On Sun, 4 Oct 2015 05:52:09 +0000 (UTC), glen herrmannsfeldt <
gah@ugcs.caltech.edu> wrote:
"(PeteCresswell)" <x@y.invalid> wrote:
Cat5E to a garden shed.
On the shed is a TV antenna.
Inside the shed are a couple of HD HomeRun digital TV tuners.
OTA TV comes in over the antenna, into the HD HomeRuns, and out to my
LAN closet on the Cat5E.
The plan is a separate CAT5e cable for each tuner (just because they are there and unused).... They could just as easily go into a little switch
and then the switch connects to one Cat5e cable....
At the risk of over-thinking this, I wonder what my network's exposure
is if lightning strikes the TV antenna.
If lightning directly strikes, all is probably toast.
But in the case of near strikes, there are other possibilities.
Would a sacrificial switch serve to isolate the shed?
It then depends on the power wires and grounding for the whole system.
UTP ethernet has, I believe, 1000V isolation transformers, but
lightning can easily pass that. You want the antenna mast to be
tied to ground as well as possible. A copper rod in the ground
is good. Note, though, that nearby strikes might come to the
shed through the ground.
I don't know how easy it would be for you to add some fiber, but
assuming you can, here is a copper to fiber converter that
might do for trick, for about $160 per pair:
http://www.newegg.com/Product/Product.aspx?Item=N82E16833114041
They support 1gb/s, which gives you some headroom on data rate.
You MIGHT get 10gb/s with multimode cable and (future) convert ors,
but for higher rates you'd need singlemode cable. Singlemode
cable MIGHT work up to 10gb/s for the distance you need.
For $280/pair you could put in single-mode:
http://www.amazon.com/Gigabit-1000BaseT-single-mode-1000Base-converter/dp/B002N90OIO
and just put in singlemode cables to begin with, which should be good
to more than 1tb/s.
Cable costs:
Multimode, outdoor: $1/foot for 12 fiber cable, but you
need to have connectors added. You need 4 for a single
pair, so perhaps $200+$1/foot and you have 10 spares.
(fewer strands cost less, but the connectors seem to
dominate the cost)
Singlemode outdoor: $0.50/foot for 12 fiber (yes, less than
multimode). Perhaps $50/connector. (Connectors dominate
the cost here even more, so I'd get 12 fibers (or more))
!Make sure that you get cable with connectors that match the
convert ors!
When I setup stuff in 2004, the rumors were that you had to
put on at least 100 connectors for multimode in order to make
good connect be good on it, even though you were using
a factory made jig and tools that are supposed to align things
automatically. I wasn't able to check if the jigs, etc have since
been improved so that no experience is needed.
For the singlemode cable, which has an active area of about 1/5 the
diameter as multimode, you always should use "factory" made
connections.
Or do the (also sacrificial) tuners already act as isolators from the network?
You might get away with a short fiber link inside the shed,
connecting to a device powered, and grounded, from the house.
-- glen
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