Interactive video distribution systems – Local video distribution system
Reexamination Certificate
1997-08-06
2003-09-16
Grant, Chris (Department: 2611)
Interactive video distribution systems
Local video distribution system
C725S082000, C725S127000
Reexamination Certificate
active
06622304
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a centralized computing architecture using a broadband home signal distribution system for transmitting data and video display signals between a plurality of communications stations, for instance personal computers and video display devices.
BACKGROUND ART
Broadband video distribution systems are widely employed by cable television (hereinafter “CATV”) system operators for providing cable television services. These systems distribute cable television signals to residential and commercial subscribers. A broadband television signal is broadcast from a cable system head-end location over a coaxial cable or hybrid fiber coaxial (hereinafter “HFC”) cable network to subscriber households or commercial locations. The cable system headend is the local originating point for broadcast signals which are transmitted over the coaxial cable or HFC network. The broadband distribution system is terminated at the subscriber site with a connection to a home coaxial cable signal distribution network.
In general, CATV signals are transmitted in parallel over the coaxial cable or HFC network using frequency division multiplexing, where each of multiple video channels is frequency modulated to a unique non-overlapping frequency and combined onto the shared radio frequency (hereinafter “RF”) medium. Each of the video channels remains independent of one another when transmitted (i.e., they do not interfere with each other because of their non-overlapping frequency assignments.) CATV signals typically use a downstream frequency having a range of from about 50 MHz to about 550 MHz for broadcast transmission. Recently, many CATV systems have been upgraded to support a higher frequency transmission, for example, up to 860 MHz or 1 GHz. In some CATV systems, the upgrade results in the replacement of coaxial cables in the system backbone with fiber optic transmission media.
The broadband cable distribution system typically includes a carrier medium, for instance, a coaxial cable or fiber optics cable, to transmit broadband video signals within the downstream frequency range from the cable headend to the subscriber. However, because a broadband signal can become reduced in energy as it travels along the coaxial cable over long distances, or when the broadband signal is split for distribution to remote locations, amplifiers (or fiber optic nodes) may be spaced periodically along the cable distribution system to regenerate the broadband signal. A cable distribution system which supports two-way communication may also include a return band. A return band is usually designed to carry signals, generated at a subscriber location, in a frequency range of from about 5 MHz to about 42 MHz. Such signals may be transmitted in a reverse direction along the return band toward the cable system headend location. These reverse signals are generally diverse and have historically been used to transmit information, such as pay-per-view event purchases, from a subscriber location back to the headend location.
Recent advances have also permitted efficient and cost effective delivery of voice telephony, highspeed data communications, and interactive video services over the broadband cable distribution system, between a subscriber location and the cable headend location. These new services have been made compatible with existing services by using frequency division multiplexing, which allows each new channel or each new cable service to remain independent of the other signals or services present on the coaxial cable network. Moreover, similar to existing video services, these new services focus on the delivery to the home or between the home and the cable system headend location using the existing signal distribution system and methods. Existing signal delivery services, as well as emerging ones, typically employ signal receiving and processing equipment, such as a settop box or a cable modem. A settop or a cable modem is used to first terminate and process communication signals from the cable distribution network and thereafter forward the signals to an appropriate home appliance, such as a TV, personal computer, or telephone.
In addition to a settop box, an existing in-home coaxial cable wiring system may also be used to connect the cable distribution system to devices within the home that receive, use, display, and interact with cable services. This in-home coaxial cable wiring system is often in a star or a tree and branch topology, and includes coaxial cable wiring, passive electrical splitters, and other additional components. Currently, the in-home coaxial cable wiring is only partially utilized as a resource for enabling activities such as an in-home multimedia computing and entertainment. To better utilize the in-home coaxial cable wiring, recently developed methods and systems seek to make use of the in-home coaxial cable wiring or a similar coaxial cable wiring configuration to create, for example, a broadband local area network (hereinafter “LAN”), multimedia network, or home automation system.
U.S. Pat. No. 4,893,326 to Duran discloses a video-telephone communication system in which audio and video signals are transmitted over a coaxial cable network between workstations and audio/video equipment. The Duran system employs a cable distribution unit to perform frequency translation and signal amplification for reduction of video signal ghosting. Duran also discloses using a dual-cable system, instead of a cable distribution unit, to enable this system without frequency translation. The Duran system, however, requires significant circuitry, electronic components, and installation of a cable distribution unit in order to work with existing home coaxial wiring schemes. Alternatively, a second coaxial cable must be installed to each terminating appliance to make this system operational in existing homes.
U.S. Pat. No. 5,534,914 to Flohr discloses a video conferencing system in which data and video signals are transmitted over a coaxial cable network between digital computer workstations and audio/video equipment. The Flohr system employs decentralized computing for the purpose of video conferencing. In other words, each workstation contains a processor and intelligence for selecting the appropriate frequency for signal transmission, reception, and processing. No centralized computing or processing is disclosed, nor are any derivative entertainment applications suggested for the Flohr system. The Flohr system uses an active electronic tuner to select an existing broadband video channel for transmission over the proposed coaxial cable network, where external signals, such as those from a cable television service, are to be transmitted in the video conferencing system. This configuration is not compatible with existing cable television services, which require that a complete broadband signal be present at each terminating home appliance, such as a television monitor, for tuning and possibly descrambling the entire range of cable television channels. Reconfiguration of the Flohr system for compatibility with existing cable television services may not be cost effective.
U.S. Pat. No. 4,935,924 to Baxter discloses a signal distribution network for transmitting video and other signals over a coaxial cable network between a plurality of signal sources and a plurality of signal receivers. A single channel allocation controller is connected on the coaxial cable and is used to transmit channel selection signals on the cable to both the sources and receivers. The employment of active electronics in the controller requires significant component and installation expense. The Baxter system also employs two cable sections, a downstream section and an upstream section, to each terminating appliance. The need for a second coaxial cable section in a home environment where only one coaxial cable currently exists can be costly.
U.S. Pat. No. 5,539,880 to Lakhani discloses a cable-based interactive multimedia workstation network using coaxial cable in a loop topology for connecting multimedia wo
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