Burglar alarm

Burglar alarm

Overview

Burglar alarms are systems designed to detect unauthorized entry into a building or area. They consist of an array of sensors, a control panel and alerting system, and interconnections. Sensors detect intruders by many methods such as monitoring door and window contacts, by passive infrared motion detectors, ultrasound, vibration, electric or magnetic fields, or microwaves. Sensors may be directly wired to a control panel that provides sensor power, or may communicate wirelessly.

Some alarm systems serve a single purpose of burglar or fire protection.
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Burglar alarms are systems designed to detect unauthorized entry into a building or area. They consist of an array of sensors, a control panel and alerting system, and interconnections. Sensors detect intruders by many methods such as monitoring door and window contacts, by passive infrared motion detectors, ultrasound, vibration, electric or magnetic fields, or microwaves. Sensors may be directly wired to a control panel that provides sensor power, or may communicate wirelessly.

Some alarm systems serve a single purpose of burglar or fire protection. Combination systems provide both fire and intrusion protection. Intrusion alarm systems may also be combined with closed-circuit television surveillance systems to automatically record the activities of intruders, and may interface to access control systems for electrically locked doors. Systems range from small, self-contained noisemakers, to complicated, multi-zoned systems with color-coded computer monitor outputs.

Burglar alarms (or perimeter security systems, perimeter detection systems, Perimeter protection, intrusion detection systems and other terms for the same thing) are used in residential, industrial, and commercial properties for protection against theft or property damage. Mobile alarm systems protect vehicles and their contents ("car alarm
Car alarm
A car alarm is an electronic device installed in a vehicle in an attempt to discourage theft of the vehicle itself, its contents, or both. Car alarms work by emitting high-volume sound when the conditions necessary for triggering are met, as well as by flashing some of the vehicle's...

s"). Prisons and military facilities use intrusion detection systems for security and control of access.

Indoor


These types of sensors are designed for indoor use. Outdoor use would not be advised due to false alarm vulnerability and weather durability.

Passive infrared detectors


The passive infrared detector (PIR) is one of the most common detectors found in household and small business environments because it offers affordable and reliable functionality. The term passive means the detector is able to function without the need to generate and radiate its own energy (unlike ultrasonic and microwave volumetric intrusion detectors that are “active” in operation). PIRs are able to distinguish if an infrared emitting object is present by first learning the ambient temperature of the monitored space and then detecting a change in the temperature caused by the presence of an object. Using the principle of differentiation, which is a check of presence or nonpresence, PIRs verify if an intruder or object is actually there. Creating individual zones of detection where each zone comprises one or more layers can achieve differentiation. Between the zones there are areas of no sensitivity (dead zones) that are used by the sensor for comparison.

Ultrasonic detectors


Using frequencies between 15 kHz and 75 kHz, these active detectors transmit ultrasonic sound waves that are inaudible to humans.
The Doppler shift principle is the underlying method of operation, in which a change in frequency is detected due to object motion. This is caused when a moving object changes the frequency of sound waves around it. Two conditions must occur to successfully detect a Doppler shift event:
  • There must be motion of an object either towards or away from the receiver.
  • The motion of the object must cause a change in the ultrasonic frequency to the receiver relative to the transmitting frequency.


The ultrasonic detector operates by the transmitter emitting an ultrasonic signal into the area to be protected. The sound waves are reflected by solid objects (such as the surrounding floor, walls and ceiling) and then detected by the receiver. Because ultrasonic waves are transmitted through air, then hard-surfaced objects tend to reflect most of the ultrasonic energy, while soft surfaces tend to absorb most energy.

When the surfaces are stationary, the frequency of the waves detected by the receiver will be equal to the transmitted frequency. However, a change in frequency will occur as a result of the Doppler principle, when a person or object is moving towards or away from the detector. Such an event initiates an alarm signal. This technology is considered obsolete by many alarm professionals, and is not actively installed.

Microwave detectors


This device 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 (monostatic) for indoor applications, and separate housings (bistatic) for outdoor applications. To reduce false alarms this type of detector is usually combined with a passive infrared detector or "Dualtec" alarm.

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.

Photo-electric beams


Photoelectric beam systems detect the presence of an intruder by transmitting visible or infrared light beams across an area, where these beams may be obstructed. To improve the detection surface area, the beams are often employed in stacks of two or more. However, if an intruder is aware of the technology's presence, it can be avoided. The technology can be an effective long-range detection system, if installed in stacks of three or more where the transmitters and receivers are staggered to create a fence-like barrier. Systems are available for both internal and external applications. To prevent a clandestine attack using a secondary light source being used to hold the detector in a 'sealed' condition whilst an intruder passes through, most systems use and detect a modulated light source.

