Hi,
About the question "why waves don't mix up?"
Why this is putting it rather crudely but ... WAVES DO MIX UP!! What
happens is that after modulation of sound or picture, we generate what
is called as frequency band. The band is centered at the modulation
carrier frequency chosen, that is the tuning frequency of your radio
set.
Now suppose this band of frequencies is located from say 1.5MHz to
2.5MHz then there is no reason why the NOISE frequencies lying in this
band won't mix up.
Secondly, if somebody in some other station also moduates the band
with the same carrier frequency your station will get blocked if his
station is quite strong. THIS IS THE EXAMPLE OF WAVES GETTING MIXED
UP.
Practically it doesn't happen becoz every station has a dedicated band
of its own and cannot go beyond it.
regds,
Aditya
