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VDL Mode 4 Airborne Architecture Study (VM4AAS)

ACP WG-M/8 Appendix J. VDL Mode 4 Airborne Architecture Study (VM4AAS). Study Overview and Conclusions. Nikos Fistas EATMP / EUROCONTROL Communications & Surveillance Management. Presentation Overview. PART I: General information Scope, Objectives, Plan, Structure PART II: Study Summary

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VDL Mode 4 Airborne Architecture Study (VM4AAS)

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  1. ACP WG-M/8 Appendix J VDL Mode 4Airborne Architecture Study(VM4AAS) Study Overview and Conclusions Nikos Fistas EATMP / EUROCONTROL Communications & Surveillance Management

  2. Presentation Overview • PART I: General information • Scope, Objectives, Plan, Structure • PART II: Study Summary • Overview of work achieved (Work Packages 1 to 4) • Conclusions • Recommendations • Next Steps

  3. PART I:GENERAL INFORMATION

  4. VM4AAS scope • Investigate airborne integration issues for VDL Mode 4, considering: • COM / SUR / COM and SUR applications • Large / Small / Light a/c • Forward-fit / Retrofit (digital and analogue) a/c

  5. VM4AAS Objectives (cont’d) • To • provide answers to questions • identify potential problems • make recommendations • contribute to decision making • provide input/guidance to manufacturers • considering current status and future trends

  6. Study Background Information • Performed by Honeywell • Started in June 2002 • Finished October 2003 • Informal external review group (open to interested “volunteers” )

  7. VM4AAS Deliverables WP3.2 D3.2 Radio Frequency Interference D3.1 WP3.1 WP3.1 WP5 WP4 29/10/03 WP4 WP4 WP5 WP4 WP4 D4 WP2.2 WP2.2 Implementation Draft Final Report Implementation Implementation Final Report VM4 Airborne Integration Meeting Implementation Implementation and Transition Avionics Avionics Architecture Architecture Plan Plan Plan Plan Architectures Architectures Requirements & Requirements & Constraints Constraints WP2.1 WP2.1 Applications Data Applications Data D2 Requirements Requirements WP1.3 WP1.3 Definitions, Definitions, Assumptions and Assumptions and D1 Baselines Baselines

  8. Deliverable Review Process External Review group (“volunteers”) Honeywell/ EUROCONTROL Resolution Airbus Avtech Sweden British Airways Boeing CNSS Dittel EasyJet PMEI Rockwell-Collins SAS SCAA Final Deliverable Final Deliverable on Web on Web Internal Honeywell/ EUROCONTROL External Draft Draft EUROCONTROL Review Deliverable Deliverable Resolution Comment Comment Resolutions Resolutions on Web on Web

  9. PART IISTUDY SUMMARY

  10. VM4AAS Work Structure Preparatory work • WP1 - D1: Assumptions and Baselines • WP2 - D2: Identifications of Requirements Investigations • WP3 - D3.2: RF Interference Analysis • WP3 - D3.1: Avionics Architectures • WP4 - D4: Implementation and Transition

  11. Work Package 1: Assumptions and Baselines • Preliminary work to form the foundations WP3 • Establish assumptions • Establish baselines

  12. WP1: Assumptions • VDL Mode 4 is acceptable to support applications • CDL only • SDL only • combined CDL and SDL • 15 other assumptions in 3 broad groups • Group 1: • SSR • Mode-S-based ACAS • Group 2: • Simultaneous VHF Communications • Group 3: • 8.33 kHz VHF Voice will be required throughout the study period

  13. WP1: Aircraft Classes • Large: take-off mass >15,000 kg • (Citation X, G-IV, ERJ, Airbus, Boeing) • Small: 5700 kg < take-off mass < 15,000 kg • (King Air 350, most Citation) • Light: take-off mass < 5700 kg • (Cessna 172, King Air C90B)

  14. WP1: Equipment Baselines (1) • Communication • VHF Voice (DSB-AM) x 2 • ACARS or Mode 2 • Simultaneous operation of voice and data link • Navigation • GNSS • ILS (Localizer and Glideslope) • VOR

  15. WP1: Equipment Baselines (2) • Surveillance • Mode S Transponder #1 • Mode S Transponder #2 or Mode C • ACAS Mode S Interrogator (Large & Small) • CDTI

  16. Work Package 2:Identification of Requirements • Identify general functional requirements • Identify internal interfaces • Identify external interfaces

