Check this URL for a kit that converts a GPS receiver to a Totally Accurate Clock: http://www.tapr.org/tapr/html/tac2.html The design is by Tom Clark, W3IWI, and provides accuracy down to the nanoseconds. It probably won't work with a hand-held GPS. It's designed around GPS boards from Garmin, Motorola or Trimble. Follow the various links on this page for lots of interesting tidbits on getting accurate time from the GPS system. Dave Mullenix, N9LTD