Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/10—Adaptations for transmission by electrical cable
  • H04N7/106—Adaptations for transmission by electrical cable for domestic distribution
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04H—BROADCAST COMMUNICATION
  • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
  • H04H20/65—Arrangements characterised by transmission systems for broadcast
  • H04H20/76—Wired systems
  • H04H20/77—Wired systems using carrier waves
  • H04H20/78—CATV [Community Antenna Television] systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
  • H04L12/2803—Home automation networks
  • H04L12/2838—Distribution of signals within a home automation network, e.g. involving splitting/multiplexing signals to/from different paths
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
  • H04L12/2803—Home automation networks
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
  • H04L12/2803—Home automation networks
  • H04L2012/2847—Home automation networks characterised by the type of home appliance used
  • H04L2012/2849—Audio/video appliances
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/1319—Amplifier, attenuation circuit, echo suppressor
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/13196—Connection circuit/link/trunk/junction, bridge, router, gateway
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/13242—Broadcast, diffusion, multicast, point-to-multipoint (1 : N)
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/13332—Broadband, CATV, dynamic bandwidth allocation

Definitions

• the invention relates to a communication system comprising a gateway and a plurality of stations, the gateway and the stations being interconnected via a coaxial cable network, the gateway being arranged for receiving broadcast signals from a transmitter and for distributing the broadcast signals in a broadcast frequency band via the coaxial cable network to the stations.
• the invention also relates to a station for receiving broadcast signals in a broadcast frequency band via a coaxial cable network.
• a communication system according to the preamble is known from
• An object of the invention is to provide a communication system, wherein the information signals can be exchanged over the coaxial network without being severely attenuated.
• This object is achieved in the communication system according to the invention, which is characterized in that at least two of the stations are arranged for exchanging information signals in an information frequency band via the coaxial cable network, the information frequency band lying below the broadcast frequency band .
• the invention is based upon the recognition that the splitters commonly used in coaxial cable networks only severely attenuate signals (which are transmitted between the two outputs of those splitters) above a certain threshold frequency, i.e. the attenuation amounts to more than 20 dB for frequencies above approximately 65 MHz. In contrast, for frequencies under 65 MHz the attenuation is smaller than 20 dB.
• the broadcast frequency band lies between 85 MHz and 860 MHz, while in the United States the broadcast frequency band lies between 54 MHz and 750 MHz.
• severe attenuation of the information signals is prevented by exchanging these information signals in an information frequency band which lies below the lower barrier of the broadcast frequency band, i.e. 65 MHz in Europe and 54 MHz in the US.
• Part of the frequency spectrum lying below the broadcast frequency band is reserved for upstream signals.
• this return channel lies between 5 MHz and 65 MHz, while in the US the return channel lies between 5 MHz and 42 MHz. In the home, (part of) the return channel can be used for the purpose of exchanging the information signals.
• a first embodiment of the communication system according to the invention is characterized in that the communication system comprises a high pass filter for a station being arranged for reception of the broadcast signals, the high pass filter being arranged for separating the broadcast signals from the information signals, and in that the communication system comprises a low pass filter for a station being arranged for reception of the information signals, the low pass filter being arranged for separating the information signals from the broadcast signals.
• the coaxial cable is simultaneously used for the distribution of broadcast signals and digital transmission between devices in the home, this impedance mismatch results in large (more or less complete) reflections of the digital signal.
• a complicating factor in this is that the maximum delay of these reflections is very large (500 ns), given the bit rates under consideration (in the order of 100 Mbit/s).
• the high pass filters ensure that the information signals are largely attenuated, which ensures that reflections that are caused by for instance TVs are very small compared to the original signal.
• the low pass filters ensure that the information signals do not interfere with the broadcast signals.
• a second embodiment of the communication system according to the invention is characterized in that the communication system comprises a diplex filter, the diplex filter comprising the low pass filter and the high pass filter.
• the diplex filters which can replace, depending on the structure of the coaxial cable network, some or most of the splitters commonly used in coaxial networks, act as frequency splitters instead of power splitters. This has the advantage that the signal loss introduced by the diplex filters is (almost) negligible, while the standard (power) splitters have an attenuation of approximately 3.5 dB.
• Figure 1 shows a block diagram of an embodiment of the communication system according to the invention
• Figure 2 shows the transfer function of a splitter commonly used in coaxial cable networks
• FIGS 3 and 4 show further embodiments of the communication system according to the invention.
• FIG. 1 shows a block diagram of an embodiment of a communication system 2 according to the invention.
• the communication system 2 comprises a gateway 4 and a plurality of stations 6.
• the gateway 4 which can be a plain wall outlet, and the stations 6 are interconnected via a coaxial cable network 8.
• the gateway 4 can be comprised in one of the stations 6.
• Broadcast signals 10, such as television signals and/or radio signals, which are received by the gateway 4 from a transmitter (not shown), are distributed by the gateway 4 via the coaxial cable network 8 to the stations 6.
