Very interesting technology! I would think that the re-transmitter will need a crystal as well for carrier generation and GPS reception, and maybe that the data needs to be time-stamped so as to know when the data was captured? Several TCXO vendors do advertise 10,000g capability on their websites, and I am quite amazed by this knowing just how sensitive oscillators usually are.. bye, Said In a message dated 7/11/2009 08:26:22 Pacific Daylight Time, holrum@hotmail.com writes: A lot of the ballistic GPS systems are actually GPS transponders attached to the back of the shell. They just retransmit the received GPS signal spectrum to a remote receiver. Much cheaper and more robust than slinging a full GPS receiver. Google TIDGET for more info...