Glass break detectors


The glass break detector
Glass break detector
A glass break detector is a sensor used in electronic burglar alarms that detects if a pane of glass is shattered or broken. These sensors are commonly used near glass doors or glass store-front windows to detect if an intruder broke the glass and entered....

 may be used for internal perimeter building protection. When glass breaks it generates sound in a wide band of frequencies. These can range from infrasonic, which is below 20 hertz (Hz) and can not be heard by the human ear, through the audio band from 20 Hz to 20 kHz which humans can hear, right up to ultrasonic, which is above 20 kHz and again cannot be heard. 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 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, depending on the type of glass and the presence of a plastic interlayer. Seismic glass break detectors “feel” these shock frequencies and in turn generate an alarm condition.

The more primitive detection method involves gluing a thin strip of conducting foil on the inside of the glass and putting low-power electrical current through it. Breaking the glass is practically guaranteed to tear the foil and break the circuit.

Smoke, heat, and carbon monoxide detectors


Most systems may also be equipped with smoke, heat, and/or carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

 detectors. These are also known as 24 hour zones (which are on at all times). Smoke detectors and heat detectors protect from the risk of fire and carbon monoxide detectors protect from the risk of carbon monoxide. Although an intruder alarm panel may also have these detectors connected, it may not meet all the local fire code requirements of a fire alarm system.

Outdoor


These types of sensors would be found most of the time mounted on fences or installed on the perimeter of the protected area.

Vibration (shaker) or inertia sensors


These devices are mounted on barriers and are used primarily to detect an attack on the structure itself. The technology relies on an unstable mechanical configuration that forms part of the electrical circuit. When movement or vibration occurs, the unstable portion of the circuit moves and breaks the current flow, which produces an alarm. The technology of the devices varies and can be sensitive to different levels of vibration. The medium transmitting the vibration must be correctly selected for the specific sensor as they are best suited to different types of structures and configurations.

A rather new and unproven type of sensors use piezo-electric components rather than mechanical circuits, which can be tuned to be extremely sensitive to vibration.
  • pros: Very reliable sensors, low false alarm rate and middle place in the price range.
  • cons: Must be fence mounted. The rather high price deters many customers, but its effectiveness offsets its high price. Piezo-electric sensors are a new technology with an unproven record as opposed to the mechanical sensor which in some cases has a field record in excess of 20 years.

Passive magnetic field detection


This buried security system is based on the Magnetic Anomaly Detection principle of operation. The system uses an electromagnetic field generator powered by two wires running in parallel. Both wires run along the perimeter and are usually installed about 5 inches apart on top of a wall or about 12"/30 cm below ground. The wires are connected to a signal processor which analyzes any change in the magnetic field.

This kind of buried security system sensor cable could be embedded in the top of almost any kind of wall to provide a regular wall detection ability, or can be buried in the ground. They provide a very low false alarm rate, and have a very high chance of detecting real burglars. However, they cannot be installed near high voltage lines, or radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 transmitters.

E-field


This proximity system can be installed on building perimeters, fences, and walls. It also has the ability to be installed free standing on dedicated poles. The system uses an electromagnetic field generator powering one wire, with another sensing wire running parallel to it. Both wires run along the perimeter and are usually installed about 800 millimetres apart. The sensing wire is connected to a signal processor that analyses:
  • amplitude change (mass of intruder),
  • rate change (movement of intruder),
  • preset disturbance time (time the intruder is in the pattern).

These items define the characteristics of an intruder and when all three are detected simultaneously, an alarm signal is generated.

The barrier can provide protection from the ground to about 4 metres of altitude. It is usually configured in zones of about 200 metre lengths depending on the number of sensor wires installed.
  • pros: concealed as a buried form.
  • cons: expensive, short zones which mean more electronics (more money), high rate of false alarms as it cannot distinguish a cat from a human. In reality it does not work that well, as extreme weather causes false alarms.

Microwave barriers


The operation of a microwave barrier is very simple. This type of device produces an electromagnetic beam using high frequency waves that pass from the transmitter to the receiver, creating an invisible but sensitive wall of protection. When the receiver detects a difference of condition within the beam (and hence a possible intrusion), the system begins a detailed analysis of the situation. If the system considers the signal a real intrusion, it provides an alarm signal that can be treated in analog or digital form.
  • pros:low cost, easy to install, invisible perimeter barrier, unknown perimeter limits to the intruder.
  • cons:extremely sensitive to weather as rain, snow and fog for example would cause the sensors to stop working, need sterile perimeter line because trees, bushes or anything that blocks the beam would cause false alarm or lack of detection.

