[R-390] r390a noise floor

[wb5uom at hughes.net]

This is a very true comment below.
I do live in a rural area that has been VERY quiet for year's .
I have about 400 feet of wire strung up in a rough configuration of a diamond.

Somewhere I have pictures I took on the lower freq ranges of -130Dbm noise floor on the antenna.
My new neighbor  likes electric fences...

David
WB5UOM
Texas USA

-----Original Message-----
From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> On Behalf Of Robert Nickels
Sent: Monday, April 22, 2019 8:11 PM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] r390a noise floor

On 4/22/2019 5:11 PM, jgedde at optonline.net wrote:
>   I wouldn't lose any sleep over the noise floor.

Very true.  The ITU, RSGB, and others have made extensive studies, in part because of the horrific RFI from VDSL in the UK which elevates the HF noise floor to the level of unsuitability despite notching the ham bands.    (VDSL uses overhead copper wiring to distribute internet/tv signals to homes using the HF spectrum - it's the bullet we in the US dodged when BPL was stillborn).

But the easiest way to cut thru the technical jargon and data is to just look at this one chart that the ARRL put together which shows typical noise levels vs. frequency in various listening environments:

https://i.imgur.com/BxWpZ3j.png

This makes it clear that unless you're in a quiet rural location and are tuning above 20 meters, you won't hear much below -122dbM, and  unless you jenjoy insanely optimal conditions -136dBm is the practical limit.

This summary from RSGB provides an easy-to-read overview and discusses measurement techniques:

http://rsgb.org/main/files/2017/12/221216-Noise-leaflet-issue-2.pdf

73, Bob W9RAN


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