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  2. Radar beacon - Wikipedia

    en.wikipedia.org/wiki/Radar_beacon

    When a racon receives a radar pulse, it responds with a signal on the same frequency which puts an image on the radar display. This takes the form of a short line of dots and dashes forming a Morse character radiating away from the location of the beacon on the normal plan position indicator radar display.

  3. VHF Data Link - Wikipedia

    en.wikipedia.org/wiki/VHF_Data_Link

    The VHF Data Link or VHF Digital Link (VDL) is a means of sending information between aircraft and ground stations (and in the case of VDL Mode 4, other aircraft). Aeronautical VHF data links use the band 117.975–137 MHz assigned by the International Telecommunication Union to Aeronautical mobile (R) service. There are ARINC standards for ...

  4. Trunked radio system - Wikipedia

    en.wikipedia.org/wiki/Trunked_radio_system

    A trunked radio system is a two-way radio system that uses a control channel to automatically assign frequency channels to groups of user radios. In a traditional half-duplex land mobile radio system a group of users (a talkgroup) with mobile and portable two-way radios communicate over a single shared radio channel, with one user at a time ...

  5. AOL Mail

    mail.aol.com

    You can find instant answers on our AOL Mail help page. Should you need additional assistance we have experts available around the clock at 800-730-2563.

  6. Domain Awareness System - Wikipedia

    en.wikipedia.org/wiki/Domain_Awareness_System

    The Domain Awareness System, the largest digital surveillance system in the world, [2] is part of the Lower Manhattan Security Initiative in partnership between the New York Police Department and Microsoft to monitor New York City. [3] It allows the NYPD to track surveillance targets and gain detailed information about them, and is overseen by ...

  7. Secondary surveillance radar - Wikipedia

    en.wikipedia.org/wiki/Secondary_surveillance_radar

    SSR antenna of Deutsche Flugsicherung at Neubrandenburg, in Mecklenburg/Western Pomerania Transponder in a private aircraft squawking 2000. Secondary surveillance radar (SSR) [1] is a radar system used in air traffic control (ATC), that unlike primary radar systems that measure the bearing and distance of targets using the detected reflections of radio signals, relies on targets equipped with ...

  8. Mobile phone - Wikipedia

    en.wikipedia.org/wiki/Mobile_phone

    A mobile phone or cell phone[ a ] is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area, as opposed to a fixed-location phone (landline phone). The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which ...

  9. Wireless device radiation and health - Wikipedia

    en.wikipedia.org/wiki/Wireless_device_radiation...

    Since at least the 1990s, scientists have researched whether the now-ubiquitous radiation associated with mobile phone antennas or cell phone towers is affecting human health. [1] Mobile phone networks use various bands of RF radiation, some of which overlap with the microwave range. Other digital wireless systems, such as data communication ...