[UFO Chicago] Wirelessness in Chicago

[Neil R. Ormos]

Jack Beglinger wrote:

> [Nate Riffe wrote:]
> > Heh, yes.  I'm obviously estimating a lot of things
> > here.  One of them is the distance to Elliot's.  My
> > initial gut estimate was 150 meters, which would be 67
> > dB.  After I got up and walked over to the liquor store
> > for a soda (just past Elliot's) I thought maybe 200 m
> > was a better estimate, but forgot to recalculate free
> > space loss.
 
> Check out the calculators at:
> http://www.ydi.com/free-space-loss.php   86.1 dB
> http://www.ydi.com/fresnel-zone.php zone 8.2 ft : 60% mark
> 4.9 ft
 
> Note: 200m = .125 miles.

I don't mean to pick on anyone here, but I find it amusing
that the calculated free-space loss of this type of link
would be reported to a precision of three significant
figures, especially when Nate indicated that the distance he
posted was an estimate.  I'm not disputing that the
published formula produced that number, but I'm concerned
that anyone might believe that any real-world link of that
length would have exactly that free-space loss.  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.