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process to accommodate new technology over time, and is consistent and compatible with existing
Integration of the various computer-based subsystems can be accomplished through compliance with
standard interfaces defined by standards bodies such as International Standards Organization (ISO),
American National Standards Institute (ANSI), and Institute of Electrical and Electronics Engineers (IEEE),
discussed in some detail in other sections of this document.
There is a balance between implementing what a vendor defines as proprietary in nature and what subscribes
to the definition of open connectivity and hence falls into the open systems architecture. There is, however,
an interaction between these two concepts being successfully implemented in a single system that includes
addressing the proprietary portion of the vendors’ offering as a module that passes data via the open systems
architecture to another module that may (or may not) be proprietary in nature. All such transfers should be
achieved by strict adherence to pre-defined standards that are recognized throughout the data and
telecommunications industry and can be found as part of the open systems architecture.
Interoperability is a measure of how well one or more elements of a security system are able to work with
other systems and components. Ideally, this should happen in a plug-and-play context, i.e., without having
to modify electrical and mechanical interfaces or write software patches, and should be implemented using
tested, proven open standards.
Interoperability is primarily a communications issue. It is increasingly important that security systems, both
legacy and new designs, are linked over facility information networks. [Refer: Section 9: Communications]
Scalability is a measure of the ease with which a system or elements of a system can be modified in size to
meet changing performance requirements.
For security systems, this may mean enrolling more people, or extending the length of a perimeter sensor,
or adding functionality such as video analytics or the networking of stand-alone equipment.
A system whose capabilities improve after adding hardware or software, proportionally to the capacity
added, is considered a scalable system.
Reliability, Maintainability, and Availability
The PACS should be designed, specified, and tested to requirements for system reliability, maintainability
and availability (RMA) appropriate for the airport’s specific physical and operational environment.
Reliability refers to the ability of the ISSA to continue to operate without a failure that compromises
the integrity of the overall system. Reliability is generally expressed as Mean Time Between Failure
(MTBF), which is derived from equipment design and manufacturing processes.
Maintainability refers to the capability of the ISSA to be subjected to normal preventive
maintenance and corrective maintenance without compromising the integrity of the overall system.
Maintainability is generally expressed as Mean Time to Repair, which is derived from equipment
design and manufacturing processes.
Availability refers to the capability of the ISSA to operate and perform normal functions such as
updates, backups, recoveries, etc., without compromising the integrity of the system. Availability
extends Reliability and Maintainability to include equipment operation and duty cycle in the airport
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