Also known as: ADS-B, ADSB
ADS-B (Automatic Dependent Surveillance–Broadcast) is an aviation surveillance system in which aircraft continuously broadcast their identity, position, altitude, and velocity on 1090 MHz (and 978 MHz UAT in the U.S.). It is the aeronautical counterpart to AIS and one of the most popular SDR applications.1
Overview
ADS-B rides on Mode S Extended Squitter messages, modulated with pulse-position modulation at 1 Mbps. Latitude/longitude are encoded with Compact Position Reporting, which resolves to a precise position from a pair of even/odd messages.
Technical characteristics
| Property | Value |
|---|---|
| Frequency | 1090 MHz (978 MHz UAT) |
| Modulation | PPM (Mode S) |
| Bit rate | 1 Mbps |
| Integrity | CRC-24 |
| Position | CPR even/odd encoding |
History
Standardised by ICAO with MOPS from RTCA (DO-260) and EUROCAE (ED-102); mandated for most controlled airspace through the 2010s–2020s.1
Deployment
Commercial and general aviation worldwide; widely received by hobbyists feeding flight-tracking networks.
Decoding it with GopherTrunk
GopherTrunk detects the 1090 MHz squitters in the magnitude domain, validates the CRC-24, and decodes aircraft state. See the ADS-B decoder page.
Sources
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Automatic Dependent Surveillance–Broadcast — Wikipedia, for the 1090 MHz ADS-B system, Mode S Extended Squitter, CPR position coding, and ICAO/RTCA/EUROCAE standardisation. ↩ ↩2