${\overrightarrow{x}}_{DGPS}$:	DGPS coordinates of the rover
$B$:	clock bias of the DGPS rover receiver
$LO{S}_{ecef}^i$:	line-of-sight unit vector of the i-th satellite in Earth-centered, Earth-fixed (ECEF) frame
${\overrightarrow{R}}^i$:	vector from the receiver to the i-th satellite
$H_{GPS}$:	observation matrix = $\left[\begin{array}{cc}LO{S}_{ecef}^1& -1\\ ⋮& ⋮\\ LO{S}_{ecef}^n& -1\end{array}\right]$