Data shown in this section can be downloaded here.
More testing results could be accessed here.
Periodically recalibrate TSC_rate is a remedy to rate error induced clock offset. Running results of an implementation that automatically recalibrate TSC_rate at 60 seconds inteval is shown below. We can see at each 60-second turn points. The offset is rectified to 0.
The advantage of periodically recalibrated clock is that it caps the offset error at rate_error * recalibrate_inteval. However, during each inteval, the clock is still free-running. 'zoom in' views of the result (fig. 1-b and fig. 2-b) clearly show this. Also, the recalibration introduces rate error spikes at turn points, which harms rate stability.
Although simple repeatitive recalibration does not improve rate accuracy. The information gathered through multiple measurements could be used for loop control, which will be introduced in the next section.
|Fig. 1-a Periodically recalibrated clock offset measurement during 12 hours.||Fig. 1-b Periodically recalibrated clock offset measurement during the first hour.|
|Fig. 2-a Periodically recalibrated clock rate error measurement during 12 hours.||Fig. 2-b Periodically recalibrated clock rate error measurement during the first hour.|