SBAS DFMC Nav&XPL Equations Inputs to IWG#26

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SBAS DFMC Nav&XPL EquationsInputs to IWG#26

05th Feb. 2014


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Reminder from IWG#21

Open issues to address until IWG#27

Conclusion / possible way forward for ICD definitionICD definition

17 January 2014 MSIL2


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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 iono terms)

• Yet some issues have to be addressed (next slide)


DFMC Nav&XPL equations


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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) ?




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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)



SBAS DFMC Nav&XPL Equations Inputs to IWG#26

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