1. Professor and ARC Federation Fellow, GNSS Research Centre, Curtin Univ. of Technology, Kent St., Perth 6152, Australia; and Delft Institute of Earth Observation and Space Systems (DEOS), Delft Univ. of Technology, 2600 GB Delft, Netherlands (corresponding author).
2. Research Fellow, GNSS Research Centre, Curtin Univ. of Technology, Kent St., Perth 6152, Australia.