Burglar
(or intrusion),fire,
and safety alarms
are all electronic today. Sensors are connected to a control unit
via a low-voltage hardwire or narrowband RF signal which is used to
interact with a response device. The most common security sensors
indicate the opening of a door or window or detect motion via
passive infrared (PIR). New construction systems are predominately
hardwired for economy. Retrofit installations often use wireless
systems for a more economical and quicker install. Some systems
serve a single purpose of burglary or fire protection. Combination
systems provide both fire and intrusion protection. Sophistication
ranges from small, self-contained noisemakers, to complicated,
multi-zoned systems with color-coded computer monitor outputs. Many
of these concepts also apply to portable alarms for protecting cars,
trucks or other vehicles and their contents (i.e., "car alarms").
See also fire alarm control panel for specific fire system issues.
Burglar alarms are sometimes referred to as
alarm systems,
see burglar alarm control panel for a discussion of hard-wired
burglar alarm system design.
Burglar alarms (or perimeter detection systems, Perimeter
protection, intrusion detection systems and many more
terms for the same thing) are divided to two main fields: home
burglar alarms and industrial burglar and perimeter intrusion
detection.
Home burglar alarms are often systems assembled from inexpensive
infrared detectors that the home owner or the security contractor
will install in front of all the windows and doors in the house.
These infrared sensors are designed for indoor use only and should
not be used outside. The cost of installing outdoor sensors is
higher and false alarm prone. A more complete home alarm also
includes magnetic sensors on the doors and windows. These sensors
will alarm the system when a door or window is opened. These sensors
do not protect against glass breakage, but additional glass break
detectors can also be used. The sensors are connected to a control
panel that is operated by a keypad. The control panel processes
intrusion signals and rings sirens and/or communicates to a
monitoring service which then calls the owner and/or police
department. This is the basic form of home alarm system.
Industrial perimeter intrusion detection systems
In the field of industrial security systems, the methodology of
protection is quite different. First is to detect, second to delay
and third to alarm. Industrial alarm systems are designed as an
integration of several sensor systems. The most important for big
facilities would be the outer fence on which a sensor is placed. It
would detect and delay the intruders before they even reach the
building itself. As described below, there are a number of different
fence mounted sensors, each with its own pros and cons. Other than
the fence mounted sensors, there are also buried perimeter sensors
that can be put on top of a wall or buried underground to create a
hidden defense line. This only allows the security system to detect
an intruder, but does not delay them. Another choice for detecting
is Closed Circuit Television (CCTV). A guard can watch the screens
or video motion detection software act the part. In any case CCTV is
ineffective as a standalone sensor because it’s affected by weather
conditions as cameras cannot see in heavy fog, rain and snow. The
last line of protection is the building itself. It can be protected
by infrared sensors, microwave sensors, smart locks and magnetic
door sensors.
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 25 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
microwaves at a receiver, either through reflection or reduction in
beam intensity. The transmitter and receiver are usually combined
inside a single housing (monostatic) for indoor applications, and
separate housings (bistatic) for outdoor applications. By generating
energy in the microwave region of the electromagnetic spectrum,
detector operates as an active volumetric device that responds to:
-
A Doppler shift frequency change.
-
A frequency phase shift.
-
A motion causing reduction in received energy.
Photo-Electric Beams
Photoelectric beam systems detect the presence of an intruder by
transmitting visible or infra red light beams across an area, where
these beams maybe 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 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.
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 simple 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. More sophisticated sensors use piezo-electric
components rather than mechanical circuits, which can be tuned to be
extremely sensitive to vibration. These sensors are more durable and
more resistant to tampering.
-
pros: Very reliable sensors, low false alarm rate and middle
place in the price range.
-
cons: Must be fence mounted would be the main con. Its rather
high price deters many customers, but its effectiveness offsets
its high price.
conclusion:
The best money for value fence mounted configuration.
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 powering with 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 foot buried in the ground.
The wires are connected to a signal processor which analyze any
change in the magnetic field. This kind of buried security system
sensor cable could be buried on the top of almost any kind of wall
to provide a regular wall detection ability or be buried in the
ground.
-
pros: Very low false alarm rate, can be put on top of any wall,
very high change to detect real burglars.
-
cons: Can't be installed in near high voltage line or radars and
airports.
conclusion:
The best solution in the buried sensors range.
E-Field
This proximity system can be installed on building perimeters,
fences, and walls, and 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 means more electronic (more
money), high rate of false alarms as it might sound as it can
define a cat from a human in reality it doesn't work that well
as well as extreme weather causes false alarms.
conclusion:
As in the buried security systems field the Passive Magnetic Field
Detection will do a better job most of the time.
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 specialized 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 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 has a very high rate of false alarms because
some of these sensors has sensitivity problems as they might be
too sensitive.
conclusion:
If you need a fence mounted sensor and you willing to add some more
money for a reliable system go with the Vibration system.
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. It should
be noted that 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.
conclusion:
Very good but very expensive system that uses 20-year-old
technology; these days there is no reason to choose Taut wire over
the other fence-mounted sensors.
