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Automatic Dependent Surveillance - Broadcast (ADS-B)
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According to the U.S. Federal Aviation Administration, "Automatic Dependent Surveillance-Broadcast (ADS-B) is FAA's satellite-based successor to radar. ADS-B makes use of GPS technology to determine and share precise aircraft location information, and streams additional flight information to the cockpits of properly equipped aircraft."
Position, speed, heading, and other flight data are determined by instruments on the aircraft, and broadcast once per second to a network of relatively simple ground stations, and directly to other aircraft.
In this case, the data are "dependent" on on-board instruments, as opposed to radar, which can determine the location of an aircraft independent of any signals transmitted by the plane. Some of the benefits of ADS-B include improved accuracy through the use of GPS, improved coverage since the system does not rely on relatively weak return radar echoes, and improved abilities to route planes directly to their destination, rather than relying on pre-determined routes between a sequence of established waypoints.
While the U.S. and other countries are building out networks of ground stations to receive ADS-B broadcasts, it will be many years before a large fraction of commercial and private aircraft are equipped with ADS-B transmiters. The U.S. hopes to have its ground station network completed by the end of 2013.
The term "ADS-B Out" refers to the broadcasts sent from the aircraft. "ADS-B In" refers to the ability of the aircraft to monitor ADS-B transmissions from other aircraft and from the ground, and display the information to the pilot. This information may include the positions of other planes, weather data, terrain data, and other information that can be encoded through ADS-B.
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Frequencies |
| Frequency | Bandwidth | Use | Service | Table |
| 978 MHz | - | ADS-B (optional frequency, U.S. only, below 18,000 ft) | Aeronautical Radionavigation | - |
| 1090 MHz | - | Primary worldwide ADS-B frequency | Aeronautical Radionavigation | - |
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