Transcript VDL Mode 4 - ATN Conference

VDL Mode 4
Overview and development status
Presented by Mike Shorthose
Helios Technology Ltd
Chamberlain House
High Street
Bagshot
Surrey
UK
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Introduction
• Basic principles
• Status of standards
• Equipment, trials and assessments
• Issues
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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
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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 slots
reserved by
ground station
2 slots
reserved by
aircraft A
VDL Mode 4 time slots
1 slot reserved
by aircraft B
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Channel Operation
En-route traffic
transmits on GSCs
GSC B
GSC A
Ground Station
transmits DoS
Terminal traffic transmits
on GSCs and LSCs
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
Periodic Broadcast
Reservation
transmitted
Reserved for
broadcast
Reserved for
broadcast
Reserved for
broadcast
Pt=3
Current
Pt=2
Reserved
Pt=1
Reserved
Pt=0
Reserved
Offset after Timeout & Reserve for
broadcast
Reserved
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Introduction
• Basic principles
• Status of standards
• Equipment, trials and assessments
• Issues
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SARPs
Standards And Recommended Practices
• 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
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EUROCAE/MOPS
European Organisation for Civil Aviation Equipment
• 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
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ETSI
European Telecommunications Standards Institute
• 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
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Introduction
• Basic principles
• Status of standards
• Equipment, trials and assessments
• Issues
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Aircraft Architecture
• GNSS transponder
Inertial
Reference
System
DME/VOR
Navigation
Systems
Flight
Displays
GNSS
Receiver
Flight
Management
Computer
VDL Mode 4
Communications
unit
• Dual redundant equipment for AT aircraft
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Equipment
• VDL Mode 4 ground and airborne equipment
becoming available from several manufacturers
• Mobile display types
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The MMI 500 and the NFS 5000
Active cursor control in NAV display
Frequency control for VHF link
The MMI 500 display
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 )
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Trials Milestones
1996
1997
1998
1999
2000
NEAN
NEAP
NEAN Network
Established
NAAN
Installations in
SAS F28
Installations in
DLH B747-200
Airborne Architecture
Group Final Report
NUP Phase I
FARAWAY I/II
FREER III
NUP Phase II
Discussions with
industry
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NEAN & NUP
North European ADS-B Network & NEAN Upgrade Programme
• 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
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MFF & Med-Up
Mediterranean Free Flight & ADS Mediterranean Upgrade Programme
• MFF is conducted by ENAV, the Italian service provider
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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
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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
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– Identify channel assignments for GSCs / local channels
• Basic principles
• Status of standards
• Equipment, trials and assessments
• Issues
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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
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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
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