[TowerTalk] Re; Need Help Remembering Something I Read
jimlux at earthlink.net
Sun Jul 8 10:34:31 EDT 2018
On 7/7/18 11:46 PM, Jim Brown wrote:
> On 7/7/2018 11:33 PM, Jim Brown wrote:
>> Another question about the presentation is the validity of the noise
>> data -- how recent is it?
> Hoping to answer my own question, I tried to load the referenced
> document. Although the reference appears to be a link, it is not, and
> must be typed. I did, and got a file not found message.
-13 is the latest rev and is dated Sep 2016 (that doesn't mean that's
when the noise level data was calculated...<grin>)
I download it by going here:
then following the link to the -13 version
then picking the English pdf download
(happens to be the link:
> Has anyone else had better luck with this?
> 73, Jim K9YC
But Figure 2 looks just the same, so it's probably not been updated.
And the data given in Table 1 for the "noise vs frequency" for 5
environments is the same.
The variability has the note:"These values were measured in the 1970s
and may change with time, dependent on the activities which may generate
man-made noise." - but I don't think that's for the noise level, more
the variability during the day.
That said - Tables 3,4,5 (measured noise data in Europe and Japan) seem
to match Figure 10, and the measurements were made in the 2000s. Of
course, the lowest frequency is 37 MHz. All those nasty switchers
produce noise that's mostlylower in frequency.
Somewhere, I have the reference to the actual 1970s measurement data..
It's probably in the list of references in the ITU report.
It might be NTIA report 85-173 by Spaulding and Washburn, April 1985
Atmospheric Radio Noise: Worldwide Levels and Other Characteristics
Might also be NTIA 96-330 Spaulding, 1996
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