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34-408: A search and rescue transponder (SART) is a self-contained, waterproof transponder intended for emergency use at sea. These devices may be either a radar-SART , or a GPS -based AIS-SART ( automatic identification system SART). The radar-SART is used to locate a survival craft or distressed vessel by creating a series of dots on a rescuing ship's radar display. A SART will only respond to

68-456: A 9 GHz X-band (3 cm wavelength ) radar. It will not be seen on S-band (10 cm) or other radar. Shipboard Global Maritime Distress Safety System (GMDSS) include one or more search and rescue locating devices. The radar-SART may be triggered by any X-band radar within a range of approximately 8 nautical miles (15 kilometers). Each radar pulse received causes the SART to transmit

102-412: A fixed internet connection are sometimes referred to as a landline (non-cellular service). Landline service is typically provided through the outside plant of a telephone company's central office, or wire center. The outside plant comprises tiers of cabling between distribution points in the exchange area, so that a single pair of copper wire, or an optical fiber, reaches each subscriber location, such as

136-430: A home or office, at the network interface. Customer premises wiring extends from the network interface ("NID") to the location of one or more telephones inside the premises. A subscriber's telephone connected to a landline can be hard-wired or cordless and typically refers to the operation of wireless devices or systems in fixed locations such as homes. Fixed wireless devices usually derive their electrical power from

170-497: A landline connection in 2020 though this could be in part explained by broadband packaging practices. In 2022, 82.9% of German households had at least one landline phone while 73 percent of U.S. households had only a cell phone, 25 percent had a landline and cell service, and 1 percent had only a landline. As of 2023, Estonia and the Netherlands have retired the legacy parts of the public switched telephone network (PSTN). In

204-414: A lap they swipe or touch the receiver which is connected to a computer and log their lap time. NASCAR uses transponders and cable loops placed at numerous points around the track to determine the lineup during a caution period. This system replaced a dangerous race back to the start-finish line . Many modern automobiles have keys with transponders hidden inside the plastic head of the key. The user of

238-766: A mobile phone. In the year 2013, 91% of adults in the United States owned a mobile phone. Almost 60% of those with a mobile had a smartphone . A National Health Interview Survey of 19,956 households by the Centers for Disease Control and Prevention released May 4, 2017 showed 45.9 percent of U.S. households still had landlines, while 50.8 percent had only cell phones . Over 39 percent had both. In Canada, more than one in five of households use cell phones as their only source for telephone service. In 2013, statistics showed that 21% of households claimed to only use cellular phones. Households that are owned by members under

272-503: A range of uplink frequencies, usually from a satellite ground station ; the transponder amplifies them, and re-transmits them on a different set of downlink frequencies to receivers on Earth, often without changing the content of the received signal or signals. A communications satellite ’s channels are called transponders because each is a separate transceiver or repeater . With digital video data compression and multiplexing , several video and audio channels may travel through

306-411: A resident's car with simple transponder is parked in the vicinity, any vehicle can come up to the automated gate, triggering the gate interrogation signal , which may get an acceptable response from the resident's car. Such units properly installed might involve beamforming , unique transponders for each vehicle, or simply obliging vehicles to be stored away from the gate. Landline A landline

340-411: A response which is swept repetitively across the complete radar frequency band. When interrogated, it first sweeps rapidly (0.4 microsecond ) through the band before beginning a relatively slow sweep (7.5 microseconds) through the band back to the starting frequency. This process is repeated for a total of twelve complete cycles. At some point in each sweep, the radar-SART frequency will match that of

374-520: A result, differences in transponder functionality also might influence the functional description of related optical modules like transceivers and muxponders . Another type of transponder occurs in identification friend or foe (IFF) systems in military aviation and in air traffic control secondary surveillance radar (beacon radar) systems for general aviation and commercial aviation . Primary radar works best with large all-metal aircraft, but not so well on small, composite aircraft. Its range

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408-418: A ship's radar screen. Sonar transponders operate under water and are used to measure distance and form the basis of underwater location marking, position tracking and navigation . Electronic toll collection systems such as E-ZPass in the eastern United States use RFID transponders to identify vehicles. Transponders are used in races for lap timing. A cable loop is dug into the race circuit near to

