acars - aircraft communication adressing and reporting system
TRANSCRIPT
ACARS - Aircraft CommunicationAdressing and Reporting System
PRESENTATION
Digital Systems
André Baptista
ACARS
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A bit of history
Created in 1978.
Developed due the necessity of reducing workload and costs ofoperation.
Only funcion: automated time clock system.
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ACARS – What is it?Stands for: Aircraft Communication Adressing and ReportingSystem.
9 million ACARS communications every week.
It is a Data-link system that enables an airplane to communicatewith land based systems, through a network of transcievers.
Consists of equipment on board, equipment on the ground, and a service provider.
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Components
Board equipmentLand equipmentDSP – Service Provider
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Components
Board equipment
Managment Unit – Heart of equipment Interface with Flight Managment System. Routes Comms. to earth Automatic choice of band used.
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Components
Board equipment
DataLink Printer Prints Uplink Comms from earth.
Maintenance computer Downlink diagnostic and fault messages to base.
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Components
Earth Equipment
Network of transcivers that enables the system do work in the entire world.
Comms to destination, mostly in VHF.
End systems Central units and user Computers in land based systems.
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Components
DSP – Service Provider
Manage the comms that deliver the messages.The are the owner´s of the netwroks.SITA and ARINC – Prime DSP´s.They send the messages from the VHF stations to end-systems.
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ComponentsACARS
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MessagesATC - Air Traffic Control MessagesATC messages are used to communicate between the aircraft and Air Traffic Control – Clearences.
AOC - Aeronautical Operational Control MessagsAAC – Airline Administrative Control MessagesAOC and AAC messages are used to communicate between cabin or
flight crew and the base operational office. Standard Messages or user defined.
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Sample MessagesDeparture Information Downlink
Weather information Downlink
FDAMS Message Downlink
OOOI EventsOut of Gate, Off the Ground, On the Ground, Into the gate.
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Sample Messages
Free text uplink message Printed Free text uplink message
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Sample Messages
Pre-flight ACARS downlink message Weather request ACARS message
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CommunicationsThree types of Communication:
VHF.HF.SatCom
Automatically chosen by the MU - Management Unit.
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CommunicationsVHF: preferred method.
Frequencies between 121.00 MHZ and 132.00 MHZ.A network of VHF stations assures that the airplane is able to communicate with ATC, AOC, AAC. Communication done in line-of-sight.Maximum distance Airplane - Antenna: 300km .Not available in Polar locations of the world.
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CommunicationsHF.
Frequencies between 3 MHZ and 30.00 MHZ.Available since 2001 – relatively new.Less bandwith than VHF os SATCOM.Only used in remote locations: Polar locations.
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CommunicationsACARS
Wave propagation diferences between VHF and HF 17
Digital Systems
CommunicationsSATCOM.
New way of communicating.INMARSAT AND IRIDIUM. Frequencies between 3 and 30 Gigahertz.More bandwith than VHF or HF.
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CommunicationsSATCOM.
ACARS
SATCOM communication diagram19
Digital Systems
CommunicationsACARS
Antennas location in an aircraft20
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DATA CODINGCODING
Data Exchange between VHF-3 and transciever it is coded by1200HZ and 2400HZ tones.1200hz tone: bit change (Change of signal – 0 to 1 or 1 to 0).2400hz tone: no bit change (signal remains the same).Transmission rate of 2400 bits per second.
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DATA CODINGCODINGWhen all bits are set to 1: enables adjustment of VHF transmitionand reception levels.
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DATA CODINGACARS
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Thruth table
DATA CODING ACARS
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QUESTIONS???
CHEERS.
Sistemas Digitais – 3º anoACARS
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