, and the other end is connected to the circuit ground.

  In this case, since the output signals of the differential amplifier AMP1 and the differential amplifier AMP2 are input with opposite polarities to the first winding n31 and the second winding n32 of the transformer T3, respectively, the same level included in each output signal The interference signal components cancel each other, and only the differential signal component indicating the communication signal is induced in the third winding n33, and is output from the transformer T3 to the reception signal processing unit 7 as the differential signal K3. As a result, the difference between the output signal of the differential amplifier AMP1 and the output signal of the differential amplifier AMP2 can be output as the difference signal K3 to the reception signal processing unit 7 using the transformer T3 instead of the differential amplifier AMP3. Thus, the power consumption of the power line carrier communication apparatus 1 can be reduced by reducing the power for operation of the differential amplifier AMP3.

  The winding ratio of the first winding n31, the second winding n32, and the third winding n33 is preferably 1: 1: 2. For example, when n31: n32: n33 = 1: 1: 1, the winding ratio of the series circuit of the first winding n31 and the second winding n32 and the third winding n33 is 2: 1. Although the difference between the output signal of the differential amplifier AMP1 and the output signal of the differential amplifier AMP2 is halved and induced in the third winding n33, n31: n32: n33 = 1: 1: 2. Thus, it is possible to output the difference signal K3 to the reception signal processing unit 7 while maintaining the level of the differential component input to the series circuit of the first winding n31 and the second winding n32.

(Second Embodiment)
Next, a power line carrier communication apparatus according to the second embodiment of the present invention will be described. FIG. 6 is a block diagram showing an example of the configuration of the power line carrier communication apparatus 1a according to the second embodiment of the present invention. The power line carrier communication apparatus 1a shown in FIG. 6 differs from the power line carrier communication apparatus 1 shown in FIG. 1 in the following points. That is, the power line carrier communication device 1a shown in FIG. 6 further includes a changeover switch SW1 and a changeover switch control unit 85 instead of the amplification factor adjustment unit 84.

  The third winding n23a in the transformer T2 includes a plurality of intermediate taps, for example, seven intermediate taps a to g (four intermediate taps are shown in FIG. 6). The changeover switch SW1 is a changeover switch that selects a signal generated in any of the intermediate taps a to g in the third winding n23a and outputs the selected signal to the reception filter BPF2 as the signal K2.

  FIG. 7 is a table showing an example of the relationship between the switching position of the changeover switch SW1 (the position of the intermediate tap in the third winding n23a) and the winding ratio of the three windings (n21, n22, n23a) in the transformer T2. It is explanatory drawing of. As shown in FIG. 7, when the changeover switch SW1 is switched to the position of the intermediate tap a, n21: n22: n23a = 1: 1: 0.7. Hereinafter, the changeover position of the changeover switch SW1 is changed from the intermediate tap a to g. As the switching is performed in order, the winding ratio of the third winding n23a increases, that is, the signal level of the output signal K2 of the changeover switch SW1 increases. It is desirable that an intermediate tap be provided so that the winding number ratio of the third winding n23a in the transformer T2 to the first winding n21 and the second winding n22 can be finely adjusted around “1”.

  The changeover switch control unit 85 switches the changeover switch SW1 using the control signal SSW so as to reduce the error rate calculated by the error rate calculation unit 83. Specifically, the changeover switch control unit 85 switches the error rate to the minimum by repeating the operation of calculating the error rate by the error rate calculation unit 83 after switching the changeover switch SW1 using, for example, the control signal SSW. A switch position of the switch SW1 is searched, and the switch SW1 is switched to the switch position.

  Other configurations and operations are the same as those of the power line carrier communication apparatus 1 shown in FIG. FIG. 8 is a sequence diagram for explaining the switching process of the changeover switch SW1. FIG. 9 is a flowchart for explaining the switching process of the selector switch SW1.

  The operation of the changeover switch control unit 85 in FIGS. 8 and 9 is different from the operation of the amplification factor adjustment unit 84 in FIGS. 2 and 3 in that the changeover switch SW1 has the highest winding ratio of the third winding n23a in step S21. At the point of switching to the small intermediate tap a, in step S22, the changeover switch SW1 is switched one by one in the order of the intermediate taps a, b, c, d, e, f, and g, so that the winding ratio of the third winding n23a is increased. Is gradually increased to increase the signal level of the output signal K2, and in step S23, the selector switch SW1 is switched one by one in the order of the intermediate taps g, f, e, d, c, b, and a. The difference is that the signal level of the output signal K2 is decreased by gradually decreasing the winding ratio of the third winding n23a.

