1.
Security alarm
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A security alarm is a system designed to detect intrusion – unauthorized entry – into a building or area. Security alarms are used in residential, commercial, industrial, and military properties for protection against burglary or property damage, car alarms likewise protect vehicles and their contents. Prisons also use security systems for control of inmates, some alarm systems serve a single purpose of burglary protection, combination systems provide both fire and intrusion protection. Systems range from small, self-contained noisemakers, to complicated, multi-area systems with computer monitoring and it may even include two-way voice which allows communication between the panel and Monitoring station. The most basic consists of one or more sensors to detect intruders. In modern systems, this is one or more computer circuit boards inside a metal enclosure. Sensors may be placed at the perimeter of the area, within it. Sensors can detect intruders by a variety of methods, such as monitoring doors and windows for opening, or by monitoring unoccupied interiors for motions, sound, vibration, alerting devices, These indicate an alarm condition. Most commonly, these are bells, sirens, and/or flashing lights, alerting devices serve the dual purposes of warning occupants of intrusion, and potentially scaring off burglars. These devices may also be used to warn occupants of a fire or smoke condition, keypads, Small devices, typically wall-mounted, which function as the human-machine interface to the system. In addition to buttons, keypads typically feature indicator lights, a small multi-character display and this may consist of direct wiring to the control unit, or wireless links with local power supplies. Security devices, Devices to detect unauthorized entry or movements such as spotlights, in addition to the system itself, security alarms are often coupled with a monitoring service. In the event of an alarm, the control unit contacts a central monitoring station. Operators at the see the signal and take appropriate action, such as contacting property owners, notifying police. Such signals may be transmitted via dedicated alarm circuits, telephone lines, when the magnet is moved away from the reed switch, the reed switch either closes or opens, again based on whether or not the design is normally open or normally closed. This action coupled with an electric current allows an alarm control panel to detect a fault on that zone or circuit. These type of sensors are very common and are found either wired directly to a control panel. The passive infrared detector is one of the most common sensors found in household
2.
Closed-circuit television
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Closed-circuit television, also known as video surveillance, is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly transmitted, though it may point to point, point to multipoint. Videotelephony is seldom called CCTV but the use of video in distance education, Surveillance of the public using CCTV is common in many areas around the world. In recent years, the use of body worn video cameras has been introduced as a new form of surveillance, video surveillance has generated significant debate about balancing its use with individuals right to privacy even when in public. In industrial plants, CCTV equipment may be used to observe parts of a process from a control room. CCTV systems may operate continuously or only as required to monitor a particular event, a more advanced form of CCTV, utilizing digital video recorders, provides recording for possibly many years, with a variety of quality and performance options and extra features. More recently, decentralized IP cameras, some equipped with sensors, support recording directly to network-attached storage devices. There are about 350 million surveillance cameras worldwide as of 2016, about 65% of these cameras are installed in Asia. The growth of CCTV has been slowing in recent years, the first CCTV system was installed by Siemens AG at Test Stand VII in Peenemünde, Nazi Germany in 1942, for observing the launch of V-2 rockets. The noted German engineer Walter Bruch, Wayne Cox, and Tashara Arnold were responsible for the technological design, in the U. S. the first commercial closed-circuit television system became available in 1949, called Vericon. Very little is known about Vericon except it was advertised as not requiring a government permit, marie Van Brittan Brown invented the home security system. The patent was granted in 1969, browns system had a set of 4 peep-holes and a camera that could slide up and down to look through each one. The system included a device that enabled a homeowner to use a set to view the person at the door. The earliest video surveillance systems involved constant monitoring because there was no way to record, the development of reel-to-reel media enabled the recording of surveillance footage. Due to these shortcomings, video surveillance was not widespread, VCR technology became available in the 1970s, making it easier to record and erase information, and use of video surveillance became more common. During the 1990s, digital multiplexing was developed, allowing cameras to record at once, as well as time lapse. This increased savings of time and money and the led to an increase in the use of CCTV, recently CCTV technology has been enhanced with a shift toward Internet-based products and systems, and other technological developments. In September 1968, Olean, New York was the first city in the United States to install video cameras along its main street in an effort to fight crime
3.
