JP2005269265A - Power line carrier communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power line carrier communication system for carrying out stable communication, by suppressing a reflected wave produced from a branch line, to which no communication apparatus is connected so as to reduce the reflection attenuation of the signal wave transmitted through communication apparatuses. <P>SOLUTION: The voltage of power from a high voltage distribution line 1 is stepped down by a pole transformer 2 and the power is distributed to homes 5a, 5b, 5c through single phase three-wire distribution lines 3. An information data signal, propagated through an optical fiber 7, is transmitted to the A home 5a including a slave station MODEM 9a and the C home 5c, including a slave station MODEM 9c through the single phase three-wire distributing lines 3 through an O/E8 and a master station MODEM 10. Since the B home 5b is not provided with an information apparatus, a high-frequency signal bypass element 11 is connected between the single-phase three-wire distribution lines 3 at an entrance of the B home 5b. The high-frequency signal bypass element 11 is an element (capacitor) that provides a low impedance for a high-frequency signal and a high impedance for a commercial frequency. Since the high-frequency signal is bypassed by the high-frequency signal bypass element 11, the effect of a reflected wave from an electric apparatus 12b1 or the like can be avoided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power line carrier communication system for performing communication using a network of power distribution lines wired to supply electric energy to an electric device.

In recent years, power line carrier communication systems that perform communication using power distribution lines (hereinafter referred to as power lines) have begun to spread. In such a power line carrier communication system, a communication network is configured by connecting a plurality of modems and a personal computer (hereinafter referred to as a personal computer) to a power line network. Therefore, such a power line carrier communication system is used as a communication network using a power line in a general home or office, or used as a so-called access communication system that connects a general home and an external network. In particular, when configuring an access communication system, for example, as disclosed in Patent Document 1, a pole transformer provided to supply 100V or 200V power from a high-voltage power line to each home. A master station modem is provided on the secondary side of the device to communicate information data of a higher-level network connected by an optical fiber or a coaxial cable via a power line, and the master station modem is connected to a power line in each household. It is configured to communicate with the station modem.
JP 2003-188780 A (see paragraphs 0009 and 0010 and FIG. 1)

  However, since the power line is not a dedicated line for communication, when power line carrier communication is performed, it is affected by noise generated from various electric devices connected to the power line, or the signal level is attenuated by reflected waves. In particular, since the internal impedance of the electrical equipment connected to the branched power line is different for each electrical equipment, a reflected wave is generated at the connection point, which causes a signal level between the modems to be attenuated. In other words, when the reflection coefficient is determined by the ratio of the characteristic impedance, which is the wiring impedance of the power line, and the internal impedance of the electrical equipment, and the length L of the branch line is an odd multiple of 1/4 wavelength of the signal wave, the signal wave to be transmitted And the reflected wave (the reflected signal wave) have a phase difference of 180 ° (πRadian), so the transmitted signal wave is most attenuated.

  Therefore, in order to solve such a problem, in the technique of Patent Document 1 described above, a high-frequency cutoff element (for example, an inductance) having a high-frequency cutoff function is connected in series with the branch line of the power line to influence the reflected wave. Is suppressed. That is, the high-frequency cutoff element connected in series to the power line has a low impedance with respect to the commercial frequency, and thus has no effect when supplying power to the electrical device. However, for a high frequency such as a signal wave, the high frequency cutoff element connected in series with the power line becomes high impedance and cuts off the branch line, thereby suppressing the influence of the reflected wave after the connection point of the branch line. be able to. However, if a high-frequency cutoff element is connected in series to the branch line, the high-frequency cutoff element has a high impedance in the high-frequency region, and thus a reflected wave may be newly generated at the connection point of the high-frequency cutoff element. . As a result, the signal wave transmitted through the power line is reflected and attenuated.

  The present invention has been made in view of the above problems, and suppresses a reflected wave generated from a branch line to which an information device (or communication device) such as a modem or a personal computer is not connected. An object of the present invention is to provide a power line carrier communication system capable of reducing attenuation of a signal wave to be transmitted.

