Abstract: A video security system (10) monitors a premises (F) to detect unwanted intrusions onto the premises. A site control unit (12) obtains and evaluates the images to determine if an intrusion has occurred, and provides an indication if an intrusion is detected. A central station (CS) includes a plurality of workstations (106), and a central alarm computer (104). The computer is responsive to an alarm indication to cause video images, and audio, to be transmitted to the central station for presentation at one of the workstations selected by the computer. Additionally, the computer supplies site specific data to the workstation for display with the video images. Control signals from the workstation back to the site are routed through the computer.

Abstract: A security system (40) monitoring displacement between a first, fixed unit (20) and a second, movable unit (21) normally in close proximity to each other. A code generator (51) in the first unit (20) generates a coded electrical signal (Sc) supplied to an optical transducer (24) that converts the signal into an optical signal transmitted at the second unit. A transducer (34) in the second unit receives the transmitted signal, converts it back into an electrical signal now supplied to a code generator (56) in the second unit This generator determines if the electrical signal corresponds to the coded signal. If so, this second code generator generates a second coded electrical signal which is supplied to a transducer (35) in the second unit that converts the signal into an optical signal transmitted back toward the first unit. A transducer (28) in the first unit receives this reply signal and converts it back into an electrical signal.