Product Code Database
A security alarm is a system designed to detect intrusions, such as unauthorized entry, into a building or other areas, such as a home or school. Security alarms protect against burglary (theft) or property damage, as well as against intruders. Examples include personal systems, neighborhood security alerts, , and prison alarms.
Some alarm systems serve a single purpose of burglary protection; combination systems provide fire and intrusion protection. Intrusion-alarm systems are combined with closed-circuit television surveillance (CCTV) systems to record intruders' activities and interface to access control systems for electrically locked doors. There are many types of security systems. Homeowners typically have small, self-contained noisemakers. These devices can also be complicated, multirole systems with computer monitoring and control. It may even include a two-way voice which allows communication between the panel and monitoring station.
In addition to the system itself, security alarms often offer a monitoring service. In the event of an alarm, the premises control unit contacts a central monitoring station. Operators at the station take appropriate action, such as contacting property owners, notifying the police, or dispatching private security forces. Such alerts transmit via dedicated alarm circuits, telephone lines, or the internet.
PIR sensors identify abrupt changes in temperature at a given point. As an intruder walks in front of the sensor, the temperature at that point will rise from room temperature to thermoregulation and then back again. This quick change triggers the detection.
PIR sensors designed to be wall- or ceiling-mounted come in various fields of view. PIRs require a power supply in addition to the detection signaling circuit.
The entire infrasound detection system consists of the following components: a speaker (infrasound sensor) as a microphone input, an order-frequency filter, an analog-to-digital (A/D) converter, and an microcomputer to analyze the recorded signal.
If a potential intruder tries to enter into a house, they test whether it is closed and locked, uses tools on openings, or/and applies pressure, creating low-frequency sound vibrations. Before the intruder breaks in, the infrasound detector automatically detects the intruder's actions.
The purpose of such a system is to detect burglars before they enter the house to avoid both theft and vandalism. The sensitivity is dependent on the size of a home and the presence of animals.
The ultrasonic detector operates by the transmitter emitting an ultrasonic signal into the area to be protected. Solid objects (such as the surrounding floor, walls, and ceiling) reflect sound waves, which the receiver will detect. Because ultrasonic waves are transmitted through air, hard-surfaced objects tend to reflect most of the ultrasonic energy, while soft surfaces tend to absorb the 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 not active in many properties as many consider this obsolete.
The graphical representation of the beam is similar to a cigar, and, when not disturbed, it runs between the transmitter and the receiver and generates a continuous signal. When an individual tries to cross this beam, it produces a disturbance that is caught by the receiver as a variation of amplitude of the received signal.
These barriers are immune to harsh weather, such as fog, heavy rain, snow and Dust storm: none of these atmospheric phenomena affect in any way the behaviour and the reliability of the microwave detection. Furthermore, the working temperature range of this technology goes from -35 °C to +70 °C.
Seismic glass-break detectors, generally referred to as shock sensors, are different in that they are installed on the glass pane. When glass breaks it produces specific shock frequencies which travel through the glass and often through the window frame and the surrounding walls and ceiling. Typically, the most intense frequencies generated are between 3 and 5 kHz, 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.
Window foil is a less advanced detection method that involves gluing a thin strip of conducting foil on the inside of the glass and putting low-power electric current through it. Breaking the glass will tear the foil and break the circuit.
Traditional smoke detectors are ionization smoke detectors which create an electric current between two metal plates, which sound an alarm when disrupted by smoke entering the chamber. Ionization smoke alarms can quickly detect the small amounts of particles produced by fast-flaming fires, such as cooking fires or those fueled by paper or flammable liquids. A newer type of the smoke detector is the photoelectric smoke detector. It contains a light source, which is positioned indirectly to the light sensitive electric sensor. Normally, light from the light source shoots straight across and misses the sensor. When smoke enters the chamber, it scatters the light, which then hits the sensor and triggers the alarm. Photoelectric smoke detectors typically respond faster to a fire in its early, smoldering stage, before the source of the fire bursts into flames.
