contsole
Premium
join:2003-12-30
Bloomfield, CT
| reply to K McAleavey
Re: Dirty signals
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"At least PHONE LINES are twisted pair, so there's some electromagnetic cancellation of the harmonics if the lines are properly balanced."
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Ironically, my phone line's 200' trip up my driveway is NON-twisted pair (looks like zip cord, heavy solid copper conductors) and the utility line IS twisted ...but I realize we're talking about the lines on the streets. |
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KB2PSM
join:2002-08-06
Long Beach, NY | I suspect that the power line is probably not twisted, but probably twisted around a line used to support the AC wires from the pole to your house. |
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bonnyman
join:2003-04-16
Rome, GA
| Re: Dirty signals (drop cable trivia)
I suspect that the power line is probably not twisted, but probably twisted around a line used to support the AC wires from the pole to your house.
Utility drops from the transformer to the home often have insulated conductors stranded around a bare, grounded messenger/neutral. This affords a measure of safety -- should the insulation fail, the line shorts straight to the bare neutral and on to ground via the utility's grounding system. Such arrangments also get special treatment under the National Electrical safety Code.
This is not done for communications reasons.
As for the telephone drop cable that looks like zip cord, that may be a self-supporting drop cable. Underneath the jacketing, one side of the zip cord-looking cable may contain a steel messenger, the other a twisted pair.
--
Al Bonnyman
Fiber Planners Inc.
See my weblog at:
Community Broadband Networks for FTTH, municipal broadband and powerline broadband news |
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Nighttime
join:2001-11-30 | reply to contsole
Re: Dirty signals
That and any harmonic generated by poor connectors. So your band all belong to us! Not just the 2 to 80 mhz! |
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xdeadhead
220, 221, Whatever It Takes.
Premium
join:2000-11-08
Mechanicsburg, PA | hahah someone set up us the bomb.
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I am not Herbert. |
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