JP2008141662A - Power line carrier communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a power line carrier communication apparatus capable of efficiently realizing band-pass filter bands different in band frequencies and bandwidths. <P>SOLUTION: The power line carrier communication apparatus comprises: an arbitrarily selective multiband band-pass filter 42 for passing a signal of a selected communication band in received signals from a transmission line 5 therethrough; a transmission line monitoring means 22 for selecting an optimal communication band by monitoring a communication status of the transmission line 5 on the basis of the signal passed through the arbitrarily selective multiband band-pass filter 42; and a filter switching means 23 for switching the arbitrarily selective multiband band-pass filter 42 to the communication band selected by the transmission line monitoring means 22, wherein the arbitrarily selective multiband band-pass filter 42 includes a plurality of low-pass filters LPFs different in cutoff frequencies, a plurality of high-pass filters HPFs different in cutoff frequencies, a first switch 421 for selecting one of the plurality of low-pass filters, and a second switch 422 for selecting one of the plurality of high-pass filters. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a power line carrier communication device that performs communication using an existing power line as a transmission path, and is a band-pass filter (band-pass filter) that is required when a network is constructed by frequency division multiplexing (FDD). The present invention relates to a power line carrier communication device provided in a receiving circuit.

  In power line communication (PLC) using an existing power line as a transmission line, a frequency division multiplexing (FDD) system that relays communication data using a different communication band for each region where the power line is installed. Thus, the network is configured. FIG. 7 is a diagram showing a schematic configuration of a network using a frequency division multiplexing communication system for power line carrier communication. As shown in FIGS. 7A and 7B, the PLC communication band is divided into four bands (F1 to F4). Since each region uses a different band for communication, a signal interference problem does not occur, and communication operation can be performed while maintaining independence of each network.

  Here, the relationship between the center station, the master device, and the slave device will be described with reference to FIG. The center station controls the entire network. The master device controls the modem device in the jurisdiction. In the area of the communication band F4 shown in the upper right of FIG. 7, assuming that the right side is upstream, there is a center station on the upstream side, and the modem device (marked with ●) provided on the large power pole is a slave device with respect to the center station. Behave as. On the other hand, in the area of the communication band F3, the modem device (● mark) provided in the large utility pole behaves as a master device with respect to the modem device (● mark) provided in each home. At this time, the modem device provided in each home behaves as a slave device.

  Such a power line carrier communication apparatus (modem apparatus) that performs communication by frequency division multiplexing (FDD) requires a band-pass filter that allows only the band to be used to pass. In particular, in PLC, since the number of bands to be divided is large, it is necessary to mount as many bandpass filters as there are.

  FIG. 8 is a circuit diagram showing a configuration of a conventional bandpass filter (see, for example, Patent Document 1). In the configuration shown in FIG. 8, an example in which a bandpass filter of a plurality of communication bands is configured is illustrated. That is, the high-pass filter 91 and a plurality of low-pass filters 93 having different cutoff frequencies and having diodes 94 connected to the output side are connected via the switch 92 to obtain a band-pass filter. Thereby, simplification and size reduction of a circuit can be achieved.

JP 2000-115740 A

  In a PLC that uses an existing power line as a transmission path, the characteristics of the transmission path may vary greatly from region to region. That is, depending on the communication area and the wiring environment, a band advantageous for communication is a high band or a low band. In addition, the characteristics of the transmission path may vary temporally depending on the state of the home appliances in operation. That is, since the power line that the PLC uses as a transmission line is not set for communication use, there is a problem that the communication characteristics are greatly deteriorated depending on the condition of the line.

  The communication rate depends on the allocated bandwidth. Especially in a communication area where high communication performance is required, there is a concern that the communication performance is insufficient because the allocated bandwidth is narrow.

