reduce the phase error over time. Alternatively, restarting the tracking
manually (see "Restart Tracking" under "Configuring the Oscillator" on
page223), or automatically via a pre-set Phase Error Limit, will quickly
reduce the phase error.
10 MHz Frequency Error: An internal estimated calculation (in Hertz) of the
internal oscillator's frequency error, based on the phase accuracy error at
the beginning and end of a frequency measurement window (the length of
this window will vary depending upon the type of oscillator installed and
the oscillator adjustment algorithm).
Current DAC Setting: Current DAC value, as determined by the oscillator
disciplining system. The value is converted into a voltage that is used to dis-
cipline the oscillator. A stable value over time is desirable and suggests
steady oscillator performance (see also the graph in the History Panel).
DAC Step: Step size for adjustments to the internal oscillator, as determ-
ined by the oscillator disciplining system. Larger steps = quicker, but
coarser adjustments. The step size is mainly determined by the type of oscil-
lator.
TFOM: The Time Figure of Merit is VersaSync’s estimation of how accur-
ately the unit is synchronized with its time and 1PPS reference inputs, based
on several factors, known as the Estimated Time Error or ETE. The larger
the TFOM value, the less accurate VersaSync believes it is aligned with its
1PPS input that is used to perform disciplining. If this estimated error is too
large, it could adversely affect the performance of oscillator disciplining.
The available TFOM range is 1 through 15.
Max TFOM for Sync: Value, as set under "Configuring the Oscillator" on
page223
Temperature(s): Three temperatures are displayed:
Oscillator temperature, which has an effect on oscillator accuracy,
and therefore can be used to interpret oscillator performance.
Board temperature (measured on the main board, sometimes also
referred to as 'System temperature')
CPU temperature
Note: Oscillator temperature is plotted over time in the
History panel on the right, while graphs for board and
CPU temperature can be found under TOOLS > SYSTEM:
System Monitor.
4.6 Quality Management
CHAPTER 4 • VersaSync User Manual Rev. 12
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