Passive infrared sensor
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A passive infrared sensor is an electronic sensor that measures infrared light radiating from objects in its field of view. They are most often used in PIR-based motion detectors, all objects with a temperature above absolute zero emit heat energy in the form of radiation. Usually this radiation isnt visible to the eye because it radiates at infrared wavelengths. The term passive in this instance refers to the fact that PIR devices do not generate or radiate any energy for detection purposes and they work entirely by detecting the energy given off by other objects. PIR sensors dont detect or measure heat, instead they detect the radiation emitted or reflected from an object. Infrared radiation enters through the front of the sensor, known as the sensor face, at the core of a PIR sensor is a solid state sensor or set of sensors, made from pyroelectric materials—materials which generate energy when exposed to heat. Typically, the sensors are approximately 1/4 inch square, and take the form of a thin film, materials commonly used in PIR sensors include gallium nitride, caesium nitrate, polyvinyl fluorides, derivatives of phenylpyridine, and cobalt phthalocyanine. The sensor is often manufactured as part of an integrated circuit, a PIR-based motion detector is used to sense movement of people, animals, or other objects. They are commonly used in burglar alarms and automatically-activated lighting systems and they are commonly called simply PIR, or sometimes PID, for passive infrared detector. The sensor converts the resulting change in the infrared radiation into a change in the output voltage. PIRs come in many configurations for a variety of applications. The most common models have numerous Fresnel lenses or mirror segments, a range of about ten meters. Models with wider fields of view, including 360 degrees, are designed to mount on a ceiling. Some larger PIRs are made with single segment mirrors and can sense changes in infrared energy over thirty meters away from the PIR. There are also PIRs designed with reversible orientation mirrors which allow either broad coverage or very narrow curtain coverage, pairs of sensor elements may be wired as opposite inputs to a differential amplifier. This allows the device to resist false indications of change in the event of being exposed to brief flashes of light or field-wide illumination, at the same time, this differential arrangement minimizes common-mode interference, allowing the device to resist triggering due to nearby electric fields. However, a pair of sensors cannot measure temperature in this configuration. The PIR sensor is mounted on a printed circuit board containing the necessary electronics required to interpret the signals from the sensor itself
4.
Radar gun
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A radar speed gun is a device used to measure the speed of moving objects. A radar speed gun is a Doppler radar unit that may be hand-held, vehicle-mounted or static. The radar speed gun was invented by John L. Barker Sr. and Ben Midlock, originally, Automatic Signal was approached by Grumman Aircraft Corporation to solve the specific problem of terrestrial landing gear damage on the now-legendary PBY Catalina amphibious aircraft. Barker and Midlock cobbled a Doppler radar unit from coffee cans soldered shut to make microwave resonators, the unit was installed at the end of the runway, and aimed directly upward to measure the sink rate of landing PBYs. After the war, Barker and Midlock tested radar on the Merritt Parkway, in 1947, the system was tested by the Connecticut State Police in Glastonbury, Connecticut, initially for traffic surveys and issuing warnings to drivers for excessive speed. Starting in February 1949, the police began to issue speeding tickets based on the speed recorded by the radar device. In 1948, radar was used in Garden City, New York. Speed guns use Doppler radar to perform speed measurements, Radar speed guns, like other types of radar, consist of a radio transmitter and receiver. They send out a signal in a narrow beam, then receive the same signal back after it bounces off the target object. From that difference, the radar speed gun can calculate the speed of the object from which the waves have been bounced. After the returning waves are received, a signal with a equal to this difference is created by mixing the received radio signal with a little of the transmitted signal. Since this type of speed gun measures the difference in speed between a target and the gun itself, the gun must be stationary in order to give a correct reading. Instead of comparing the frequency of the signal reflected from the target with the transmitted signal, the frequency difference between these two signals gives the true speed of the target vehicle. Modern radar speed guns normally operate at X, K, Ka, Radar guns that operate using the X band frequency range are becoming less common because they produce a strong and easily detectable beam. Also, most automatic doors utilize radio waves in the X band range, as a result, K band and Ka band are most commonly used by police agencies. For these reasons, hand-held radar typically includes an on-off trigger, Radar detectors are illegal in some areas. Traffic radar comes in many models, hand-held units are mostly battery powered, and for the most part are used as stationary speed enforcement tools. Stationary radar can be mounted in vehicles and may have one or two antennae
5.