Microphonic systems


Microphonic based systems vary in design but each is generally based on the detection of an intruder attempting to cut or climb over a chainwire fence. Usually the microphonic detection systems are installed as sensor cables attached to rigid chainwire fences, however some specialised versions of these systems can also be installed as buried systems underground. Depending on the version selected, it can be sensitive to different levels of noise or vibration. The system is based on coaxial or electro-magnetic sensor cable with the controller having the ability to differentiate between signals from the cable or chainwire being cut, an intruder climbing the fence, or bad weather conditions.

The systems are designed to detect and analyse incoming electronic signals received from the sensor cable, and then to generate alarms from signals which exceed preset conditions. The systems have adjustable electronics to permit installers to change the sensitivity of the alarm detectors to the suit specific environmental conditions. The tuning of the system is usually accomplished during commissioning of the detection devices.
  • pros: very cheap, very simple configuration, easy to install.
  • cons: some systems have a high rate of false alarms because some of these sensors might be too sensitive. Although systems using DSP (Digital Signal Processing)
    Digital signal processing
    Digital signal processing is concerned with the representation of discrete time signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing...

     will largely eliminate false alarms on some cases.

Taut wire fence systems


A taut wire perimeter security system is basically an independent screen of tensioned tripwires usually mounted on a fence or wall. Alternatively, the screen can be made so thick that there is no need for a supporting chainwire fence. These systems are designed to detect any physical attempt to penetrate the barrier. Taut wire systems can operate with a variety of switches or detectors that sense movement at each end of the tensioned wires. These switches or detectors can be a simple mechanical contact, static force transducer or an electronic strain gauge. Unwanted alarms caused by animals and birds can be avoided by adjusting the sensors to ignore objects that exert small amounts of pressure on the wires. This type of system is vulnerable to intruders digging under the fence. A concrete footing directly below the fence is installed to prevent this type of attack.
  • pros: low rate of false alarms, very reliable sensors and high rate of detection.
  • cons: Very expensive, complicated to install and old technology.

Fibre optic cable


A fibre-optic cable can be used to detect intruders by measuring the difference in the amount of light sent through the fibre core. If the cable is disturbed, light will 'leak' out and the receiver unit will detect a difference in the amount of light received. The cable can be attached directly to a chainwire fence or bonded into a barbed steel tape that is used to protect the tops of walls and fences. This type of barbed tape provides a good physical deterrent as well as giving an immediate alarm if the tape is cut or severely distorted. Other types work on the detection of change in polarization which is caused by fiber position change.
  • pros: very similar to the Microphonic system, very simple configuration, easy to install.
  • cons: high rate of false alarm or no alarms at all for systems using light that leaks out of the optical fiber. The polarization changing system is much more sensitive but false alarms depend on the alarm processing.

H-field


This system employs an electro-magnetic field disturbance principle based on two unshielded (or 'leaky') coaxial cables buried about 10–15 cm deep and located at about 1 metre apart. The transmitter emits continuous Radio Frequency (RF) energy along one cable and the energy is received by the other cable. When the change in field strength weakens due to the presence of an object and reaches a pre-set lower threshold, an alarm condition is generated. The system is unobtrusive when it has been installed correctly, however care must be taken to ensure the surrounding soil offers good drainage in order to reduce nuisance alarms.
  • pros: concealed as a buried form.
  • cons: can be affected by RF noise, high rate of false alarms, hard to install.

System connections


The trigger signal from each sensor
Sensor
A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated...

 is transmitted to one or more control unit
Control unit
A control unit in general is a central part of the machinery that controls its operation, provided that a piece of machinery is complex and organized enough to contain any such unit. One domain in which the term is specifically used is the area of computer design...

(s) either through wires or wireless means (radio, line carrier, infrared). Wired systems are convenient when sensors (such as PIRs, smoke detectors etc.) require power to operate correctly, however, they may be more costly to install. Entry-level wired systems utilize a Star network
Star network
Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages...

 topology, where the panel is at the center logically, and all devices "home run" its wire back to the panel. More complex panels use a Bus network
Bus network
A bus network topology is a network architecture in which a set of clients are connected via a shared communications line, called a bus. There are several common instances of the bus architecture, including one in the motherboard of most computers, and those in some versions of Ethernet...

 topology where the wire basically is a data loop
Dual loop
This article refers to the electrical circuit as used in burglar alarms. Several other uses for the term "Dual loop" may also exist.Dual-loop is a method of electrical circuit termination used in electronic security applications, particularly modern intruder alarms. It is called 'dual-loop' because...

 around the perimeter of the facility, and has "drops" for the sensor devices which must include a unique device identifier integrated into the sensor device itself (e.g. iD biscuit). Wired systems also have the advantage, if wired properly, of being tamper-evident
Tamper-evident
Tamper-evident describes a device or process that makes unauthorized access to the protected object easily detected. Seals, markings or other techniques may be tamper indicating.-Tampering:...

