150 million is bs, by the way. Have another read on ground station coverage...other than the ADS-B sites and coms sites. Have another read of the trial under way, covering east coast...if you are being advised that Baro is the way...just turn quietly and walk away from these people. Baro was only instigated so CASA could tick an ICAO box to provide for vertical guidance about eight years ago. Baro is not the answer!