A320-FMGS- GPS page indicting ground speed.
On the GPS page showing ground speed, is this calculated by pure change of GPS position by elapsed time? If so during ADR mismatch can I pick this ground speed (which will not be affected and be correct) and then compare it to the PFD shown ground speed. If matching with either can I safely assume that the TAS and the IAS shown on that PFD is correct? Thanks for your inputs.