  17. WP2: Internal Interfaces • Interconnections • VDLM4 to and from other avionics • Data Flow Diagrams • Data Dictionary • Precision Time Interface (PTI) • CONCLUSION: • Only PTI and baseband interface issues are unique to VDL Mode 4 compared to any other CDL/SDL “modem” technology

  18. WP2: Context-Level DFD • An example: Level 1 - external interactions

  19. WP2: External Interface Issues • RF Interference to/from other avionics • Focus on same-aircraft or co-site problems • Detailed study in WP3.2 • Derived work on integrity, availability, and continuity of service • Traffic Loading estimates for 2015 based on MACONDO

  20. Work Package 3.2:Interference Analysis (1) • RF Interference Issues • VHF Communications • Sources: DSB-AM, VDL Mode 2, VDL Mode 4 • Communication Victims: DSB-AM, VDL Mode 4, VDL Mode 2 • Navigation Victims: Localizer, VOR, VDB, Glideslope • Large, Small, Light Aircraft

  21. Work Package 3.2:Interference Analysis (2) • Same-side, Opposite-side antennas • Link-budget analysis using published standards or carefully documented assumptions • 3 issues: Desensitization, Off-Channel Emissions, RF (front end) Saturation

  22. WP3.2: VHF COM I/f Problem +20 minimum digital transmitter output (16 W = +42 dBm) -40 dB -20 +129 dB (!) -60 Power Spectral Density dBm/Hz -100 reference signal level -98 dBm -87 dBm -140 minimum signal level receiver noise floor -98 dBm thermal noise thermal noise -180

  23. WP3.2: Key Assumptions • MOPS -87 dBm reference signal level • Emissions levels • DO-186A (Voice), DO-281/ED-92 (Mode 2), ED108 (Mode 4) • Assumed noise floors • Using ARINC 716 isolations • MOPS adjacent channel rejection • ACR is a desensitization spec • Figure of merit Es/N0 or S/P

  24. WP3.2: 3 VHF-on-VHF i/f scenarios • Voice on digital • RF Saturation • IF Desensitization • Off-channel emissions (residual phase noise) • Digital on voice • RF Saturation • Squelch break • Audio S/P concerns • Digital on digital • RF Saturation • Desensitization IF • Off-Channel emissions (residual phase noise)

  25. WP3.2: Voice on digital i/f • Mechanism • Primarily phase noise and RF saturation • IF desensitization is lesser effect • Challenges • 100% voice duty factor • Mitigations • Better in-band filtering for digital receiver (IF) • “Better-than-MOPS” phase noise of voice transmitter • Increased isolation • Channel separation • Robust application protocols • Clear continuity definitions • Reduced use of AM voice as data use increases

  26. WP3.2: Digital on voice i/f • Mechanism • Primarily phase noise and RF saturation • IF desensitization is lesser effect • Challenges • Better than MOPS sensitivity of most AT voice receivers • Mitigations • Better than MOPS emissions for digital transmitter • Increased isolation • Channel separation • Constrain protocols to short pulse widths (adverse impact on “clicks”) • Consider cooperative suppression during transmissions

  27. WP3.2: Digital on digital i/f • Mechanism • Primarily phase noise and RF saturation • IF desensitization is lesser effect • Challenges • Multiplicity of antennas/limited isolation • Low-noise figure designs with FM protection • Mitigations • Better emissions for digital transmitter • “Better-than-MOPS” adjacent channel rejection • Increased isolation • Channel separation • Robust applications and protocols • Clear continuity definitions

  28. WP3.2: Off-channel & Desensitization Required frequency separations in (KHz) to solve the interference problem (additional analysis is being finalised)

  29. WP3.2: RF Saturation Certain: In band signal > +10 dBm and within ~3 MHz Very Probable: In band signal >-10 dBm and within ~3 MHz Probable: In band signal >-25 dBm and within ~3 MHz Possible: In band signal >-33 dBm (MOPS Specification) None: In band signal <-33 dBm (MOPS Specification) • New result (not in original WP3.2) • Supported by Boeing/Honeywell testing (Sept 2003 - data not yet released) • May be the limiting factor!

