When we had analogue TV and the signal to noise ratio was poor we would
say the picture was snowy.
When we had satellite TV with FM video and the signal to noise ratio was
poor we would say the picture had sparklies. They were white or black.
You had to tune the receiver to the midpoint where the white and black
were about the same intensity.
On modern HD CCTV snow can look like sparkles. Not at all like 'snow'!
We should have called 'snow' sparklies. But how were we to know?
Anyway, I well remember the excitement when I first dragged in a feeble
CNN from 27.5W, sometime in the 1980s. I used to watch CNN a lot after
that, then it was fascinating meeting some of the people I'd seen on
screen when years later I worked for CNN at their various London premises.