JP2017034592A - Power line communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power line communication device that comprises an AGC circuit and is capable of achieving stable and good communication quality as much as possible.SOLUTION: A power line communication device comprises: a filter unit that receives a communication signal; and an AGC circuit that receives a signal having passed through the filter unit. The filter unit includes: a bandpass filter; and a switchable filter circuit that is provided at the previous stage or subsequent stage of the bandpass filter and capable of switching between an additional filter is provided or not provided on a transmission path of the communication signal to the AGC circuit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power line communication device, and more particularly to a power line communication device including an AGC circuit.

  In power line communication (PLC), a high frequency signal in a range of several kHz to several tens of MHz or more is used as a communication signal (hereinafter also referred to as a PLC signal) through a power line through which a current of commercial frequency such as 50 Hz or 60 Hz flows. This is a communication method for transmission.

  As an example of equipment used for power line communication, for example, Japanese Patent Laid-Open No. 2008-28904 (Patent Document 1) discloses the following signal measuring device for power line communication. That is, the signal measuring device includes a connection unit for a power line on which a PLC signal for power line communication is superimposed, a filter unit for extracting a signal under measurement in a frequency band of power line communication supplied from the connection unit, and the filter A power measurement unit that measures the signal strength of the signal under measurement extracted by the unit, a display unit that displays the measurement results obtained by the measurement unit, and a power range that can be measured by the power measurement unit Intensity increasing / decreasing means for amplifying or reducing the signal under measurement so as to obtain the signal intensity to be supplied to the power measuring unit.

JP 2008-28904 A

  For example, various electric devices such as home appliances and network terminals are connected to the power line used for power line communication via an outlet. For this reason, the magnitude of the PLC signal received by the power line communication device varies depending on the installation environment, and the PLC signal may be affected by noise caused by these devices, and the communication performance may deteriorate.

  In order to satisfactorily perform reception processing of such a PLC signal whose level varies, an AGC circuit is often provided in a receiving circuit in a power line communication apparatus.

  For example, in the signal measuring instrument described in Patent Document 1, the signal to be measured that has passed through the filter unit is amplified or reduced by the intensity increasing / decreasing means so that the signal intensity is suitable for the power range that can be measured by the power measuring unit. The power is supplied to the power measurement unit.

  However, even when a filter and an AGC circuit are provided in the power line communication device, if the noise cannot be sufficiently attenuated because of a high noise level, for example, a certain amount of noise is supplied to the AGC circuit together with the PLC signal. Is done.

  In this case, gain adjustment that correctly reflects the magnitude of the PLC signal is not performed in the AGC circuit, and communication quality may deteriorate.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power line communication device capable of realizing more stable and good communication quality in a configuration including an AGC circuit. is there.

  (1) In order to solve the above problem, a power line communication apparatus according to an aspect of the present invention includes a filter unit that receives a communication signal and an AGC (Auto Gain Control) circuit that receives a signal that has passed through the filter unit. The filter unit is provided in a preceding stage or a succeeding stage of the bandpass filter, and a switching filter circuit capable of switching whether or not an additional filter is provided in a transmission path of the communication signal to the AGC circuit; including.

  The present invention can be realized not only as a power line communication apparatus including such a characteristic processing unit, but also as a method using such characteristic processing as a step, or as a program for causing a computer to execute such a step. You can do it. In addition, the present invention can be realized as a semiconductor integrated circuit that realizes part or all of the power line communication device, or as a system including the power line communication device.

  According to the present invention, more stable and good communication quality can be realized in a configuration including an AGC circuit.

FIG. 1 is a diagram showing a configuration of a power information collection system according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of the power line communication apparatus according to the embodiment of the present invention. FIG. 3 is a diagram showing a configuration of an AC coupling circuit in the power line communication apparatus according to the embodiment of the present invention. FIG. 4 is a diagram showing a configuration of the switching filter circuit in the power line communication apparatus according to the embodiment of the present invention. FIG. 5 is a diagram schematically showing an example of frequency components of a received signal of the power line communication apparatus according to the embodiment of the present invention.

  First, the contents of the embodiment of the present invention will be listed and described.

