The “Wanders” of Timing: Detecting Slow Phase Variations in Clock Signals

• Philippa Hazell (CERN)

Room: Zoom conference room When specifying high precision timing requirements for clocks signals employed in the detectors - understanding how to specify clock quality is key. The quality of a periodic timing signal can be assessed in terms of short-term (fast) phase variations and long-term (slow) phase variations. Short-term variations occur more frequently (> 10 Hz) and can be quantified in the time domain (jitter) or the frequency domain (phase noise). Long-term phase variations occur at a slower rate (< 10 Hz) and can be in the form of wander (a continuous, slow-moving change in phase which is linked to the gradual environmental changes such as temperature) and determinism (discrete jumps in phase which represent discrete events, e.g. machine resets or power cycles). Both categories are equal in importance, however this seminar just focusses on observing long-term variations. This involves measuring phase and monitoring its variation over time. This presentation presents different phase measurement methods, as well as several points of consideration. Case studies demonstrating examples where these measurement methods were employed are also presented and aid in highlighting the importance of investigating long-term phase variations.

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