User:Brtneynguyen/Security Alarm

Compact surveillance radar emits microwaves from a transmitter and detects any reflected microwaves. They are similar to microwave detectors but can identify the precise location of intruders in areas extending over hundreds of acres. With the capability of measuring the range, angle, velocity, direction, and size of the target, a CSR can pinpoint a precise GPS coordinate of an intruder. This target information is typically displayed on a map, user interface, or situational awareness software that defines geographical alert zones or geofences with different types of actions initiated depending on the time of day and other factors. CSR is commonly used to protect outside the fence line of critical facilities such as electrical substations, power plants, dams, and bridges.

Photoelectric beams[edit source]
Photoelectric beam systems detect the presence of an intruder by transmitting invisible 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 at one time, an intruder passes through, most systems use and detect a modulated light source. - Advantages: low cost, easy to install. Require little sterile clearance area to operate - Disadvantages: Affected by fog or high luminosity. The position of the transmitter can be located with some cameras.

Glass-break detection[edit source]
A glass-break detector may be used for internal perimeter building protection. Glass-break acoustic detectors are mounted close to the glass panes and listen for sound frequencies associated with glass breaking.

Seismic glass-break detectors, generally referred to as shock sensors, are different because they are installed on the glass pane. When glass shatters, it produces specific shock frequencies that 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 sophisticated, generally outdated 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 is ensured to tear the foil and break the circuit.

Smoke, heat, and carbon monoxide detectors[edit source]
Most systems can also be equipped with smoke, heat, and or carbon monoxide detectors. These are also known as 24-hour zones (which are on at all times). Smoke and heat detectors protect from the risk of fire using different detection methods. Carbon monoxide detectors help protect from the danger of carbon monoxide poisoning. 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.

Traditional smoke detectors are technically ionization smoke detectors that create an electric current between two metal plates, which sounds an alarm when disrupted by smoke entering the chamber. Ionization smoke alarms can quickly detect the small amounts of smoke produced by fast-flaming fires, such as cooking fires or those fueled by paper or flammable liquids. A newer and perhaps safer type is a photoelectric smoke detector. It contains a light source in a light-sensitive electric sensor, positioned at a 90-degree angle to the sensor. Typically, light from the light source shoots straight across and misses the sensor. When smoke enters the chamber, it will scatter the said 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.