  As described above, if the band frequency to be used (selection of high band / low band) and the bandwidth are not appropriate, the communication rate in the communication area is lowered. As with the bandpass filter described above, a single high-pass filter cannot appropriately select the band frequency and bandwidth. And the fall of the communication rate became a bottleneck, and there was a problem that the communication performance of the whole PLC network deteriorated.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to arbitrarily select a combination of a high-pass filter and a low-pass filter with different band frequencies and bandwidths. A power line carrier communication device capable of efficiently realizing a band pass filter band is obtained.

  A power line carrier communication device according to the present invention is provided in a power line carrier communication network in which a center station that controls the entire network and a plurality of modem devices that behave as master devices or slave devices are provided, and communication is performed using an existing power line as a transmission path. , An optional multiband bandpass filter that passes a signal in a communication band selected from signals received from the transmission path, and a signal that has passed through the optional multiband bandpass filter. A power line provided with transmission path monitoring means for monitoring the communication status and selecting an optimum communication band, and filter switching means for switching the optional multiband bandpass filter to the communication band selected by the transmission path monitoring means In the carrier communication device, the optional multi-band bandpass filter is a blocking device. A plurality of low-pass filters having different frequencies, a plurality of high-pass filters having different cutoff frequencies, a first switch that selects one of the plurality of low-pass filters, and the plurality of high-pass filters A second switch for selecting one of the filters is included, and the first switch and the second switch are connected in series with each other.

  The power line carrier communication apparatus according to the present invention can arbitrarily select a combination of a high-pass filter and a low-pass filter, and can efficiently realize band pass filter bands having different band frequencies and bandwidths. There is an effect.

Embodiment 1 FIG.
A power line carrier communication apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 is a diagram showing a configuration of a power line carrier communication apparatus according to Embodiment 1 of the present invention. In the following, in each figure, the same reference numerals indicate the same or corresponding parts.

  In FIG. 1, a modem device 1 which is a power line carrier communication device according to the first embodiment is provided with a control circuit 2, a transmission circuit 3, and a reception circuit 4, and a PLC using an existing power line as a transmission line 5. carry out.

  The control circuit 2 includes a demodulator 21, a transmission line monitoring unit 22, and a filter switching unit 23. The control circuit 2 executes digital signal modulation processing and demodulation processing in the demodulator 21. Further, the transmission line monitoring unit 22 monitors the transmission line condition and the communication performance state based on the demodulated signal of the demodulator 21. When it is determined by the transmission line monitoring unit 22 that the communication band has been changed, the communication band of the optional multiband bandpass filter 42 described later can be changed via the filter switching unit 23. The control circuit 2 is further provided with a writable nonvolatile memory such as a CPU and a flash memory.

  The reception circuit 4 is provided with a reception switch 41, an optional multiband bandpass filter 42, and a reception amplifier 43. Even if an out-of-band signal is present on the transmission line 5, it is blocked by the optional multi-band bandpass filter 42 and is not input to the inside, so that problems of interference and communication band interference do not occur.

  FIG. 2 is a diagram showing a configuration of an optional multiband bandpass filter of the power line carrier communication apparatus according to Embodiment 1 of the present invention.

  In FIG. 2, an optional multiband bandpass filter 42 includes a first switch 421, a plurality of low-pass filters LPF1 to LPF4 having different cutoff frequencies, and a plurality of high-pass filters HPF1 to HPF4 having different cutoff frequencies. And a second switch 422 is provided. The first switch 421 and the second switch 422 are connected in series with each other.

  The first switch 421 selects one low-pass filter from the low-pass filters LPF1 to LPF4. Similarly, the second switch 422 selects one high-pass filter from the high-pass filters HPF1 to HPF4. Therefore, by controlling the first switch 421 and the second switch 422 by the filter switching means 23, it is possible to obtain a bandpass filter that can efficiently realize a combination of a large number of passbands. In this example, each filter has an example of four bands, but the number of filters is not limited to this.

  Next, the operation of the power line carrier communication apparatus according to the first embodiment will be described with reference to the drawings.

