JP2009071851A - Communicating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system which is suitable for a building provided with a plurality of houses to do community reception of image and sound signals. <P>SOLUTION: The communication system has a communication line 110 which is laid to the building 90 provided with the plural houses 200 and 210 to do the community reception of the image and sound signals and is used for a signal transmission line. The building 90 is provided with a distributor (first distributor) 102 to distribute the image and sound signals obtained from a signal distribution side to each house and a plurality of branch communication lines 111 to 114 to be connected to the distributor 102 and to transmit the image and sound signals to each house. Then, injection and extraction of a communication signal are performed to each of the branch communication lines by a communication apparatus (master modem 10) capable of modulating and demodulating the communication signal to a frequency band except a frequency band of the image and sound signals. Attenuation caused by an amplifier 101 and the distributor 102 is prevented by performing the injection and the extraction of the communication signal without intervening the amplifier 101 and the distributor 102. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication system suitable for a building having a plurality of houses for jointly receiving video and audio signals. In particular, the present invention relates to a communication system that can reduce the attenuation of communication signals.

  2. Description of the Related Art Conventionally, in a building such as an apartment house or a commercial building having a plurality of houses, a form called joint reception is used as a reception form of video and audio signals such as TV signals and CATV signals. In this form, generally, a video / audio signal transmitted from a signal distribution side such as a TV station is distributed by a distributor and received by a plurality of houses. FIG. 5 is an explanatory diagram showing an outline of a joint reception mode of TV signals. In the drawings, the same reference numerals denote the same items. In the form shown in FIG. 5, an antenna 100 that wirelessly receives a TV signal from a station 500 such as a TV station that distributes video and audio signals, an amplifier 101 that amplifies the TV signal, and a TV signal that is sent to each house 200 The building 90 includes a distributor 102 that distributes the signals to each other and a communication line 110 that transmits a TV signal to each house 200. The communication line 110 is branched into a plurality of branch communication lines 111 to 114 via the distributor 102, and a plurality of houses share one branch communication line. For example, the house 200 can receive a TV signal by connecting a receiver 300 such as a television to the terminal unit 120 included in the branch communication line 111. In FIG. 5, a configuration in which the signal reception side building 90 includes the antenna 100 is shown. However, in the CATV signal or the like, the signal distribution side normally distributes the signal to the building via a cable, It is distributed from the cable by a distributor and transmitted to each house.

  On the other hand, in recent years, communication using a power line, for example, power line communication (PLC) that transmits a communication signal to a low-voltage distribution line and performs high-speed communication has been studied (for example, see Non-Patent Document 1). ). This communication system usually includes a PLC modem that modulates and demodulates the frequency of the communication signal at several tens of MHz or less, and the communication signal is appropriately modulated and demodulated by the PLC modem, thereby enabling high-speed communication using the power line as a signal transmission path.

Kiyoshi Eto, “Current Status of Power Line Communication (PLC)”, Interface, CQ Publisher, September 2000, p.70-81

  In recent years, there has been a demand for further large capacity and high speed communication, and the use of existing communication infrastructure is effective for realizing at a lower cost. Communication infrastructure includes optical fiber cables, pair cables, coaxial cables, and the like. Of these, optical fiber cables are capable of large capacity and high-speed communication, but are not yet widespread and need to be newly laid depending on the location. On the other hand, since the penetration rate of coaxial cables is very high in housing complexes and the like, when coaxial cables are used as signal transmission lines, additional capital investment can be reduced or unnecessary. Therefore, the present inventors have studied to construct a communication system that uses a coaxial cable as a signal transmission line and performs high-speed communication using a PLC modem. However, this communication system has a problem that a communication signal modulated / demodulated by a PLC modem may be greatly attenuated by an amplifier or a distributor.

  Accordingly, a main object of the present invention is to provide a communication system in which the attenuation of a communication signal modulated / demodulated by a communication device is small when a communication line installed in a building that performs joint reception of video and audio signals is used as a signal transmission line. There is to do.