  30. Work Package 3.1:Architecture Descriptions • 11 different forward fit architectures • 1 radio retrofit architecture • Recommendations • Multi-function VHF radio • 8.33 kHz, 25 kHz, VDLm2, VDLm4 • Independent transmit and receive capabilities • Baseband control and flexibility

  31. WP3.1: requirements and constraints • Integrity • RMER 10-6 to 10-8 • Continuity • Loss of Continuity 1 x 10-5 to 5 x 10-4 • Availability • Communication system MTBF 1000 days • Surveillance system MTBF 1000 day

  32. WP3.1: Architecture Candidate #5 • ARINC 750 form factor New VHF Digital Radio (NVDR) • 4R1T, half duplex transceivers (not available today) • High-speed baseband information sharing • Independently reconfigurable R/T capabilities

  33. WP3.1: Architecture Candidate #9 • Remote mount high-end B/RA New VHF Digital Radio (NVDR) • 4R1T, half duplex transceivers (not available today) • High-speed baseband information sharing • Independently reconfigurable R/T capabilities

  34. WP3.1: Architecture Candidate #10 • Retains existing analog voice radio for GA aircraft • Small form factor (panel mount?) NVDR • 4R1T, half duplex transceivers (not available today) • Independently reconfigurable R/T capabilities • Somewhat limited under certain failure conditions

  35. WP3.1: Architecture Candidate #11 • Retains existing analog voice radio for GA aircraft • Small form factor (panel mount?) NVDR • 4R1T, half duplex transceivers (not available today) • Independently reconfigurable R/T capabilities • Somewhat limited under certain failure conditions

  36. WP3.1: Other Products • Allocation table showing how each transmitter and receiver is used • Availability/continuity analysis tables • Analytical Appendices

  37. Work Package 4:Implementation and Transition • Relative normalized costs of installation in a variety of configurations • “Typical” and “Best-Case” schedules

  38. WP4: Summary of Relative Costs

  39. WP4: Serial Task Schedule

  40. WP4: Aggressive Schedule

  41. Work Package 5: Final Report & Summary • Summarize WPs 1, 2, 3.2, 3.1, and 4 • Review external comments • Conclusions • Recommendations • Open Items and Future Work

  42. WP5: Review of External Comments • Comments critical of WP 3.2 • VHF Voice assumptions were too severe • Worst-case and not statistical analysis • Not supported by field data and/or trial experience • Comments about cost analysis with lack of benefit analysis • Comments about intermodulation • Comments about saturation

  43. WP5: Study Conclusions (1) • Interference Problem: • VHF-on-VHF interference will exist • VHF-on-VHF interference may prevent simultaneous voice and data usage provided by separate systems (valid for all VDLs) • Voice-on-VDL interference is more critical • Only half-duplex is achievable • Uplink data applications must be made sufficiently robust to sustain transfer delay due to downlink voice • Technical mitigations seem insufficient

  44. WP5: Study Conclusions (2) • Aircraft Integration Problem: • Recommended architectures are based on multi-function half-duplex VHF transceiver with 1 TX and 4 RXs • Recommended architectures require interconnected transceivers • VDL Mode 4 specific integration issues limited to PTI and baseband connections

  45. WP5: Study Conclusions (3) • General • VDL Mode 4 installation plans should be coordinated with ADS-B and/or advanced data link upgrades • Simultaneous operation of multiple VDLs and voice should be avoided

  46. WP5: Study Recommendations • Investigate operational impact of VDL Mode 4 interference to voice and vice versa to determine if and which applications can be supported • Complete feasibility analysis (safety, ..) of recommended architectures and facilitate as appropriate the development of multi-function 4R1T transceiver with • 8.33/25 kHz analog voice, VDL Mode 2, VDL Mode 4 • common baseband coordination • quasi-independent R/T functions • Use VMAAS results as input to other efforts to complete VDL Mode 4 specific cost/benefit analysis (CBA) to support link decision • Coordinate any aircraft upgrades with ADS-B and advanced CDL application upgrades

  47. WP5: Open Items/Future Work (1) • Assess operational impact of voice-on-data interference • Adopt GFSK BER analysis as part of a standard for reference • Adopt VDL Mode 4 link budget to level of detail comparable with other VDL data links

  48. WP5: Open Items/Future Work (2) • Perform or refine system-level cost benefit analysis based on relative costs provided by WP4 • Perform, publish, and publicize additional measurements of VHF-on-VHF interference effects

  49. VM4AAS • Remarks & Questions • More info and available draft deliverables: www.eurocontrol.int/vdl4/architecture.html • Comments and input welcome nikolaos.fistas@eurocontrol.int christophe.hamel@honeywell.com chuck.laberge@honeywell.com

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