Lol, in simple terms.....
Consider a radio signal.....it works by line of sight between the transmitter/receiver.
Normaly a radio signal can not go a long way because of the curvature of the earth (20-30miles is typical) under normal conditions. The earth gets in the way!.
What happens sometimes is that you get an inversion where you have dry air on top of cold damp air... (i.e. fog!) and this creates a wave guide (a bit like coax cable) which means the radio signals can now effectively turn corners and in this case its the curvature of the earth.
The attenuation of the signal is often less to!
Hence you can get interference between say your local tv or radio station and one 100's of miles away that uses the same frequencies.
There are actualy some ways round it with careful aerial choice etc (its more common when the aerial is pointing over a large body of water i.e. The Wash)
Which is probably why i nearly put my fist thro the screen of the 'command' unit in the Viano early (posh name merc give to their stereo/phone/satnav units)
I pushed the 'station list' button, and its suppose to come up with the names of radio stations it can receive, it came up with load of BBC ones including BBC Wales, BBC Cyrwa (or summat like that!) and missed most of the local ones off the list

It was only when I got to within about 1 mile of the transmitter of the local radio station i wanted to listen to.....it put it in the list of choices

No chance of trying to select FM 107.7 manually, well if there is a way on the unit, god is the only one that knows how to
