Mailinglist Archive: opensuse (1777 mails)

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Re: [opensuse] Moving to IPv6
  • From: "Carlos E. R." <robin.listas@xxxxxxxxx>
  • Date: Tue, 14 Sep 2010 21:11:31 +0200
  • Message-id: <4C8FC8E3.1070308@xxxxxxxxx>
On 2010-09-14 10:52, John Perry wrote:
On 9/13/2010 4:29 PM, Carlos E. R. wrote:
On 2010-09-13 01:48, Ilya Chernykh wrote:

Why do you think cable TV coaxial(or anything) is better than UTP? To
have
cable TV you also have to make wiring.
Coaxial is more capable than twisted pair. But quite more expensive, too.

Actually, no.

Coax is much easier to build as a true constant-impedance line, but it
has higher loss, especially at higher frequencies, which is the true
limiting characteristic. If you can build a twisted pair to a very high
standard of consistency, it will give greater ultimate range due to the
lower signal loss. Coax needs less signal conditioning over shorter
distances, and less complex conditioning over any distance because it's
normally better controlled (that's why short instrumentation cables like
oscillosope probes are almost always coax), but twisted pair gives
greater range and acceptable signal fidelity once you've done the signal
conditioning.

I thought that the old submarine telephone cables were coaxials with underwater
repeaters :-?


That's also why the ancient Ethernet cables were coax, but limited
essentially to 10Mbps and short distances, and we had to go to twisted
pair (cat-5, cat-5E, cat-6) to get higher bandwidth and signal fidelity
over longer distances. Manufacturers are building Ethernet cables much
more carefully than they do short-range, low-frequency twisted pair, and
for longer distances the transceivers are more complex to compensate for
the poorer signal fidelity,.

Those cable systems that still use coax have frequent repeaters with
frequency-dependent loss compensation.

Pedantic John Perry

:-)

The first switches I installed were twisted pair for the run to each computer,
and coaxial for the
run to another switch, which could be far away. Actually, the coax passed a
tooling workshop with
heavy electric motors. Worked fine, at 10Mbps, which was the speed at that time.

I do believe those switches were subject to collisions, too.



--
Cheers / Saludos,

Carlos E. R.
(from 11.2 x86_64 "Emerald" GM (Elessar))

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