"Constant surveillance" refers to continuously watching or monitoring someone or something, usually using cameras or other technologies. Full definition
You must keep toy - sized dogs under constant surveillance and leash / arm control. (yourpurebredpuppy.com)
Some circumstances or activities may, however, involve an unacceptable risk to children unless they are subject to supervision, or even constant surveillance. (newlawjournal.co.uk)
This system not only raises our level of security, but more importantly it allows us to access constant surveillance of our hospitalized patients from both on and off the premises. (theanimalhospital.com)