Recommendation 1 of the 88th CIPM (1999)

Future global navigation satellite systems

The Comité International des Poids et Mesures,

considering that

• the International Committee already recommended “that the reference times (modulo 1 second) of satellite navigation systems with global coverage be synchronized as closely as possible with UTC” and “that the reference frames for these systems be transformed to be in conformity with the ITRF”, Recommendation 1 (CI-1996),
• both the GPS and GLONASS systems follow these guidelines,
• these systems are now widely used for time and frequency comparisons,

recommends that

• all global navigation satellite systems be designed so that it is possible to use their signals for time and frequency comparisons,
• these systems broadcast, in addition to their own System Time (ST):
  1. the time difference between ST and a real-time realization of UTC and TAI;
  2. a prediction of the time differences between ST and UTC and TAI,
• manufacturers develop receivers and processing systems designed for time and frequency comparison purposes.

DOI : 10.59161/CIPM1999REC1E