. Wireless systems, on the other hand, often use battery-powered transmitters which are easier to install, but may reduce the reliability of the system if the sensors are not supervised, or if the batteries are not maintained. Depending on distance and construction materials, one or more wireless repeaters may be required to get the signal reliably back to the alarm panel. Hybrid systems utilize both wired and wireless sensors to achieve the benefits of both. Transmitters, or sensors can also be connected through the premises electrical circuits to transmit coded signals to the control unit (line carrier). The control unit usually has a separate channel or zone for burglar and fire sensors, and better systems have a separate zone for every different sensor, as well as internal "trouble" indicators (mains power loss, low battery, wire broken, etc.).

Alarm connection and monitoring


Depending upon the application, the alarm output may be local, remote or a combination. Local alarms do not include monitoring, though may include indoor and/or outdoor sounders (e.g. motorized bell or electronic siren) and lights (e.g. strobe light
Strobe light
A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope...

) which may be useful for signaling an evacuation notice for people during fire alarms, or where one hopes to scare off an amateur burglar quickly. However, with the widespread use of alarm systems (especially in cars), false alarms are very frequent and many urbanites tend to ignore alarms rather than investigating, let alone contacting the necessary authorities. In short, there may be no response at all. In rural areas (e.g., where nobody will hear the fire bell or burglar siren) lights or sounds may not make much difference anyway, as the nearest responders could take so long to get there that nothing can be done to avoid losses.

Remote alarm systems are used to connect the control unit to a predetermined monitor of some sort, and they come in many different configurations. High-end systems connect to a central station
Central Station (Alarm Monitoring Center)
Central-Station is a common term used to refer to a company that provides services to monitor burglar, fire and residential alarm systems. The central-station may also provide watchman and supervisory services....

 or responder (e.g. Police/ Fire/ Medical) via a direct phone wire, a radio network (i.e GPRS/GSM) or an IP path. In the case of a dual signalling system two of these options are utilised simulatneously. The alarm monitoring includes not only the sensors, but also the communication transmitter itself. While direct phone circuits are still available in some areas from phone companies, because of their high cost and the advent dual signalling with its comparitively lower cost they are becoming uncommon. Direct connections are now most usually seen only in Federal, State, and Local Government buildings, or on a school campus that has a dedicated security, police, fire, or emergency medical department (in the UK communication is only possible to an Alarm Receiving Centre - communication direct to the emergency services is not permitted). More typical systems incorporate a digital telephone dialer unit that will dial a central station (or some other location) via the Public Switched Telephone Network
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...

 (PSTN) and raise the alarm, either with a synthesized voice or increasingly via an encoded message string that the central station decodes. These may connect to the regular phone system on the system side of the demarcation point
Demarcation point
In telephony, the demarcation point is the point at which the public switched telephone network ends and connects with the customer's on-premises wiring. It is the dividing line which determines who is responsible for installation and maintenance of wiring and equipment -- customer/subscriber, or...

, but typically connect on the customer side ahead of all phones within the monitored premises so that the alarm system can seize the line by cutting-off any active calls and call the monitoring company if needed. A dual signalling system would raise the alarm wirelessly via a radio path (GPRS/GSM) using the phone line as a back-up overcoming any compromise to the phone line. Encoders can be programmed to indicate which specific sensor was triggered, and monitors can show the physical location (or "zone") of the sensor on a list or even a map of the protected premises, which can make the resulting response more effective. For example, a water-flow alarm, coupled with a flame detector
Flame detector
There are several types of flame detector. The optical flame detector is a detector that uses optical sensors to detect flames. There are also ionisation flame detectors, which use current flow in the flame to detect flame presence, and thermocouple flame detectors.-Ultraviolet:Ultraviolet ...

 in the same area is a more reliable indication of an actual fire than just one or the other sensor indication by itself. Many alarm panels are equipped with a backup communication path for use when the primary PSTN circuit is not functioning. The redundant dialer may be connected to a second phone line, or a specialized encoded cellular phone, radio, or internet interface device to bypass the PSTN entirely, to thwart intentional tampering with the phone line(s). Just the fact that someone tampered with the line could trigger a supervisory alarm via the radio network, giving early warning of an imminent problem (e.g., arson). In some cases a remote building may not have PSTN phone service, and the cost of trenching and running a direct line may be prohibitive. It is possible to use a wireless cellular or radio device as the primary communication method.

