The importance of resilient position-fixing for e-Navigation George Shaw PNT Seminar, RNN, Stockholm 18 May 2011

Resilient PNT: a role for eLoran?  Maritime dependence on GPS  GNSS vulnerabilities -GLA ship trials of GPS jamming -Space weather / ionospheric scintillation  Public awareness / media coverage -Royal Academy of Engineering report  Options for maritime Resilient PNT -The case for eLoran  eLoran: status & wider benefits

Source: Northern Lighthouse Board Visual Signalling  Bell Rock Lighthouse celebrates 200 years  Lights & buoys are crucial…  … now and in future for navigation close-to-danger  But GPS has become the principal maritime Aid-to- Navigation…

GLA DGPS augmentation for accuracy and integrity The GLAs operate 14 DGPS stations

e-Navigation needs resilient PNT ≠ resilient PNT due to GNSS vulnerability… +  e-Navigation by : “the harmonized collection, integration, exchange, presentation and analysis of maritime information...to enhance berth to berth navigation…”  IMO says: “e-Navigation systems should be resilient …. robust, reliable and dependable. Requirements for redundancy, particularly in relation to position fixing systems should be considered” Picture Courtesy of US National Executive Committee

Flamborough Head Jamming Trial 2008 Erroneous GPS reported positions, courses and speeds AIS radar overlay included erroneous positions Reference:

THV Galatea Trial 2009  With full denial of the GPS signal, some large position errors were observed -Blue ship icon is GPS indicated position -Green circle is true position (from eLoran): eLoran was unaffected by the jamming Reference:

THV Galatea Trial 2009  With higher power jamming, the GPS position visited some wide spread locations  With lower power jamming comparable to the GPS signal level caused -Hazardously Misleading Information (HMI) -No alarms sounded -Erroneous positions and velocities, some of them barely noticeable! ‘wide spread locations’

THV Galatea Trial 2009  With a little more jammer power, alarms began to sound  Eventually all of these bridge systems failed…. -ECDIS: Electronic Chart Display -Ship’s Autopilot -DGPS: Differential GPS -Heli-deck stabilisation system -DSC-GMDSS: Maritime Distress Safety System -Radar -Gyro-compass -AIS: Automatic Identification System

Mitigation of GNSS vulnerability  Cost Benefit Analysis of alternative PNT options (by )  Compared four options -Option 1: ‘Do Minimum’ -Option 2: Physical and radar Aids-to-Navigation (AtoN) -Option 3: GNSS ‘hardening’ and GNSS monitoring -Option 4: eLoran  Rigorous business case provided to the UK Department for Transport in Sept ?? = resilient PNT

Option 2: Physical & Radar AtoN  Enhanced visual AtoN -e.g. synchronised/sequenced  ‘New Technology’ radar  Absolute positioning  Coastal infrastructure -Radar reflectors -Target enhancers  NT compatible radar beacons (Racons)  Independent of GNSS

Option 3: GNSS Hardening  Multi-constellation GNSS -GPS, Galileo, GLONASS -DGNSS infrastructure  GNSS interference mitigation -external monitoring -receiver – advanced RAIM -robust systems integration  Integrated SBAS (EGNOS)?  Sifted out due to 2018 timescale -adaptive antennas -inertial augmentation -signals of opportunity User Transmitter Source: NSL Integrity Monitor SW Processing Reference Station SW Processing Integrity Monitor Receiver Reference Station Receiver

Option 4: eLoran  Independent, complementary and dissimilar to GNSS  Low frequency / high power / terrestrial  Modern s/w Rx on powerful h/w platform available  Chip-level integration possible  Meets maritime performance requirements for coastal and harbour approach navigation -accuracy, availability, integrity, and continuity

Results of Analysis of Options  eLoran has largest economic return over 10 to 15 year lifetime -Balance of physical and radionavigation AtoN allows removal of some lights  Other options have negative returns  Only eLoran has been demonstrated to provide fully effective mitigation against the vulnerability of GNSS  Allowing full benefits of e-Navigation for maritime  Substantial cross-sector benefits

eLoran features – core service  Precise timing, locked to UTC -independent of GNSS -2-way time satellite transfer (TWTST) -radically different from Loran-C  no ‘chains’  no 2-way time baselines -supports autonomous control and monitoring by each nation  All-in-View receivers -uses all available transmitters -single transmitter provides time -3 transmitters provide 2D position and time

eLoran features - augmentation  Signal propagation corrections -Additional Secondary Factors (ASFs) -compensate for propagation delay over land -one-off coastal survey -database in eLoran receiver  Differential Loran (DLoran) -local reference stations for harbour approach -real-time corrections for temporal variations  eLoran Data Channel (Eurofix) -integrity alerts within time to alarm -transmit DLoran corrections DLoran Ref Station Loran Station ASF Map

Source: Williams and Hargreaves, eLoran Performance in the Orkney Archipelago, Proc ILA 38, October 2009, Portland ME, USA

Prototype eLoran on air in Europe with better than 10 metre accuracy Accuracy: ~10m (95%)

Status of eLoran in the UK  Prototype eLoran routinely operates (since 2009)  Anthorn Tx with >99.9% availability  Prototype DLoran established in Harwich (and rapid mobile deployment, for trials)  Combined ASFs / DLoran proven  Initial Operational Capability in Covers 6 SOLAS class Channel ports  Full Operational Capability in Covers further 22 SOLAS class ports

European Status of (e)Loran  9 Loran transmitters operational at various standards, monitored and controlled from CCB at Brest  Informal cooperation since end of NELS agreement  No policy to move to eLoran  European Radio Navigation Plan?  France: trials of DLoran and study of TWTST  Norway: bilateral with Russia for Loran / Chayka (Tumanny station) compatibility by 2013

Wider Status of (e)Loran  US position on a backup for GPS remains uncertain -closure of Loran-C (460m 95%) -consolidation of industry (UrsaNav) -concept of ‘LF Phoenix’  Russia: modernisation of Chayka -planned operation to at least eChayka: 7 -20m accuracy, differential corrections and data channel  Saudi Arabia -planned upgrade to eLoran  FERNS -Japan decision to withdraw -S Korea, China, Russia continue

Conclusions eLoran is only system, when combined with GNSS, that can achieve resilient PNT by 2018 for maritime e-Navigation eLoran potential cross-sector benefits of accuracy, integrity, availability and continuity include seamless PNT information for: protection of critical national infrastructure police and emergency services telecomms / internet power generation banking / financial transactions land-based transport agriculture

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