442-408: A single transponder on a single wideband carrier . Original analog video only has one channel per transponder, with subcarriers for audio and automatic transmission identification service ( ATIS ). Non-multiplexed radio stations can also travel in single channel per carrier (SCPC) mode, with multiple carriers (analog or digital) per transponder. This allows each station to transmit directly to

476-597: Is a telephone connection that uses metal wires from the owner's premises also referred to as: POTS , Twisted pair , telephone line or public switched telephone network (PSTN) . Landline services are traditionally provided via an analogue copper wire to a telephone exchange . Landline service is usually distinguished from other more modern forms of telephone services which use Internet Protocol based services over optical fiber ( Fiber-to-the-x ) or other broadband services ( VDSL / Cable ) using Voice over IP , although sometimes modern fixed phone services delivered over

510-405: Is also limited by terrain and rain or snow and also detects unwanted objects such as automobiles, hills and trees. Furthermore, it cannot always estimate the altitude of an aircraft. Secondary radar overcomes these limitations but it depends on a transponder in the aircraft to respond to interrogations from the ground station to make the plane more visible. Depending on the type of interrogation,

544-439: Is in the general area. SARTs are typically cylindrical, about the size of a person's forearm, and brightly coloured. Transponder In air navigation or radio frequency identification , a flight transponder is an automated transceiver in an aircraft that emits a coded identifying signal in response to an interrogating received signal. In a communications satellite , a satellite transponder receives signals over

578-412: Is mandatory in controlled airspace in many countries. Some countries have also required, or are moving toward requiring, that all aircraft be equipped with Mode S, even in uncontrolled airspace . However, in the field of general aviation there have been objections to these moves, because of the cost, size, limited benefit to the users in uncontrolled airspace, and, in the case of balloons and gliders ,

612-676: Is similar in Canada, where more than one in five households used mobile phones as their only source for telephone service in 2013. However, voice over IP (VoIP) services offer an alternative to traditional landlines, allowing numbers to remain in use without being tied to a physical location, making them more adaptable to modern ways of working. The FCC maintains both landline and Voice over IP subscriber numbers to monitor long term trends in usage. In many countries, landline service has not been readily available to most people. In some countries in Africa,

646-537: Is the ability to carry high-speed internet popularly known as Digital subscriber line (DSL) which links back to the digital subscriber line access multiplexer (DSLAM) within the central office, T-1/T-3 , or ISDN . In 2003, the CIA World Factbook reported approximately 1.263 billion main telephone lines worldwide. China had more than any other country, at 350 million, and the United States

680-406: The 12 responses generated during the fast sweeps. These additional dot responses, which also are equally spaced by 0.64 nautical mile (1.2 km), will be interspersed with the original line of 12 dots. They will appear stronger and larger the closer the interrogating radar gets, slowly becoming arcs at first until the SART is within 1NM, the arcs will become full circles indicating the active SART

714-543: The United Kingdom, the analogue copper landline network is due to be terminated in 2025. The VoIP replacement is known as "Digital Voice" (on a BT service) in the UK. France, Germany and Japan are also in the process of replacing theirs. By means of porting, voice over IP services can host landline numbers previously hosted on traditional fixed telephone networks. VoIP services can be used anywhere an internet connection

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748-476: The advancement of mobile network technology and the obsolescence of copper wire networking. It is more difficult to install landline copper wires to every user than it is to install transmission towers for mobile service that many people can connect to. Some predict that these metallic networks will be deemed completely out of date and replaced by more efficient broadband and fiber optic landline connections extending to rural areas and places where telecommunication

782-488: The age of 35 have a considerably higher percentage of exclusive cell phone use. In 2013, 60% of young household owners claimed to only use cell phones. In 2019, 54% of Canadian households and 80% of French households had a landline telephone. In June 2020, it was reported that 60% of Australian adults used only mobile phones, with no landline. In 2021, only 14.5% of Australian and 29.4% of American households used landline at home. In contrast, 73% of UK households still had

