Norsk Marinteknisk Forskningsinstitutt

Ørnulf Jan Rødseth Research Director, MARINTEK – Maritime Transport Systems

OrnulfJan.Rodseth@marintek.sintef.no

Measured Performance of Satellite Systems in the Arctic

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MARINTEK Norwegian Marine Technology Research Institute

NTNU Norwegian University

of Science and Technology

Cavitation tunnel

Towing tank

Ocean basin Structural testing

The Maritime Technology Center Trondheim, Norway

Energy and engine laboratory

Integrated operations laboratory

Presentation overview

• The MARENOR project

• Satellite systems in the Arctic – the issues

• Actual VSAT performance

• Low Earth Orbit – Iridium

• AIS Satellite AISSat-1 and AISSat-2

The MARENOR project

• EMGS – Project Owner • MARINTEK – Technical Coordinator • Duration Feb 2012 – Jan 2015 • Supported by

Research Council of Norway

MARENOR shall quantify the system performance of the most common navigation and communication systems being used by maritime users in the Arctic.

In-situ measurements of satellite performance

MV Atlantic Guardian Mexican Gulf Norwegian Sea

FV Remøy Greenland Sea Barents Sea

Kjell Henriksen Observatory Svalbard

Satellite systems in the Arctic – the issues

Icing

Strong ionospheric activity Visibility from geostationary orbit

Ionospheric scintillation

• Well known phenomena

• Normally more pronounced around equator

• Known to impact GNSS accuracy

• May also impact low frequency communication L-band, VHF etc.

• Effect varies with solar activity, time of day and other parameters.

© Copyright Commonwealth of Australia 2015, Bureau of Meteorology (ABN 92 637 533 532)

Rain fade ?

The rain rate (mm/h) exceeded for 0.01% of the average year from Recommendation ITU-R P.837-5.

D

d r = 6 371d = 9D = 339 (=38*9)

rR D2 = R2 – r2

Presentation overview

• The MARENOR project

• Satellite systems in the Arctic – the issues

• Actual VSAT performance

• Low Earth Orbit – Iridium

• AIS Satellite AISSat-1 and AISSat-2

VSAT Data recorded from Remøy Using ASTRA 4A Ku-band

Svalbard-Trømsø transit each 6 weeks

Results of measurements

• Good performance up to 78° N.

• No statistically significant degradation below 78° N.

• Intermittent communication breaks above 78°. Sometimes up to 82° N.

• Expected round-tip time (RTT) is 700 ms

• 14% more than 1.4 seconds

• 1.4% more than 7 seconds.

Presentation overview

• The MARENOR project

• Satellite systems in the Arctic – the issues

• Actual VSAT performance

• Low Earth Orbit – Iridium

• AIS Satellite AISSat-1 and AISSat-2

Iridium: Low Earth Orbit System – Global coverage

Main measurements on Svalbard, but also elsewhere

Results of Iridium measurements (on Svalbard) - 1

• Expected RTT is 1.5s

• … except first message from ship, RTT is 3.5s

• … and first message from shore, RTT is about 15s

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Results of Iridium measurements (on Svalbard) - 2

• A relatively high incidence of connection breaks over the four month period.

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Break length Number over 4 months < 900 seconds 95 > 900 < 2800 seconds 11 > 2800 seconds 8

Iridium: Similar results from other areas

• Svalbard

• Barents Sea

• Mexican Gulf

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Presentation overview

• The MARENOR project

• Satellite systems in the Arctic – the issues

• Actual VSAT performance

• Low Earth Orbit – Iridium

• AIS Satellite AISSat-1 and AISSat-2

AIS Signal reception via AISSat-1

• Polar orbit: Normally coverage each 1.6 hours down to about 75°N.

• AISSat-2 launched in July 2014. Decreasing interval to about 50 minutes.

• Tracked FV Remøy over almost 12 months.

Very good detection probability

• 98% detection probability. Many drop-outs due to port calls and narrow fjords. • AISSat-2 entered service in July

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AISSat-1 Some details

• Many drop-outs close to Longyearbyen and Tromsø (fjord and port calls).

• Sensitivity dependent on satellite height over horizon (inversely)

y = -0,0139x + 1,2873R² = 0,2424

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Conclusions

• VSAT over Ku works well up to fairly high latitudes. − Variance in RTT may have an impact on some critical applications. − East/West longitude will reduce maximum latitude

• Must be verified with each satellite and service provider !

• Iridium over L-band works ok elsewhere in the Arctic region, but with limitations: − Limited bandwidth − Relatively long RTT − Very high variance in RTT − Some drop-outs

• AIS satellite is a very good system for monitoring ships in the area