In the UK the most popular solution of this kind is similar in principle to the above but with the primary and back up paths reversed. Utilising a radio path (GPRS/GSM) as the primary signalling path is not only quicker than PSTN but also allows huge cost savings as unlimited amounts of data can be sent at no extra expense.

Broadband Alarm Monitoring


Increasing deployment of voice over IP technology (VoIP) is driving the adoption of broadband signaling for alarm reporting. Many sites requiring alarm installations no longer have conventional telephone lines (POTS), and alarm panels with conventional telephone dialer capability do not work reliably over some types of VoIP service.

Dial up analog alarm panels or systems with serial/parallel data ports may be migrated to broadband through the addition of an alarm server device which converts telephone signaling signals or data port traffic to IP messages suitable for broadband transmission. But the direct use of VoIP (POTS port on premises terminal) to transport analog alarms without an alarm server device is problematic as the audio codecs used throughout the entire network transmission path cannot guarantee a suitable level of reliability or quality of service acceptable for the application.

In response to the changing public communications network, new alarm systems often can use broadband signaling as a method of alarm transmission, and manufacturers are including IP reporting capability directly in their alarm panel products. When the Internet is used as a primary signaling method for critical security and life safety applications, frequent supervision messages are configured to overcome concerns about backup power for network equipment and signal delivery time. But for typical applications, connectivity concerns are controlled by normal supervision messages, sent daily or weekly.

Various IP Alarm transmission protocols exist but most in use today are proprietary. Just as the formats used for conventional telephone reporting were standardized and published, broadband signaling for alarm reporting is being standardized today. In 2007, US alarm manufacturers developed an open standard called DC-09. This standard has been accepted as an American National Standard, and is published as ANSI/SIA DC-09-2007. [ref: ANSI/SIA DC-09-2007] The protocol provides an encoding scheme and transport mechanism to carry data from 17 previously defined alarm protocols, including the latest Contact ID, SIA DC-03 and SIA 2000 protocols. [ref: ANSI/SIA DC-07-2001.04] Several manufacturers of panels and receivers are reported to be developing or have released support for DC-09.

Radio Alarm Monitoring/Dual signalling


Dual Signalling is a method of alarm transmission that uses a mobile phone network and a telephone and/or IP path to transmit intruder, fire and personal attack signals at high speed from the protected premises to an Alarm Receiving Centre (ARC). It most commonly uses GPRS or GSM, a high-speed signalling technology used to send and receive ‘packets’ of data, with a telephone line in addition. The option of IP is not used as frequently due to issues with installation and configuration as a high level of I.T expertise is often required in addition to alarm installation knowledge.

A dual signalling communication device is attached to a control panel on a security installation and is the component that transmits the alarm to the ARC. It can do this in a number of different ways, via the GPRS radio path, via the GSM radio path or via the telephone line/or IP if that has been chosen. These multiple signalling paths are all present and live at the same time backing each other up to minimise exposure of the property to intruders. Should one fail there is always one form of back up and depending on the manufacturer chosen up to three paths working simultaneously at any one time.

Utilising two signalling paths means that the second path can distinguish the status of the alarm e.g. both a radio path fail and telephone line fail would indicate a genuine attack on the alarm. This helps eliminate false alarms and the problem of the Police and keyholders being called to premises unnecessarily. Dual signalling has helped considerably with the restoration of Police response as in an instance where a phone line is cut as the the dual signalling device can continue to send alarm calls via one of its alternative paths either confirming or denying the alarm from the initial path.

Dual signalling has revolutionised the security Industry as prior to its arrival there was only a single path choice for secure signalling. Dual signalling has helped to drive up the quality of signalling in the Security Industry and its capacity to be built into familiar hardware allowed Alarm Installation Engineers to make the easy transition from installing single to dual path signalling.

Listen In Alarm monitoring


Monitored alarms and speaker phones allow for the central station to speak with the homeowner and/or intruder. This may be beneficial to the owner for medical emergencies. For actual break-ins, the speaker phones allow the central station to urge the intruder to cease and desist as response units have been dispatched. Listen in alarm monitoring is also known as Immediate Audio-Response monitoring in the UK.

Alarm monitoring Services


The list of services to be monitored at a Central Station has expanded over the past few years to include: Access Control
Access control
Access control refers to exerting control over who can interact with a resource. Often but not always, this involves an authority, who does the controlling. The resource can be a given building, group of buildings, or computer-based information system...

; CCTV Monitoring; Environmental Monitoring; Intrusion Alarm Monitoring; Fire Alarm & Sprinkler Monitoring; Critical Condition Monitoring; Medical Response Monitoring; Elevator Telephone Monitoring; Hold-Up or Panic Alarm Monitoring; Duress Monitoring; Auto Dialer tests; Open & Close Signal Supervision & Reporting; Exception Reports; and PIN or Passcode Management. Increasingly, the Central Stations are making this information available directly to end users via the internet and a secure log-on to view and create custom reports on these events themselves.

