[R-390] r390a noise floor

[Robert Nickels]

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