  The present invention uses a communication device capable of modulating / demodulating a communication signal to a frequency band excluding the frequency band of the video / audio signal, and does not branch after injecting the communication signal into the communication line, but to each of the branch communication lines. The above object is achieved by injecting a communication signal.

  That is, the present invention is a communication system in a building having a plurality of houses for jointly receiving video and audio signals, the first distributor for distributing the video and audio signals to each house, and the first distributor And a plurality of branch communication lines for transmitting video and audio signals to each house. Furthermore, the first communication device for modulating / demodulating the communication signal to a frequency band excluding the frequency band of the video / audio signal and the communication transmitted to the branch communication line by being connected to the terminal part of the branch communication line provided in each house And a second communication device capable of injecting a communication signal into the signal extraction / branch communication line. The first communication device is characterized by injecting / extracting a communication signal to each branch communication line. The present invention will be described in detail below.

  The present invention is directed to a building having a plurality of houses, for example, a commercial building such as an apartment house, an office building, a multi-purpose building, etc., in which the plurality of houses jointly receive video and audio signals. And That is, a building including a first distributor that distributes video and audio signals to each house and a plurality of branch communication lines that are connected to the first distributor and transmit the video and audio signals to each house is used. . And this invention utilizes the said branch communication line arrange | positioned in a building as a signal transmission path.

  Examples of video / audio signals include TV signals and CATV (Community Antenna TV) signals. Examples of the first distributor include a distributor generally used for distributing TV signals and CATV signals. The branch communication line may be a coaxial cable that is generally used for transmission of TV signals and CATV signals. The arrangement state of the branch communication lines is a state in which one end side of each branch communication line is connected to the first distributor, that is, a so-called tree-like arrangement form in which each branch communication line branches from the first distributor. It is done. In addition, a form in which a plurality of houses share one branch communication line is common. At this time, by providing a plurality of terminal units on one branch communication line and arranging these terminal units in each house, it is possible to receive video and audio signals such as TV signals.

  In the building in which the above-described joint reception form of the video / audio signal is constructed, the present invention is capable of modulating / demodulating the communication signal to a frequency band excluding the frequency band of the video / audio signal for injection / extraction of the communication signal. Use communication devices. The first communication device has a configuration capable of injecting a communication signal into a branch communication line / extracting a communication signal from the branch communication line, for example, each configuration such as a transmission / reception unit for transmitting / receiving a communication signal, a transmission / reception unit, etc. Examples include a power supply unit including a power supply circuit for obtaining power for operating the unit, an interface necessary for communication with the outside, and the like.

  In particular, the first communication device is configured to be able to modulate / demodulate the communication signal in a frequency band excluding the frequency band of the video / audio signal. Since the use frequency band of the video / audio signal is generally a high frequency, for example, the modulation / demodulation frequency band of the first communication device may be a low frequency band that does not overlap with the high frequency band. Specifically, for example, the frequency band of the TV signal is 90 MHz to 222 MHz in the VHF band, 470 MHz to 770 MHz in the UHF band, and the frequency band of the CATV signal is 70 to 770 MHz in the distribution signal. Therefore, the frequency band in which the first communication device performs modulation / demodulation includes less than 70 MHz. In particular, when the frequency is 50 MHz or less, interference with the video / audio signal hardly occurs. In particular, when the frequency is 1.7 MHz to 50 MHz, interference with AM radio broadcasting or the like can be avoided. In the CATV signal, the frequency band of the reply signal is 10 to 50 MHz, and about 40 MHz is often used. Therefore, when modulation / demodulation is performed at 10 to 50 MHz, the first communication device masks the frequency band used in the video / audio signal so that the frequency band of the communication signal is different from the frequency band used in the video / audio signal. For example, the modulation and demodulation may be performed.

  As a modulation / demodulation method, for example, a method of modulating / demodulating a communication signal with a carrier frequency of 50 MHz or less at any of a single frequency, a plurality of frequencies, and a continuous frequency can be cited. Specifically, a single frequency sine wave is distributed and transmitted over a wide frequency and restored to the original single frequency sine wave at the time of reception. OFDM (Orthogonal Frequency Domain Multiplex) method, other FSK (Frequency shift keying) method, PSK (Phase Shift Keying; Phase modulation) and the like.

