19-05-2024, 09:40 AM
Yes I think it was loss of signal that triggered it, that is a loss of sync pulses. As you say there's no way of it knowing if it's an intentional black image or not.
Very different in the digital world. That sort of thing can't be done at a transmitter as all the services arrive together as a single stream of data. But at a baseband video level, things like loss of audio, and frozen image are standard in equipment along with loss of signal.
Frozen video also catches out a full frame of black of course, and it will have a hold off so it doesn't go off until it lasts x number of seconds and not repeat until a certain amount of time after.
What the broadcaster does with that alarm is up to them, however I don't think there's many auto captions in use except for the 'Signal Loss' type alarms on decoders
Very different in the digital world. That sort of thing can't be done at a transmitter as all the services arrive together as a single stream of data. But at a baseband video level, things like loss of audio, and frozen image are standard in equipment along with loss of signal.
Frozen video also catches out a full frame of black of course, and it will have a hold off so it doesn't go off until it lasts x number of seconds and not repeat until a certain amount of time after.
What the broadcaster does with that alarm is up to them, however I don't think there's many auto captions in use except for the 'Signal Loss' type alarms on decoders