(1) A power line communication device according to an embodiment of the present invention includes a filter unit that receives a communication signal,
An AGC (Auto Gain Control) circuit that receives a signal that has passed through the filter unit, and the filter unit is provided at a preceding stage or a subsequent stage of the bandpass filter and the AGC circuit. And a switching filter circuit capable of switching whether or not to provide an additional filter in the transmission line.

  In this way, a noise removal filter is added to the receiving circuit, and the configuration in which the filter can be enabled or disabled can be selected. However, since an optimal communication signal can be given to the AGC circuit, the AGC circuit can be operated stably and deterioration of communication performance can be prevented. That is, in a power line communication device provided with a permanent filter and an AGC circuit, noise is supplied to the AGC circuit together with a communication signal even if the noise cannot be sufficiently attenuated because the noise level is high. It is possible to perform gain adjustment in the AGC circuit that suppresses and correctly reflects the magnitude of the communication signal. As a result, it is possible to satisfactorily perform reception processing of a communication signal whose level varies depending on the installation environment using the AGC circuit, and to realize good communication quality. Therefore, in the power line communication apparatus according to the embodiment of the present invention, more stable and good communication quality can be realized in the configuration including the AGC circuit.

  (2) Preferably, the additional filter is a low-pass filter or a high-pass filter.

  With such a configuration, noise existing outside the communication band can be effectively attenuated while suppressing the attenuation of the signal in the communication band with a simple circuit configuration compared to a configuration using a bandpass filter.

  (3) Preferably, the switching filter circuit includes a plurality of the additional filters having different at least one of an attenuation gradient and a cutoff frequency, and an additional filter provided in the transmission line is selected from the plurality of additional filters. Selectable.

  With such a configuration, a plurality of filters having different characteristics can be provided as additional filters, and an optimum filter corresponding to various types of noise can be selected, so that an optimum communication signal can be sent to the AGC circuit in more various environments. Can be given.

  (4) Preferably, the power line communication device further calculates the magnitude of each frequency component of the communication signal based on the output signal of the AGC circuit, and switches the switching filter circuit based on the calculation result. A control unit for controlling is provided.

  With such a configuration, after confirming the magnitude and frequency of the noise, it is possible to appropriately select whether to enable or disable the additional filter or to select the type of additional filter according to the noise environment. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. Moreover, you may combine arbitrarily at least one part of embodiment described below.

  FIG. 1 is a diagram showing a configuration of a power information collection system according to an embodiment of the present invention.

  Referring to FIG. 1, power information collection system 201 includes customer device 151 and power measurement device 152.

  For example, the power information collection system 201 measures the amount of power consumption at home and work for the purpose of power saving, collects power information indicating the measured amount of power consumption, and transmits it to a server such as a power company.

  The power measuring device 152 is connected to the concentrator 153 via the power line 91, and is connected to the customer device 151 via the power line 91.

  For example, when the power information collection system 201 is used in an apartment house, the power measuring device 152 is provided on each floor of the apartment house. The concentrator 153 is provided on the first floor of an apartment house, for example.

  In the power information collecting system 201, for example, power information from each power measuring device 152 that is a slave unit is aggregated in a concentrator 153 that is a master unit by using power line communication, and a head (not shown) that is a server of a power company or the like. Sent to the end.

  The power measuring device 152 and the concentrator 153 perform transmission / reception of signals including various information by power line communication using the power line 91.

  Specifically, the power measuring device 152 is a power measuring device with a communication function such as a smart meter, and transmits power information as a measurement result to the concentrator 153 (“A route” shown in FIG. 1).

  The concentrator 153 is an aggregation device connected to the plurality of power measurement devices 152 via the power line 91, and transmits power information received from each power measurement device 152 to the head end.

  The customer device 151 is, for example, a HEMS (Home Energy Management System) device, and is connected to one or a plurality of electric devices 161 via a power line 91. The customer apparatus 151 communicates with one or a plurality of electric appliances 161 in the home by power line communication using the power line 91. The electric device 161 is, for example, an air conditioner, a television, or a refrigerator.

