Progress in Carrier Phase Time Transfer

The progress of the joint Pilot Project for time transfer, formed by the International GPS Service (IGS) and the Bureau International des Poids et Mesures (BIPM), was recently reviewed. Three notable milestones were set. 1) The IGS will implement, at least in a test mode, an internally realized time scale based on an integration of combined frequency standards within the IGS network. This will eventually become the reference time scale for all IGS clock products (instead of the current GPS broadcast time). 2) A new procedure for combined receiver and satellite clock products will be implemented officially in November 2000. Receiver clocks are an entirely new product of the IGS. 3) The BIPM will coordinate an effort to calibrate all Ashtech Z12-T (and possibly other) receivers suitable for time transfer applications, either differentially or absolutely. Progress reports will be presented publicly in the spring 2001.