Year
1992
Abstract
An alarm multiplexer communication system provides the integral functions for indoor or outdoor intrusion detection and reporting. Such a system generally consists of large quantities and various types of sensors, multiplexers, controllers, and communication lines, as well as complex software and communication protocols. Moreover, the system usually operates over vast physical areas. Due to its complexity, potential exist in the system to be compromised oy knowledgeable and skillful insiders. Various system/line security protective techniques have been suggested and implemented in such systems. Line supervision is one of the many security measures that can be incorporated into a new system design or retrofitted to an existing one. In this report, various system/line security protective considerations, especially line supervision techniques and options, as well as several commercially available off-the-shelf devices are discussed, in particular the point-to-point DES (Data Encryption Standard) Enhanced-Line-Security (ELS) device. The ELS can provide effective protection for analog data links between the sensor and the multiplexer. Another available, low-cost technique using a dynamic DC supervision scheme to protect the analog data links is also discussed.