1. SBAS DFMC Nav&XPL Equations Inputs to IWG#26
05th Feb. 2014

2. Open issues to address until IWG#27
Reminder from IWG#21
Open issues to address until IWG#27
Conclusion / possible way forward for ICD definitionICD definition
17 January 2014
MSIL2 2

3. 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 iono terms)
Yet some issues have to be addressed (next slide)
17 January 2014
MSIL2 3

4. 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) ?
17 January 2014
MSIL2 4

5. 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)
17 January 2014
MSIL2 5