A type of motion sensor was used by the Japanese since ancient times. In the past, "(m)any people in Japan kept singing crickets and used them like watch dogs."Mathiews, Franklin K. "The Boy Scouts Book of Outdoor Hobbies," D, Appleton-Century Company, Incorporated, New York 1938, page 193. Although a dog would bark when it senses an intruder, a cricket stops singing when approached by an intruder. The crickets are kept in decorative cages resembling bird cages, and these cages are placed in contact with the floor. During the day, the house is busy with normal daytime tasks. When activity reduces at night, the crickets start singing. If someone comes into the house at night, the floor starts to vibrate. "The vibration frightens the crickets and they stop singing. Then everyone wakes up --- from the silence.Mathiews, Franklin K. "The Boy Scouts Book of Outdoor Hobbies," D, Appleton-Century Company, Incorporated, New York 1938, page 194. The family is used to hearing crickets at night and knows something is wrong if the crickets aren't singing. A similar observation was made in England about millers who lived in their mills. A mill wheel makes a great deal of noise, but the miller only awakens when the mill wheel stops turning.
MEMS accelerometer can be divided into two groups, piezoresistive and capacitive-based accelerometers. The former consists of a single-degree-of-freedom system of a mass suspended by a spring. They also have a beam with a proof mass at the beam’s tip and a Piezoresistive patch on the beam web.
On the contrary, capacitive-based accelerometers, also known as vibration sensors, rely on a change in electrical capacitance in response to acceleration. (2025). 9780080965338 ISBN 9780080965338
In this way, the acquired signals are amplified, filtered and converted in digital signals with the supervision of specific control circuits. MEMS' incorporations evolved from a single, stand-alone device to the integrated inertial motion units that are available today.
This technology uses a variety of transduction mechanisms to detect the displacement. They include capacitive, piezoresistive, thermal, optical, piezoelectric and tunneling. (2025). 9783038974154, MDPI. ISBN 9783038974154
MEMS accelerometer can be applied as a sensor in the earthquake disaster prevention, since one of the main characteristics of MEMS accelerometers is the linear frequency response to DC to about 500 Hz, and this capability offers an improvement in measuring ground motion at lower-frequency band.
Another practical application of MEMS accelerometers is in machine condition monitoring to reduce machines’ maintenance. Wireless and embedded technologies such as Micro-electro Mechanical system sensors offer a wireless smart vibration measurement of machine’s condition.
Moving to the arms industry field, it can be applied in fence-mounted intrusion detection systems. Since MEMS sensors are able to work in a wide temperature range, they can prevent intrusions in outdoors and very spread-off perimeters.
MEMS accelerometers’ significant advantages also stem from their small size and high measurement frequency; additionally, they can be integrated with multiple sensors with different functions.
The barrier can provide vertical protection from the ground to the height of the mounting posts (typically 4–6meters of height), depending on the number of sensor wires installed. It is usually configured in zones of about 200 metre lengths. Electrostatic field sensors are high-security and difficult to defeat, and have high vertical detection field. However, these sensors are expensive and have short zones, which contributes to more electronics (and thus a higher cost).
The systems are designed to detect and analyze incoming electronic signals received from the sensor cable, and then to generate alarms from signals which exceed pre-set 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 done during commissioning of the detection devices.
Microphonic systems are relatively inexpensive compared to other systems and easy to install, but older systems may have a high rate of false alarms caused by wind and other distances. Some newer systems use DSP to process the signal and reduce false alarms.
Taut wire fence systems have low false alarm rates, reliable sensors, and high detection rates, but is expensive and complicated to install.
Being cable-based, fiber optic cables are very similar to the microphonic system and easy to install and can cover large perimeters. However, despite performing in a similar manner to microphonic-based systems, fiber optic cables have higher cost and is more complex due to the use of fiber-optic technology.
Electric fences are less expensive than many other methods, less likely to give false alarms than many other alternative perimeter security methods, and have highest psychological deterrent of all methods, but there is a potential for unintended shock.
Wired systems are convenient when sensors, such as passive infrared motion sensors and smoke detectors require external power to operate correctly; however, they may be more costly to install. Basic wired systems utilize a star network topology, where the panel is at the center logically, and all devices home run their line wires back to the panel. More complex panels use a Bus network topology where the wire basically is a dual 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 for example by dual loop, of being tamper-evident.
Wireless systems, on the other hand, often use battery-powered which are easier to install and have less expensive start-up costs, but may fail if the batteries are not maintained. Depending on distance and construction materials, one or more wireless may be required to bring the signal to the alarm panel reliably. A wireless system can be moved to a new property easily. An important wireless connection for security is between the control panel and the monitoring station. Wireless monitoring of the alarm system protects against a burglar cutting cables or from failures of an internet provider. This setup is commonly referred to as fully wireless.
