Funny the things we take for granted. The communications setup on Mt. Wilson isn't just a stray TV antenna or two - it's a monstrous collection of towers, dishes and buildings that provide signals for two dozen or so FM stations and almost as many TV stations. At last check the area was still threatened by fire - and with it, many millions of dollars worth of equipment. Scott Fybush, whose site fybush.com follows this broadcast transmission world, posted a two-part backgrounder in 2005 on Mt. Wilson. I would guess lots of the information is outdated by now, but it at least gives you a sense of how huge the operation is up there - and how what we see and hear each day is dictated by those towers.
The neat thing is, the sheer height of Mount Wilson, coupled with its line of sight to pretty much the entire market, means that even the least of the signals up here enjoys terrific coverage of the market. And the terrain that surrounds the Los Angeles market, coupled with the lack of protection for any signal beyond a standard class B contour, means that even with all that huge power, the largest of the signals up here don't get out that much better than the smallest.