"Scott Dorsey" wrote in message
...
David Eduardo wrote:
Kludge writes:

My experience is entirely in rural areas where most of the issue is QRM
from power lines and other local sources, but where adjacent-channel
interference in the daytime is nonexistent. Where does the high noise
level in LA come from?

Computers, traffic light controllers, leaky power lines, ignitions,
diathermy equipment, dimmers, fluorescent lights, motors, etc., etc. It
takes at least a 15 mv/m signal to overcome it consistently in LA.

Wow. That's horrifying to even imagine... but that noise is mostly QRM
rather than adjacent channel trash?

Yes, the reason why such an intense signal is needed on AM in most metros is
the noise level from man made interference, not adjacent channel
interference... Since very little rated market listening is done to signals
below 70 dbu on FM and 10 to 12 mv/m on AM, adjacent channel stuff is a moot
point as FCC protections are far more rigid than the actual listenable
signal areas.