  As a result, as in the case of the power line carrier communication apparatus 1 shown in FIG. 1, the changeover switch SW1 is automatically switched so as to reduce the error rate EX in the power line carrier communication apparatus 1a. Can be improved.

  Note that the third winding n23a is not limited to the example in which the winding ratio with respect to the first winding n21 and the second winding n22 is made variable using a plurality of intermediate taps and the changeover switch SW1, for example, The three windings n23a may be configured to continuously change the winding number ratio like a slidac.

  The changeover switch control unit 85 may not be provided, and the changeover switch SW1 may be configured as a manual changeover switch, or may be provided with an operation knob that makes the turn ratio of the third winding n23a variable. In this case, the user operates the changeover switch SW1 and the operation knob as appropriate while confirming the operating state of the power line carrier communication device 1, thereby reducing the error rate EX in the power line carrier communication device 1a and improving the reliability of the power line carrier communication. Can be improved.

(Third embodiment)
Next, a power line carrier communication apparatus according to the third embodiment of the present invention will be described. FIG. 10 is a block diagram showing an example of the configuration of the power line carrier communication apparatus 1b according to the third embodiment of the present invention. The power line carrier communication apparatus 1b shown in FIG. 10 is different from the power line carrier communication apparatus 1 shown in FIG. 1 in the following points. That is, the power line carrier communication device 1b shown in FIG. 10 further includes switches SW2 and SW3 and a power supply controller 86.

  The switch SW2 is a switch that turns on and off the signal path through which the output signal of the differential amplifier AMP2 is output to the differential amplifier AMP3. The switch SW3 is a switch that turns on and off the supply of operating power from the power supply unit 10 to the differential amplifier AMP2.

  The power supply control unit 86 turns off the switch SW2 when the error rate EX calculated by the error rate calculation unit 83 is less than a preset determination value REF, for example, 30%, and turns the differential amplifier AMP2 into a differential amplifier. Disconnecting from AMP3 and turning off the switch SW3 stops the supply of operating power from the power supply unit 10 to the differential amplifier AMP2. When the error rate EX exceeds the determination value REF, the switch SW2 is turned on to perform differential operation. The amplifier AMP2 is connected to the differential amplifier AMP3 and the switch SW3 is turned on to supply operating power from the power supply unit 10 to the differential amplifier AMP2.

  When the error rate EX is less than the determination value REF without using the transformer T2, the reception filter BPF2, and the differential amplifier AMP2, that is, when there is no influence of the interference signal and sufficient communication performance is obtained, the switch SW2 , SW3 is turned off to reduce power consumption, and when the error rate EX is equal to or higher than the determination value REF, that is, when sufficient communication performance cannot be obtained due to the influence of the interference signal, the switches SW2 and SW3 are turned on. T2, the reception filter BPF2, and the differential amplifier AMP2 are operated to reduce the influence of interference signals.

  Since other configurations and operations are the same as those of the power line carrier communication apparatus 1 shown in FIG. 1, the description thereof will be omitted, and characteristic operations of the power line carrier communication apparatus 1b will be described. FIG. 11 is a sequence diagram for explaining a power control operation by power supply control unit 86. FIG. 12 is a flowchart for explaining the power control operation by the power supply control unit 86.

  First, a transmission permission request command requesting permission for transmission is transmitted from the power line carrier communication device 1b 'to the power line carrier communication device 1b (# 1). Then, the power controller 86 in the power line carrier communication device 1b confirms whether or not the received data is a transmission permission request command (step S31), and since it is a transmission permission request command (YES in step S31), the switch SW2 , SW3 is turned off, the differential amplifier AMP2 is disconnected from the differential amplifier AMP3, and the supply of operating power from the power supply unit 10 to the differential amplifier AMP2 is stopped (step S32).

  Next, a transmission request response is transmitted from the power line carrier communication device 1b to the power line carrier communication device 1b '(step S34). Then, a control information command is transmitted from power line carrier communication apparatus 1b 'to power line carrier communication apparatus 1b (# 2). The control information command is set to, for example, a preset data amount, for example, a 1 kB data amount.

