GPS World, April 2014

INNOVATION System Design Test 50 45 40 35 30 25 20 15 10 05 0 Protection level meters VPL LPL 166 168 170 172 174 176 178 180 182 Time of day hours FIGURE 8 Vertical and lateral protection levels VPL and LPL judgment these results show the practicability of this multiconstellation GBAS approach on an experimental basis Conclusion and Outlook In this article experimental extensions to GBAS have been developed to support GPS GLONASS and Galileo simultaneously Based on these extensions an optimized VDB transmission scheme has been created In this way the number of transmittable differential corrections could be maximized 8VLQJ ÀLJKW WULDOV WKH PXOWL FRQVWHOODWLRQ 6 FRQFHSW KDV VXFFHVVIXOO EHHQ YHUL HG 7KH H SHULPHQWDO DLUERUQH GBAS subsystem was able to calculate a valid GBAS solution including GPS GLONASS and Galileo satellites continuously It has been shown that multi constellation GBAS is possible from a purely technical perspective On the other hand neither operational nor approval aspects for satellite navigation systems other than GPS have been addressed yet Additionally further testing would be necessary to ensure the compatibility with legacy GPS only GBAS equipment However in theory all modifications for Galileo are backward compatible 1HYHUWKHOHVV LW KDV WR EH DVVXUHG WKDW FHUWL HG 6 PXOWL mode receivers only use the GPS part of the VDB data and are not disturbed by additional VDB messages or additional UDQJLQJ VRXUFHV IRU H DPSOH 7KH UHTXLUHG WHVWV DUH SODQQHG for the future 7KH RSHUDWLRQDO EHQHILW RI PXOWL FRQVWHOODWLRQ 6 V VWHPV FDQQRW EH IRUHVHHQ HW FHUWL FDWLRQ IRU WKLV ZLOO take several years and could only be addressed by the GBAS FRPPXQLW DIWHU WKH FRPSOHWLRQ RI WKH 67 FHUWL FDWLRQ Most probably the use of GNSS signals on multiple frequencies could provide a highly improved GBAS service and will allow PXFK PRUH RSHUDWLRQDO EHQH W 0DQ RI WKH VDWHOOLWH QDYLJDWLRQ systems have already introduced additional frequencies LQFOXGLQJ VLJQDOV LQ WKH SURWHFWHG DYLDWLRQ EDQG 7KH XVH 0 02 04 06 08 10 12 VPE VAL VPL VAL 12 10 08 06 04 02 0 2260 1044 482 223 103 48 22 10 5 2 FIGURE 9 Normalized vertical Stanford plot of flight trials GAST D using GPS GLONASS and Galileo Color scale indicates number of occurrences of multiple frequencies for satellite navigation in aviation can remove most ionospheric errors effectively and mitigate a PDMRU VRXUFH RI XQFHUWDLQW 7KXV PXOWL FRQVWHOODWLRQ 6 can just be seen as a preliminary step on the way towards multi IUHTXHQF 6 7KH FRQFHSWV DQG LQIUDVWUXFWXUH GHVFULEHG LQ this article will serve as a basis for more research in this area Acknowledgments Most of our work on multi constellation GBAS was done within the research project Bürgernahes Flugzeug which was established in 2009 and is partly funded by the German IHGHUDO VWDWH RI RZHU 6D RQ 7KLV LV JUDWHIXOO DFNQRZOHGJHG by the authors Additionally the authors would like to thank all colleagues involved for constructive discussions and their VXSSRUW 7KLV DUWLFOH LV EDVHG RQ WKH SDSHU 0XOLWSOH 6DWHOOLWH Navigation for the Ground Based Augmentation System SUHVHQWHG DW 70 7KH QVWLWXWH RI 1DYLJDWLRQ QWHUQDWLRQDO 7HFKQLFDO 0HHWLQJ KHOG LQ 6DQ LHJR DOLIRUQLD DQXDU MIRKO STANISAK is a research assistant at the Institute of Flight Guidance IFF at the Technische Universität TU Braunschweig in Germany He received his diploma in mechanical engineering Dipl Ing in 2009 from TU Braunschweig MARK BITTER holds a Dipl Ing in mechanical engineering from TU Braunschweig and has been employed as a research engineer at TU Braunschweig IFF since 2003 THOMAS FEUERLE received his Dipl Ing in mechanical engineering in 1997 from TU Braunschweig He joined the TU Braunschweig IFF in May 1997 Since 2005 he has been the leader of the Air Traffic Management Team at the IFF In April 2010 he completed his Ph D dissertation at TU Braunschweig MORE ONLINE Further Reading For references related to this article go to gpsworld com and click on Innovation in the navigation 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