1. 1 Presented by Mike Shorthose Helios Technology Ltd Chamberlain House High Street Bagshot Surrey UK VDL Mode 4 Overview and development status

2. 2 Introduction Basic principles Status of standards Equipment, trials and assessments Issues

3. 3 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

4. 4 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 slots reserved by ground station 2 slots reserved by aircraft A 1 slot reserved by aircraft B VDL Mode 4 time slots

5. 5 Channel Operation Ground Station transmits DoS En-route traffic transmits on GSCs LSCs GSC A GSC B Terminal traffic transmits on GSCs and LSCs

6. 6 Periodic Broadcast Protocol Reserves slots in future superframes –All stations build up a ‘reservation table’ –Broadcast of position and ID information Reserved Current 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

7. 7 Introduction Basic principles Status of standards Equipment, trials and assessments Issues

8. 8 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

9. 9 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

10. 10 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

11. 11 Introduction Basic principles Status of standards Equipment, trials and assessments Issues

12. 12 Aircraft Architecture GNSS transponder Dual redundant equipment for AT aircraft Inertial Reference System GNSS Receiver DME/VOR Navigation Systems Flight Management Computer Flight Displays VDL Mode 4 Communications unit

13. 13 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

14. 14 Trials Milestones NEAP 19961997199819992000 NEAN NUP Phase I NAAN NUP Phase II NEAN Network Established Installations in DLH B747-200 Installations in SAS F28 FARAWAY I/II FREER III Airborne Architecture Group Final Report Discussions with industry

15. 15 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

16. 16 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

17. 17 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

18. 18 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

19. 19 Basic principles Status of standards Equipment, trials and assessments Issues

20. 20 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

21. 21 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