816-546: The car may not even be aware that the transponder is there, because there are no buttons to press. When a key is inserted into the ignition lock cylinder and turned, the car's computer sends a signal to the transponder. Unless the transponder replies with a valid code, the computer will not allow the engine to be started. Transponder keys have no battery; they are energized by the signal itself. Transponders may also be used by residents to enter their gated communities . However, having more than one transponder causes problems. If

850-427: The interrogating radar and be within the passband of the radar receiver. If the radar-SART is within range, the frequency match during each of the 12 slow sweeps will produce a response on the radar display, thus a line of 12 dots equally spaced by about 0.64 nautical mile (1,185 km) will be shown. When the range to the radar-SART is reduced to about 1 nautical mile (1,852 km), the radar display may show also

884-466: The power requirements during long flights. Transponders are used on some military aircraft to ensure ground personnel can verify the functionality of a missile’s flight termination system prior to launch. Such radar-enhancing transponders are needed as the enclosed weapon bays on modern aircraft interfere with prelaunch, flight termination system verification performed by range safety personnel during training test launches. The transponders re-radiate

918-505: The rise in cell phones has outpaced growth in landline service. Between 1998 and 2008, Africa added only 2.4 million landlines. In contrast, between 2000 and 2008, cell phone use rose from fewer than 2 in 100 people to 33 out of 100. There has also been a substantial decline of landline phones in the Indian subcontinent , in urban and even more in rural areas. In the early 21st century, installations of landline telephones has declined due to

952-530: The satellite, rather than paying for a whole transponder, or using landlines to send it to an earth station for multiplexing with other stations. In fiber-optic communications , a transponder is the element that sends and receives the optical signal from a fiber . A transponder is typically characterized by its data rate and the maximum distance the signal can travel. The term "transponder" can apply to different items with important functional differences, mentioned across academic and commercial literature: As

986-850: The signals allowing for much longer communication distances. The International Maritime Organization 's International Convention for the Safety of Life at Sea (SOLAS) requires the Automatic Identification System (AIS) to be fitted aboard international voyaging ships with 300 or more  gross tonnage  (GT), and all passenger ships regardless of size. AIS transmitters/receivers are generally called transponders , but they generally transmit autonomously, although coast stations can interrogate class B transponders on smaller vessels for additional information. In addition, navigational aids often have transponders called RACON (radar beacons) designed to make them stand out on

1020-436: The start/finish line. Each individual runner or car has an active transponder with a unique ID code. When the individual passes the start/finish line, the lap time and the racing position is shown on the score board. Passive and active RFID systems are used in motor sports , and off-road events such as Enduro and Hare and Hounds racing, the riders have a transponder on their person, normally on their arm. When they complete

1054-467: The transponder sends back a transponder code (or "squawk code", Mode A) or altitude information (Mode C) to help air traffic controllers to identify the aircraft and to maintain separation between planes. Another mode called Mode S (Mode Select) is designed to help avoiding over-interrogation of the transponder (having many radars in busy areas) and to allow automatic collision avoidance. Mode S transponders are backward compatible with Modes A and C. Mode S

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1088-433: The utility mains electricity, unlike mobile wireless or portable wireless, which tend to be battery-powered . Although mobile and portable systems can be used in fixed locations, efficiency and bandwidth are compromised compared with fixed systems. Mobile or portable, battery-powered wireless systems can be used as emergency backups for fixed systems in case of a power blackout or natural disaster . Other aspects of landline

1122-464: Was much more sparse. In 2009, The Economist wrote "At current rates the last landline in America will be disconnected sometime in 2025." In 2004, only about 45% of people in the United States between the ages of 12 and 17 owned cell phones. At that time, most had to rely on landline telephones. Just 4 years later, that percentage climbed to about 71%. That same year, 2008, about 77% of adults owned

1156-510: Was second with 268 million. The United Kingdom had 23.7 million residential fixed home phones. A 2013 International Telecommunication Union report showed that the total number of fixed-telephone subscribers in the world was about 1.26 billion. In many parts of the world, including Africa and India, the growth in mobile phone usage has outpaced that of landlines. In the United States, while 45.9 percent of households still had landlines as of 2017, more than half had only mobile phones. This trend

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