• the broadcast signals 10 are distributed in a broadcast frequency band, e.g.
• the broadcast frequency band may lie between 85 MHz and 860 MHz, while in the United States the broadcast frequency band may lie between 54 MHz and 750 MHz.
• Some of the stations 6, such as a TV, a VCR, a radio (not shown) and a set-top box (not shown), are arranged for the reception of the broadcast signals.
• Some of the stations 6, such as a PC and a printer are arranged for the exchange of (digital) information signals via the coaxial cable network 8.
• a station such as a digital TV, a digital radio or a PC with a television receiver card, might also be arranged for the reception of the broadcast signals and for the exchange of the information signals.
• the information signals which carry for instance status information or control information, are exchanged in an information frequency band which lies below the broadcast frequency band, i.e. below 85 MHz in Europe or below 54 MHz in the United States.
• an information frequency band which lies below the broadcast frequency band
• As part of the frequency spectrum lying below the broadcast frequency band is reserved for the transmission of upstream signals via the return channel (in Europe this return channel lies between 5 MHz and 65 MHz, while in the US the return channel lies between 5 MHz and 42 MHz), in the home (part of) this return channel can be used for the purpose of exchanging the information signals.
• the coaxial cable network 8 comprises a number of splitters (not shown) for making interconnections between different branches of coax cable.
• the passive splitters commonly used in coaxial cable networks have a single input and two outputs. These splitters attenuate the broadcast signals which are transmitted from the input to the outputs with approximately 3.5 dB. This attenuation is relatively independent of the frequency of the broadcast signals. For the transmission of the information signals the situation is different.
• the information signals are transmitted from one output of the splitters to the other output.
• the transfer function 20 of the splitters i.e. the attenuation of an information signal that is transmitted from one output to the other output as function of the frequency of that information signal, is shown in Figure 2.
• the splitters commonly used in coaxial cable networks only severely attenuate information signals (which are transmitted between the two outputs of those splitters) above a certain threshold frequency, i.e. the attenuation amounts to more than 20 dB for frequencies above approximately 65 MHz. In contrast, for frequencies under 65 MHz the attenuation is smaller than 20 dB.
• FIG. 3 shows a first embodiment of the commumcation system 2 according to the invention.
• the commumcation system 2 comprises a wall outlet A, which serves as a gateway, and three stations 6, i.e. a TV and two PCs (PCI and PC2).
• the wall outlet 4 and the stations 6 are interconnected via a coaxial cable network 8.
• Broadcast signals 10 are distributed by the wall outlet 4 via the coaxial cable network 8 to the stations 6.
• the PCI and PC2 stations 6 can exchange (digital) information signals via the coaxial cable network 8.
• the communication system 2 comprises a high pass filter 30 for those stations 6 which are arranged for the reception of the broadcast signals, i.e. in this embodiment only the TV.
• the high pass filter 30 separates the broadcast signals from the information signals.
• the commumcation system 2 further comprises a low pass filter 32 for those stations 6 which are arranged for the reception of the information signals, i.e. in this embodiment PCI and PC2.
• the low pass filter 32 separates the information signals from the broadcast signals.
• the communication system 2 comprises a further high pass filter 30 for the gateway 4.
• the further high pass filter 30 prevents the information signals from being transmitted to the outside world.
• the high pass filters 32 ensure that the information signals are largely attenuated, which ensures that reflections that are caused by for instance TVs are very small compared to the original signal.
• the low pass filters 30 ensure that the information signals do not interfere with the broadcast signals.
• the cut off frequencies of the low pass filters 32 and the high pass filters 30 depend on the frequency band being used by the information signals and the broadcast signals. For the European situation 65 MHz is a suitable cut off frequency for the low pass filters 32, and 85 MHz is a suitable cut off frequency for the high pass filters 30. For the United States 42 MHz is a suitable cut off frequency for the low pass filters 32, and 54 MHz is a suitable cut off frequency for the high pass filters 30.
• the low pass filters 32 and the high pass filters 30 can, for example, be included in the coaxial cable network 8, in the stations 6 or in connectors which are used to connect the stations 6 to the coaxial cable network 8.
• Figure 4 shows a second embodiment of the communication system 2 according to the invention.
• This second embodiment only differs from the first embodiment as shown in Figure 3 in that each triplet of a low pass filter 32, a high pass filter 30 and a splitter is replaced by a diplex filter 40.
• Each diplex filter 40 includes a low pass filter 32 and a high pass filter 30. Suitable cut off frequencies for the low pass filters 32 and the high pass filters 30 are as described for Figure 3.
• the diplex filters 40 can, for example, be included in the coaxial cable network 8 or in connectors which are used to connect the stations 6 to the coaxial cable network 8.

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• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Multimedia (AREA)
• Automation & Control Theory (AREA)
• Computer Networks & Wireless Communication (AREA)
• Small-Scale Networks (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (1)

Family

ID=8240576

Family Applications (1)

Country Status (3)

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Family Cites Families (4)

• 2000
  • 2000-08-08 EP EP00949473A patent/EP1125385A1/de not_active Withdrawn
  • 2000-08-08 WO PCT/EP2000/007698 patent/WO2001017143A1/en not_active Application Discontinuation
  • 2000-08-08 JP JP2001520972A patent/JP2003508963A/ja not_active Withdrawn

Non-Patent Citations (2)

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