  The first communication device having the communication signal injection / extraction and modulation / demodulation functions may use a known PLC modem used as a so-called parent modem. Using a PLC modem enables high-speed communication. An example of the location of the first communication device is the vicinity of the first distributor in which a plurality of branch communication lines are collected so that communication signals can be easily injected / extracted.

  A distributor normally used for distributing video and audio signals such as TV signals and CATV signals may not take into account the loss of frequency bands other than the frequency band of the signals. On the other hand, in the present invention, the communication signal is injected into each of the branch communication lines branched from the first distributor, and the communication signal is extracted from each of the branch communication lines. Attenuation of communication signals can be prevented.

  When the first communication device injects / extracts communication signals with respect to each branch communication line, different branch communication lines are connected to each other via the first communication device. Here, in many cases, adjustments such as matching the impedances of the branch communication lines are made so that the transmission characteristics of the video and audio signals are good. For this reason, the transmission characteristics of the video / audio signal may be deteriorated by connecting a plurality of different branch communication lines by the first communication device. Therefore, in order to effectively prevent the deterioration of the transmission characteristics of the video / audio signal, a filter for blocking the signal in the frequency band of the video / audio signal is provided between the first distributor and the first communication device. Is preferred. For example, when the video / audio signal is in a high frequency band, this filter includes a low-pass filter that blocks the video / audio signal, and a bandpass filter that blocks signals other than a specific frequency band (excluding the frequency band of the video / audio signal). Can be mentioned.

  Moreover, in this invention, the 2nd communication apparatus which is connected to the terminal part of the branch communication line with which each house is provided and can communicate with said 1st communication apparatus by a communication signal is provided. That is, the second communication device can extract the communication signal transmitted from the first communication device to the branch communication line / inject the communication signal into the branch communication line. For example, there may be provided a power supply unit including a power supply circuit for obtaining power for operating each component such as a transmission / reception unit and a transmission / reception unit for transmitting and receiving communication signals. A known PLC modem used as a so-called child modem may be used. Using a PLC modem enables high-speed communication.

  A plurality of houses including the second communication device may exist in the building. At this time, the first communication device is configured to be able to transmit communication signals to the plurality of second communication devices, specifically, for example, by controlling the time sharing of each second communication device, It is good to use what has the structure which transmits a communication signal to each of two communication apparatuses. In addition, in this invention, a house does not necessarily mean only a general residence but the inside of a building is divided | segmented into several space, and let it be this divided | segmented small space. Specifically, for example, individually independent homes, companies, offices, rooms, etc. that require communication.

  The second communication device is connected to a terminal portion of a branch communication line provided in each house, for example, a branching device that branches a video / audio signal such as a TV signal or a CATV signal. The branching device used for branching TV signals and CATV signals usually adjusts impedance matching to the frequency band used for the signal, and signals in frequency bands other than the same signal are used. There is a risk that the loss will increase. Therefore, it is preferable to bypass the terminal unit such as a branching unit. Specifically, the branch communication line and the second communication device are connected by a first bypass line. However, if the video / audio signal is transmitted to the first bypass line, there is a risk that impedance may not be matched with the video / audio signal transmitted to the terminal unit. Therefore, it is preferable that the first bypass line includes a filter capable of blocking a signal in the frequency band of the video / audio signal. For example, when the video / audio signal is in a high frequency band, this filter includes a low-pass filter that blocks the video / audio signal, and a bandpass filter that blocks signals other than a specific frequency band (excluding the frequency band of the video / audio signal). Can be mentioned.

  The first communication device and the second communication device each have impedance matching so as to match the impedance of the branch communication line serving as the signal transmission path.

