2. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE1 / INNOVATIVE RESEARCH XX ‘Aircraft Identification Tag’ – AIT Safety and Security Increase for ATM through unnoticeable Watermark Aircraft Identification Tag transmitted with the VHF Voice Communication Horst Hering, ERC Bretigny, France Martin Hagmüller, Gernot Kubin, TU Graz, Graz, Austria

3. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE2 / INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT  Introduction  AIT Technology  Watermark Technology  AIT Advantages  Conclusion

4. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE3 / INNOVATIVE RESEARCH VHF Air/Ground Voice Communication  Party-line communication in a ATC sector:  One frequency for all AC and the unique ATC controller  For identification all pilot voice messages start with the AC call-sign

5. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE4 / INNOVATIVE RESEARCH Call-sign ambiguity through:  Low quality of the VHF transmission  Call-sign is incompletely transmitted  Very similar call-signs of different AC  Pilot used a shorted/ omitted the call-sign  Error of comprehension/ speaking  Short AC transmission without any speech  Controller occupied, caught parts of the msg. only  ……  Resulting by increase of controller’s workload

6. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE5 / INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT  Introduction  AIT Technology  Watermark Technology  AIT Advantages  Conclusion

7. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE6 / INNOVATIVE RESEARCH Technical Idea for a Solution  ‘Watermark’ technique  Watermark for paper  Digital ‘Watermark’ technique  Commercial use for IPR protection:  Digital pictures  Digital videos  Digital audio sources  ….

8. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE7 / INNOVATIVE RESEARCH Aircraft Identification Tag - AIT Tag Aircraft  Ground VHF-Radio Communication: voice with added tag (hidden watermark) Ground : Special displays Innovative functions in the ODS  Voice hearing  Tag decoding and data dispatching an for supplementary visual stimulus 3D audio

9. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE8 / INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ - AIT  AIT’s aim for the air – ground voice link:  Automatic identification of the originator  Not noticeable for partners on the party-line  In time with ongoing speech (real-time)  Without any pilots intervention  No modification to existing AC equipments  Secure voice link

10. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE9 / INNOVATIVE RESEARCH Digital Audio-Watermarks  Special audio watermark equipment:  Watermark Encoder  Watermark Decoder

11. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE10 / INNOVATIVE RESEARCH VHF Communication Link TX RX Voice frequency (analogue 300 …. 3400 Hz) Aircraft system ATC system PTT* switch * PTT (Push To Talk) Data (e.g. Call-sign) Watermark Encoder Including unnoticeable watermark Tag Watermark Decoder Innovative ATC functions Data (e.g. Call-sign)

12. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE11 / INNOVATIVE RESEARCH AIT Specifications (basic)  Payload Data (‘call-sign’)  12 bits (SSR code)  24 bits (‘Mode S’ identifier)  36 bits (General avionic tail-number)  Timing:  Signal Watermark Ratio  < 14 db (similar channel signal noise ratio) pure Speech ~ 800 ms Watermarked Speech start delay Microphone output PTT TX voice t

13. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE12 / INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT  Introduction  AIT Technology  Watermark Technology  AIT Advantages  Conclusion

14. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE13 / INNOVATIVE RESEARCH Watermark Encoder (simplified) 001110110 100101011 110110010 …. 011110110 101010101 010101100 …. Digital Speech Digital Payload Data A/D Converter D/A Converter Analogue Speech Analogue Speech with Watermark 01101…01101… Digital Speech with Watermark Encoder Watermark Embedder

15. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE14 / INNOVATIVE RESEARCH Watermark Embedder Payload Data Speech Channel Coding (BCH-Code) MUX Sync. Sequence Spectral Shaping Spreading Sequence MUX Multiplexer SNR Signal Noise Ratio SNR Calculation Watermarked Speech Watermark Data Embedder

16. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE15 / INNOVATIVE RESEARCH Watermark Decoder (simplified) A/D Converter Analogue Speech with Watermark Digital Speech with Watermark Payload Data 01101.. Watermark Extractor 011110110 101010101 010101100 …. Decoder

17. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE16 / INNOVATIVE RESEARCH Watermark Extractor Payload Data Channel Coding (BCH-Code) Sync. Sequence Integrator Spreading Sequence Synchron. Watermarked Speech Time Variant Whitening Filter Confidence Extractor

18. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE17 / INNOVATIVE RESEARCH Results from Experiments  Experiments (1000 watermarked voice samples / campaign)  Data rate 80/ 100 bits per second  Payload data 12/24/36 bits  Dependency: MER -- Signal Watermark Ratio/Watermark Floor  Result (example):  Data rate 80 bits/s  Payload 12 bits  Watermark floor: –18db  > 9000 voice samples  1 payload data error

19. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE18 / INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT  Introduction  AIT Technology  Watermark Technology  AIT Advantages  Conclusion

20. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE19 / INNOVATIVE RESEARCH C W P ATC Implementation of AIT SSR Data (Position, Ident, FL) RX - VHF Audio Operational Display System Flight-Plan Data AIT Decoder (Payload Data + Confidence) Correlation (SSR/AIT) for ODS Selection Track Selection

21. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE20 / INNOVATIVE RESEARCH Track 4 Track1 Track2 Track3

22. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE21 / INNOVATIVE RESEARCH Benefits from – AIT (I) Air-Ground Voice Communication:  Automatic identification of the originator (signature)  Security against fake voice com. (terrorists)  No modification to certified AC equipment  Not noticeable for party-line partners

23. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE22 / INNOVATIVE RESEARCH Benefits from – AIT (II) ATC System:  Digital AC call sign is available in time with pilots VHF voice communication  Innovative functions on the ODS (i.e. Radar track selection during voice communication)  Support of controller’s SA through supplementary visual stimuli's  Add redundancy to the voice channel AC identification  Prevent from supplementary workload caused by call-sign ambiguity for the controller  Support for correlation unusual ‘AC telephone names’ and belonging ‘3-letter call-signs’ (e.g. ‘Airkibris’  KYV)  Protection against fake AC voice communication

24. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE23 / INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT  Introduction  AIT Technology  Watermark Technology  AIT Advantages  Conclusion

25. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE24 / INNOVATIVE RESEARCH AIT for Air-Ground Voice Communication  Benefit for safety of air transportation  Address the security aspect against fake voice com.  Automatically without any humans intervention  Standard technology; no AC modification  Realised demonstrator:  High performance  Robustness against transmission problems (noise, fading, …)  Usage in general avionics for airfields  Tested with VHF; usage in oceanic areas with HF probable

26. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE25 / INNOVATIVE RESEARCH Speech Samples  Original speech (without watermark)  Watermarked speech (W-floor: -20db; SWR: 16db)  Watermarked speech (W-floor: -24db; SWR: 20db)  Watermarked speech (W-floor: -28db; SWR: 24db)

27. EUROCONTROL RESEARCH & DEVELOPMENT CENTRE26 / INNOVATIVE RESEARCH ? Aircraft Identification Tag - AIT Thank you! g.kubin@ieee.org horst.hering@eurocontrol.int hagmueller@inw.tugraz.at