  Then, the power control unit 86 in the power line carrier communication device 1b confirms whether or not the received data is a transmission permission request command (step S31), and is not a transmission permission request command (NO in step S31). Is a control information command (step S35), and since it is a control information command (YES in step S35), the error rate calculation unit 83 calculates the current error rate (step S36). Specifically, the error rate calculation unit 83 subtracts the data amount actually received as the reception signal Rx from the preset reception data amount with respect to a preset data amount, for example, 1 kB, that is, reception The ratio of the data amount that could not be calculated is calculated as the actual error rate EX.

  Next, the power control unit 86 compares the error rate EX with a determination value REF, for example, 30% (step S37). If the error rate EX is smaller than the determination value REF (YES in step S37), there is no influence of the interference signal. A transmission permission command is transmitted from the power line carrier communication device 1b to the power line carrier communication device 1b 'to start data transmission from the power line carrier communication device 1b' when it is determined that sufficient communication performance is obtained (step S38). Data transmission from the carrier communication device 1b ′ to the power line carrier communication device 1b is started (# 5).

  On the other hand, if the error rate EX is equal to or higher than the determination value REF (NO in step S37), the power supply control unit 86 determines that the influence of the interference signal is large and sufficient communication performance cannot be obtained, and the switches SW2 and SW3 are turned on. (Step S39), the transformer T2, the reception filter BPF2, and the differential amplifier AMP2 operate to reduce the influence of the interference signal, and then to start data transmission from the power line carrier communication device 1b ′. A transmission permission command is transmitted from the device 1b to the power line carrier communication device 1b ′ (step S40), and data transmission from the power line carrier communication device 1b ′ to the power line carrier communication device 1b is started (# 5).

  Then, the power control unit 86 in the power line carrier communication device 1b confirms whether or not the received data is a transmission permission request command (step S31), and is not a transmission permission request command (NO in step S31). Is not a control information command (step S35), and is not a control information command (NO in step S35), the data reception process is executed by the reception processing unit 82 (step S41).

  As described above, when the processing in steps S31 to S41 is not affected by the interference signal and sufficient communication performance is obtained, the switches SW2 and SW3 can be turned off to reduce the power consumption and the influence of the interference signal. If sufficient communication performance cannot be obtained, the switches SW2 and SW3 are turned on to operate the transformer T2, the reception filter BPF2, and the differential amplifier AMP2, thereby reducing the influence of the interference signal.

  The switches SW2 and SW3 and the power supply controller 86 may be provided in the power line carrier communication devices 1, 1a and 1b shown in FIGS.

It is a block diagram which shows an example of a structure of the power line carrier communication apparatus which concerns on the 1st Embodiment of this invention. It is a sequence diagram for demonstrating the adjustment process of the gain of the differential amplifier shown in FIG. 3 is a flowchart for explaining an adjustment process of an amplification factor of the differential amplifier shown in FIG. 1. FIG. 2 is an explanatory diagram illustrating an example of a relationship between a level of a gain control signal shown in FIG. It is a block diagram which shows the modification of the power line carrier communication apparatus shown in FIG. It is a block diagram which shows an example of a structure of the power line carrier communication apparatus which concerns on the 2nd Embodiment of this invention. It is explanatory drawing of the table format which showed an example of the relationship between the switching position of the selector switch shown in FIG. 6, and the turns ratio of the three windings in a transformer. It is a sequence diagram for demonstrating the switching process of the changeover switch shown in FIG. It is a flowchart for demonstrating the switching process of the selector switch shown in FIG. It is a block diagram which shows an example of a structure of the power line carrier communication apparatus which concerns on the 3rd Embodiment of this invention. It is a sequence diagram for demonstrating the electric power control operation | movement by the power supply control part shown in FIG. It is a flowchart for demonstrating the electric power control operation | movement by the power supply control part shown in FIG. It is a block diagram which shows the structure of the power line carrier communication apparatus which concerns on background art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a, 1b Power line carrier communication apparatus 2,3 Connection terminal 4 Ground terminal 5 Coupling circuit 6 Transmission signal processing part 7 Reception signal processing part 8 Control part 9 Impedance upper 10 Power supply part 81 Transmission processing part 82 Reception processing part 83 Error rate Calculation unit 84 Amplification rate adjustment unit 85 Changeover switch control unit 86 Power supply control unit AMP1, AMP2, AMP3 Differential amplifier BPF1, BPF2 Reception filter C1, C2 Capacitor K3 Difference signal L, N Conductor line REF Judgment value SW1 Changeover switch SW2, SW3 Switch T1, T2, T3 Transformer ag Intermediate tap n11 Primary winding n12 Secondary winding n21, n31 First winding n22, n32 Second winding n23, n23a, n33 Third winding