  The power line carrier communication system of the present invention was created to achieve the above-mentioned object, and uses a power line carrier communication modem to perform communication by superimposing a high frequency signal on a power line that supplies electric energy to an electric device. A power line carrier communication system, comprising a high frequency signal bypass element having a low impedance for a frequency of a high frequency signal and a high impedance for a commercial frequency, the high frequency signal bypass element of the power line carrier communication modem It is characterized in that it is connected between the unconnected branch power lines. The high-frequency signal bypass element can be connected between lines such as a watt hour meter, a breaker, and an outlet connected to the branch power line. Further, the high-frequency signal bypass element can be constituted by a capacitor, or can be constituted by a composite element in which a capacitor and a resistor are connected in series.

  According to the power line carrier communication system of the present invention, when the power line carrier communication modem is not connected after the branch point of the power line, the impedance becomes low with respect to the high frequency performing the power line carrier communication, and with respect to the commercial frequency. A high-frequency signal bypass element having high impedance is connected between power lines after the branch point. In addition, if a high frequency signal bypass element is connected between lines, such as a watt-hour meter, a breaker, and an outlet after a branch point, it can be easily attached. Thereby, the signal which performs the power line carrier communication which flows into the power line before a branch point flows into a high frequency signal bypass element, and does not flow into the power line after a branch point. Therefore, the reflected wave generated in the power line after the branch point is also reduced, and the reflection attenuation of the signal performing the power line carrier communication can be suppressed. Further, since the high frequency signal bypass element has a high impedance with respect to the commercial frequency, power is not consumed by the high frequency signal bypass element. Further, the high-frequency signal bypass element can be realized at low cost by a capacitor. Further, if the high-frequency signal bypass element is a series composite element of a capacitor and a resistor, the attenuation characteristic hardly fluctuates even if the frequency of the high-frequency signal fluctuates, so that stable communication characteristics can be maintained.

  According to the power line carrier communication system of the present invention, since the signal for power line carrier communication flowing in the power line before the branch point bypasses the high frequency signal bypass element, the signal does not flow in the power line after the branch point. For this reason, the reflected wave generated in the power line after the branch point is also reduced, so that the reflection attenuation of the signal for power line carrier communication can be suppressed. Further, since the high frequency signal bypass element has a high impedance with respect to the commercial frequency, power is not consumed by the high frequency signal bypass element. Furthermore, noise generated from the electrical equipment connected to the power line after the connection point of the high frequency signal bypass element is bypassed by the high frequency signal bypass element and returned to the electrical equipment side, so that the information equipment (or communication equipment) is connected. Since the modem of the power line carrier communication system is not affected by noise, stable communication can be performed.

  Hereinafter, several embodiments of a power line carrier communication system according to an embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in drawing used for each embodiment described below, and the overlapping description is abbreviate | omitted as much as possible.

<< First Embodiment >>
FIG. 1 is a configuration diagram of a power line carrier communication system for access communication applied to the first embodiment of the present invention. In FIG. 1, high-voltage power supplied from the high-voltage distribution line 1 is converted into low-voltage power of 100 V / 200 V by the pole transformer 2, and the low-voltage power is converted by the single-phase three-wire distribution line 3. Supplied to the home. At this time, electric power is supplied to the electric device 12a via the watt hour meter 4a in the A home 5a, and electric power is supplied to the electric devices 12b1 and 12b2 via the watt hour meter 4b in the B home 5b. In, electric power is supplied to the electric device 12c via the watt-hour meter 4c.

  In addition, a high-frequency signal is superimposed on the single-phase three-wire distribution line 3 that supplies power, and information data is communicated by power line conveyance. That is, information data of a higher-level network connected to the Internet or the like is input to an optoelectric conversion device (O / E) 8 connected to the optical fiber 7, and further, a master station modem 10 for realizing a power line carrier communication system. It is comprised so that it may transmit to the single phase three-wire type distribution line 3 via.

  On the other hand, a slave station modem 9a and a personal computer 13a are connected to the A home 5a as information devices, and a slave station modem 9c and a personal computer 13c are connected to the C home 5c as information devices. Note that no information device is connected to the B home 5b. The information data transmitted from the slave station modems 9a and 9c installed in the A home 5a and the C home 5c to the power lines in each home is a single-phase three-wire system via the connection points of the respective watt-hour meters 4a and 4c. It is transmitted to the distribution line 3 and received by the master station modem 10. In this way, the host network such as the Internet and the personal computers 13a and 13c installed in the homes 5a and 5c are connected via the power line carrier communication modem (that is, the master station modem 10 and the slave station modems 9a and 9c). It becomes a form.

