Must Read****
teledotcom.com
Techonomics
Is the Future Finally Here?
by Michael Arellano. Michael Arellano is an analyst with Degas Communications Group Inc.(New York), a market researcher. He can be reached over the Internet at degascomm@earthlink.net.
One variation of an old cable industry punch line is that interactive television is the technology of the future--and always will be. AT&T may be on the verge of turning that joke on its head by creating a technical infrastructure that could make the future actually happen.
AT&T's hybrid fiber/coax (HFC) telephony trial in Fremont, Calif., features HFC nodes serving 600 homes passed. In Salt Lake City, however, AT&T Broadband Internet Services (formerly TCI) engineers, working from plans developed five years ago by AT&T Labs, are taking things a step further and readying a 50-home-per-node trial for the fall.
ITV becomes very interesting at this node density. In full-service HFC networks, video traffic from the headend to the node is broadcast. The same 80 to 100 video channels are sent to each node. There, video signals are put onto coaxial cable in a bus topology, and all the signals are sent to each home (with some bandwidth reserved for voice and high-speed data). This differs from traditional telephone networks, in which a star topology creates a dedicated path from the local switch--the equivalent of the HFC node--to each subscriber, who only has access to the signal intended for him or her.
If a Sonet ring links the headend to the HFC nodes, each of which is connected to the ring by an add/drop multiplexer (ADM), different video signals can be "dropped off" at each node. In a 600-homes-passed-per-node network--likely with 400 to 500 video subscribers, many with more than one TV set--this capability doesn't mean much because the coax from the node to the homes served has a limit of 80 to 100 channels. If there are only 50 homes passed per node, true interactive TV--including user control of start time, pause, rewind and fast-forward (and no trips to the video store)--becomes feasible. It's still bus topology from the node to the home, but the key is that each television served has a "private" channel.
This could be the turning point for cable.
Silicon Investor sucks now, this may be my last time in it.
Tim |
