GPS World, October 2009

THE SYSTEM Solutions Sought to GNSS Vulnerabilities Baska conference report by David Last The second conference on GNSS Vulnerabilities and Solutions September 2 5 in Baska Croatia focused on GNSS vulnerability to space weather unintentional interference jamming and multipath propagation The conference was a joint venture by the Royal Institute of Navigation London and Nottingham Universitys Institute of Engineering Surveying and Space Geodesy Sixty four delegates mostly European came from 21 countries Nearly half the papers focused on space weather and ionospheric and tropospheric propagation taking in long term and short term solar effects scintillation signal attenuation tropospheric delay variations meteorological infl uences and even gravity waves The approach of the physicists was Understand these things and maybe you can mitigate your vulnerability to them GNSS vulnerability can threaten safety critical and mission critical systems including navigation in the air maritime automatic identifi cation systems and the transportation of nuclear waste and other dangerous materials on land Mitigations include EGNOS the European WAAS and GBAS groundbased augmentation systems Road Tolling An unexpectedly hot topic was the enthusiasm of European governments to deploy road user charging schemes based largely on GNSS technology Some say road pricing is a rare and novel case of GNSS users who are hostile to the technology and seeking to exploit its vulnerability to the maximum To enforce charges through the legal system may require levels of integrity approaching those of aircraft instrument approach systems Suggestions for jamming defenses came mostly from Germany Ulrich Engel and Angelika Hirrle proposed exciting new mathematical techniques to help separate GNSS signals from noise and interference while Michael Felux sought refuge in low cost inertial systems Hank Skalski of the U S Department of Transportation laid out U S government plans to detect and track down sources of GPS jamming The SETS Space Event Tracking System will deploy aircraft vans fi xed base units and trained technicians See Lasts report on low cost jammers in criminal employ Expert Advice page 8 Smartpath Approved The U S Federal Aviation Administration FAA has certified Honeywells Smartpath precision landing system for airport installations As this magazine went to press neither the FAA nor the Department of Transportation had issued an official release but industry contacts were notified in mid September The ground based augmentation system provides aircraft with precise navigation data for CAT I approaches and landings enabling closely spaced parallel and curved path approaches to increase airport capacity It asserts improved navigation accuracy over instrument landing systems ILS using differential GPS and broadcasting both pseudorange corrections for each satellite in view as well as approach path information in a digital broadcast According to Honeywell most current production Airbus and Boeing aircraft now carry GBAS avionics or offer it as an option Future Smarpath upgrades include the ability for CAT III approaches Arctic Passage Traversed by Merchant Ships Two German merchant ships traversed the Northeast Passage from South Korea leaving in late July to Siberia and plan to continue their journey to Rotterdam in the Netherlands A sea lane traditionally blocked by heavy ice floes or solid sheet ice this route has opened because of to global warming In 2007 Arve Dimmen director of maritime safety for Norways Coastal Administration told the U S National Space Based Positioning Navigation and Timing Advisory Board that disappearing ice across the Arctic poses potential threats 25 percent of undiscovered oil resources lie in that region and the route could now be used by supertankers and large container ships as it is more economical and less time consuming Precision navigation faces more challenges north of the Artic Circle from atmospheric affects in polar regions and the low elevation of SBAS satellites at those latitudes A June 2009 study on GNSS use in the high Arctic by Richard Langley however found that conventional horizontal marine navigation works well north of the Arctic Circle Still others held that this is another reason why eLoran is so important someone at USCG State Commerce needs to use this as a wake up call 3XOVH HDGHU LQ QWHQQDV IRU 7HOHPDWLFV SSOLFDWLRQV URP YHKLFXODU PRXQW DQWHQQDV WR HPEHGGHG FHUDPLF FKLS VROXWLRQV 3XOVH KDV WKH ULJKW DQWHQQD IRU RXU DSSOLFDWLRQ 9LVLW RXU ZHE VLWH DW ZZZ SXOVHHQJ FRP DQWHQQDV GPS World October 2009 www gpsworld com 16