INNOVATIVE RESEARCH Aircraft Identification Tag AIT Safety and

INNOVATIVE RESEARCH ‘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 1 / XX EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT u Introduction u AIT Technology u Watermark Technology u AIT Advantages u Conclusion 2/ EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH VHF Air/Ground Voice Communication u Party-line communication in a ATC sector: èOne frequency for all AC and the unique ATC controller ðFor identification all pilot voice messages start with the AC call-sign 3/ EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Call-sign ambiguity through: Low quality of the VHF transmission u Call-sign is incompletely transmitted u Very similar call-signs of different AC u Pilot used a shorted/ omitted the call-sign u Error of comprehension/ speaking u Short AC transmission without any speech u Controller occupied, caught parts of the msg. only u …… u Resulting by increase of controller’s workload 4/ EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT u Introduction u AIT Technology u Watermark Technology u AIT Advantages u Conclusion 5/ EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Technical Idea for a Solution u ‘Watermark’ technique è Watermark u for paper Digital ‘Watermark’ technique è Commercial use for IPR protection: ð Digital pictures ð Digital videos ð Digital audio sources ð …. 6/ EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Aircraft Identification Tag - AIT Aircraft Ground VHF-Radio Communication: voice with added tag (hidden watermark) Tag Innovative functions in the ODS Special displays Ground : 3 D audio Voice hearing Tag decoding and data dispatching an for supplementary visual stimulus 7/ EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ - AIT u AIT’s aim for the air – ground voice link: èAutomatic identification of the originator ðNot noticeable for partners on the party-line ðIn time with ongoing speech (real-time) ðWithout any pilots intervention ðNo modification to existing AC equipments ðSecure voice link 8/ EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Digital Audio-Watermarks u Special audio watermark equipment: èWatermark Encoder èWatermark Decoder 9/ EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH VHF Communication Link Aircraft system Watermark Encoder PTT* switch TX ATC system Tag RX Data (e. g. Call-sign) Watermark Decoder Voice frequency (analogue 300 …. 3400 Hz) Including unnoticeable watermark * PTT (Push To Talk) 10 / Data (e. g. Call-sign) Innovative ATC functions EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH AIT Specifications (basic) u Payload Data (‘call-sign’) 12 bits (SSR code) ð 24 bits (‘Mode S’ identifier) ð 36 bits (General avionic tail-number) ð u Timing: Microphone output PTT start delay t TX voice ~ 800 ms pure Speech Watermarked Speech u Signal è 11 / Watermark Ratio < 14 db (similar channel signal noise ratio) EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT u Introduction u AIT Technology u Watermark Technology u AIT Advantages u Conclusion 12 / EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Watermark Encoder (simplified) Encoder Digital Speech with Watermark Analogue Speech A/D Converter 001110110 100101011 110110010 …. Digital Speech 13 / 011110110 Watermark 10101 Embedder 010101100 …. D/A Converter 0 1 1 0 Digital 1 Payload Data … Analogue Speech with Watermark EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Watermark Embedder Watermarked Speech Sync. Spreading Sequence Spectral Shaping MUX Channel Coding (BCH-Code) MUX Multiplexer SNR Signal Noise Ratio SNR Calculation Watermark Data Embedder Payload Data 14 / EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Watermark Decoder (simplified) Decoder A/D Converter Analogue Speech with Watermark 15 / Digital Speech with Watermark 011110110 1010101100 …. Watermark Extractor Payload 01101. . Data EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Watermark Extractor Watermarked Speech Extractor Sync. Spreading Sequence Time Variant Whitening Filter Synchron. Integrator Channel Coding (BCH-Code) Payload Data Confidence 16 / EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Results from Experiments u Experiments (1000 watermarked voice samples / campaign) è Data rate 80/ 100 bits per second è Payload data 12/24/36 bits Dependency: MER -- Signal Watermark Ratio/Watermark Floor k = 12 bits 5 u Result (example): è Data rate 80 bits/s è Payload 12 bits ð Watermark floor: – 18 db ð > 9000 voice samples ð 1 payload data error MER [%] u 4 3 -18 d. B -24 d. B -28 d. B 2 1 0 12 17 / Watermark floor 16 20 SWR [d. B] 24 28 EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT u Introduction u AIT Technology u Watermark Technology u AIT Advantages u Conclusion 18 / EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH ATC Implementation of AIT SSR Data (Position, Ident, FL) Flight-Plan Data RX - VHF Audio CWP Operational Display System 19 / AIT Decoder (Payload Data + Confidence) Track Selection Correlation (SSR/AIT) for ODS Selection EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Track 1 Track 3 Track 2 Track 4 20 / EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Benefits from – AIT (I) Air-Ground Voice Communication: Automatic identification of the originator (signature) u Security against fake voice com. (terrorists) u è No modification to certified AC equipment è Not noticeable for party-line partners 21 / EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Benefits from – AIT (II) ATC System: u u 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 è Add redundancy to the voice channel AC identification è Prevent from supplementary workload caused by call-sign ambiguity for the controller è Support for correlation unusual ‘AC telephone names’ and belonging ‘ 3 -letter call-signs’ (e. g. ‘Airkibris’ KYV) è u 22 / Protection against fake AC voice communication EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH ‘Aircraft Identification Tag’ – AIT u Introduction u AIT Technology u Watermark Technology u AIT Advantages u Conclusion 23 / EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH AIT for Air-Ground Voice Communication Benefit for safety of air transportation u Address the security aspect against fake voice com. u Automatically without any humans intervention u Standard technology; no AC modification u Realised demonstrator: u ð High performance ð Robustness against transmission problems (noise, fading, …) Usage in general avionics for airfields u Tested with VHF; usage in oceanic areas with HF probable u 24 / EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Speech Samples 25 / u Original speech (without watermark) u Watermarked speech (W-floor: -20 db; SWR: 16 db) u Watermarked speech (W-floor: -24 db; SWR: 20 db) u Watermarked speech (W-floor: -28 db; SWR: 24 db) EUROCONTROL RESEARCH & DEVELOPMENT CENTRE

INNOVATIVE RESEARCH Aircraft Identification Tag - AIT ? Thank you! horst. hering@eurocontrol. int hagmueller@inw. tugraz. at g. kubin@ieee. org 26 / EUROCONTROL RESEARCH & DEVELOPMENT CENTRE