A "bel", https://en.wikipedia.org/wiki/Decibel is a logarithmic measure of
relative amplitude, most commonly used when values vary by many factors of 10.
While most people think of it in terms of sound intensity, it is also a
description of radio signal strength, antenna gain, and other values.
a "3 decibel" difference is approximately a factor of 2 in power. So, if an
optical fiber has an optical loss of "0.15 dB/kilometer", that means that 20
kilometers of fiber has about 20 kilometers x 0.15 dB/kilometer = 3 dB loss, or
a factor of 2 in power.--Despite the fact that I had absolutely nothing to do
with selecting my name, I can manage a minor gloat by saying that I am one of
few people whose name is also the name of an ASCII character:
https://en.wikipedia.org/wiki/ASCII
(Jim) Bel(l)Tab (Hunter)Del (Webb, or Shannon)
On Sunday, January 5, 2020, 02:06:11 PM PST, \0xDynamite
<[email protected]> wrote:
> But even at about 1550 nanometers, 50 kilometers of fiber has: 50 km x 0.15
> dB/km = 7.5 dB of optical loss
Isn't there a better unit than Bells (dBs) for optics, like
transparency or opacity? It seems Bells are directly related to air
pressure....
Mark
