What is ADS-B and how it works?

ADS-B system is a hardware equipment installed onboard aircraft and it transmits automatically the location (latitude, longitude) of the aircraft and its movement data (speed, heading, altitude) via a digital data link (1090 MHz). These transmissions are received and can be used by other aircraft and traffic control centers to display the aircraft’s position its movement without the need for radar.

ADS-B system determines the position of the aircraft using GPS. The transmitter broadcasts that position, heading and speed at regular intervals. Transmitted packets also include the aircraft’s identity, altitude, speed and other data. ADS-B ground stations receive the broadcast data and relay the information to air traffic control centers for precise tracking of the aircraft.

The ADS-B abbreviation means:

Automatic – Requires no pilot input or external interrogation.

Dependant – Depends on accurate position and velocity data from the aircraft’s navigation system (eg. GPS).

Surveillance – Provides aircraft position, altitude, velocity, and other surveillance data to facilities that require the information.

Broadcast – Information is continually broadcast for monitoring by appropriately equipped ground stations or aircraft.

ADS-B data is transmitted every half-second on a 1090MHz, digital data link.

Individual aircraft are assigned a unique 24-bit address defined by the ICAO (International Civil Aviation Organization), often referred to as a Mode-S or Hex (hexadecimal) code.  This unique address can be transmitted by the aircraft’s transponder and/or interrogated by ground based radar.  Mode-S operates on the radio frequencies 1030/1090 Mhz.