R1A (t) = p1A(t) + c(ẟ1(t) - ẟA(t))
R2A (t) = p2A(t) + c(ẟ2(t) - ẟA(t))
R3A (t) = p3A(t) + c(ẟ3(t) - ẟA(t))
R4A (t) = p4A(t) + c(ẟ4(t) - ẟA(t))
where RnA(t) is the observed range (Known as pseudorange) from receiver A to satellite 1 through 4 at epoch (time) t
pnA(t) is geometric range
c is the speed of light in a vacuum
ẟ1(t) is the satellite clock bias
ẟA(t) is the receiver clock bias