  3 and 4 are diagrams showing examples of filter characteristics and communication band selection of the band-pass filter of the power line carrier communication apparatus according to Embodiment 1 of the present invention.

  In FIG. 3, the horizontal axis is the frequency, and the frequency increases toward the right. FH1 to FH4 shown in (a) are cutoff frequencies of the high-pass filters HPF1 to HPF4, respectively. Further, FL1 to FL4 shown in (b) are cutoff frequencies of the low-pass filters LPF1 to LPF4, respectively. Further, (c) shows an example in which a low-pass filter LPF4 and a high-pass filter HPF4 are selected and a bandpass filter having passbands FH4 to FL4 is configured.

  In FIG. 4, the horizontal axis is the frequency, and the frequency increases toward the right. FH1 to FH4 shown in (a) are cutoff frequencies of the high-pass filters HPF1 to HPF4, respectively. Further, FL1 to FL4 shown in (b) are cutoff frequencies of the low-pass filters LPF1 to LPF4, respectively. Furthermore, (c) shows an example in which a low-pass filter LPF4 and a high-pass filter HPF3 are selected and a bandpass filter having passbands FH3 to FL4 is configured.

  As described above, since the high-pass filters HPF1 to HPF4 and the low-pass filters LPF1 to LPF4 can be selected in arbitrary combinations, the modem device 1 is a bandpass filter having different band frequencies and bandwidths. Can be obtained efficiently.

  Here, if the communication band can be changed online by remote control, there are the following advantages. In other words, for example, when it is determined that the communication performance is deteriorated in a communication band (for example, high frequency FH4 to FL4) according to the operating state of home appliances, as shown in FIG. The communication band is selected from FH3 to FL4 and is changed by remote control from the center station so as to widen the bandwidth. By widening the bandwidth and increasing the communication rate, it is possible to maintain a good communication state even when the communication path characteristics are poor. Alternatively, the communication state can be kept good by changing the communication band from the high band FH4 to FL4 to the low band FH1 to FL1. That is, the center station has a low-pass filter LPF in which the optional multiband bandpass filter 42 has a wide band when the transmission characteristics of the five transmission lines are poor or when a high communication rate is required in the transmission line 5. And a change instruction for selecting a combination of the high-pass filter HPF.

  In this way, when the communication performance is monitored online and it is judged that the communication performance has deteriorated, the bandwidth frequency (high bandwidth / low bandwidth selection) and bandwidth can be changed by remote control from the center station become. Accordingly, it is possible to suppress deterioration in communication performance even in communication channel characteristics that vary greatly depending on the communication area and wiring environment, and in communication channel characteristics that vary with time.

  FIG. 5 is a flowchart showing the operation at power-on of the power line carrier communication apparatus according to Embodiment 1 of the present invention.

  First, in steps 100 to 101, the transmission line monitoring means 22 of the modem device 1 acting as a slave device monitors the communication state of the transmission line 5 based on the demodulated signal from the demodulator 21 when the power is turned on. Select the communication band.

  That is, the filter switching unit 23 reads communication band information that is a combination of a high-pass filter and a low-pass filter and is stored in the nonvolatile memory, and an optional multiband bandpass filter 42 based on the communication band information. Control to switch. Initially, nothing is stored in the non-volatile memory, so the optional multi-band bandpass filter 42 is switched so that a predetermined communication band is obtained. Then, the transmission line monitoring unit 22 monitors a beacon signal (detection signal) from the master device. When the beacon signal cannot be detected, the communication band selected according to the selection algorithm is transmitted to the filter switching means 23. This selection algorithm selects the communication band from low to high in order, or conversely selects the communication band from high to low in order, or randomly selects the communication band, The bandwidth of the communication band is sequentially selected from a narrow band to a wide band.

