Description

A free-running frequency standard drift with time and move away from its nominal value. To make a stable frequency standard it needs to trace a reference standard. A GNSS disciplined oscillator is one of the media for reference to a free-running frequency standard is used. The frequency standard may be disciplined directly to a reference standard or a GNSS system in the co-located. In this work, the free running frequency standards are reference standard (UTC (NPLI) timescale) and are co-located. Therefore, the free running frequency standard is locked to the timescale and makes the free standard a NPLI disciplined system. The frequency and time stability have been measured for the free running and locked rubidium frequency standard. The stability improved in the locked rubidium frequency standard.