  A business operator that provides such a communication service connects the master station modem 10 to the single-phase three-wire distribution line 3 on the secondary side of the pole transformer 2, and the home of the user who wants the service (that is, the A home). Slave station modems 9a and 9c are installed in 5a and C home 5c) to communicate information data. At this time, although it depends on the power capacity of the pole transformer 2, normally, when configuring a power line carrier communication system, about 5 to 20 homes are connected in such a form. In addition, although the single-family house is assumed in the system configuration of FIG. 1, it can be set as the connection form of the same power line carrier communication system also in apartment houses, such as an apartment and a condominium.

  As shown in FIG. 1, the single-phase three-wire distribution line 3 connected from the pole transformer 2 to each home 5a, 5b, 5c is branched at a plurality of locations. It is a wiring form of the power line branched into two. The terminal of the power line branched in this way is connected to an electrical device or an information device (that is, a slave station modem and a personal computer), or is not connected to an open end. At the end of such a power line, a reflected wave is generated because the characteristic impedance of the power line is different from the internal impedance of the electric device, that is, the impedance is not matched. For example, when the terminal is an open end, the characteristic impedance becomes infinite, and a large reflected wave is generated at the open end.

  That is, if the distance from the branch point to the end of the power line is L, a signal having a wavelength such that an odd multiple of a quarter wavelength of the signal wave is equal to L generates a large return loss. In other words, when a signal having a wavelength four times (4L) is propagated, where L is the length from the branch point to the end, the reflected wave signal reflected from the end propagates the distance 2L ( In other words, since half the wavelength has been propagated), the phase difference from the phase of the signal in the positive direction that has propagated to the branch point is π, and the two cancel each other, resulting in a large return loss.

  The speed of the signal on the power line differs depending on the line type, but is usually about 60% of the speed of light. Therefore, when the distance from the branch point to the end is 10 m, a signal of 4 MHz to 5 MHz is reflected and attenuated. Not only a frequency having a wavelength of 4L but also an odd multiple of the signal is attenuated. Therefore, when the distance from the branch point to the end is 10 m, signals of frequencies of 5, 15, and 25 MHz are reflected and attenuated.

  In the configuration of the power line in the power line carrier communication system as shown in FIG. 1, reflection attenuation occurs at various frequencies due to the presence of many branch lines, and large reflection attenuation occurs when the reflected wave and the signal wave overlap with each other in opposite phases. Bring. A countermeasure for reducing such reflection attenuation is to terminate at the end of the power line with matching impedance equal to the characteristic impedance of the power line. However, in reality, there are a large number of ends of the power line, so that it is practically impossible to terminate with matching impedances that match each. Further, in the case of a house that does not have an information device and does not subscribe to a communication service, such as the B home 5b in FIG. 1, it is practically impossible to perform impedance matching measures for the end of the power line. The reflected wave is also generated at the branch point where the line type of the power line is different.

  Therefore, in the power line carrier communication system according to the embodiment of the present invention, as shown in FIG. 1, a single-phase three-wire distribution line is provided to the home 5b that does not subscribe to a communication service because no information device is connected. The high-frequency signal bypass element 11 has a low impedance with respect to a high frequency for performing power line carrier communication and a high impedance with respect to a commercial frequency of 50 Hz or 60 Hz between the lead-in wires from 3 to B home 5b. Connect. Accordingly, since the high frequency signal is bypassed by the high frequency signal bypass element 11 in the B home 5b, the reflected wave from the electric equipment 12b1 and the electric equipment 12b2 in the B home 5b disappears, and as a result, at the end in the B home 5b. The reflected wave can be suppressed. Therefore, there is no possibility that the information data signal transmitted through the A home 5a and the B home 5b is reflected and attenuated.