  In addition, the consumer device 151 performs wired communication or wireless communication in accordance with the Ethernet (registered trademark) standard with one or more electrical devices 162 in the house. The electric device 162 is, for example, a smart phone, a tablet, a PC (personal computer), a power conditioner (PCS) of a solar power generation device, or a charging stand of an electric vehicle.

  Further, for example, the power measuring device 152 and the concentrator 153 are connected to one or a plurality of electric devices 161 via the power line 91.

  The power measuring device 152 transmits power information as a measurement result to the consumer device 151 via the power line 91 (“B route” shown in FIG. 1). Then, the consumer device 151 performs in-house power management using the received power information, for example, by displaying the power information received from the power measuring device 152 on a smart phone, tablet, or PC display in the home.

  Moreover, the consumer apparatus 151 can communicate with other apparatuses, such as a server, via the external network 301, such as the Internet, for example, and transmits information related to home power management to the other apparatuses.

  The consumer device 151, the power measuring device 152, and the concentrator 153 include a power line communication device 101 for performing power line communication via the power line 91. The power line communication device 101 can be mounted on other types of devices, or can be used as a single device.

  FIG. 2 is a diagram showing a configuration of the power line communication apparatus according to the embodiment of the present invention.

  Referring to FIG. 2, power line communication apparatus 101 includes an AC coupling circuit 11, a filter unit 12, an AGC (Auto Gain Control) circuit 13, an ADC (analog / digital converter) 14, and a control unit 15. The filter unit 12 includes a BPF (band pass filter) 21 and a switching filter circuit 22. The control unit 15 is realized by, for example, a DSP (digital signal processor). Note that a part or all of each component in the power line communication device 101 excluding the AC coupling circuit 11 may be included in one semiconductor integrated circuit.

  AC coupling circuit 11 is connected to power line 91 and AC couples power line 91 and BPF 21.

  The filter unit 12 performs a filtering process on the PLC signal received via the power line 91 and the AC coupling circuit 11.

  The AGC circuit 13 receives the PLC signal that has passed through the filter unit 12, amplifies the received PLC signal, and outputs the amplified PLC signal to the ADC 14. For example, the AGC circuit 13 adjusts the gain in the amplification of the PLC signal so that the average level of the output signal becomes an optimal constant value as the reception level of the ADC 14.

  The ADC 14 converts the PLC signal, which is an analog signal received from the AGC circuit 13, into a digital signal and outputs the digital signal to the control unit 15.

  The control unit 15 performs signal processing such as IFFT (Inverse Fast Fourier Transform) in the OFDM (Orthogonal Frequency Division Multiplex) method on the digital signal received from the ADC 14, and performs various processing using the digital signal after the signal processing. Do.

  For example, the control unit 15 generates a selection signal SEL based on the digital signal received from the ADC 14 and outputs the generated selection signal SEL to the switching filter circuit 22 in the filter unit 12.

  In the filter unit 12, the BPF 21 attenuates a component outside a predetermined frequency band among the frequency components of the PLC signal received via the power line 91 and the AC coupling circuit 11.

  The switching filter circuit 22 is provided, for example, in the subsequent stage of the BPF 21 and can switch whether or not an additional filter is provided in the transmission path of the PLC signal from the filter unit 12 to the AGC circuit 13.

  FIG. 3 is a diagram showing a configuration of an AC coupling circuit in the power line communication apparatus according to the embodiment of the present invention.

  Referring to FIG. 3, AC coupling circuit 11 includes a capacitor 31 and a transformer 32.

  The capacitor 31 is connected between the power line 91 and the first end of the primary winding of the transformer 32. The second end of the primary winding of the transformer 32 is connected to the power line 91. A first end of the secondary winding of the transformer 32 is connected to the BPF 21, and a second end is connected to a ground node to which a ground voltage is supplied.

  As described above, the configuration using the capacitor 31 and the transformer 32 eliminates the need to use a high-voltage component for the filter unit 12 or the like for an AC voltage such as AC100V or AC200V applied to the power line 91, so that the power line communication apparatus 101 Manufacturing cost can be reduced.

  FIG. 4 is a diagram showing a configuration of the switching filter circuit in the power line communication apparatus according to the embodiment of the present invention.

