Automatic Dependent Surveillance–Broadcast (ADS-B)
ADS-B is an international standard that is meant to improve aviation safety. ADS-B provides improved situational awareness for aircraft and ground stations by enabling aircraft to broadcast their identity, position, speed, altitude and heading. This enables other aircraft, air traffic control and interested ground stations to identify and track nearby aircraft. This enhances overall situational awareness without requiring everyone to have an active surveillance system (radar) of their own. They only need to be able to receive, decode and process the data.
ADS-B vs UAT
Aircraft that operate internationally or that fly above 18,000 feet in the U.S. must use the 1090MHz ADS-B Extended Squitter (ES) service. Almost all commercial aircraft will use ADS-B.
ADS-B broadcasts occur on 1090.0 MHz for Mode-S, a periodic burst data transmission. The interrogator frequency for ADS-B is 1030.0 MHz.
ADS-B broadcasts are not encrypted so they can be received, decoded and even mapped to provide a real-time traffic picture of the airways.
Universal Access Transceiver (UAT) is another part of the ADS-B standard. In the U.S, aircraft that operate domestically and below 18,000 feet can use the UAT system, which broadcasts at 978Hz, instead of ADS-B. This system is used by the very large population of General Aviation aircraft.
ADS-B only provides basic position data. With UAT aircrews can also access other valuable flight data through free Flight Information Service-Broadcast (FIS-B) and Traffic Information Service-Broadcast (TIS-B) services. These give them weather reports (METARs), Temporary Flight Restrictions (TFRs) and general notices (NOTAMs).
Receiving ADS-B
There are a number of online sites that provide free ADS-B information. These are the most comprehensive collections of online ADS-B data. They provide interactive maps that display the aggregated data. You can click on an aircraft icon on their maps to pop up detailed info on the craft. They depend on numerous participants providing their own data feeds which are then aggregated and shared. Providers like ADS-B Exchange and FlightAware also have information that can help you build your own system:
- The ADS-B Exchange aggregates and publishes flight data 🔗 ADS-B Exchange
- FlightAware also aggregates and publishes flight data 🔗 FlightAware Website
- ADS-B Program Examples ⓘ ADSB Examples
There are a number of commercially-available ADS-B receiver systems that can be purchased. An inexpensive SDR with an appropriate antenna and a computer with ADS-B software can also be used to receive and decode ADS-B data.
A simple ADS-B receive station can be built easily with low-cost SDRs and free software.
Here is an example -- ⓘ An Example of a simple ADS-B station
References:
- RTL-SDR Blog's ADS-B Tutorial (old but still good) 🔗 RTL-SDR Tutorial: Cheap ADS-B Aircraft RADAR
- The FAA's ADS-B FAQ 🔗 ADSB FAQ
- Wikipedia 🔗 Automatic Dependent Surveillance–Broadcast
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Information is provided for education and instructional purposes only.