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SBAS DFMC Nav&XPL Equations Inputs to IWG#26. 05 th Feb. 2014. Reminder from IWG#21 Open issues to address until IWG#27 Conclusion / possible way forward for ICD definition ICD definition. DFMC Nav&XPL equations. Reminder
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SBAS DFMC Nav&XPL EquationsInputs to IWG#26 05th Feb. 2014
Reminder from IWG#21 • Open issues to address until IWG#27 • Conclusion / possible way forward for ICD definitionICD definition MSIL2
DFMC Nav&XPL equations • Reminder • IWG#21 did not recommend to broadcast biases (effect of floor on VPL, penalizing for low VAL targets) • Morevoer DFMC ICD bandwidth nearly full for up to 91SV capability (i.e. not much place for additional parameters) • Pro-SBAS starting assumption for XPL • SBAS L1 legacy like Nav+XPL equations are assumed to be re-conducted for DFMC (replacing broadcast iono corrections/GIVE by DF ionoterms) • Yet some issues have to be addressed (next slide) MSIL2
DFMC Nav&XPL equations • Open issues to address until IWG#27 • Kh/Kv factor values : SBAS L1 legacy values re-conducted for DFMC or re-tuning of Kh/Kv values to recover perfo. margins? • Inter-system bias • Accurate estimation possible by system, yet necessitates to use Message Type H for navigation • Could be compensated by receiver (5th unknown) yet user estimation uncertainty possibly higher than by system VPL penalty ? • Receiver inter signal bias • what bias size (likely dependent on the relative characteristics of the GNSS to augment : GPS/GAL receiver bias will differ GPS/GLO one) ? • Possible safety issue if bias not very small • How to handle this bias : by Rx spec or by Rx estimation? • what receiver complexity (incl. possible calibration) ? MSIL2
DFMC Nav&XPL equations • Previous issues could be addressed until IWG#27 (work plan is being built by EPO/Pro-SBAS) in order to define DFMC baseline and system/receiver apportionment concerning Nav&XPL equations • Yet no major impact is expected for system performances (Kh/Kv tuning issue seems fine optimization, bias issue seems manageable thanks to SV redundancies in DFMC) MSIL2