The Satellite Navigation (SatNav) Toolbox allows the user to simulate both C/A and P-code measurements on multiple frequencies. Ionospheric delay emulation is a function of the chosen carrier frequency and the user can change the ionospheric content (i.e., total electron content). Dissimilar error sources such as noise and multipath also can be emulated appropriately. As a result, all current codes and frequencies can be emulated as well as those planned under the GPS modernization program.