TV static/white noise

[Flight Recorder]

Why does it look the way it does - a mass collection of white little popcorn/snow pieces bouncing around everywhere along a black background?

[Simon_Jester]

Well, you get it on analog signals; what's happening is that the TV isn't picking up a real signal, just whatever totally random stuff happens to be pinging around the atmosphere, or along the cable. So there's no picture- just a bunch of random pseudo-signal.

Now, imagine what a sequence of random numbers looks like to a TV. One microsecond it sees a large incoming signal- white spot on the screen. The next microsecond, very little incoming signal- black spot. And so on, with white spots and black spots being chosen at random, based on whatever stuff happens to be bouncing around in the absence of a strong enough signal to overpower the static.

So the mass of popcorn is the random bits of signal that don't mean anything, but are powerful enough to catch the TV's attention.