  Referring to FIG. 4, switching filter circuit 22 includes additional filters 42 and 43 and switches 44 and 45.

  The additional filters 42 and 43 are, for example, high-pass filters, and attenuate components below a predetermined frequency among the frequency components of the received signal. Note that the additional filters 42 and 43 may be low-pass filters. In this case, the frequency components of the received signal are attenuated at a predetermined frequency or higher.

  For example, the switching filter circuit 22 includes a plurality of additional filters that differ in at least one of the attenuation gradient and the cutoff frequency.

  Specifically, for example, the additional filter 43 has a steep frequency characteristic compared to the additional filter 42, that is, has a larger attenuation gradient than the additional filter 42. The additional filter 43 may be, for example, a filter whose cutoff frequency is closer to the carrier frequency of the PLC signal than the additional filter 42. Further, the additional filter 43 may be a filter having a steep frequency characteristic as compared with the additional filter 42 and having a cutoff frequency closer to the carrier frequency of the PLC signal.

  The cutoff frequency of the additional filters 42 and 43 is preferably outside the PLC communication band. More preferably, the end of the pass band of the additional filters 42 and 43 coincides with the end of the pass band of the BPF 21 or is outside the end.

  The switch 44 is connected between the BPF 21 and the additional filters 42 and 43 and the switch 45, and switches the connection destination of the BPF 21. More specifically, the switch 44 selects one of the additional filters 42 and 43 and the switch 45 as a connection destination of the BPF 21 based on the selection signal SEL received from the control unit 15.

  The switch 45 is connected between the AGC circuit 13 and the additional filters 42 and 43 and the switch 44 and switches the connection destination of the AGC circuit 13. More specifically, the switch 45 selects any one of the additional filters 42 and 43 and the switch 44 as a connection destination of the AGC circuit 13 based on the selection signal SEL received from the control unit 15.

  FIG. 5 is a diagram schematically showing an example of frequency components of a received signal of the power line communication apparatus according to the embodiment of the present invention. In the graph of FIG. 5, the vertical axis is power and the horizontal axis is frequency.

  Referring to FIG. 5, signals received by power line communication apparatus 101 include, for example, noises N <b> 1 and N <b> 2 caused by electric device 161 connected to power line 91 in addition to main signal S that is a PLC signal, Line dark noise N3 is included.

  For example, the frequency band of the main signal S is a range from frequencies f2 to f3, which is a PLC communication band. The noise N1 exists in the range from the frequency f1 to f2 near the low frequency side of the PLC communication band, and the noise N2 falls in the range from the frequency f3 to f4 near the high frequency side of the PLC communication band. Existing. In particular, the noise N1 is mainly confirmed at the time of operation of the electric device 161 which is an inverter home appliance, for example. The passband of the BPF 21 is in the range from frequencies f1 to f4.

  The frequencies f1, f2, f3, and f4 are, for example, 10 kHz, 150 kHz, 400 kHz, and 550 kHz, respectively.

  Since the noises N1 and N2 are higher in level than the main signal S and are present in the vicinity of the PLC communication band, the noises N1 and N2 are included in the pass band of the BPF 21 and are difficult to attenuate in the BPF 21. Further, since the noises N1 and N2 are present near the boundary of the pass band of the BPF 21 even when the pass band of the BPF 21 is narrower than the pass band shown in FIG. 5, it is difficult to sufficiently attenuate the noise in the BPF 21. is there. In such a case, it is difficult for the power line communication apparatus 101 to receive a PLC signal satisfactorily.

  Therefore, the control unit 15 calculates the magnitude of each frequency component of the PLC signal based on the output signal of the AGC circuit 13, and controls switching of the switching filter circuit 22 based on the calculation result.

  More specifically, the control unit 15 calculates the magnitude of each frequency component of the PLC signal from the IFFT calculation result for the digital signal received from the ADC 14, and generates the selection signal SEL based on the calculation result. The control unit 15 outputs the generated selection signal SEL to the switching filter circuit 22 in the filter unit 12.