  In some cases, one of the branch communication lines connected to the first distributor (hereinafter referred to as a main branch communication line) is further branched into a plurality of sub branch communication lines. That is, in addition to the first distributor, a second distributor connected to any of the main branch communication lines to further distribute the video / audio signal may be provided. When the second distributor is generally used for distribution of TV signals and CATV signals in the same manner as the first distributor, the loss of signals in the frequency band other than the frequency band of the same signal is not considered. Sometimes. Therefore, it is preferable to bypass the second distributor instead of transmitting the communication signal from the main branch communication line to the sub branch communication line via the second distributor. Specifically, it is preferable to provide a second bypass line that connects the main branch communication line and the sub branch communication line, and to transmit a communication signal through the second bypass line. Here, in the same way as above, each sub-branch communication line is often adjusted such as impedance matching, and by connecting a plurality of different sub-branch communication lines by the second bypass line, There is a possibility that the transmission characteristic of the video / audio signal is deteriorated. In order to effectively prevent this deterioration, it is preferable to provide a filter that cuts off a signal in the frequency band of the video / audio signal. Examples of this filter include a low-pass filter and a band-pass filter.

  As described above, in the case of the joint reception mode including a plurality of distributors such as the second distributor in addition to the first distributor, the signal injection / extraction point of the communication signal of the first communication device and the second The signal extraction / injection point of the communication signal of the communication device may be separated. At this time, there is a possibility that communication using the communication signal cannot be performed between the first communication device and the second communication device due to an increase in the attenuation amount of the communication signal. Therefore, even if the signal injection / injection point in the first communication device and the signal extraction / injection point in the second communication device are separated, the second bypass can be performed. The line preferably comprises a repeater. The repeater extracts the communication signal injected by the first communication device and transmitted to the main branch communication line, injects the communication signal to the second bypass line / extracts the communication signal transmitted to the second bypass line, and extracts the main branch communication. A communication signal can be injected into a line, and a waveform distorted during transmission can be reproduced in a normal state. A known repeater may be used.

  The present invention can provide an excellent effect that high-speed communication can be performed at low cost by using a communication line such as a coaxial cable as a signal transmission path and using a communication device such as a PLC modem. In particular, in the present invention, since the communication signal is injected / extracted to / from each of the branch communication lines, the communication signal is not attenuated by the distributor to which the branch communication line is connected, and the communication state is good. Can be provided.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic diagram showing an outline of the communication system of the present invention. In the system 90 according to the present invention, in a building 90 having a plurality of houses (200, 210) that jointly receive video and audio signals, the communication line 110 used for transmission of the video and audio signals is used as a signal transmission path of the communication signals, and the communication signals are transmitted. In this configuration, communication using a communication signal is performed using a modem (parent modem 10) that can be modulated and demodulated to a frequency band other than the frequency band of the video / audio signal. In particular, in the present invention, a communication signal is injected / extracted by the parent modem 10 with respect to each of the branch communication lines 111 to 114 branched and arranged in each house. This will be described in detail below.

  The building 90 includes a plurality of houses 200 and 210 that jointly receive video and audio signals. The building 90 receives and amplifies the video and audio signals transmitted from the signal distribution side, and the video and audio signals are received from each house. A distributor (first distributor) 102 that distributes to 200 and 210 and a communication line 110 that transmits video and audio signals to the houses 200 and 210 are provided. The communication line 110 is branched to a plurality of branch communication lines 111 to 114 via the distributor 102, and a plurality of houses share one branch communication line. Each branch communication line 111 to 114 includes a plurality of terminal units 120, and each terminal unit 120 is arranged in each house. Therefore, the house 200 can receive a video / audio signal by connecting the receiver 300 such as a television to the terminal unit 120 included in the branch communication line 111. In this example, the distributor 102 is a known one that can distribute a TV signal and a CATV signal. The branch communication lines 111 to 114 are known coaxial cables used for transmission of TV signals and CATV signals.

  In the building 90 that jointly receives such video and audio signals, the communication signals are injected into each of the branch communication lines 111 to 114 in order to use the branch communication lines 111 to 114 as signal transmission paths of the communication signals. A parent modem 10 that extracts a communication signal from each of the branch communication lines 111 to 114 is provided. Further, the house 210 that performs communication using the communication signal includes the child modem 20 that can extract the communication signal transmitted from the parent modem 10 to the branch communication line 114 and can inject the communication signal into the branch communication line 114.