Microwave
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Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter, with frequencies between 300 MHz and 300 GHz. Different sources define different frequency ranges as microwaves, the broad definition includes both UHF and EHF bands. A more common definition in radio engineering is the range between 1 and 100 GHz, in all cases, microwaves include the entire SHF band at minimum. Frequencies in the range are often referred to by their IEEE radar band designations, S, C, X, Ku, K, or Ka band. The prefix micro- in microwave is not meant to suggest a wavelength in the micrometer range and it indicates that microwaves are small, compared to waves used in typical radio broadcasting, in that they have shorter wavelengths. The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study. At the high end of the band they are absorbed by gases in the atmosphere, microwaves are extremely widely used in modern technology. Although at the low end of the band they can pass through building walls enough for useful reception, therefore on the surface of the Earth microwave communication links are limited by the visual horizon to about 30 -40 miles. Microwaves are absorbed by moisture in the atmosphere, and the attenuation increases with frequency, beginning at about 40 GHz, atmospheric gases also begin to absorb microwaves, so above this frequency microwave transmission is limited to a few kilometers. A spectral band structure causes absorption peaks at specific frequencies, in a microwave beam directed at an angle into the sky, a small amount of the power will be randomly scattered as the beam passes through the troposphere. A sensitive receiver beyond the horizon with a high gain antenna focused on that area of the troposphere can pick up the signal. This technique has been used at frequencies between 0.45 and 5 GHz in tropospheric scatter communication systems to communicate beyond the horizon and their short wavelength allows narrow beams of microwaves to be produced by conveniently small high gain antennas from a half meter to 5 meters in diameter. Therefore beams of microwaves are used for point-to-point communication links, an advantage of narrow beams is that they allow frequency reuse by nearby transmitters. Parabolic antennas are the most widely used directive antennas at microwave frequencies, flat microstrip antennas are being increasingly used in consumer devices. Where omnidirectional antennas are required, for example in wireless devices and Wifi routers for wireless LANs, small monopoles, dipole, or patch antennas are used. Due to the high cost and maintenance requirements of waveguide runs, the term microwave also has a more technical meaning in electromagnetics and circuit theory. As a consequence, practical microwave circuits tend to away from the discrete resistors, capacitors. Open-wire and coaxial transmission lines used at lower frequencies are replaced by waveguides and stripline, high-power microwave sources use specialized vacuum tubes to generate microwaves
6.
Ultrasound
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Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is no different from normal sound in its physical properties and this limit varies from person to person and is approximately 20 kilohertz in healthy, young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz, Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances, Ultrasound imaging or sonography is often used in medicine. In the nondestructive testing of products and structures, ultrasound is used to detect invisible flaws, industrially, ultrasound is used for cleaning, mixing, and to accelerate chemical processes. Animals such as bats and porpoises use ultrasound for locating prey, scientist are also studying ultrasound using graphene diaphragms as a method of communication. Acoustics, the science of sound, starts as far back as Pythagoras in the 6th century BC, echolocation in bats was discovered by Lazzaro Spallanzani in 1794, when he demonstrated that bats hunted and navigated by inaudible sound and not vision. The first technological application of ultrasound was an attempt to detect submarines by Paul Langevin in 1917, the piezoelectric effect, discovered by Jacques and Pierre Curie in 1880, was useful in transducers to generate and detect ultrasonic waves in air and water. Ultrasound is defined by the American National Standards Institute as sound at frequencies greater than 20 kHz, in air at atmospheric pressure ultrasonic waves have wavelengths of 1.9 cm or less. The upper frequency limit in humans is due to limitations of the middle ear, auditory sensation can occur if high‐intensity ultrasound is fed directly into the human skull and reaches the cochlea through bone conduction, without passing through the middle ear. Children can hear some high-pitched sounds that older adults cannot hear, the Mosquito is an electronic device that uses a high pitched frequency to deter loitering by young people. Bats use a variety of ultrasonic ranging techniques to detect their prey and they can detect frequencies beyond 100 kHz, possibly up to 200 kHz. Many insects have good hearing and most of these are nocturnal insects listening for echolocating bats. This includes many groups of moths, beetles, praying mantids, upon hearing a bat, some insects will make evasive manoeuvres to escape being caught. Ultrasonic frequencies trigger an action in the noctuid moth that cause it to drop slightly in its flight to evade attack. Tiger moths also emit clicks which may disturb bats echolocation, dogs and cats hearing range extends into the ultrasound, the top end of a dogs hearing range is about 45 kHz, while a cats is 64 kHz. The wild ancestors of cats and dogs evolved this higher hearing range to hear sounds made by their preferred prey. A dog whistle is a whistle that emits ultrasound, used for training and calling dogs, porpoises have the highest known upper hearing limit, at around 160 kHz
7.