  More specifically, since the high-frequency signal bypass element 11 has a low impedance with respect to the frequency at which power line carrier communication is performed, the signal from the master station modem 10 or the slave station modem 9a of the A home 5a and the slave station of the C home 5c Since the signal from the modem 9c causes a signal current to flow through the high-frequency signal bypass element 11, the signal current flowing through the power line on the B home 5b side after the high-frequency signal bypass element 11 decreases. Thus, since the signal current decreases on the B home 5b side, the intensity of the reflected wave from the electrical equipment 12b1 and the electrical equipment 12b2 at the end of the B home 5b also decreases in proportion to the signal current. As a result, the reflected wave reflected from the branch line of the B home 5b becomes an extremely small value, so that the signal from the master station modem 10 or the slave station modem 9a of the A home 5a and the slave station modem 9c of the C home 5c. The signal is hardly reflected and attenuated.

  In this way, a high-frequency signal having a low impedance with respect to a high frequency for performing power line carrier communication and a high impedance with respect to a commercial frequency, between the service lines of the B home 5b that does not subscribe to the communication service. When the bypass element 11 is connected, the reflection attenuation of the signal wave is reduced and the quality of the communication signal is improved, so that the communication performance is improved. The high-frequency signal bypass element 11 connected between the branch power lines has a high impedance with respect to the commercial frequency. Therefore, power at the commercial frequency is consumed as thermal energy by the high-frequency signal bypass element 11. Absent.

  As described above, according to the power line carrier communication system of the first embodiment, the high frequency signal bypass element is connected between the lines of the power line, thereby suppressing the generation of the reflected wave at the terminal after the branch point of the power line. Thus, reflection attenuation can be reduced. Therefore, stable communication can be performed when information data is transmitted through the power line.

<< Second Embodiment >>
FIG. 2 is a connection configuration diagram of a high-frequency signal bypass element applied to the power line carrier communication system according to the second embodiment of the present invention. As shown in FIG. 2, in the second embodiment, the high-frequency signal bypass element is connected between the lines of the watt-hour meter 4 installed on the entrance side of the home. The watt-hour meter 4 has input terminals 14a, 14b, and 14c that are connected to the pole transformer side and input electric power, and output terminals 14d, 14e, and 14f that are connected to home-side power wiring. Capacitors 15a and 15b are connected as high-frequency signal bypass elements between terminals 14a and 14b and between 14b and 14c, respectively. If there is an electric device used at 200V in the home, it is necessary to connect a capacitor as a high-frequency signal bypass element between the input terminals 14a and 14c.

  That is, the high-frequency signal bypass element having a low impedance at a high frequency and a high impedance at a commercial frequency can be realized by a capacitor. Since the impedance of the capacitor is 1 / (ωC) when the capacitance is C, the impedance decreases as the angular frequency ω of the signal (that is, the frequency f) increases, so it is high for commercial frequencies of 50 Hz and 60 Hz. It becomes an impedance, and becomes a low impedance with respect to a frequency of a signal for performing power line carrier communication of 10 kHz or more.

For example, since the impedance Z is Z = 1 / (ωC) = 1 / (2πfC), if C = 1 μF, the impedance Z when f = 50 Hz is Z = 1 / (2π × 50 × 10). ^-6 ) ≒ 3.2kΩ. The impedance Z when f = 10 kHz is Z = 1 / (2π × 10 × 10 ³ × 10 ⁻⁶ ) ≈16Ω. Further, the impedance Z when f = 10 MHz is Z = 1 / (2π × 10 × 10 ⁶ × 10 ⁻⁶ ) ≈0.016Ω.

  By using the capacitor in this manner, a low impedance element can be realized at a high frequency, so that a high frequency signal bypass element can be realized at low cost. When a capacitor is used as the high frequency signal bypass element, a tantalum capacitor having good high frequency characteristics and a small tan δ is desirable.

  In addition, since the lead-in wire to the home is usually covered with an insulating material, the lead-in wire is exposed to connect a high-frequency signal bypass element (for example, a capacitor) between the lead-in wires. Is necessary. However, in the second embodiment, since the capacitors 15a and 15b are connected using the connection terminals (that is, the input terminals 14a, 14b, and 14c) of the watt-hour meter 4, it is not necessary to process the lead wires. Therefore, the capacitors 15a and 15b can be easily connected.

