Alarm & Intrusion
Security is a fundamental aspect of our lives. We rely on good systems to help prevent crime, warn us before danger strikes. There are different types of alarm which ask also for different actions. Advanced systems allow differentiation between technical, intrusion and panic alarm. Depending on size and use of the building the system must support many different arming areas which could be part of one or more arming groups. In combination with an access control system arming areas should be equivalent to the access area. This allows automatic disarming of an area when access is permitted. Special function allows automatic arming on time schedule if no activity was detected in a given time before. Arming could also be activated by the T&A system, if the last member of an area leaves the building and gives notice on the T&A terminal if system can’t be armed, because a window is still open or a door is unlocked. The battery management system should be capable to bridge at least 78h hours, to maintain full function in case of power fail during the weekend.
To minimize cabling, detectors will be connected over tamper proof bus lines. State of the art system allow the use of all temper proof inputs of the system to be used as alarm input.
Cable versus RF:
Small house systems can use also RF (radio frequency) detectors for alarm transmission. The better ones allow automatic switch to a different frequency if the used frequency is disturbed (either by bad surrounding or professional attack). This problem shows also the weakness of RF Alarm systems in addition to the need of exchange and to monitor the battery’s in each detector.
There are many different alarm detection methods for different detection problems. Movement detectors are either using IR-detection or micro wave. The passive infrared (PIR) motion detector is one of the most common sensors. It offers affordable and reliable functionality. It works entirely by detecting the heat energy given off by other objects. PIR sensors do not detect motion, they detect abrupt changes in temperature at a given point.
Microwace detectors emits microwaves from a transmitter and detects any reflected microwaves or reduction in beam intensity using a receiver. The transmitter and receiver are usually combined inside a single housing for indoor applications, and separate housings for outdoor applications. To reduce false alarms this type of detector is usually combined with a passive infrared detector. Microwave detectors respond to a Doppler shift in the frequency of the reflected energy, by a phase shift, or by a sudden reduction of the level of received energy. Any of these effects may indicate motion of an intruder.
Glass break detectors may be used for internal perimeter building protection. Glass break acoustic detectors are mounted in close proximity to the glass panes and listen for sound frequencies associated with glass breaking.
Seismic glass break detectors, referred also as "shock sensors" are different in that they are installed on the glass pane. When glass breaks it produces specific shock frequencies which travel through the glass and often through the window frame and the surrounding walls and ceiling. Typically, the most intense frequencies generated are between 3 and 5 kHz. Seismic glass break detectors “feel” these shock frequencies and in turn generate an alarm condition.
State off the art alarm systems are strong integrated with the rest of the building control system. Technical alarms, like heating and air condition problems, water leaking, power fail and many more could be automatically reported by SMS to the technical staff or the building owner.
Intrusion events will not only transmit alarm messages to the police and activate siren, it will switch on light, activate CCTV recording, trigger voice messages (warning or dog barking, etc.).