The world of intrusion alarm

IAS Basics

A Security System consists of 3 basic elements:

• DETECTORS, that sense the actions or presence of an intruder

• CONTROL PANEL, that arms and disarms the system, receives the signals from the sensors, processes these signals and initiates the alarm warning devices

• ALARM WARNING DEVICES, for either remote and/or local warning.

• COMMUNICATION SYSTEMS for remote and central monitoring / warning.

IAS Basics -Detectors

DETECTORS are normally configured to provide 3 levels of security:

• Perimeter detection - that is used to sense intrusion as the thief attempts to breach the perimeter of the protected premises

• Interior detection - that provides security to strategic areas in which valuables may be found

• 24 hour detection - that is used to describe devices that are active in both the armed and disarmed modes of the system

Perimeter Detection• Perimeter protection is the type of protection that detects someone entering your

home or building from the outside. Obviously, you enter through a door but intruders often use other means of entrance. For the best protection, you will need to protect any opening that can be used as an entrance. This will include not only doors, but also windows, ducts, and any other opening large enough for someone to go through.

• The most common form of protection are "magnetic contacts" which are placed so that if a door or window is opened, a signal will be sent to the control panel and an alarm will results. Contacts may be either recessed, where the contact is usually mounted within the door or window casing and is hidden, or surface mounted. If you look at the top of the door in a retail store, you will usually see a surface mounted contact. Because door casings are steel and the walls are concrete, recessed contacts are difficult to mount in this type of building. Being open to vision, surface contacts can also be a deterrent.

Switches installed to all the exterior opening doors, windows, etc

Perimeter Detection

What if only the glass is broken in a door or window and entrance is gained without opening the door or window? The magnetic contact will not detect a breach and will not signal an alarm. For this you will need a "glass break sensor" to signal the breach. Glass break sensors will detect either the acoustic, or sound of the glass breaking, the seismic, or feel of the glass breaking, or both.

Break glass or vibration sensors installed to detect breakage of windows

Perimeter Detection

The last type of perimeter protection actually uses interior protectors. An "infrared

detector" is set to form a virtual "barrier" along a wall instead of covering a large area. When someone passes through this barrier, an alarm will be set off.

External sensors such as photo-electric beams, special PIR

sensors installed to detect intrusion at the perimeter of the property

Interior Detection

INTERIOR DETECTION

• Provides security to areas such as the master bedroom, entertainment areas, hallways, study, home office, dining room or other areas that valuables are stored.

• In some instances the system may consist of only interior detection, especially in the lower end of the market.

• Normally consists of Passive Infra Red Sensors (PIR) due to low cost and ease of installation

Interior Detection

Interior protection is the type of protection used to detect an intruder inside your home

or building. Generally infrared detectors are used for this type of protection. There are

two basic types of infrared detectors: ceiling mounted and wall mounted.

Interior Detection -PIR

The most common detectors are the passive infrared (PIR)

sensors which react to the infrared heat energy emitted by people. PIR sensors emit no radiation. They are passive and are normally designed to detect motion of a heat source.

A multifaceted (Fresnel) lens in front of the pyroelectric transducer focuses infrared energy from a multitude of narrow, discrete beams or cones. As a warm body moves across the field of view of the detector, the transducer output has peaks and valleys. If the variation is sufficiently intense and rapid, a circuit triggers and closes a relay. This relay provides the dry contact closure normally found on PIR detectors.

Interior Detection

24 Hour Detectors - that include:

• Duress, panic and medical alarms, consisting of fixed button and portable wireless units

• Fire alarms including smoke sensors, heat sensors and fixed temperature sensors.

• Plant monitoring devices for freezers, furnaces, air-conditioning, etc

• Tamper devices installed to siren units, control panels and detectors

The security system has 3 basic modes of operation:

• Stay (home) armed mode, where zones are automatically bypassed to allow the occupants to move around in pre-programmed areas.

• Away armed mode where all zones are active

• Disarmed mode when all zones with the exception of 24 hour zones are turned off.

IAS –Panels

• Contains the microprocessor and electronic circuits that controls system operation.

• Contains the power supply and standby (re-chargeable batteries) required to power the system.

• A control panel is normally selected to suit the number of detection zones, as well as the number of code holders required to operate the system

• Normally one electronic detector is connected to an individual zone

Control Panels

• The system is controlled by a number of keypads installed near the entry foyer, in the master bedroom, etc.

• Control of the system can also be by wireless remote control or by a remote telephone connection

• The control panel is programmed to suit the individual users requirements either by use of the system keypad, locally by direct connection to a PC, or remotely via a modem.

Control Panel - Keypads

The type of alarm warning selected depends upon:

• The geographical location of the premises

• The frequency of patrols in the area

• The type and value of risk involved

• The customers ability to afford the cost involved with central station monitoring

Alarm Warning Devices

Communication systems

When the alarm sensor activates, the panel will “seize” the telephone line and transmit a digital signal to the Central Monitoring Station receiver. The alarm information and required response information is displayed on a computer terminal for operator evaluation and action

The receiver sends a handshake tone

Panel now sends alarm data

After successful reception, a “kiss off” tone is sent

Sequence of Events - data transfer takes around 4.5 seconds

Central Monitoring Station

Panel Dials the receiver

Information displayed to the Central Station operator includes:

• Customer name & address

• Emergency telephone numbers (police, fire brigade, ambulance, re-call numbers etc.)

• Type of system

• Response action requirements

• A description of zone(s) that are in alarm

• Priority of the alarm

C.M.S