Thales ADS-B - Chapter 1 System Description

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Description, Operation and Maintenance System Description
ADS−B
1−1Ed. 10.07
CHAPTER 1
SYSTEM DESCRIPTION
1.1 GENERAL
ADS−B is a data link application or principle that makes use of navigational data that are available
onboard of an aircraft. Aircraft avionics permanently determines the aircraft’s navigational position
and movement vector. Most air transport aircraft are also equipped with a flight management system
that guides the aircraft along waypoints programmed by the pilot.
The principle of ADS−B refers to making available this information by means of an automatic broad-
cast via digital data link. ADS−B is an acronym for Automatic Dependent Surveillance Broadcast:
Automatic no human intervention is required,
Dependent the surveillance solution is not determined by the observer but provided by the
observed object
Surveillance data provided include position, velocity vector etc.
Broadcast transmitted without external trigger (e.g. interrogation) without any specific addressee
This broadcast information may be received and processed by other aircraft or ground systems for
use in improved situational awareness, conflict avoidance and airspace management. Three ADS−B
data link technologies are emerging as possible contenders − namely, Universal Access Transceiver
(UAT), VHF Data Link (VDL) Mode 4 and 1090MHz Extended Squitter (Mode S data link). The interna-
tional civil aviation organization ICAO has recommended to use the 1090 MHz (Mode S) data link as
global data link technology for ADS−B purposes. The other two data links are seen only for regional
applications. Fig. 1−1 shows the system and its components in an example view.
ADS−B LAN A
RCMS 1
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Ground Network
RCMS 2
ADS−B LAN B
ADS−B LAN A
ADS−B LAN B
ATC−Center ATC−Center
GPS Satellites
Aircrafts, MODE S data
Ground−Station data
ADS−B operational data
Maintenance data
1090 ES SIS
GPS SIS
ATC
ATC
ADS−B RX GPS RX
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Fig. 1−1 System overview ADS−B, examplary configuration