  Specifically, in a state where the switching filter circuit 22 does not select an additional filter, that is, in a state where the BPF 21 and the AGC circuit 13 are connected without an additional filter, the control unit 15 calculates from the IFFT calculation result, If it is determined that the level outside the PLC communication band is large, a selection signal SEL for selecting the additional filter 42 is output to the switching filter circuit 22.

  The switching filter circuit 22 selects the additional filter 42 according to the selection signal SEL received from the control unit 15. More specifically, in the switching filter circuit 22, the switch 44 receives the selection signal SEL from the control unit 15 and connects the additional filter 42 to the BPF 21. The switch 45 receives the selection signal SEL from the control unit 15 and connects the additional filter 42 to the AGC circuit 13.

  On the other hand, when the noises N1 and N2 are not present or the level is low, the main signal S is somewhat larger than the line dark noise N3, so the power line communication apparatus 101 provides an additional filter in the transmission path of the PLC signal. Therefore, the PLC signal can be received satisfactorily.

  When the control unit 15 determines that the level outside the PLC communication band is small from the IFFT calculation result in a state where the switching filter circuit 22 selects the additional filter 42, the selection signal for invalidating the additional filter SEL is output to the switching filter circuit 22.

  The switching filter circuit 22 connects the BPF 21 and the AGC circuit 13 without an additional filter in accordance with the selection signal SEL received from the control unit 15. More specifically, in the switching filter circuit 22, the switch 44 receives the selection signal SEL from the control unit 15 and connects the BPF 21 and the switch 45. Further, the switch 45 receives the selection signal SEL from the control unit 15 and connects the switch 44 and the AGC circuit 13.

  Note that, for example, the power line communication apparatus 101 performs power line communication by invalidating the additional filter in the initial setting. More specifically, the control unit 15 performs control so that the additional filter is not selected in the switching filter circuit 22 in the initial setting.

  Then, the control unit 15 monitors the communication quality of the PLC signal such as the S / N ratio, the packet loss rate, and the communication availability based on the digital signal received from the ADC 14 and determines that the communication quality is good. In this case, the switching filter circuit 22 continues to perform control so that the additional filter is not selected. This communication quality monitoring may be performed, for example, by transmitting and receiving a PLC signal including a quality measurement packet between the power line communication apparatuses 101 in each apparatus, or using a PLC signal including a normal communication packet. You may go.

  Here, in general, it is difficult to produce an ideal filter, and the filter is normally used because the frequency component in its passband is also slightly attenuated as compared with an ideal filter. Then, the PLC signal that is not originally attenuated is always attenuated, which causes the communication quality to deteriorate. In particular, the closer the filter cutoff frequency is to the carrier frequency of the PLC signal, and the steeper the frequency characteristics of the filter, the greater the degree of attenuation of the PLC signal.

  On the other hand, in the power line communication apparatus 101, the configuration of disabling the additional filter as described above minimizes the use of the additional filter, and the communication performance deteriorates in a good communication environment with a small noise level. Can be prevented.

  On the other hand, the control unit 15 monitors the communication quality of the PLC signal such as the packet loss rate and communication availability based on the digital signal received from the ADC 14, and determines that the communication quality is poor, from the IFFT calculation result. The magnitude of each frequency component of the PLC signal is calculated, and the selection signal SEL is generated based on the calculation result.

  Specifically, the control unit 15 confirms, for example, the frequency at which a signal having a level higher than the main signal S exists from the IFFT calculation result, and if the signal is outside the PLC communication band, the signal is Since the noise cannot be sufficiently attenuated by the BPF 21, the switching filter circuit 22 performs control for selecting the additional filter 42.

  On the other hand, when a signal having a level larger than the main signal S does not exist outside the PLC communication band, it is another factor such as a limit of reception performance of the power line communication apparatus 101 having a small noise level but a small PLC signal level. there is a possibility. In this case, the control unit 15 performs control so that the additional filter 42 is not selected in the switching filter circuit 22.

  Further, for example, the switching filter circuit 22 can select an additional filter provided in the transmission path from the additional filters 42 and 43.

  Specifically, the control unit 15 performs control for selecting the additional filter 42 in the switching filter circuit 22, and then confirms the communication quality of the PLC signal again.