Alarm response


Depending upon the zone triggered, number and sequence of zones, time of day, and other factors, the monitoring center can automatically initiate various actions. They might be instructed to call the ambulance, fire department or police department immediately, or to first call the protected premises or property manager
Property caretaker
A Property caretaker is a person, group or organization that cares for real estate for trade or financial compensation, and sometimes as a barter for rent-free living accommodations...

 to try to determine if the alarm is genuine. They could also start calling a list of phone numbers provided by the customer to contact someone to go check on the protected premises. Some zones may trigger a call to the local heating oil company to go check on the system, or a call to the owner with details of which room may be getting flooded. Some alarm systems are tied to video surveillance
Surveillance
Surveillance is the monitoring of the behavior, activities, or other changing information, usually of people. It is sometimes done in a surreptitious manner...

 systems so that current video of the intrusion area can be instantly displayed on a remote monitor, not to mention recorded.

The first video home security system was patented on December 2, 1969 to inventor Marie Brown. The system used television surveillance.

Access control and bypass codes


To be useful, an intrusion alarm system is deactivated or reconfigured when authorized personnel are present. Authorization may be indicated in any number of ways, often with keys or codes used at the control panel or a remote panel near an entry. High-security alarms may require multiple codes, or a fingerprint, badge, hand-geometry, retinal scan, encrypted response generator, and other means that are deemed sufficiently secure for the purpose.

Failed authorizations should result in an alarm or at least a timed lockout to prevent "experimenting" with possible codes. Some systems can be configured to permit deactivation of individual sensors or groups. Others can also be programmed to bypass or ignore individual sensors (once or multiple times) and leave the remainder of the system armed. This feature is useful for permitting a single door to be opened and closed before the alarm is armed, or to permit a person to leave, but not return. High-end systems allow multiple access codes, and may even permit them to be used only once, or on particular days, or only in combination with other users' codes (i.e., escorted). In any case, a remote monitoring center should arrange an oral code to be provided by an authorized person in case of false alarms, so the monitoring center can be assured that a further alarm response is unnecessary. As with access codes, there can also be a hierarchy of oral codes, say, for furnace repairperson to enter the kitchen and basement sensor areas but not the silver vault in the butler's pantry. There are also systems that permit a duress code
Duress code
A duress code is a covert signal used by an individual that is under duress to indicate their state. The term duress code typically refers to a signal embedded in normal communication, such as a word or phrase used during conversation to alert other personnel of the duress...

 to be entered and silence the local alarm, but still trigger the remote alarm to summon the police to a robbery.

Fire sensors can be "isolated", meaning that when triggered, they will not trigger the main alarm network. This is important when smoke and heat is intentionally produced. The owners of buildings can be fined for generating False alarms that waste the time of emergency personnel.

False / no alarms


System reliability can be a problem when it causes nuisance alarms, false alarm
False alarm
A false alarm, also called a nuisance alarm, is the fake report of an emergency, causing unnecessary panic and/or bringing resources to a place where they are not needed. Over time, repeated false alarms in a certain area may cause occupants to start to ignore all alarms, knowing that each time it...

s, or fails to alarm when called for; in all cases, the costs are significant. In many jurisdictions, law enforcement fees for multiple false alarms are significant, and even lead to loss of service, while losses due to undeterred crimes can be large or even priceless. Approximately 1% of police alarm calls actually involve a crime. Nuisance alarms occur when an unintended event evokes an alarm status by an otherwise properly working alarm system. A false alarm also occurs when there is an alarm system malfunction that results in an alarm state. In all three circumstances, the source of the problem should be immediately found and fixed, so that responders will not lose confidence in the alarm reports. It is easier to know when there are false alarms, because the system is designed to react to that condition. Failure alarms are more troublesome because they usually require periodic testing to make sure the sensors are working and that the correct signals are getting through to the monitor. Some systems are designed to detect problems internally, such as low or dead batteries, loose connections, phone circuit trouble, etc. While earlier nuisance alarms could be set off by small disturbances, like insects or pets, newer model alarms have technology to measure the size/weight of the object causing the disturbance, and thus are able to decide how serious the threat is, which is especially useful in burglar alarms.

False-Alarm Reduction


Home and business owners can now choose a new type of keypad control panel designed to help reduce false alarms.

Based on a standard called CP-01-2000, developed by the American National Standards Institute
American National Standards Institute
The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...

 and Security Industry Association, the new generation of keypad control panels takes aim at user error by building in extra precautions that minimize unwarranted dispatch of emergency responders.

