FAA WAAS LPV procedures can be used with a certified WAAS GPS system only.
You cannot upgrade your existing system system to WAAS capability. Current systems are certified under TSO C129, a completely different criteria.
TSO C145 and 146 certifies the unit as a standalone receiver.
The antenna’s are different from the TSO 129 box to what’s certified on a 145/146.
Installation is currently being done by STC and requires:
- dual WAAS approved GPS receivers,
- other equipment mods, such as the scaling and autopilot,
- annunciation, whether it’s external or on an EFIS system,
- and a flight test procedure are all required.
WAAS-capable avionics do not automatically mean that you can fly to an LPV minimum. To accomplish the LPV minimums, you need dual WAAS receivers, and the ac must be certified under TSO 145/146.
This may help
What is LPV.