  When it is determined that the communication quality of the PLC signal is poor, the control unit 15 performs control for selecting the additional filter 43 in the switching filter circuit 22.

  In addition, for example, the control unit 15 compares the communication quality when the additional filter 42 is selected with the communication quality when the additional filter 43 is selected, and adds the one having the better communication quality among the additional filters 42 and 43. A filter may be selected. Further, the control unit 15 may invalidate the additional filter without selecting the additional filters 42 and 43 when the communication quality is the best when the additional filter is invalidated.

  The additional filters 42 and 43 are not limited to the high-pass filter or the low-pass filter, but may be other types of filters, for example, a band-pass filter or a notch filter. That is, various noise reduction effects can be obtained by appropriately selecting the type of filter. Even when the additional filters 42 and 43 are bandpass filters, the degree of attenuation of signals outside the pass band can be increased, so that noise outside the PLC communication band can be further attenuated.

  However, the additional filters 42 and 43 are preferably a high-pass filter or a low-pass filter rather than a band-pass filter in order to make it difficult for signals in the PLC communication band to be attenuated.

  Further, the additional filters 42 and 43 can be different types of filters, for example, a high-pass filter and a low-pass filter, respectively.

  In addition, since the high frequency region than the PLC communication band is often a band in which noise emitted to the power line is regulated, the main signal S is lower in the lower frequency region than the PLC communication band. There is a high possibility that noise with a higher level than that will occur.

  For this reason, in the system using power line communication, it is preferable that the additional filters 42 and 43 are high-pass filters rather than low-pass filters.

  Further, the additional filters 42 and 43 may be configured to include at least a part of the pass band of the BPF 21 as the pass band. For example, when OFDM is adopted in power line communication as described above, good communication can be performed even if an additional filter is provided in the transmission line by selectively using each subcarrier in the PLC communication band. .

  The control unit 15 may be configured to determine the quality of the PLC signal based on the output signal of the AGC circuit 13 and perform switching control in the switching filter circuit 22 when the quality satisfies a predetermined condition.

  More specifically, the control unit 15 monitors the communication quality of the PLC signal such as the packet loss rate and communication availability based on the digital signal received from the ADC 14, and determines that the communication quality is good. When the switching filter circuit 22 performs control for selecting no additional filter and determines that the communication quality is poor, the magnitude of each frequency component of the PLC signal is calculated from the IFFT calculation result as described above. The selection signal SEL is generated based on the calculation result.

  Moreover, in the power line communication apparatus according to the embodiment of the present invention, the switching filter circuit 22 is configured to be provided at the subsequent stage of the BPF 21, but the present invention is not limited to this. The switching filter circuit 22 may be configured to be provided in the preceding stage of the AGC circuit 13, and may be configured to be provided in the preceding stage of the BPF 21, for example.

  By the way, even when a filter and an AGC circuit are provided in the power line communication device, for example, when the noise cannot be sufficiently attenuated in the filter due to a high noise level, a certain amount of noise is supplied to the AGC circuit together with the PLC signal. Is done. In this case, gain adjustment that correctly reflects the magnitude of the PLC signal is not performed in the AGC circuit, and communication quality may deteriorate.

  That is, noise that is stronger than the PLC signal received by the power line communication device exists in the vicinity of the carrier wave of the PLC signal, for example, so that the operation of the AGC circuit is rate-controlled by the noise rather than the PLC signal and It cannot be adjusted, and there is a high possibility that the demodulation of the PLC signal will fail, and as a result, the communication performance deteriorates.

  In contrast, in the power line communication device according to the embodiment of the present invention, filter unit 12 receives a PLC signal. The AGC circuit 13 receives the signal that has passed through the filter unit 12. In the filter unit 12, the switching filter circuit 22 is provided before or after the BPF 21, and can switch whether or not an additional filter is provided in the PLC signal transmission path to the AGC circuit 13.

  In this way, a noise removal filter is added to the reception circuit, and the configuration in which the filter can be enabled or disabled can be selected, and even in an environment where noise stronger than the PLC signal is received in the vicinity of the PLC communication band Even under this condition, an optimal PLC signal can be supplied to the AGC circuit 13, so that the AGC circuit 13 can be operated stably and deterioration of communication performance can be prevented.