Claims (9)

A power line carrier communication device that communicates with another power line carrier communication device via a pair of conductor lines shared for power supply and transmission of communication signals,
First and second connection terminals for connecting to the pair of conductor wires, respectively;
A grounding terminal used for grounding;
A first transformer in which a primary winding is connected between the first and second connection terminals;
A second transformer comprising first, second and third windings;
A first filter unit that selectively passes a signal of a frequency used for the communication from a first signal generated in a secondary winding of the first transformer;
The second signal generated in the third winding of the second transformer selectively passes a signal having a frequency used for the communication, and the characteristics of allowing the signal to pass through the first filter unit are substantially the same. A second filter section,
A difference signal output unit that outputs a difference signal between a signal passing through the first filter unit and a signal passing through the second filter unit;
A reception processing unit that acquires the differential signal output from the differential signal output unit as the communication signal;
Both ends of a series circuit in which the first and second windings are connected in series in the same polarity direction are connected to the first and second connection terminals, respectively, and the first and second windings in the series circuit are connected. A point is connected to the ground terminal;
The winding ratio between the primary winding and the secondary winding in the first transformer is a winding ratio between the first winding and the third winding, and a winding ratio between the second winding and the third winding. A power line carrier communication device characterized by being equal to a line ratio. The differential signal output unit is
A first amplifying unit for amplifying a signal passing through the first filter unit;
A second amplifying unit for amplifying a signal passing through the second filter unit and having a signal amplification factor set to be substantially the same as that of the first amplifying unit;
The power line carrier communication apparatus according to claim 1, further comprising: a difference unit that outputs a difference between the signal amplified by the first amplification unit and the signal amplified by the second amplification unit as the difference signal. . The difference unit is configured using a three-winding third transformer including fourth, fifth, and sixth windings,
A series circuit in which the fourth winding and a fifth winding having the same number of windings as the fourth winding are connected in series in the same polarity direction, the signal output terminal of the first amplification unit and the second amplification unit Connected to a signal output terminal, the connection point of the fourth and fifth windings in the series circuit is connected to the ground, and a signal generated in the sixth winding is output as the differential signal. The power line carrier communication apparatus according to claim 2. The second amplification unit has a variable amplification factor,
An error rate calculation unit that calculates an error rate that is a rate at which the communication signal transmitted from the other power line carrier communication device is erroneously received by the reception processing unit;
4. The power line carrier according to claim 2, further comprising: an amplification factor adjustment unit that adjusts the amplification factor of the second amplification unit so as to reduce the error rate calculated by the error rate calculation unit. 5. Communication device. The power line carrier communication device according to any one of claims 1 to 3, wherein the third winding has a variable winding ratio with respect to the first and second windings. The third winding includes a plurality of intermediate taps,
A changeover switch that selects a signal generated in any of the plurality of intermediate taps and outputs the second signal as the second signal to the second filter unit, thereby changing a winding ratio of the third winding; The power line carrier communication device according to claim 5, comprising: An error rate calculation unit that calculates an error rate that is a rate at which the communication signal transmitted from the other power line carrier communication device is erroneously received by the reception processing unit;
The power line carrier communication apparatus according to claim 6, further comprising: a changeover switch control unit that switches a signal selected by the changeover switch so as to reduce the error rate calculated by the error rate calculation unit. A power supply for supplying power for operation of the first and second amplifying units based on the power supply received by the first and second connection terminals;
A switch for turning on and off a signal path through which a signal amplified by the second amplification unit is output to the difference unit;
An error rate calculation unit that calculates an error rate that is a rate at which the communication signal transmitted from the other power line carrier communication device is erroneously received by the reception processing unit;
When the error rate calculated by the error rate calculation unit is less than a predetermined determination value, the switch is turned off and the supply of operating power from the power supply unit to the second amplification unit is stopped, The power supply control part which supplies the said operation | movement electric power from the said power supply part to the said 2nd amplification part while turning on the said switch when it exceeds the preset judgment value further, It is characterized by the above-mentioned. The power line carrier communication device described. The power supply unit is connected to the first and second connection terminals via a filter having a high impedance with respect to a signal having a frequency used for the communication and a low impedance with respect to a commercial power supply frequency. The power line carrier communication apparatus according to claim 8.

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