Wavelength
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In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the waves shape repeats, and thus the inverse of the spatial frequency. Wavelength is commonly designated by the Greek letter lambda, the concept can also be applied to periodic waves of non-sinusoidal shape. The term wavelength is also applied to modulated waves. Wavelength depends on the medium that a wave travels through, examples of wave-like phenomena are sound waves, light, water waves and periodic electrical signals in a conductor. A sound wave is a variation in air pressure, while in light and other electromagnetic radiation the strength of the electric, water waves are variations in the height of a body of water. In a crystal lattice vibration, atomic positions vary, wavelength is a measure of the distance between repetitions of a shape feature such as peaks, valleys, or zero-crossings, not a measure of how far any given particle moves. For example, in waves over deep water a particle near the waters surface moves in a circle of the same diameter as the wave height. The range of wavelengths or frequencies for wave phenomena is called a spectrum, the name originated with the visible light spectrum but now can be applied to the entire electromagnetic spectrum as well as to a sound spectrum or vibration spectrum. In linear media, any pattern can be described in terms of the independent propagation of sinusoidal components. The wavelength λ of a sinusoidal waveform traveling at constant speed v is given by λ = v f, in a dispersive medium, the phase speed itself depends upon the frequency of the wave, making the relationship between wavelength and frequency nonlinear. In the case of electromagnetic radiation—such as light—in free space, the speed is the speed of light. Thus the wavelength of a 100 MHz electromagnetic wave is about, the wavelength of visible light ranges from deep red, roughly 700 nm, to violet, roughly 400 nm. For sound waves in air, the speed of sound is 343 m/s, the wavelengths of sound frequencies audible to the human ear are thus between approximately 17 m and 17 mm, respectively. Note that the wavelengths in audible sound are much longer than those in visible light, a standing wave is an undulatory motion that stays in one place. A sinusoidal standing wave includes stationary points of no motion, called nodes, the upper figure shows three standing waves in a box. The walls of the box are considered to require the wave to have nodes at the walls of the box determining which wavelengths are allowed, the stationary wave can be viewed as the sum of two traveling sinusoidal waves of oppositely directed velocities. Consequently, wavelength, period, and wave velocity are related just as for a traveling wave, for example, the speed of light can be determined from observation of standing waves in a metal box containing an ideal vacuum. In that case, the k, the magnitude of k, is still in the same relationship with wavelength as shown above
8.
Digital camera
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A digital camera or digicam is a camera that produces digital images that can be stored in a computer, displayed on a screen and printed. Most cameras sold today are digital, and digital cameras are incorporated into many devices ranging from PDAs, Digital and movie cameras share an optical system, typically using a lens with a variable diaphragm to focus light onto an image pickup device. The diaphragm and shutter admit the correct amount of light to the imager, just as with film, however, unlike film cameras, digital cameras can display images on a screen immediately after being recorded, and store and delete images from memory. Many digital cameras can also record moving videos with sound, some digital cameras can crop and stitch pictures and perform other elementary image editing. The history of the camera began with Eugene F. Lally of the Jet Propulsion Laboratory. His 1961 idea was to take pictures of the planets and stars while travelling through space to give information about the astronauts position, unfortunately, as with Texas Instruments employee Willis Adcocks filmless camera in 1972, the technology had yet to catch up with the concept. Steven Sasson as an engineer at Eastman Kodak invented and built the first electronic camera using a charge-coupled device image sensor in 1975, earlier ones used a camera tube, later ones digitized the signal. Early uses were military and scientific, followed by medical. In the mid to late 1990s digital cameras became common among consumers, by the mid-2000s digital cameras had largely replaced film cameras, and higher-end cell phones had an integrated digital camera. By the beginning of the 2010s, almost all smartphones had a digital camera. The two major types of image sensor are CCD and CMOS. A CCD sensor has one amplifier for all the pixels, while each pixel in a CMOS active-pixel sensor has its own amplifier, compared to CCDs, CMOS sensors use less power. Cameras with a small sensor use a back-side-illuminated CMOS sensor, overall final image quality is more dependent on the image processing capability of the camera, than on sensor type. The resolution of a camera is often limited by the image sensor that turns light into that discrete signals. The brighter the image at a point on the sensor. Depending on the structure of the sensor, a color filter array may be used. The number of pixels in the sensor determines the cameras pixel count, in a typical sensor, the pixel count is the product of the number of rows and the number of columns. For example, a 1,000 by 1,000 pixel sensor would have 1,000,000 pixels, final quality of an image depends on all optical transformations in the chain of producing the image
9.