  As described above, according to the power line carrier communication system of the second embodiment, when a power line carrier communication system is used as a so-called access communication system that connects a general home and an external network, information equipment (or The high frequency signal bypass element can be connected between the lines of the watt-hour meter installed in the home that does not join the access communication system because it does not have a communication device. Since the high-frequency signal bypass element can be directly connected between the terminals of the watt-hour meter in this way, processing work such as peeling off the coating of the power line is unnecessary, and the installation work of the high-frequency signal bypass element is simplified. . Moreover, since the high-frequency signal bypass element is installed integrally with the watt hour meter, it can be easily installed without taking an installation place.

<< Third Embodiment >>
FIG. 3 is a configuration diagram of a high-frequency signal bypass element applied to the third embodiment of the present invention. As shown in FIG. 3, the high-frequency signal bypass element according to the third embodiment is a low-impedance element at a high frequency by connecting a capacitor 16a, a resistor 17, and a capacitor 16b in series. If two high-frequency signal bypass elements having the configuration shown in FIG. 3 are used and replaced with the capacitor 15a and the capacitor 15b in FIG. 2, a low-impedance element at a high frequency can be realized.

  As shown in FIG. 3, by connecting a resistor 17 in series with capacitors 16a and 16b, the impedance in the high frequency region can be fixed by the impedance of the resistor. That is, when the high-frequency signal bypass element is configured only by the capacitor, the impedance value varies due to the frequency variation in the high-frequency region. However, with the circuit configuration as shown in FIG. 3, the impedance of the capacitor in the high-frequency region is Since it is an extremely small value and can be ignored compared to the resistance value, the impedance of the high-frequency signal bypass element is fixed to the resistance value of the resistor 17 even if the frequency fluctuates in the high-frequency region. That is, when the impedance of the high-frequency signal bypass element changes depending on the communication frequency band, the reflection attenuation characteristic also depends on the frequency. Therefore, it is desirable that the impedance of the high-frequency signal bypass element is constant in the high-frequency region. In FIG. 3, the capacitors are provided on both sides of the resistor 17 because the circuit configuration is the same regardless of which power line terminal is connected. Theoretically, if one capacitor and one resistor are connected in series, the high-frequency signal bypass device of the third embodiment can be configured.

  In addition, since the characteristic impedance of the power line is usually about 100 to 200Ω, if the impedance of the high-frequency signal bypass element is too small compared to the characteristic impedance, a reflected wave is generated at the connection point of the high-frequency signal bypass element or reflected. Attenuation may increase. From this point of view, it can be said that it is desirable to configure a high-frequency signal bypass element by connecting a resistor in series with a capacitor.

  As described above, according to the high-frequency signal bypass device of the third embodiment, the impedance can be kept constant with respect to the frequency fluctuation in which the power line carrier communication is performed as compared with the case where only the capacitor is configured. The reflection attenuation characteristic in the communication frequency band can be stabilized. That is, since the impedance of the capacitor is extremely smaller than the resistance for the high frequency at which the power line carrier communication is performed, the impedance of the composite element is almost the same as the resistance value. For this reason, since the impedance is constant in the high frequency region, even if the frequency of the high frequency signal fluctuates, the attenuation characteristic hardly fluctuates, so that stable communication characteristics can be maintained.

<< Fourth Embodiment >>
FIG. 4 is a configuration diagram of a power line carrier communication system applied to the fourth embodiment of the present invention. That is, this figure shows a configuration of a power line carrier communication system in a case where power line carrier communication is realized using a power line wired in one home or one factory. In FIG. 1, the case where the power line carrier communication system of the embodiment of the present invention is applied to the access communication connecting the host network and each home has been described. However, in the fourth embodiment shown in FIG. The carrier communication can be used as a network in a home, office or factory.

  In FIG. 4, the electric power supplied from the single-phase three-wire distribution line 3 is supplied to each power line 24a, 24b by a three-wire breaker 18a and two-wire breakers 19a, 19b, 19c, 19d installed on the distribution board 26. , 24c, 24d and connected to the respective outlets 20a, 20b, 20c, 20d. Such a power line configuration is commonly found in homes, offices or factories. The slave station modem 21a and the personal computer 22a, which are power line carrier communication modems, are connected to the power line via the outlet 20a, the slave station modem 21b and the personal computer 22b are connected to the power line via the outlet 20d, and the slave station modem 21c. The printer 23 is connected to the power line through the outlet 20d. In such a configuration, communication between personal computers and communication with a printer is performed.