Hybrid systems use both wired and wireless sensors to achieve the benefits of both. Transmitters 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 more advanced systems have a separate zone for every different sensor, as well as internal trouble indicators, such as mains power loss, low battery, and broken wires.
Remote alarm systems are used to connect the control unit to a predetermined monitor of some sort, and they are available in many different configurations. Advanced systems connect to a central station or first responder (e.g. police/fire/medical) via a direct phone wire, a cellular network, a radio network, or an IP path. In the case of a dual signaling system two of these options are utilized simultaneously. 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 of dual signaling with its comparatively lower cost, their use is being phased out. 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 United Kingdom, communication is only possible to an alarm receiving centre, and communication directly to the emergency services is not permitted.
More typical systems incorporate a digital cellular communication unit that will contact the central station or a monitoring station 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. A dual signaling system would raise the alarm wirelessly via a radio path or cellular path using the phone line or broadband line as a backup 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 of the sensor on a list or even a map of the protected premises, which can make the resulting response more effective.
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 communication path, or a specialized encoded mobile phone, radio, or internet interface device to bypass the PSTN entirely, to thwart intentional tampering with the phone lines. Tampering with the line could trigger a supervisory alarm via the radio network, giving early warning of an imminent problem. 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 backup paths reversed. Utilizing a radio path as the primary signaling path is not only quicker than PSTN but also allows significant cost savings as unlimited amounts of data can be sent at no extra expense.
Dial-up analogue 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. However, the direct use of VoIP to transport analogue 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 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.
A dual signaling 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. These multiple signaling paths are all present and live at the same time backing each other up to minimize exposure of the property to intruders. Should one fail, there is always a back up and depending on the manufacturer chosen up to three paths working simultaneously at any one time.
Dual paths allow distinction between hardware failures and a genuine attack on the alarm. This helps eliminate false alarms and unnecessary responses. Dual signaling has helped considerably with the restoration of police response as in an instance where a phone line is cut as the dual signaling device can continue to send alarm calls via one of its alternative paths either confirming or denying the alarm from the initial path.
In the UK, CSL DualCom Ltd pioneered dual signaling in 1996. The company offered an alternative to existing alarm signaling while setting the current standard for professional dual path security monitoring. Dual signaling is now firmly regarded as the standard format for alarm signaling and is duly specified by all of the leading insurance companies.
Depending upon the zone triggered, number and sequence of zones, time of day, and other factors, the alarm monitoring center may automatically initiate various actions. Central station operators might be instructed to call emergency services immediately, or to first call the protected premises or property manager to try to determine if the alarm is genuine. Operators 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 check on the system, or a call to the owner with details of which room may be 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 and recorded.
Some alarm systems use real-time audio and video System monitor technology to verify the legitimacy of an alarm. In some Municipality around the United States, this type of alarm verification allows the property it is protecting to be placed on a "verified response" list, allowing for quicker and safer police responses.
Failed authorizations would result in an alarm or 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 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 only permit them to be used 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, for example, for furnace repairperson to enter the kitchen and basement sensor areas but not the silver vault in the 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 and user error are the cause of most false alarms, sometimes called "nuisance alarms." False alarms can be very costly to local governments, local law enforcement, security system users and members of local communities. In 2007, the Department of Justice reported that in just one year, false alarms cost local municipalities and their constituents at least $1.8 billion.
In many municipalities across the United States, policies have been adopted to fine home and business owners for multiple false alarm activations from their security system. If multiple false alarms from the same property persist, that property could be added to a "no response" list, which prevents police dispatch to the property except in the event of verified emergency. 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.
Some municipalities across the United States require alarm verification before police are dispatched. Under this approach, alarm monitoring companies must verify the legitimacy of alarms (except holdup, duress, and panic button) before calling the police. Verified response typically involves visual on-scene verification of a break-in, or remote audio or video verification.
Audio and video verification techniques use microphones and cameras to record audio frequencies, video signals, or image snapshots. The source audio and video streams are 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 be used to plan a more strategic and tactical approach of a property, and later as prosecution evidence.
An example of this system 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 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.
The United States Department of Justice states that legislation requiring alarm companies to verify the legitimacy of an alarm, before contacting law enforcement (commonly known as "verified response") is the most effective way to reduce false burglar alarms. The Department of Justice considers audio, video, or an eye-witness account as verification for the legitimacy of a burglar alarm.
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.
ECV, as it cannot confirm an actual intrusion event and will not prompt a priority law enforcement dispatch, is not considered true alarm verification by the security industry.
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