Video game console
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A video game console is an electronic, digital or computer device that outputs a video signal or visual image to display a video game that one or more people can play. The term video game console is used to distinguish a console machine primarily designed for consumers to use for playing video games. An arcade machine consists of a video game computer, display, game controller, a home computer is a personal computer designed for home use for a variety of purposes, such as bookkeeping, accessing the Internet and playing video games. There are various types of game consoles, including home video game consoles, handheld game consoles, microconsoles. Although Ralph Baer had built working game consoles by 1966, it was nearly a decade before the Pong game made them commonplace in regular peoples living rooms. Through evolution over the 1990s and 2000s, game consoles have expanded to additional functions such as CD players, DVD players, Blu-ray disc players, web browsers, set-top boxes. The first video appeared in the 1960s. They were played on massive computers connected to vector displays, not analog televisions, Ralph H. Baer conceived the idea of a home video game in 1951. In the late 1960s, while working for Sanders Associates, Baer created a series of game console designs. In 1972, Magnavox released the Magnavox Odyssey, the first home game console which could be connected to a TV set. Magnavox replaced the switch design with separate cartridges for each game, by autumn 1975, Magnavox, bowing to the popularity of Pong, cancelled the Odyssey and released a scaled-down version that played only Pong and hockey, the Odyssey 100. A second, higher end console, the Odyssey 200, was released with the 100 and added on-screen scoring, up to four players, almost simultaneously released with Ataris own home Pong console through Sears, these consoles jump-started the consumer market. All three of the new consoles used simpler designs than the original Odyssey did with no board game pieces or extra cartridges, in the years that followed, the market saw many companies rushing similar consoles to market. Most of the consoles from this era were dedicated consoles playing only the games came with the console. These video game consoles were often just called video games, because there was reason to distinguish the two yet. While a few companies like Atari, Magnavox, and newcomer Coleco pushed the envelope, Fairchild released the Fairchild Video Entertainment System in 1976. The VES, however, contained a programmable microprocessor so its cartridges only needed a single ROM chip to store microprocessor instructions, RCA and Atari soon released their own cartridge-based consoles, the RCA Studio II and the Atari 2600, respectively. The first handheld console with interchangeable cartridges was the Microvision designed by Smith Engineering
10.
Pickup (music technology)
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The signal from a pickup can also be recorded directly, using a DI box or broadcast on the radio or television. Most electric guitars and electric basses use magnetic pickups, acoustic guitars, upright basses and fiddles often use a piezoelectric pickup. A magnetic pickup consists of a permanent magnet with a core of such as alnico or ferrite. The pickup is most often mounted on the body of the instrument, Magnetic pickups used with string basses can be attached to the bridge. The permanent magnet creates a field, the motion of the vibrating steel strings disturbs the field, changing magnetic flux. The pickup is then connected with a cable to an amplifier which amplifies the signal to a sufficient magnitude of power to drive a loudspeaker. A pickup can also be connected to recording equipment via a patch cable, there may also be an internal preamplifier device mounted in an acoustic guitar or in an external box. When a preamp is used in way, it is between the pickup and cable and can significantly reduce the equivalent impedance of the pickup coil. The output voltage of magnetic pickups varies between 100 mV rms to over 1 V rms for some of the higher output types, some high-output pickups achieve this by employing very strong magnets, thus creating more flux and thereby more output. This can be detrimental to the sound because the magnets pull on the strings can cause problems with intonation as well as damp the strings. Other high-output pickups have more turns of wire to increase the voltage generated by the strings movement, however, this also increases the pickups output resistance/impedance, which can affect high frequencies if the pickup is not isolated by a buffer amplifier or a DI unit. The turns of wire in proximity to each other have an equivalent self-capacitance that and this resonance can accentuate certain frequencies, giving the pickup a characteristic tonal quality. The more turns of wire in the winding, the higher the output voltage, the inductive source impedance inherent in this type of transducer makes it less linear than other forms of pickups, such as piezo-electric or optical. The tonal quality produced by this nonlinearity is, however, subject to taste, the external load usually consists of resistance and capacitance between the hot lead and shield in the guitar cable. The electric cable also has a capacitance, which can be a significant portion of the overall system capacitance and this arrangement of passive components forms a resistively-damped second-order low-pass filter. Single coil pickups act like an antenna and are prone to pick up mains hum along with the musical signal. Mains hum consists of a signal at a nominal 50 or 60 Hz, depending on local alternating current frequency. The changing magnetic flux caused by the mains current links with the windings of the pickup, the pickups also are sensitive to the electromagnetic field from nearby cathode ray tubes in video monitors or televisions