  In this example, a coaxial cable for transmitting a TV signal and a CATV signal is used as a signal transmission path for communication signals. Therefore, a TV signal and a CATV signal are normally transmitted to the branch communication lines 111 to 114. Therefore, in this example, the parent modem 10 can modulate the communication signal injected from the parent modem 10 into each of the branch communication lines 111 to 114 into a frequency band other than the use frequency band of the TV signal or CATV signal, and branch communication. A PLC modem capable of demodulating the communication signal transmitted to the lines 111 to 114 in a frequency band other than the frequency band used for the TV signal or CATV signal was used. In this example, the modem method of the parent modem 10 is the OFDM method.

  The parent modem 10 is connected to each of the branch communication lines 111, 112, 113, 114 via wirings 111 ′, 112 ′, 113 ′, 114 ′, and each branch is connected via these wirings 111 ′ to 114 ′. Injection / extraction of communication signals to the communication lines 111 to 114 is performed. That is, the parent modem 10 injects / extracts communication signals on the downstream side of the amplifier 101 and the distributor 102 as viewed from the distribution side of the TV signal and CATV signal. As described above, in the present invention, since the communication signal is injected / extracted to each of the branch communication lines 111 to 114 by bypassing the distributor 102, the amplifier 101 and the distributor 102 are other than the frequency band of the TV signal and the CATV signal. Even if the signal in the frequency band is not taken into consideration, the communication signal can be prevented from being attenuated by the amplifier 101 or the distributor 102. In this example, the parent modem 10 is arranged in the vicinity of the distributor 102 where the branch communication lines 111 to 114 are collected so that communication signals can be easily injected / extracted.

  On the other hand, the child modem 20 can also demodulate the communication signal transmitted to the branch communication lines 111 to 114 to a frequency band other than the use frequency band of the TV signal or the CATV signal, similarly to the parent modem / to the branch communication lines 111 to 114. A PLC modem that can modulate the communication signal to be injected into a frequency band other than the frequency band used for TV signals and CATV signals was used. In this example, the modem method of the slave modem 20 is the OFDM method.

  The child modem 20 is connected to the terminal unit 121 of the branch communication line 114 disposed in the house 210 and injects / extracts communication signals to / from the branch communication line 114. In this example, the terminal unit 121 is a known branching device that can branch a TV signal and a CATV signal. Note that the impedances of the parent modem 10 and the child modem 20 are matched so as to match the impedance of the branch communication line.

  With the above configuration, when the communication user of the house 210 receives a communication signal from the upper network 600, the communication signal is transmitted to the parent modem 10 via the optical fiber cable 150 connected to the upper network 600, and the TV signal And modulated to a frequency other than the frequency band of the CATV signal. In this example, modulation is performed by the OFDM method with a carrier frequency of 50 MHz or less. The modulated communication signal is transmitted to each of the branch communication lines 111 to 114 via the wirings 111 ′ to 114 ′. The communication signal transmitted to the branch communication line 114 is extracted and demodulated by the child modem 20 via the terminal unit 121 included in the house 210, and is received by being extracted by the terminal device 400 such as a personal computer. In this example, demodulation is performed by the OFDM method with a carrier frequency of 50 MHz or less.

  On the other hand, when the communication user of the house 210 transmits a communication signal to the upper network 600, the communication signal from the terminal device 400 such as a personal computer is modulated by the slave modem 20 to a frequency other than the frequency band of the TV signal and the CATV signal. And injected into the terminal unit 121. In this example, modulation is performed by the OFDM method with a carrier frequency of 50 MHz or less. The communication signal injected into the terminal unit 121 is transmitted to the branch communication line 114, extracted by the parent modem 10 via the wiring 114 ′, demodulated, and transmitted to the upper network 600 via the optical fiber cable 150. The In this example, demodulation is performed by the OFDM method with a carrier frequency of 50 MHz or less. Further, although the parent modem 10 includes a media converter (MC) capable of converting an optical signal / electric signal, the MC may be separately provided.

