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Adam Parkinson, Helios

Space-based ADS-B

A small step for technology a giant leap for ATM?

The challenges facing ATM

• Ageing infrastructure technologies

• Congested airspace• Poor interoperability• Fragmented airspace• Low level of automation• Poor predictability

The role of ADS-B

• Potential benefits:• Faster update rates compared to radar• Lower cost infrastructure• Potentially higher position accuracy (not range dependent)• Wider range of data items available• Enable new applications (eg ADS-B-NRA)

• Issues• Co-operative dependent system• High level of equipage required

The oceanic problem

Current solutions

Future solutions using ADS-B (-in) under assessment in SESAR

• Airborne Traffic Situational Awareness – In Trail Procedure• Lower limits for procedural climb – improve fuel efficiency

• Airborne Separation – In Trail Procedure• Requires new separation standards not yet defined

• Enable new passing manoeuvres in procedural oceanic airspace

Why do satellite ADS-B?

• Investigate cost-effective radar-like surveillance service in regions without surveillance infrastructure

• Natural extension of focus of SESAR for:• Use of ADS-B• Use of satellite systems for communication and navigation• Global interoperable ATM system

• Potential to enable new procedures and maximise efficiency of airspace

Key questions:

• Is it technically feasible?• Can we decode ADS-B transmissions on a satellite in the

presence of interference from other transmissions on the channel?

• Is it cost-effective?

Assessment of satellite ADS-B potential performance

Key results and observations

Calculating expected position update rates –oceanic region

• 160 aircraft supported in spot beam with 5 second update rate (95%)

• Assumes:• 2Hz transmission rate for position data• Interference signals will be largely ADS-B transmission we want

to decode all with similar signal levels • Overlap of transmissions will lead to garbling of message • Probability of detection driven by probability of overlap

Other considerations1090Mhz ES Bent-pipe Regenerative

Channel bandwidth

2.6Mhz (-3dB point) Typcially 10’s of MHz for Ka/Ku band

Typcially 10’s of MHz for Ka/Ku band

Data rate

22/111 Kpbs required for decode of Extended Squitters from 32/160 aircraft

Typically 1000’s Kbps per sub-channel

Typically 1000’s Kbps per sub-channel

Latency ~0.5 seconds Up to 2 seconds

Pros

Shorter latencies

Offers ability ro post process signal on ground for better decode performance

More efficient use of downlink bandwidth

Time of applicability of ADS-B report can be adjusted for latency of satellite link

Cons

Time of applicability of ADS-B report ignores latency of satellite link

Less efficient use of downlink bandwidth

Longer latencies

Satellite ADS-B initiatives

• SESAR OPTIMI – support search and rescue in remote regions

• ESA initiative for ADS-B satellite in orbit demonstration• Globalstar signed agreement with ADS-B technologies to

develop satellite ADS-B system• Iridium plan to install ADS-B receivers on next

generation of 66 communication satellites

The maritime case study

• AIS=ADS-B• ExactEarth offering commercial satellite AIS service

using 2 micro satellites with plans for more• However, the requirements are different

• Ships slower than aircraft• Aimed at search and rescue, environmental monitoring and

national security

• Current experience shows variable detection performance

Conclusions

• Feasible to provide radar like position update rates in oceanic airspace out of radar range in scenarios beyond 2015

• Unlikely that it will ever be used on its own to provide radar-like separation• No redundant cover• Impact of longer latencies

• Could enable new more efficient oceanic procedures not feasible with ADS-C• Reduced separations => increased capacity

Final observations

• Maritime domain has demonstrated feasibility of commercial service• Initial ADS-B satellite service may be available by 2015

European ADS-B mandate• However, ADS-B performance must be verified• Also need to address voice comms

• Impact on current SESAR activities• Business case required

• What is the market for the service?

www.askhelios.com

Space

Telecoms

Air Traffic Management

Airports

Rail

Maritime

Thank you for your attention

Adam Parkinsonadam.parkinson@askhelios.com