Reference Clock Phase Shifter with Direct Digital Synthesis Circuit

The basic distribution methods of time and frequency reference signals are satellite and fiber-optic links as well as the usage of packet networks. All these techniques, however, are exposed to failures and interruptions in the delivery of the reference signal. One of the solutions to solve this problem is implement of backup reference sources-the critical issue is switching the basic signal to the spare one, without losing reference phase. Jumps of phase are highly unwanted for almost every group of users of time and frequency reference signal-from scientists, through the energy industry, to operators of telecommunications networks. In the paper the preliminary measurement results of phase shifter module dedicated to compensate phase shift in the time and frequency transfer system was presented. The module use a typical integrated frequency synthesizer to move phase between input and output signals. System parameters were characterised by the phase noise and the phase shift stability.