  The present invention having the above configuration uses a communication line laid in a building that jointly receives video and audio signals as a signal transmission path, and modifies and demodulates a communication signal such as a PLC modem to a frequency band other than the frequency band of the signal. High-speed communication can be realized at low cost by injecting / extracting communication signals using a possible communication device. In particular, in the present invention, the communication signal is not attenuated by the distributor or the amplifier because the communication signal is not injected / extracted through the distributor for distributing the video / audio signal and the amplifier for amplifying the signal. Can provide a good communication state. Further, in the present invention, since the frequency band of the communication signal to be transmitted is other than the use frequency band of the video / audio signal, problems such as interference between the video / audio signal and the communication signal are unlikely to occur. Also, a good communication state can be achieved.

  In the example shown in FIG. 1, an example is shown in which one building is provided in the building for communication using a communication signal, but a plurality of houses may be provided. At this time, each house is provided with a child modem and may be connected to a terminal portion of a branch communication line provided in each house, and the parent modem has a configuration capable of controlling the time sharing of each child modem. Good. In this example, the OFDM method is used as the modulation / demodulation method, but an SS method, an FSK method, a PSK method, or the like can be used as appropriate. Further, when there is a place where the frequency band of the communication signal overlaps with the use frequency band of the video / audio signal, the frequency band may be masked or modulated so as to be different from the frequency band of the video / audio signal.

(Example with filter)
In the above example, different branch communication lines 111 to 114 are connected to each other by the parent modem 10 (wirings 111 ′ to 114 ′). For this reason, the transmission characteristics of TV signals and CATV signals may be deteriorated in the respective branch communication lines 111 to 114. In order to effectively prevent the deterioration of the transmission characteristics, it is preferable to arrange a filter 30 capable of blocking TV signals and CATV signals in the wirings 111 ′ to 114 ′ as shown in FIG. The filter 30 may be a low-pass filter that can cut off a high-frequency signal such as a TV signal or a CATV signal, or a band-pass filter that can pass a signal in a specific frequency band excluding the frequency band used for the TV signal or the CATV signal. The filter 30 may be provided on any wiring (same wiring 114 ′) connected to at least a branch communication line (in this example, the branch communication line 114) used as a signal transmission path for communication signals, and all the wirings 111 ′. ˜114 ′.

  On the other hand, in the above example, the slave modem 20 is connected to the terminal unit 121 to inject / extract communication signals. However, depending on the terminal unit 121, the loss of communication signals may increase. In the case of such a terminal unit 121, a bypass line (first bypass line) 130 that bypasses the terminal unit 121 may be arranged to connect the child modem 20 and the branch communication line 114. At this time, there is a risk that the TV signal or CATV signal transmitted to the bypass line 130 may not be matched in impedance with the TV signal or CATV signal transmitted to the terminal unit 121. Therefore, it is preferable to arrange a filter 40 capable of blocking TV signals and CATV signals in the bypass line 130. The filter 40 may be a low-pass filter or a band-pass filter, like the filter 30.

  In the first embodiment, an example in which one distributor is provided in the building has been described. However, in a large building or the like, a plurality of distributors may be provided in multiple stages. In this example, a case where a plurality of distributors are provided will be described. FIG. 3 is an explanatory diagram showing an outline of a signal transmission path in the system of the present invention, and shows an example including another distributor connected to a branch communication line and further branching a video / audio signal. The basic configuration of the joint reception form of the building shown in this example is the same as that of the first embodiment, and the difference is that each of the branch communication lines 111 to 114 connected to the distributor 102 is connected to the TV signal. Further, distributors (second distributors) 103 to 106 for further distributing the CATV signal are provided, and the sub-branch communication lines 111A to 114A are connected to the distributors 103 to 106, respectively. The distributors 103 to 106 are known distributors capable of distributing TV signals and CATV signals in the same manner as the distributor 102 described above.

  When the distributors are arranged in multiple stages as described above, similarly to the distributor 102, the distributors 103 to 106 may not consider signals in a frequency band other than the frequency band of the TV signal or the CATV signal. Therefore, in this example, not only the distributor 102 but also the distributors 103 to 106 are bypassed. The example shown in FIG. 3 includes a bypass line 160 that bypasses the distributor 103 and connects the branch communication line 111 and the sub-branch communication line 111A. In this example, bypass lines 161 to 164 connected to the branch communication line 111 are arranged for the sub-branch communication lines 111a to 111d connected to the distributor 103 and branched.