  Next, when the beacon signal can be detected in steps 102 to 103, the transmission path monitoring means 22 switches the high-pass filter HPF and the low-frequency band when the optional multiband bandpass filter 42 is switched. The selected communication band information including the combination of the pass filters LPF and the communication band information instructed to be changed are stored in the nonvolatile memory to update the communication band information. The control circuit 2 starts communication in that state.

  In step 104, when there is an instruction to change the communication band via the master device (modem apparatus) by remote control from the center station, the control circuit 2 sends the instructed communication band to the filter switching means 23. introduce. Thus, even when there is an instruction to change the communication band from the center station, communication is performed when the beacon signal can be detected by changing the band of the optional multiband bandpass filter 42 according to the flow shown in FIG. To resume. Thereby, even if the optional multiband bandpass filter 42 is changed for changing the communication band, the communication state can be restored again.

  In step 105, the filter switching unit 23 switches the communication band of the optional multiband bandpass filter 42 based on the selected communication band transmitted from the transmission line monitoring unit 22 when the beacon signal cannot be detected. In addition, the communication band of the optional multiband bandpass filter 42 is switched based on the communication band of the change instruction transmitted from the center station, that is, from the control circuit 2.

  As described above, the information that the optional multiband bandpass filter 42 is switched is stored in the nonvolatile memory. As a result, when the power is turned on, the communication state of the optional multiband bandpass filter 42 used last time can be quickly shifted to the communication state.

  FIG. 6 is a diagram showing another selection example of the filter characteristics and communication band of the bandpass filter of the power line carrier communication apparatus according to Embodiment 1 of the present invention.

  In FIG. 6, the horizontal axis represents the frequency, and the frequency increases toward the right. FH1 to FH4 shown in (a) are cutoff frequencies of the high-pass filters HPF1 to HPF4, respectively. Further, FL1 to FL4 shown in (b) are cutoff frequencies of the low-pass filters LPF1 to LPF4, respectively.

  Furthermore, as shown in FIG. 6C, when a combination (FL1-FH4) in which the cutoff frequency of the high-pass filter HPF is higher than the cutoff frequency of the low-pass filter LPF is selected, all received signals are blocked. That is, the switch cutoff function can be substituted. Therefore, during the reception operation, normal band pass filter band setting is performed, and during the transmission operation, for example, the operation is switched to the combination of the cutoff frequencies FL1-FH4. As a result, the reception switch 41 can be eliminated, the component area can be reduced, and the cost can be reduced.

  According to the power line carrier communication apparatus according to Embodiment 1 of the present invention, the optional multiband bandpass filter 42 is arbitrarily selected from the plurality of high-pass filters HPF1 to HPF4 and the plurality of low-pass filters LPF1 to LPF4. Since it is configured by combination, bandpass filter bands having different band frequencies and bandwidths can be efficiently realized. As a result, the number of parts can be greatly reduced, and the size and cost of the apparatus can be reduced. Further, the transmission line monitoring means 22 monitors the transmission line status and communication state, and if it is determined that the communication band needs to be changed, the filter switching means 23 changes the band of the optional multiband bandpass filter 42. Since the configuration is such that communication path characteristics that vary greatly depending on the communication area and wiring environment, and communication path characteristics that vary with time, it is possible to suppress deterioration in communication performance.

  In addition, since the band of the optional multi-band bandpass filter 42 can be changed by remote control from the center station, when it is determined that the communication performance has deteriorated, the band frequency (high band / low band Selection) and bandwidth changes are possible online. Thereby, even when the communication performance is deteriorated, there is an effect that the communication band is changed by remote control and the performance deterioration of the entire system can be suppressed.

  When the power is turned on, the slave device monitors the beacon signal (detection signal) from the master device. If no beacon signal is detected, the slave device sequentially changes the band of the optional multiband bandpass filter 42 while controlling the master. It is set as the structure which searches the beacon signal from an apparatus. Thereby, even if the optional multiband bandpass filter 42 is changed for changing the communication band, the communication state can be restored again.

