Enclosed space surveillance system - monitors signals representative of two parameters, triggering alarm when signals exceed step value

摘要

The method is for guarding a space against unauthorised entry. Data emitted from unauthorized persons in the space is detected during their movement in the space. This data corresponds to at least two different physical parameters. An alarm being actuated when such data is detected. A number of separate parts of the space are monitored. The signals detected from these parts of the space are permanently compared. Signals detected within a determined time internal from several of the space parts are eliminated. Unique signals from a part or from a small number of parts of the space are used to trigger an alarm when the detected signals corresponding to one of the parameters exceed a first determined step value. When the signals are detected for the other parameter the first step value is reduced to a second value lower than that required for the first parameter.