Towards Selective Addressing of Aircraft with Voice Radio ... · Towards Selective Addressing of Aircraft with ... Triggers the radio transmitter ... Towards Selective Addressing

1European Organisation for the Safety of Air Navigation

Long Term Investigations, EEC

Towards Selective Addressing of Aircraft withVoice Radio Watermarks

Horst Hering, Konrad Hofbauer

EUROCONTROL Experimental Centre (EEC),Bretigny, France



Outline

Introduction Aircraft Identification Tag (AIT) basics

AIT benefits

Motivation for R&D Issues of the radio communication

Proposed solution Selective PTT switch

Demonstrator

Experimentation

Results and conclusion



Introduction

Air traffic guidance based on: Standardised voice radio communication

VHF channels (118133 MHz)

AM - modulation

technique known to be sensitive for disturbance - poor voice quality

Party line concept One voice channel /sector

One controller

All aircraft obligation for identification (down- & up-link)

Voice Signal(pilot/ ATCO)

VHF Transmitter

PTT Switch

VHF Receiver

Voice Signal(ATCO /pilot)



Aircraft Identification Tag*

FM broadcast radios Radio Data System - RDS identify radio channel for listener

Watermark techniques for conventional ATC radio channels Embedding digital data in analogue speech

Not noticeable in transmitted speech

* H. Hering, M. Hagmueller, G. Kubin, Safety and security increase for air traffic management through unnoticeable watermark aircraft identification tagtransmitted with the VHF voice communication, in proceedings of the 22nd Digital Avionics Systems Conference (DASC 2003), Indianapolis, USA (2003)

Voice Signal(pilot/ ATCO)

Watermark Embedder

VHF Transmitter

Signature(Originator)

PTT Switch



Aircraft Identification Tag



AIT Initial Feasibility Study*

Deployment-driven requirements Rapid and simple deployment Legacy system compliance Bandwidth efficiency Minimal aircraft modifications Cost efficiency

User-driven requirements Perceptual quality Data rate Real-time availability Error rate Maintaining established procedures No user interaction

*AIT- Initial Feasibility Study, EATMP Info-centre, EUROCONTROL Brussels, Belgium (2006) (consortium: Sofreavia, Frequentis, Rockwell-Collins)



Current AIT R&D

Speech consists of segments with: periodic structure - voiced speech (vowel, semi-vowels and nasal sounds)

noise-like structure - unvoiced speech (most of the consonants)

Watermarking in unvoiced speech* Advantages

High perceptual quality

High data rate (capacity)

Ex.: Original signal

Ex.: Watermarked signal with 2000 bits per second

*K. Hofbauer and G. Kubin, High-rate data embedding in unvoiced speech, in Proceedings of the International Conference on Spoken LanguageProcessing (INTERSPEECH), (Pittsburgh, PY, USA), Sept. 2006.



Aircraft Identification Tag

Benefits Call sign confusion and ambiguity

Mis-identification

Safety Threat

Malicious messages Radio transmissions issued by unauthorized 3rd party

Security Threat

Increase ATCOs situation awareness Visual stimuli reinforce audio hearing



Motivation for R&D

High load of the radio communication channelover core Europe Small sectors (57 minutes fly through time)

VOCALIS study* 60 hours of voice communications 12 different French en-route sectors featuring heavy traffic periods

Watching party line is a hard task for pilots Average of 324 speech acts per hour About 5 speech acts per minute

*L. Graglia et al., VOCALISE: Assessing the Impact of Data Link Technology on the Radio Telephony Channel, in proceedings of the 24th DigitalAvionics Systems Conference (DASC 2005), Washington DC, USA (2005)



Issues for the Radio Communication

AIT downlink of a digital aircraft signature for the ATCO toincrease safety and security

Uplink of the aircraft address ??? similar benefits for the aircrew

Generation of an attention getter



Proposed Solution Uplink the aircraft address via AIT

ATCO has to indicate the destination of each voice messageto the AIT system

On board of the addressed aircraft an attention getter is created

Voice Signal(ATCO)

Watermark Embedder

VHF Transmitter

Signature(ATCO)

PTT Switch

Address(Destination)



