COMPARISON OF GLONASS AND GPS TIME TRANSFERS

The Russian global space navigation system GLONASS could provide a tec hnique similar to GPS for international time comparison. The main limi tation to its use for time transfer is the lack of commercially availa ble time receivers. The University of Leeds built a GPS/GLONASS receiv er five years ago and since then has provided continuous information a bout GLONASS time and its comparison with GPS time. For the last two y ears the VNIIFTRI and several other Russian time laboratories have use d Russian-built GLONASS navigation receivers for time comparisons. Sin ce June 1991, the VNIIFTRI has operated a GPS time receiver which offe rs, for the first time, an opportunity for the direct comparison of ti me transfers using GPS and GLONASS. This seven-month experiment shows that even with relatively imprecise data recording and processing, in terms of time metrology, GLONASS can provide continental time transfer at a level of several tens of nanoseconds.