Surveillance system using TV cameras - with comparison of successive video images raising alarm when given value is exceeded for given duration

摘要

The surveillance system, for detecting any movement or variation in a surveillance zone, employs a number of tv cameras, the image supplied by each being stored for comparison with a subsequent image from the same camera. An alarm signal is supplied when the difference between the compared signals exceeds a given pulse for a given duration. The cameras are connected in time multiplex via an electronic switch to a common store and via a second electronic switch to a comparator supplied with the store contents via a further switch. The second switch is controlled via a programmed control circuit synchronised with the store.