These are Block IIF birds, designed as a holding position until the newer birds are available as the GPS
constellation was getting close to having no redundancy
They have a few new characteristics ( wiki summary)
Broadcasting L5 "safety of life" navigation
signal demonstrated on USA-203
Broadcasting a new M-code signal
Doubling in the predicted accuracy
Better resistance to jamming
Reprogrammable processors that can receive software
The first GPS satellites not to have Selective Availability hardware
installed which degraded civilian accuracy when turned on in the original satellite
of life , is for aircraft etc, GPS enabled landings...hmmmmmm
I believe all these block IIF are carrying the new civilian L2C channel for enhanced position accuracy, when the constellation is updated, this will provide the same or better then m,military to dual receiver based GPS receivers
. mm accuracy.
Interesting re SA hardware
, this wasn't expected until GPS III, of course wiki could be wrong.!!