Some of the features of CP-01 keypads include a progress annunciation function that emits a different sound during the last 10 seconds of delay, which hastens exit from the premises. Also, the exit time doubles if the user disables the pre-warning feature.

Other "rules" address failure to exit premises, which results in arming all zones in Stay Mode and a one-time, automatic restart of exit delay. However, if there is an exit error, an immediate local alarm will sound.

In the UK the inventors of dual signalling, CSL DualCom Ltd were the single biggest contributor to the reduction of false alarms in the last 15 years. Utilising a dual signalling systems uses the basic ‘belt and braces’ principle in which the radio path (GPRS/GSM) is backed up by the telephone line. In a scenario where the telephone line is cut, a dual signalling device is able to send further signals wirelessly to confirm the alarm. Prior to the availability of dual signalling systems, Police and keyholders were often called out to the premises because of an alarm signal on the telephone path only to discover that it was a network fault and not a genuine alarm.

Cross zoning reduces alarms


Cross zoning is an innovative alarm-system strategy that does not require a new keypad. Using multiple sensors to monitor activity in one area, advanced software analyzes input from all the sources.

For example, if a motion detector trips in one area, the signal is recorded and the central-station monitor notifies the customer. A second alarm signal - received in an adjacent zone in close time proximity, is the confirmation the central-station monitor needs to request a dispatch immediately. This builds in increased protection and a fail safe should a door blow open or a bird rattle an exterior window.

Enhanced Call Verification


Enhanced Call Verification (ECV) helps reduce false dispatches 25-50% while still protecting citizens, and is mandated in several US jurisdictions, although the alarm industry has successfully opposed it in others. ECV requires central station personnel to attempt to verify the alarm activation by making a minimum of two phone calls to two different responsible party telephone numbers before dispatching law enforcement to the scene.

The first alarm-verification call goes to the location the alarm originated. If contact with a person is not made a second call is placed to a different number. The secondary number, best practices dictate, should be to a telephone that is answered even after hours, preferably a cellular phone of a decision maker authorized to request or bypass emergency response.

Video verification


Video verification documents a change in local conditions by using cameras to record video signals or image snapshots. The source images can be sent over a communication link, usually an Internet protocol (IP) network, to the central station where monitors retrieve the images through proprietary software. The information is then relayed to law-enforcement and recorded to an event file, which can later be used as prosecution evidence.

An example of how this system works is when a passive infrared or other sensor is triggered a designated number of video frames from before and after the event is sent to the central station.

A second video solution can be incorporated into to a standard panel, which sends the central station an alarm. When a signal is received, a trained monitoring professional accesses the on-site digital video recorder (DVR) through an IP link to determine the cause of the activation. For this type of system, the camera input to the DVR reflects the alarm panel's zones and partitioning, which allows personnel to look for an alarm source in multiple areas.

Independent certification


Some insurance companies and local agencies require that alarm systems be installed to code or be certified by an independent third party. Independent certification ensures a system meets a level of criteria above and beyond what a sales representative may offer.
The alarm system is required to have a maintenance check carried out every 6 – 12 months (in the UK, 'Audible Only' intruder alarm systems require a routine service visit once every 12 months and monitored intruder alarm systems require a check twice in every 12 month period) to ensure all internal components, sensors and PSUs are functioning correctly. In the past, this would require an alarm service engineer to attend site and carry the checks out. With the use of the Internet or radio path and a compatible IP/radio transmitting device (at the alarmed premises) some checks can now be carried out remotely from the central station.

This insures you have a system that will be reliable when needed. Third-party alarm certifying agencies include:
  • local fire department
  • building department
  • (UL) Underwriters Laboratories
    Underwriters Laboratories
    Underwriters Laboratories Inc. is an independent product safety certification organization. Established in 1894, the company has its headquarters in Northbrook, Illinois. UL develops standards and test procedures for products, materials, components, assemblies, tools and equipment, chiefly dealing...

  • (NFPA) National Fire Protection Association
    National Fire Protection Association
    The National Fire Protection Association is a United States trade association that creates and maintains private, copywrited, standards and codes for usage and adoption by local governments...

  • (NEC) National Electrical Code
  • (NFBAA) National Fire & Burglar Alarm Association
  • (CSAA) Central Station Alarm Association
  • BAFE - British Approvals for Fire Equipment (UK Market)
  • FSA - Fire and Security Association (UK Market)
  • NSI - National Security Inspectorate (UK Market)
  • ISIA - Irish Security Industry Association
  • SSAIB - Security & Alarms Inspection Board (UK & ROI)
  • VdS VdS Schadenverhütung Germany

See also

  • Access control
    Access control
    Access control refers to exerting control over who can interact with a resource. Often but not always, this involves an authority, who does the controlling. The resource can be a given building, group of buildings, or computer-based information system...

