Abstract: A system for detecting objects includes a digital image device such as CCD camera to control a defined area for unauthorized intrusions. The digital imaging device views a predetermined pattern positioned across the defined area from the device. A processor periodically compares an image stored in the memory with a digital representation of the predetermined pattern, and a signal is sent to a control unit when the correlation is missing as a result of the object entering field of vision of the digital imaging device and obscuring said predetermined pattern.

Abstract: A back-up power supply for supplying operational power to a barrier movement apparatus when a mains supply of power is not present, including an enabling circuitry responsive to transmitted security codes for connecting operational power from the back-up power supply to the barrier movement apparatus. The back-up power supply includes a mains power input; a storage apparatus for storing power from the mains supply; converting apparatus for converting power stored by the storage apparatus into substitute mains power; and a control apparatus responsive to user generated request signals for enabling the converting apparatus to convert stored power into substitute mains power for use by the equipment. In accordance with another aspect of the invention, when a controller of a barrier movement apparatus identifies that a power reduction by a substitute power supply was caused by the barrier striking an obstruction, the controller directs the opening of the barrier, away from the obstruction when power is returned.