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.
-
pros: very similar to the Microphonic system, very simple
configuration, easy to install.
-
cons: high rate of false alarm or no alarms at all, some sell it
as buried system which function VERY bad as buried or on top of
a wall.
conclusion:
Some people choose fiber optic systems only because of the price
which is a very wrong decision for a security system, as a fence
mounted the microphonic and the Vibration sensors would do a better
job for the same price range.
H-Field
This system employs an electro-magnetic field disturbance principle
based on two unshielded (or ‘leaky’) coaxial cables buried about
10-15cm deep and located at about 2.1 metres 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: affected by RF noise, high rate of false alarms, hard to
install.
conclusion:
Choose one of the other 2 buried security systems sensors.
The trigger signal from each sensor is transmitted to one or more
control unit(s) either through wires or wireless means (radio, line
carrier, infrared). Wired systems are convenient when sensors (such
as smoke detectors) require power to operate correctly, however,
they may be more costly to install. Entry-level wired systems
utilize a Star network 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 topology where the wire
basically is a data loop 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. Wired
systems also have the advantage, if wired properly, of being
tamper-evident. 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
The desired result of an alarm system is to cause an appropriate
alarm output and response when the sensors indicate the valid
conditions for triggering of the alarm. The ability of the panel to
communicate back to the Monitoring Center is crucial to the concept
of monitoring, and it is often overlooked or down played.
Depending upon the application, the alarm output may be local or
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) 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 or
responder (e.g. Police/ Fire/ Medical) via a direct phone wire (or
tamper-resistant fiber optic cable), and the alarm monitoring
includes not only the sensors, but also the communication wire
itself. While direct phone circuits are still available in some
areas from phone companies, because of their high 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. 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 (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, 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. 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 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 dialer capability 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.
There is controversy within the alarm industry as to the usage of
the Internet as a primary signaling method, due to the lack of
quality of service within the current design of the public digital
network (internet) particularly when using VoIP with legacy dialup
analog Alarm designs. This issue has been resolved by ALARM
International Inc 2002 who conceived an Alarm power supply unit
(APSU) that incorporated an IP stack combined with a large DC supply
that could power (and reboot) the router modem during various
failures or outages. Alarm manufacturers are incorporating these
power features together with preferred UDP, SNMP and TCP/IP
signaling methods as many newer installations do not include analog
telephone circuitry (POTS). ISP's generally only provide VoIP (POTS
emulation) as an alternative which is very problematic for analog
alarms, and because new alarm systems often depend on broadband as
the only method of Alarm transmission, manufacturers are including
IP stacks directly on their Alarm panel products.
Legacy dial up analogue alarm panels or systems with serial/parallel
data ports are normally migrated to broadband by the addition of a
Alarm Server device which converts those DTMF tones or RS232/485
data bits to IP.
The direct use of VoIP (POTS port on broadband Homehub/RGW) to
transport analogue Alarms without an alarm server device is not
recommended by the networks as the audio codecs used throughout the
entire network transmission path cannot guarantee a suitable level
of reliability or quality of service acceptable to the industry.
Various IP Alarm transmission protocols exist but most are
proprietary, however a number of US based Alarm manufacturers in
2007 tried to implement an open standard called SIA (DC09). Other
global Alarm manufacturers view this protocol as too limiting,
cumbersome and are following the ALARM International Inc methodology
by adopting their open standard protocol called CSV IP ALARM which
supports SIA, ContactID and many other formats simultaneously.
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.
The list of services to be monitored at a Central Station has
expanded over the past few years to include: Access Control; 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.
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 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
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 (patent
#3,482,037) 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 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.
System reliability can be a problem when it causes nuisance alarms,
false alarms, or fails to alarm when called for. 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.
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 (ANSI) and Security Industry
Association (SIA)), 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.
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 (ECV)helps reduce false dispatches while
still protecting citizens. 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.
In-the-field proof that ECV practices are the best solution for
false-alarm reduction while maintaining the safety of taxpayers
comes from the state of Florida. As of July 1, 2006, the
implementation date of the nation’s first statewide ECV law, the
Palm Beach County Sheriff’s Department reduced dispatches from
12,712 between October 2005 and December 2005 to 8,802 during the
same period in 2006. Tennessee has also adopted EVC policies, as has
Reno, Nevada policies among other municipalities including St.
Louis, MO, Providence, RI, Bethlehem, PA and Golden, CO, among
others.
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.
This insures you have a system that will be reliable when needed.
3rd party alarm certifying agencies include:
-
your local fire department
-
Your building department
-
(UL) Underwriters Laboratories
-
(NFPA) National Fire Protection Association
-
(NEC) National Electrical Code
-
(NFBAA) National Fire & Burglar Alarm Association
-
(CSAA) Central Station Alarm Association
-
SSAIB Security & Alarms Inspection Board (UK & ROI)
-
NSI National Security Inspectorate (UK Market)
-
BAFE fire alarms (UK Market)
-
VdS VdS Schadenverhütung Germany