  • Alarms
  • Alarm management
    Alarm management
    Alarm management is the application of human factors along with instrumentation engineering and systems thinking to manage the design of an alarm system to increase its usability...

  • Burglar
  • Burglar alarm control panel
    Burglar alarm control panel
    A burglar alarm control panel is a wall-mounted unit where the detection devices and wiring of the alarm are ultimately connected and managed. These include devices such as bells, sirens, door contacts, motion detectors, smoke detectors, etc. Typical panels are located in utility closets or access...

  • Door security
    Door security
    Door security relates to prevention of door-related burglaries. Such break-ins take place in various forms, and in a number of locations; ranging from front, back and side doors to garage doors.- Common residential door types :...

  • Dual loop
    Dual loop
    This article refers to the electrical circuit as used in burglar alarms. Several other uses for the term "Dual loop" may also exist.Dual-loop is a method of electrical circuit termination used in electronic security applications, particularly modern intruder alarms. It is called 'dual-loop' because...

  • Emergency service
    Emergency service
    Emergency services are organizations which ensure public safety and health by addressing different emergencies. Some agencies exist solely for addressing certain types of emergencies whilst others deal with ad hoc emergencies as part of their normal responsibilities...

  • Environmental design
    Environmental design
    Environmental design is the process of addressing surrounding environmental parameters when devising plans, programs, policies, buildings, or products...

  • False alarm
    False alarm
    A false alarm, also called a nuisance alarm, is the fake report of an emergency, causing unnecessary panic and/or bringing resources to a place where they are not needed. Over time, repeated false alarms in a certain area may cause occupants to start to ignore all alarms, knowing that each time it...

  • Fire
    Fire
    Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....

  • Fire alarm
  • Fire alarm control panel
    Fire alarm control panel
    A Fire Alarm Control Panel , or Fire Alarm Control Unit , is the controlling component of a Fire Alarm System. The panel receives information from environmental sensors designed to detect changes associated with fire, monitors their operational integrity and provides for automatic control of...

  • Glass break detector
    Glass break detector
    A glass break detector is a sensor used in electronic burglar alarms that detects if a pane of glass is shattered or broken. These sensors are commonly used near glass doors or glass store-front windows to detect if an intruder broke the glass and entered....

  • Physical security
    Physical security
    Physical security describes measures that are designed to deny access to unauthorized personnel from physically accessing a building, facility, resource, or stored information; and guidance on how to design structures to resist potentially hostile acts...

  • ADT Security Services
    ADT Security Services
    ADT Security Services, originally American District Telegraph, now also known as simply ADT, is a division of Tyco International and a worldwide supplier of electronic security systems, fire alarm systems, communication systems, and integrated building management systems.-History:There were many...

  • Chubb Locks
    Chubb Locks
    Chubb Locks is a brand name of the Mul-T-Lock subsidiary of the Assa Abloy Group, which manufactures high security locking systems for residential, secure confinement and commercial applications.-History:...

  • Yale (company)
    Yale (company)
    Yale is a lock manufacturer owned by Assa Abloy. It is associated with the pin tumbler lock, which is often known as the Yale lock.- History :...

  • Business Technology Association
    Business Technology Association
    The Business Technology Association is an international not-for-profit trade association serving independent dealers, value-added resellers, systems integrators, manufacturers and distributors in the business equipment and systems industry...

  • Westminster Group
  • Chubb Electronic Security
    Chubb Locks
    Chubb Locks is a brand name of the Mul-T-Lock subsidiary of the Assa Abloy Group, which manufactures high security locking systems for residential, secure confinement and commercial applications.-History:...

  • Security lighting
    Security lighting
    In the field of physical security, security lighting is often used as a preventative and corrective measure against intrusions or other criminal activity on a physical piece of property. Security lighting may be provided to aid in the detection of intruders, to deter intruders, or in some cases...

  • Radio Alarm Monitoring/Dual signalling

Sources


  • Trimmer, H. William (1981). Understanding and Servicing Alarm Systems. Stoneham: Butterworth.
  • Weber, Thad L. (1985). Alarm Systems and Theft Protection (2d ed.). Stoneham, MA: Butterworth.
  • Walker, Philip (1985). Electronic Security Systems. Cambridge, UK: University Press
  • Ramsey, Anthony Home Security.
  • Schatz, David A., et al. Video safety curtain. U.S. Patent No. 6,297,844, Issued Oct. 2, 2001.
  • Atss, R. Nandakumar.
  • Aii, N. Clifton. "Broadband CSV, XML Alarm data Standards" Auckland NZ, (2002)

External links