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Many people are tuning into the Internet
channel on their TV. Of all the high-speed Internet access
solutions, cable TV systems are probably the most talked about.
That's partly because they take advantage of existing broadband
cable TV networks and partly because they promise to deliver
high-speed access at an affordable price.
Internet access via cable is
spreading rapidly. However, to reach the mainstream, cable operators
face an uphill battle. Like phone companies offering ISDN service,
cable operators must gain expertise in data communications if
they're going to win and keep customers.
Technical hurdles abound: while
satellites are only one-way devices, cable modems can work in both
directions if cable operators make their one-way networks into
interactive HFC networks. When this is accomplished, the technology
could offer the best price/performance combination of any Internet
access method to date, delivering close to 10-Mbps speeds at less
than $50 per month, which is significantly better than the
cost/performance factor of ISDN access.
As discussed, making the cable-to-PC
connection requires a cable modem to modulate and demodulate the
cable signal into a stream of data. The similarity with analog
modems ends there. Cable modems also incorporate a tuner (to
separate the data signal from the rest of the broadcast stream);
parts from network adapters, bridges, and routers (to connect to
multiple computers); network-management software agents (so the
cable company can control and monitor its operations); and
encryption devices (so your data isn't intercepted or sent someplace
else by mistake).
Each cable modem has an Ethernet port
that connects to the computer (or network) on one side and a port
for the coaxial cable connection on the other. You install an
Ethernet adapter in the PC, then connect it to the cable modem
Ethernet port with a standard Ethernet cable. As far as your PC is concerned, it's hooked directly to the Internet
via an Ethernet cable. There are no phone numbers to dial and no
limitations on serial-port throughput (as is the case with ISDN
modems). What you do get is high-speed throughput: downlinks vary
from 500 Kbps to 30 Mbps, while uplinks can range from 96 Kbps to 10
Mbps.
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