After pressing 'record'', a normal VCR takes about 20 seconds before it starts recording usable pictures. With and alarm activated recorder it can be set so that the tape is ready to start recording in about one second. The signal to begin recording can be from an alarm or any other input.
ALARM ACTIVATED VCR
Meaning of ALARM ACTIVATED VCR in English
Film and video English vocabulary. Английский словарь фильмов и видео. 2012