1 Presented by Mike Shorthose Helios Technology Ltd Chamberlain House High Street Bagshot Surrey UK VDL Mode 4 Overview and development status
Dec 17, 2015
1
Presented by Mike Shorthose
Helios Technology LtdChamberlain House
High StreetBagshotSurrey
UK
VDL Mode 4Overview and development status
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What is VDL Mode 4 ?
• VDL Mode 4 is a time-critical digital data link– Operates in 108-137 MHz range using a 25 KHz
communications channel
– Operates without the need for ground infrastructure
– Gaussian-filtered Frequency Shift Keying
– Modulation rate is 19,200 bits/s
• Provides a range of communications services– Main focus is surveillance applications
• Provides built-in ADS-B function• Supports air-to-air surveillance
– Also ATN compliant
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Self-Organising TDMA
• A superframe = 4500 slots/minute• Beginning of each time-slot synchronised to UTC• Slots reserved in advance by all stations• Management of time-slots shared amongst stations• Efficient use of data-link
4 slotsreserved byground station
2 slots reserved by aircraft A
1 slot reserved by aircraft B
VDL Mode 4 time slots
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Channel Operation
Ground Station transmits DoS
En-route traffic transmits on GSCs
LSCs
GS
C A
GS
C B
Terminal traffic transmits on GSCs and LSCs
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Periodic Broadcast Protocol
• Reserves slots in future superframes– All stations build up a ‘reservation table’
– Broadcast of position and ID information
Reserved
Current
Reserved
Reserved
Pt=3
Pt=2
Pt=1
Pt=0
Periodic Broadcast
Reservation
transmitted
Reserved for
broadcast
Reserved for
broadcast
Offset after Time-out & Reserve for
broadcast
Reserved
Reserved for
broadcast
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SARPs
• ICAO standards for VDL Mode 4 cover:– SARPS (physical layer)
– Technical Manual (higher layers)
• Milestones– Accepted by ICAO in early 2000 at AMCP/7
– Reviewed by states – state letters produced
– Expected final acceptance and incorporation in Annex 10 in November 2001
• Expect subsequent update of Technical Manual
Standards And Recommended Practices
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EUROCAE/MOPS
• WG-51: ADS-B: Use of broadcast communication for increased airborne surveillance information
• Set performance standards for VDL Mode 4 airborne transceiver
• “Interim VDL Mode 4 MOPS” – ED108– Published (July 2001)– Will be updated as system develops further– RTCA not publishing these MOPS
European Organisation for Civil Aviation Equipment
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ETSI
• Produces telecommunications standards throughout Europe
• Current activities– Certification of VDL Mode 4 ground
equipment currently being reviewed by RP05 working group
– Physical layer expected to be finalized by July 2001
– Higher layers expected to be finalized by November 2001
European Telecommunications Standards Institute
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Aircraft Architecture• GNSS transponder
• Dual redundant equipment for AT aircraft
Inertial Reference
System
GNSSReceiver
DME/VORNavigationSystems
FlightManagement
Computer
FlightDisplays
VDL Mode 4Communications
unit
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Equipment
• VDL Mode 4 ground and airborne equipment becoming available from several manufacturers
• Mobile display types – The MMI 500 and the NFS 5000
– Active cursor control in NAV display
– Frequency control for VHF link
– Provisions for dedicated VDL Mode 4 transceivers
– Interfaces to VHF link
• Fixed ground displays – RIMS system (fitted with runway incursion monitoring )
– GRPU (display ADS-B and radar data simultaneously )
The MMI 500 display
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Trials Milestones
NEAP
1996 1997 1998 1999 2000
NEAN
NUP Phase I
NAAN
NUP Phase II
NEAN NetworkEstablished
Installations inDLH B747-200
Installations inSAS F28
FARAWAY I/II
FREER III
Airborne ArchitectureGroup Final Report
Discussions with industry
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NEAN & NUP
• NEAN aimed at developing new technologies for data links and networking – WP1 aimed at checking coverage, network reliability
and end-to-end performance– WP3 aimed at development and implementation of the
ground part of the ADS-B network
• NUP– Aims at establishing a European ADS-B network based
on global standards – Phase 2 being planned
North European ADS-B Network & NEAN Upgrade Programme
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MFF & Med-Up
• MFF is conducted by ENAV, the Italian service provider– Determine concept of free flight in Mediterranean
– Defines operational requirements and procedures
– Guidelines to implement free flight operations
– Programme consists of six phases
• Med-up– Contributes to the Eurocontrol ADS work programme
– Provides testing of technical infrastructure
– Large-scale experimentation using several equipped aircraft
Mediterranean Free Flight & ADS Mediterranean Upgrade Programme
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Russian Activities
• Tyumen project – Investigation of ADS-B operation for en-route and
terminal areas
– Support of flights in regions currently without radar surveillance
• Southern Ring Project – VDL Mode 4 equipped flights
– Deployment of ground equipment
• Offshore oil and gas exploration – JV Gasprom considered equipping aircraft with VDL
Mode 4 transponders
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ADS-B Technical Link Assessment Team (TLAT)
• Evaluation of three ADS-B candidate technologies– FAA/Eurocontrol/Service providers/industry
• Results for VDL Mode 4– Aid to visual acquisition – generally not supported– Conflict/collision avoidance – supported beyond 3nm– Separation assurance/sequencing – generally supported– Airport surface – not assessed– Air-to-air applications – not assessed
• Issues for Mode 4– Optimisation of some system functions required
• Channel management/ trajectory change points / ground antenna design
– Identify channel assignments for GSCs / local channels
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System development
• Further development of surveillance capability– Channel management
• Need to prove concept in high-density environment
– TIS-B / FIS-B
• Evolution of point-to-point functions– To make more efficient for ATN applications
– Re-working of data link service sublayer
– Review of connection to ATN
– Consideration of additional error checking/correction
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Spectrum
• Frequency issues– VDL Mode 4 needs multiple VHF channels
• The exact number is not known• ADS-B (2 GSCs plus local channels)• + channels for other services (TIS, FIS, point to point etc)
• Interference issues– Careful engineering of onboard systems required to
prevent interference between VDL Mode 4 and Mode 2 or with VHF voice R/T
– More trials needed to find optimum configurations