UAT meaning in Telecommunication ?

Automatic Dependent Surveillance–Broadcast (ADS–B) is a surveillance technology in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts it, enabling it to be tracked. The information can be received by air traffic control ground stations as a replacement for secondary surveillance radar, as no interrogation signal is needed from the ground. It can also be received by other aircraft to provide situational awareness and allow self-separation.ADS–B is "automatic" in that it requires no pilot or external input. It is "dependent" in that it depends on data from the aircraft's navigation system.

ADS–B is being incorporated in various jurisdictions worldwide. It is an element of the United States Next Generation Air Transportation System (NextGen), the Airports Authority of India upgrade plans in line with the ICAO Global Plan Initiatives and Aviation System Block Upgrade (ASBU), and the Single European Sky ATM Research project (SESAR). ADS–B equipment is mandatory for instrument flight rules (IFR) category aircraft in Australian airspace; the United States requires many aircraft (including all commercial passenger carriers and aircraft flying in areas that required a transponder) to be so equipped as of January 2020; and, the equipment has been mandatory for some aircraft in Europe since 2017. Canada uses ADS–B for surveillance in remote regions not covered by traditional radar (areas around Hudson Bay, the Labrador Sea, Davis Strait, Baffin Bay and southern Greenland) since January 15, 2009. Aircraft operators are encouraged to install ADS–B products that are interoperable with US and European standards, and Canadian air traffic controllers can provide better and more fuel efficient flight routes when operators can be tracked via ADS–B.