  With this configuration, since the communication signal transmitted to the branch communication line 111 is transmitted to the sub-branch communication lines 111a to 111d via the bypass lines 161 to 164, attenuation by the distributor 103 does not occur, which is favorable. It can be in a communication state. Further, since the communication signals transmitted to the sub-branch communication lines 111a to 111d are transmitted to the branch communication line 111 via the bypass lines 161 to 164, they are not attenuated by the distributor 103 as well.

  Furthermore, as shown in FIG. 4, when the communication signal injection / extraction point of the child modem 20 is far from the communication signal injection / extraction point of the parent modem 10, the attenuation of the communication signal increases, Communication with the communication signal with the child modem 20 may be impossible or difficult. In order to solve such a problem, it is preferable that the bypass line 160 includes a repeater 60. As the repeater 60, a known one capable of reproducing a waveform distorted during transmission to a normal state is used.

  By providing the repeater 60, even the child modem 20 connected to the terminal unit 122 of the sub-branch communication line 111c can communicate with the parent modem 10 using communication signals.

  The system of the present invention is most suitable when performing high-speed communication in a building having a plurality of houses that perform joint reception. In particular, in the present invention, the construction cost of the system can be reduced by using the communication line laid in the building as a signal transmission path.

It is a schematic diagram which shows the outline | summary of this invention communication system. It is a schematic diagram which shows the outline of the signal transmission path of this invention communication system, Comprising: The example which provides a filter between a parent modem and a divider | distributor is shown. It is a schematic diagram which shows the outline of the signal transmission path of this invention communication system, Comprising: The example which provides a divider | distributor in multiple stages is shown. An example in which a repeater is further provided in the communication system of the present invention shown in FIG. It is explanatory drawing which shows the outline of the joint reception form of TV signal in the building which provides a some house.

Explanation of symbols

10 Parent modem 20 Child modem 30,40,50 Filter 60 Repeater 90 Building
100 Antenna 101 Amplifier 102 to 106 Divider 110 Communication line
111 to 114 Branch communication line 111 'to 114'
111A, 112A, 113A, 114A, 111a to 111d Sub-branch communication line
120 to 122 Terminal unit 130,160 to 164 Bypass line 150 Optical fiber cable
200, 210 House 300 Receiver 400 Terminal equipment 500 Station
600 top networks

Claims (6)

A communication system in a building having a plurality of houses for jointly receiving video and audio signals,
A first distributor for distributing the video and audio signals to each house;
A plurality of branch communication lines connected to the first distributor and transmitting video and audio signals to each house;
A first communication device that modulates and demodulates a communication signal to a frequency band excluding the frequency band of the video and audio signal;
A second communication device connected to a terminal portion of the branch communication line provided in each house and capable of extracting a communication signal transmitted to the branch communication line / injecting a communication signal into the branch communication line;
The first communication device performs communication signal injection / extraction on each branch communication line.   2. The communication system according to claim 1, further comprising a filter between the first distributor and the first communication device that blocks a signal in a frequency band of the video / audio signal. Furthermore, the branch communication line and the second communication device are connected to each other, and the first bypass line for bypassing the terminal portion of the branch communication line is provided.
2. The communication system according to claim 1, wherein the first bypass line includes a filter that blocks a signal in a frequency band of the video / audio signal.   2. The communication system according to claim 1, wherein the first communication device modulates / demodulates the communication signal at a carrier frequency of 50 MHz or less to any of a single frequency, a plurality of frequencies, and a continuous frequency. A second distributor connected to one of the branch communication lines connected to the first distributor and further distributing the video / audio signal;
Connecting a branch communication line connected to the first distributor and a sub-branch communication line connected to the second distributor, and comprising a second bypass line that bypasses the second distributor;
2. The communication system according to claim 1, wherein the second bypass line includes a filter that blocks a signal in a frequency band of a video / audio signal.   The communication system according to claim 5, further comprising a repeater in the second bypass line.

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