  That is, in a power line communication device provided with a permanent filter and an AGC circuit, even if the noise cannot be sufficiently attenuated in the filter because the noise level is large, the noise is supplied to the AGC circuit together with the PLC signal. It is possible to perform gain adjustment in the AGC circuit 13 while suppressing and correctly reflecting the magnitude of the PLC signal. As a result, it is possible to satisfactorily perform the reception process of the PLC signal whose level varies according to the installation environment using the AGC circuit 13 and realize a good communication quality.

  Therefore, in the power line communication apparatus according to the embodiment of the present invention, more stable and good communication quality can be realized in the configuration including the AGC circuit.

  In the power line communication apparatus according to the embodiment of the present invention, the additional filter is a low-pass filter or a high-pass filter.

  With such a configuration, noise existing outside the PLC communication band can be effectively attenuated while suppressing the attenuation of the signal in the PLC communication band with a simple circuit configuration compared to the configuration using the BPF 21.

  Further, in the power line communication device according to the embodiment of the present invention, the switching filter circuit 22 includes a plurality of additional filters that differ in at least one of the attenuation gradient and the cutoff frequency, and from among the plurality of additional filters, An additional filter provided in the transmission line can be selected.

  With such a configuration, a plurality of filters having different characteristics can be provided as additional filters, and an optimal filter corresponding to various types of noise can be selected. Therefore, an optimal PLC signal can be sent to the AGC circuit 13 in more diverse environments. Can be given to.

  In the power line communication apparatus according to the embodiment of the present invention, the control unit 15 calculates the magnitude of each frequency component of the PLC signal based on the output signal of the AGC circuit 13, and switches the filter based on the calculation result. The switching of the circuit 22 is controlled.

  With such a configuration, after confirming the magnitude and frequency of the noise, it is possible to appropriately select whether to enable or disable the additional filter or to select the type of additional filter according to the noise environment. it can.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The above description includes the following features.

[Appendix 1]
A power line communication device,
A filter unit for receiving communication signals;
An AGC (Auto Gain Control) circuit that receives a signal that has passed through the filter unit;
The filter unit is
A bandpass filter,
A switching filter circuit that is provided before or after the band-pass filter, and that can switch whether or not to provide an additional filter in the transmission path of the communication signal from the filter unit to the AGC circuit,
The power line communication device further includes a control unit that calculates the magnitude of each frequency component of the communication signal based on the output signal of the AGC circuit and controls switching of the switching filter circuit based on the calculation result. ,
The control unit determines a quality of the communication signal based on an output signal of the AGC circuit, and switches the additional filter when the quality satisfies a predetermined condition.

11 AC coupling circuit 12 Filter unit 13 AGC circuit 14 ADC
15 Control unit 21 BPF
DESCRIPTION OF SYMBOLS 22 Switching filter circuit 31 Capacitor 32 Transformer 42, 43 Additional filter 44, 45 Switch 91 Power line 101 Power line communication apparatus 151 Consumer apparatus 152 Power measuring apparatus 201 Power information collection system

Claims (4)

A filter unit for receiving communication signals;
An AGC (Auto Gain Control) circuit that receives a signal that has passed through the filter unit;
The filter unit is
A bandpass filter,
A power line communication apparatus, comprising: a switching filter circuit that is provided before or after the band-pass filter and is capable of switching whether or not an additional filter is provided in a transmission path of the communication signal to the AGC circuit.   The power line communication apparatus according to claim 1, wherein the additional filter is a low-pass filter or a high-pass filter.   The switching filter circuit includes a plurality of the additional filters having different attenuation slopes and / or cutoff frequencies, and an additional filter provided in the transmission path can be selected from the plurality of additional filters. The power line communication apparatus according to claim 1 or 2. The power line communication device further includes:
The control part which calculates the magnitude | size of each frequency component of the said communication signal based on the output signal of the said AGC circuit, and controls switching of the said switching filter circuit based on a calculation result is provided. The power line communication apparatus according to any one of the above.

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