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Re: [RFI] [BULK] Re: Ambient Noise Levels

To: "Jim Brown" <jim@audiosystemsgroup.com>, <rfi@contesting.com>
Subject: Re: [RFI] [BULK] Re: Ambient Noise Levels
From: "Jim P" <jvpoll@dallas.net>
Date: Thu, 10 Aug 2006 09:14:25 -0500
List-post: <mailto:rfi@contesting.com>
Brown wrote:

   "But for most sources, the transition from 
    near to far field occurs at roughly 1/6 wavelength"

I don't believe sources I cited not a month of two back 
are in agreement with that statement NOR does it 
agree with the empirical  results that those using 
shielded magnetic loops experience (which I had
just alluded to in, I think, my previous post.)

I will provide those sources again this evening when 
I've got more time. 

As to your contention that a measureable amount of
noise, from man-made incidental radiators, can create
S4 levels of noise, say, 100 miles distant, even 
considering cumulative effects (that is, many sources
adding together to create 'the noise') I cannot at this 
moment accept.

Jim P

----- Original Message ----- 
From: "Jim Brown" <jim@audiosystemsgroup.com>
To: <rfi@contesting.com>
Sent: Thursday, August 10, 2006 12:18 AM
Subject: Re: [RFI] [BULK] Re: Ambient Noise Levels

> On Wed, 9 Aug 2006 23:37:54 -0500, Jim P wrote:
> >I don't know that I entirely agree with that statement of
> >the origins of the noise, however.
> Of course the noise at any location will be the sum of noise 
> from many sources, some of them local, some of them distant. A 
> few of those that are local may be close enough to be in their 
> near field. But for most sources, the transition from near to 
> far field occurs at roughly 1/6 wavelength, so at HF and above, 
> most noise sources that aren't in our own home are far field  
> sources. I live and work in the pro audio world, where virtually 
> all of our baseband noise sources are power-related magnetic 
> sources, and our systems are in their VERY near field. 
> My point, and Tom's, is that once you've cleaned all the local 
> noise out of your QTH and leveled your neighbors's homes, you're 
> still left with skywave. 
> 73,
> Jim K9YC
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