  In the configuration of FIG. 4, electrical devices 25a and 25b are connected to the outlet 20b of the power line 24b and the outlet 20c of the power line 24c, respectively, but no information device such as a modem is connected. Therefore, between the terminals on the output side of the two-wire breaker 19b and the two-wire breaker 19c, a high-frequency signal that has a low impedance for a high frequency for power line carrier communication and a high impedance for a commercial frequency. Bypass elements 11a and 11b are connected to each other. As a result, reflected waves generated from the electric devices 25a and 25b at the ends of the power lines 24b and 24c are suppressed, and stable communication is achieved by suppressing attenuation of communication signals between the modems (that is, between the slave station modems 21a, 21b, and 21c). Can be realized. The high-frequency signal bypass elements 11a and 11b are preferably attached to the output side of the two-wire breakers 19b and 19c so that they can be connected and removed while the two-wire breakers 19b and 19c are cut off.

  As described above, according to the power line carrier system of the fourth embodiment, since the high frequency signal bypass element can be connected to the breaker of the branch power line, the work of attaching and detaching the high frequency signal bypass element is extremely easy.

<< Fifth Embodiment >>
FIG. 5 is a configuration diagram of a power line carrier communication system applied to the fifth embodiment of the present invention. The configuration of the fifth embodiment shown in FIG. 5 differs from the configuration of the fourth embodiment shown in FIG. 4 in that the connection positions of the high-frequency signal bypass elements 11a and 11b are changed to outlets 20b and 20c. It is only a point. That is, the outlets 20a and 20d in the home are connected to information devices such as modems, but the outlets 20b and 20c are connected to the electric devices 25a and 25b, or are vacant terminals. If the high-frequency signal bypass elements 11a and 11b are connected to the outlets 20b and 20c, respectively, which become such vacant terminals or electrical devices are connected, the signals transmitted through the power lines 24a and 24d are not attenuated by reflected waves. . When the outlet exists in this way, the high-frequency signal bypass element can be easily connected by using the outlet.

  As described above, according to the power line carrier system of the fifth embodiment, since the high-frequency signal bypass element can be connected between the lines of the outlet, for example, the information device (or communication device) and the electric device Even when the outlet is replaced, the high-frequency signal bypass element can be easily transferred to the outlet side to which the information device (or communication device) is not connected.

<< Example using high-frequency signal bypass element >>
FIG. 6 is a characteristic diagram in which the reflection attenuation effect by the high frequency signal bypass element is tested in the power line carrier communication system according to the embodiment of the present invention, where (a) is a connection configuration of power line carrier communication, and (b) is a capacitor. A high-frequency signal bypass element, (c) shows a high-frequency signal bypass element using a capacitor and a resistor, and (d) shows reflection attenuation characteristics. In the characteristic diagram of (d), the horizontal axis represents the signal frequency (MHz) and the vertical axis represents the received voltage (dBμV).

  A cable tap having a length of 5 m was connected as shown in FIG. That is, the sections indicated by squares in the wiring of FIG. 6A are cable taps each having a length of 5 m. Each frequency signal was transmitted from the transmission end Tx, and the voltage was measured at the reception end Rx. As the connection configuration of the high-frequency signal bypass element, only a capacitor as shown in FIG. 6 (b) is connected to the element connection point, and a capacitor is connected to both ends of a 50Ω resistor as shown in FIG. 6 (c). The case where the composite element was connected to the element connection point was prepared. Furthermore, the change in voltage at the receiving end Rx was measured including the case where the high-frequency signal bypass element was not connected.

  As can be seen from the characteristic diagram of FIG. 6 (d), in the vicinity of the frequency of 8.5 MHz, when nothing is connected (A), the received voltage is 55 dBμV, whereas when the capacitor is connected (B). The reception voltage is 69 dBμV, and the reception voltage when the composite element of the resistor and the capacitor is connected (C) is 75 dBμV. Thus, it can be seen that, compared to the case where nothing is connected, the reception voltage is increased in the vicinity of the frequency of 8.5 MHz by connecting the high-frequency signal bypass element, and the reflection attenuation can be reduced. It can also be seen that the effect of reducing the return loss is more pronounced when the composite element of the resistor and the capacitor is connected (C) than when the capacitor is connected (B).

