Using an OEM GPS receiver with a PPS output should be as good as and in some cases better than other sources discussed. For example, in the US one can purchase the Lassen iQ for $50, which has a PPS output rated to +/-50 nS of UTC according to the atomic clocks on the satellites, which are referenced to the atomic clocks at the GPS nav stations. I don't know what their accuracy is - but since it's a PPS that is within 50nS of the atomic clocks you can easily rely on it for this type of application. The fact that some GPS receivers report time incorrectly is not related to the PPS output, and more likely to the way a specific receiver converts GPS reported time to local time. Since the position fix is based on the atomic time, the PPS output has to be accurate - else there is no position fix. -Adam On 1/11/06, Jinx wrote: > > But aren't we losing sight of what Jinx wants to do? > > The conversation has wandered a little but I'm still in the > market for a solution. Presently I'm waiting for answers > to queries to govt agencies. I will post what I find out and > decide to do as I'm sure it will be useful to others > > I've an on-going project that may involve GPS. If so, that > would be a convenient solution at that time. If not, I'm not > sure I'd want to buy anything that will get used just once. > Although I could tlook around for one to borrow. But I've > been doing a little surfing -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist