Hard to believe that a few scant years ago TV stations were not 24 hour affairs and that there were ‘off air’ parts of the day. I have to admit I always found the BBC test card to be a little bit ‘creepy’. All very much of its day I guess but the ‘dummy’ always seemed a little macabre [in a ventriloquist's doll kinda way].
Of course the test patterns were not just station ident place holders but functional calibration, alignment and signal checking devices in much the same way that printers run test prints after ink cartridge changes to ensure consistent functioning.
I guess it shouldn’t be surprising to learn that there are actually test card aficionados and even the music from these ‘broadcasts’ now have a cult following. Unfortunately outside these fan bases the only time one is likely to see test cards these days is in the unlikely event of station signal failure?