My understanding about this subject is that Craig is right if you are using one of the modular GPS receiver solutions that just has the serial interface. On the otherhand I am to understand that if you work at the level of getting inside the receiver itself it is possible to recover a clock of very high accuracy. The number parameters of accuracy escape me. It is possible that you can find an OEM type receiver module that provides a GPS synchronized clocking signal in addition to the serial port.

Michael Karas