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Re: Trans Noise - Support Needed!!

Subject: Re: Trans Noise - Support Needed!!
From: "Avocet" madl74
Date: Thu Mar 17, 2011 7:13 pm ((PDT))
> Using
> http://www.sengpielaudio.com/calculator-air.htm I get about 6dB loss
> per 100 feet. So assuming an additional drop in the noise of -12 db
> (-20 db total under background ambience) would still mask
> communications, we get 150' + 200' or  350 feet on both sides of the
> cables at 11 K hz.

Rob,

Yes, but they will shoot you down in flames of you don't include all 
the variables. In addition you have the DB drop due to distance, which 
is not quite inverse squared at 6dB per double the distance. At 30KHx 
sengpiel gives -28dB at 100 feet plus distance loss, so the high 
frequency response of audio mics is academic.

Electromagnetic radiation is more important. This comes from corona 
discharges especially in wet an icy weather. Electric companies will 
quote warm and dry figures. In effect, the whole line is a giant radio 
antenna which loses a percentage of the power it transmits (in 
gigawatts).

What effect does the alternaiing magnetic field have on birds which 
use the Earth's magnetic field for navigation, like pigeons? I don't 
know and I don't think anyone knows as the research hasn't been done.

> condenser capsules mostly can
deliver dozens of khz. so you probably better use a microphone built
for measurement purposes.

Or a bat detector as in my earlier message. Here's one, the songmeter:
http://www.batecho.eu/html/frame18.html:

> As for determining "public necessity" for the double circuit 345Kv
> line, our studies suggest so far that the high capacity project is
> not needed.

The usual argument is that they are needed to "average out" 
intermittent wind power, which is my anti campaign. This is adding 
insult to injury after the turbines have chopped up large numbers of 
bats and birds. Wind power is a highly visible "greenwash" with very 
little overall benefit, but that's another campaign. I've always
maintained that nuclear energy is the answer. Don't try that one now. 
:-) Of course the real solution is to stop extracting oil and gas but 
I'm not putting any money on that one either.

David

David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce







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