  Similarly, in the vicinity of a frequency of 25 MHz, when nothing is connected (A), the received voltage is 67 dBμV, whereas when a capacitor is connected (B), the received voltage is 72 dBμV, a combination of a resistor and a capacitor. When the elements are connected (C), the reception voltage is 75 dBμV. Thus, it can be seen that, compared to the case where nothing is connected, the reception voltage becomes considerably high near the frequencies of 8.5 MHz and 25 MHz by connecting the high-frequency signal bypass element, and the reflection attenuation can be reduced.

  As described above, according to the power line carrier communication system of the embodiment of the present invention, the generation of the reflected wave at the end of the power line after the branch point is suppressed by connecting the high frequency signal bypass element between the power lines. Thus, reflection attenuation can be reduced. Therefore, stable communication can be performed when information data is transmitted through the power line.

  Communication dedicated lines such as telephone lines have few branch points, and connected communication devices are also terminated with the same characteristic impedance as the communication lines. However, there are many communication lines having a relatively large number of branches, such as on-site broadcast lines for schools and public facilities. Therefore, when a frequency higher than the current frequency band is used using a communication line in these on-site broadcasting facilities, a high-frequency signal bypass element applied to the power line carrier communication system of the embodiment of the present invention is used. Can be used.

1 is a configuration diagram of a power line carrier communication system for access communication applied to an embodiment of the present invention. It is a connection block diagram of the high frequency signal bypass element applied to the power line carrier communication system of the 2nd Embodiment of this invention. It is a block diagram of the high frequency signal bypass element applied to the 3rd Embodiment of this invention. It is a block diagram of the power line carrier communication system applied to the 4th Embodiment of this invention. It is a block diagram of the power line carrier communication system applied to the 5th Embodiment of this invention. In the power line carrier communication system of the embodiment of the present invention, it is the characteristic diagram which experimented the reflection attenuation effect by the high frequency signal bypass element, (a) is the connection configuration of the power line carrier communication, (b) is the high frequency signal bypass element by the capacitor , (C) shows a high-frequency signal bypass element composed of a capacitor and a resistor, and (d) shows reflection attenuation characteristics.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High voltage distribution line 2 Transformer on pole 3 Single-phase three-wire distribution line 4, 4a, 4b, 4c Electricity meter 5a A home 5b B home 5c C home 7 Optical fiber 8 O / E (photoelectric converter)
9a, 9c, 21a, 21b, 21c Slave station modem 10 Master station modem 11, 11a, 11b High-frequency signal bypass element 12a, 12b1, 12b2, 12c, 25a, 25b Electric equipment 13a, 13c, 22a, 22b Personal computers 15a, 15b, 16a, 16b Capacitor 17 Resistance 18a Three-wire breaker 19a, 19b, 19c, 19d Two-wire breaker 20a, 20b, 20c, 20d Outlet 23 Printer 24a, 24b, 24c, 24d Power line 26 Distribution board

Claims (6)

A power line carrier communication system that uses a power line carrier communication modem to perform communication by superimposing a high frequency signal on a power line that supplies electric energy to an electric device,
A high-frequency signal bypass element having a low impedance for the frequency of the high-frequency signal and a high impedance for the commercial frequency,
The power line carrier communication system, wherein the high-frequency signal bypass element is connected between the branch power lines to which the power line carrier communication modem is not connected.   The power line carrier communication system according to claim 1, wherein the high-frequency signal bypass element is connected between watt-hour meters connected to the branch power line.   The power line carrier communication system according to claim 1, wherein the high-frequency signal bypass element is connected between breaker lines connected to the branch power line.   2. The power line carrier communication system according to claim 1, wherein the high-frequency signal bypass element is connected between lines of an outlet connected to the branch power line.   The power line carrier communication system according to any one of claims 1 to 4, wherein the high-frequency signal bypass element is a capacitor.   The power line carrier communication system according to any one of claims 1 to 4, wherein the high-frequency signal bypass element is a composite element in which a capacitor and a resistor are connected in series.

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