[AMRadio] FCC's Definition of Bandwidth


Robert Bethman oldrotorheadsarge at outlook.com
Fri Oct 7 16:05:50 EDT 2016


Don,

What you see is indeed true!

The FCC has fouled up more regulations than any of us can count or keep track of!

Too many cooks spoil the broth!

Bob N0DGN

-----Original Message-----
From: Donald Chester [mailto:k4kyv at charter.net] 
Sent: Friday, October 07, 2016 2:52 PM
To: 'Robert Bethman' <oldrotorheadsarge at outlook.com>; 'AM Radio List' <AMradio at mailman.qth.net>
Subject: RE: [AMRadio] FCC's Definition of Bandwidth

> You've hit upon the crux of all of its entirety!  Things have been put
into
> words at very different times by far too many disparate entities!
> 
> None of which have been reconciled nor thoughtfully been adequately 
> proofread by the mess in Washington!
> 
> Those entities that I worked for have never found ANY cohesive pieces 
> amongst anything that has CFR in its title!


> Bob - N0DGN


There are the ITU definitions, from which the national requirements are
derived:

" 1.152 necessary bandwidth: For a given class of emission, the width of the frequency band which is just sufficient to ensure the transmission of information at the rate and with the quality required under specified conditions.

1.153 occupied bandwidth: The width of a frequency band such that, below the lower and above the upper frequency limits, the mean powers emitted are each equal to a specified percentage β/2 of the total mean power of a given emission.

Unless otherwise specified in an ITU-R Recommendation for the appropriate class of emission, the value of β/2 should be taken as 0.5%."

The original document is here:
http://www.itu.int/dms_pub/itu-s/oth/02/02/S02020000244501PDFE.PDF
(you may have to copy & paste the url into your browser to make it work) Scroll down to page 21.

Apparently, when writing Part 97, the FCC added 3 dB the wrong way from -23 dB, so it became -26 dB instead of -20 dB which would be consistent with the ITU-RR language as stated above, and the FCC's own definitions in § 2.202.



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