eurocontrol research & development centre1 / innovative research xx ‘aircraft identification...

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


INNOVATIVE RESEARCH


IntroductionAIT TechnologyWatermark TechnologyAIT AdvantagesConclusion


INNOVATIVE RESEARCH

VHF Air/Ground Voice Communication

Party-line communication in a ATC sector:

One frequency for all AC and the unique ATC controllerFor identification all pilot voice messages

start with the AC call-sign


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


INNOVATIVE RESEARCH




INNOVATIVE RESEARCH

Technical Idea for a Solution

‘Watermark’ technique Watermark for paper

Digital ‘Watermark’ technique Commercial use for IPR protection:

Digital picturesDigital videosDigital audio sources….


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


INNOVATIVE RESEARCH

‘Aircraft Identification Tag’ - AIT

AIT’s aim for the air – ground voice link:

Automatic identification of the originatorNot noticeable for partners on the party-lineIn time with ongoing speech (real-time)Without any pilots interventionNo modification to existing AC equipmentsSecure voice link


INNOVATIVE RESEARCH

Digital Audio-Watermarks

Special audio watermark equipment:

Watermark EncoderWatermark Decoder


INNOVATIVE RESEARCH

VHF Communication Link

TX

RX

Voice frequency (analogue 300 …. 3400 Hz)

Aircraft system

ATC systemPTT* switch

* PTT (Push To Talk)

Data(e.g. Call-sign)

WatermarkEncoder

Including unnoticeable watermark

Tag

WatermarkDecoder

Innovative ATC functions

Data(e.g. Call-sign)


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


INNOVATIVE RESEARCH




INNOVATIVE RESEARCH

Watermark Encoder (simplified)

001110110100101011110110010….

011110110101010101010101100….

Digital Speech

Digital Payload Data

A/DConverter

D/AConverter

Analogue Speech

Analogue Speech with Watermark

01101…

Digital Speech with Watermark

Encoder

WatermarkEmbedder


INNOVATIVE RESEARCH

Watermark Embedder

Payload Data

Speech

ChannelCoding

(BCH-Code)

MUX

Sync.Sequence

SpectralShaping

SpreadingSequence

MUX Multiplexer

SNR Signal Noise Ratio

SNRCalculation

Watermarked Speech

Watermark Data

Embedder


INNOVATIVE RESEARCH

Watermark Decoder (simplified)

A/DConverter

Analogue Speech with Watermark

Digital Speech with Watermark

Payload Data

01101..

WatermarkExtractor

011110110101010101010101100….

Decoder


INNOVATIVE RESEARCH

Watermark Extractor

Payload Data

ChannelCoding

(BCH-Code)

Sync.Sequence

Integrator

SpreadingSequence

Synchron.

Watermarked Speech

Time VariantWhitening

Filter

Confidence

Extractor


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 samples1 payload data error

12 16 20 24 280

1

2

3

4

5

SWR [dB]

ME

R [

%]

Watermark floor

-18dB -24dB -28dB

k = 12bits


INNOVATIVE RESEARCH




INNOVATIVE RESEARCH

C W P

ATC Implementation of AIT

SSR Data(Position, Ident, FL)

RX - VHF Audio

OperationalDisplaySystem

Flight-PlanData

AIT Decoder(Payload Data+ Confidence)

Correlation(SSR/AIT) for

ODS Selection

Track Selection


INNOVATIVE RESEARCH

Track 4

Track1

Track2

Track3


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


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


INNOVATIVE RESEARCH




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 performanceRobustness against transmission problems (noise, fading, …)

Usage in general avionics for airfields Tested with VHF; usage in oceanic areas with HF

probable


INNOVATIVE RESEARCH

Speech Samples

Original speech (without watermark)

Watermarked speech (W-floor: -20db; SWR: 16db)




INNOVATIVE RESEARCH

?Aircraft Identification Tag - AIT

Thank you!

[email protected]

[email protected]

[email protected]

eurocontrol research & development centre1 / innovative research xx ‘aircraft identification...

Documents

sign slide

sign watermark encoder

austria slide

signal watermark ratio

d audio slide

controllers workload

automatic identification

ods voice hearing tag