  Further, the modem device 1 includes a writable nonvolatile memory (flash memory), and stores the information in the nonvolatile memory when the band of the optional multiband bandpass filter 42 is changed. Thus, even when the power is turned on next time, there is an effect that a predetermined optional multiband bandpass filter 42 is selected and a communication operation can be started promptly.

  Further, an optional multiband bandpass filter 42 is arranged at the input section of the receiving circuit 4, and a combination in which the cutoff frequency of the high-pass filter HPF is higher than the cutoff frequency of the low-pass filter LPF is selected during transmission operation. . As a result, the function of switching off the switch can be realized by the optional multiband bandpass filter 42, so that there is no need for the reception switch 41 and the number of parts can be reduced.

It is a figure which shows the structure of the power line carrier communication apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the option type | mold multiband band pass filter of the power line carrier communication apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the selection example of the filter characteristic and communication band of a band pass filter of the power line carrier communication apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows another example of selection of the filter characteristic and communication band of a band pass filter of the power line carrier communication apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the operation | movement at the time of power activation of the power line carrier communication apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the other selection example of the filter characteristic and communication band of a band pass filter of the power line carrier communication apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows schematic structure of the network using the frequency division multiplexing communication system of power line carrier communication. It is a circuit diagram which shows the structure of the conventional band pass filter.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Modem apparatus, 2 Control circuit, 3 Transmission circuit, 4 Reception circuit, 5 Transmission path, 21 Demodulator, 22 Transmission path monitoring means, 23 Filter switching means, 41 Reception switch, 42 Optional multiband band pass filter, 43 Reception amplifier, 421 first switch, 422 second switch.

Claims (6)

In a power line carrier communication network that is provided with a center station that controls the entire network and a plurality of modem devices that behave as a master device or a slave device, and that communicates using an existing power line as a transmission path,
An optional multiband bandpass filter that passes a signal in a communication band selected from signals received from the transmission path;
Transmission path monitoring means for monitoring the communication status of the transmission path based on the signal that has passed through the optional multiband bandpass filter, and selecting an optimal communication band;
A power line carrier communication device comprising filter switching means for switching the optional multiband bandpass filter to a communication band selected by the transmission line monitoring means,
The optional multiband bandpass filter is:
A plurality of low-pass filters having different cutoff frequencies;
A plurality of high-pass filters having different cutoff frequencies;
A first switch for selecting one of the plurality of low pass filters;
A power line carrier communication apparatus, comprising: a second switch that selects one of the plurality of high-pass filters; and the first switch and the second switch being connected in series to each other. The transmission path monitoring means monitors a beacon signal from the transmission path at power-up, and when the beacon signal cannot be detected, transmits the communication band selected according to a selection algorithm to the filter switching means,
The power line carrier communication apparatus according to claim 1, wherein the filter switching means switches the optional multiband bandpass filter to a communication band selected by the transmission line monitoring means. It further comprises a writable non-volatile memory,
The power line carrier communication apparatus according to claim 2, wherein the transmission line monitoring unit stores a communication band of the optional multiband bandpass filter used for communication in the nonvolatile memory. The power line carrier communication apparatus according to claim 1, wherein the filter switching unit switches the optional multiband bandpass filter to a communication band instructed to change by the center station. When the transmission characteristics of the transmission path are poor, or when a high communication rate is required on the transmission path, the center station has a low-pass filter and a high-pass filter in which the optional multiband bandpass filter has a wide band. The power line carrier communication device according to claim 4, wherein a change instruction for selecting a combination of the band pass filters is issued. During the transmission operation of the transmission signal to the transmission path, the optional multi-band bandpass filter includes a low-pass filter and a high-pass filter such that a cutoff frequency of the high-pass filter is higher than a cutoff frequency of the low-pass filter. The power line carrier communication device according to claim 1, wherein the received signal is blocked by selecting a combination of high-pass filters.

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