[UFO Chicago] Wirelessness in Chicago

[Neil R. Ormos]

On Mon, 25 Mar 2002, Nate Riffe wrote:

> Just now Neil R. Ormos made 15 LEDs in my apartment flash
> with this:
> > Also, the
> > models for these types of links, and the link budget
> > analyses based on them, have several fudge factors built in,
> > which I'm not sure Nate has taken into account.
 
> such as...
 
> Fade Margin?

Some models include an "atmosphere factor" and account for a
number of link impairments; some include factors to account
for temperature and age related degradation of antenna,
transmission-line, and RF equipment, etc.  Some models
include estimates of interference from other similar users
and from other services.  I'm sure I'm missed a zillion of
these; I'm not an expert.

I don't mean to pick on your analysis, and there's nothing
wrong IMO with running the numbers.  But RF systems
engineering is as much an art as it is a science, and unless
you do extensive experimentation or otherwise acquire an
understanding of the meaning of the numbers in the
underlying models, I believe the numbers provide an
extremely coarse prediction of real-world performance, no
matter how many significant figures the models may spit out.