On Wed, 18 Dec 2013 09:21:54 -0700, Tony Hwang wrote:

First of all two kinda noises. One is internal, the other is external.
Under this two there are many different kind of noises.

I see what you mean.

I'm only looking at external noise (AFAIK) with these
spectrum analysis runs.

These plots are all taken in a direction looking *away*
from the city of San Jose. I'm pretty sure I'd get quite
different results had I pointed directly at the Fairmont
Plaza building!