Selective PTT Switch Concept

The selective PTT switch: Triggers the radio transmitter

Interacts with the ATM system to define the called aircraft address

Signature(ATCO)

Voice Signal(ATCO)

Watermark Embedder

VHF Transmitter

Address(aircraft)

Selective PTT

ATM System

MousePosition

Last ACAIT



Selective PTT Switch Logic

Last aircraft calling in (AIT) is memorised for ~20 seconds

Physical PTT switch triggers a selective logic

Selective logic: Mouse cursor hovers above memorised aircraft

this aircraft is called if PTT switch pressed

Mouse cursor does not hover above an aircraft

this memorised aircraft is called if PTT switch pressed

Mouse cursor hovers above different aircraft

this aircraft is called if PTT switch pressed

memorised unanswered aircraft is highlighted for 2 seconds

Mouse cursor hovers above Public call button

all aircraft in the sector are called



Selective PTT Switch

Based on AIT watermark technology

Uplink voice messages with an embedded digital destination address Supports aircrew with automatic attention getter for own radio messages

Benefits for on board safety

Benefits for the secured voice communication

Implements digital features in analogue radio communication



Selective PTT Switch Demonstrator

Demonstrator setup

Static air traffic situation (simulation screen shoot)

Animated with audio and visual cues Aircraft calling in

AIT highlighting of the aircraft calling in

Selective PTT switch representation



Demonstrator Screen



Calling Aircraft

Demonstrator assumption: all aircraft AIT equipped

Blinking frame while aircraft is calling in



Selective PTT Switch Pressed

Calling LOT232 - aircraft that called in last

Calling YUBRZ - system reminds that LOT232 called last



Demonstration/ Experiments

12 operational experts of the EEC (ex-controllers)

From 8 different European countries

Period August 2007

Questionnaire Selective PTT switch Concept - Usability Based on an evaluated IBM computer usability questionnaire*

*J. R. Lewis, IBM Computer Usability Satisfaction Questionnaires: Psychometric Evaluation and Instructions for Use, International Journalof Human-Computer Interaction, 1995 v.7 n.1 p.57-78



Global Question

Usage of the selective PTT switch requires change of thecurrent working procedures for the controller Selection of the called aircraft by hover the label

and

Pressing the PTT switch

Is this change of the working procedures acceptable for thecontrollers ?



Questions and Answers1. Overall, I am satisfied with how easy it is to use this concept

2. It was simple to use this concept

3. I can effectively complete my work using this concept

4. I am able to complete my work quickly using this concept

5. I am able to efficiently complete my work using this concept

6. I feel comfortable using this concept

7. It was easy to learn to use this concept

8. I believe I became productive quickly using this concept

9. Whenever I make a mistake using the concept, I recover easilyand quickly

10. The information on-screen provided with this concept is clear

11. It is easy to find the information I needed

12. The information provided for the concept is easy to understand

13. The information is effective in helping me complete the tasks andscenarios

14. The organization of information on the demonstrator screen isclear

15. The interface of this concept is pleasant

16. I like using the interface of this concept

17. This concept has all the functions and capabilities I expect it tohave

18. Overall, I am satisfied with this concept

stronglyagree

stronglydisagree1 2 3 654 7

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question

Mean

Standard Deviation (1)

Dominant/mode

Conceptuse

Informationquality

Interfacequality



Result and Conclusion

Interface usability results Overall satisfaction of the selective PTT switch concept : 2.49*

Usage of the selective PTT switch : 2.38*

Quality of the presented info : 2.35*

Quality of the interface : 3.00*

Globally the new working procedures with selective PTT switch areacceptable

Open ways for other com features (digital communication like)

AIT together with the selective PTT switch represent for analogue radiosa preliminary step towards digital end-to-end radio communication

*Scale : strongly agree = 1 ... neutral = 4 strongly disagree = 7



Towards Selective Addressing of Aircraft withVoice Radio Watermarks

Horst Hering, Konrad Hofbauer

EUROCONTROL Experimental Centre (EEC)

Documents

Towards Selective Addressing of Aircraft with Voice Radio ... · Towards Selective Addressing of Aircraft with ... Triggers the radio transmitter ... Towards Selective Addressing