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AD9548 - Holdover Drift

Question asked by Fred1 on May 7, 2012
Latest reply on May 11, 2012 by pkern



I have the following scenario:


1. AD9548 locked to GPS. Output frequency nice and stable.

2. Switching AD9548 in Holdover because GPS is disconnected.

3. Phase of output signal drifts away over time. E.g. 4µs in 24h.

4. GPS signal is reapplied and device switches back in active mode.

5. The result is now that the output stays now ~4µs offset to the 1PPS (GPS-Time).


My question is now what is the best way to get the output signal back so it is again phase aligned with the 1PPS signal?

Resynchronizing the output divider to the 1PPS reference input is not an option as the output signal generation would be interrupted for around two 1PPS cycles and that is not acceptable.