Fig. 8From: Investigating GNSS PPP–RTK with external ionospheric constraintsThe convergence time of a PPP-AR, and the ionospheric delay corrections with an error of 3 TECU while b the variance is very small (< 1 TECU), c the variance is the optimum (= 3 TECU), and d the variance is large (> 5TECU)Back to article page