ok..I'm just learning with the geeks...so ...if ..one GPS 'antenna' that outputs Seatalk, another that produces only the RF signal and a third that provides NMEA LAT/LON....this means..that you can approach coast line...only using ground stations...so...you go dark...15 minutes...than you receive a signal, retrieve to the mother network, 7 to 7 seconds (something like this...) and finally use stupid mobile phone ground antenna...hum...I'm just trying to think by my own..