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 determined by the oscil-
lator disciplining system. Larger steps = quicker, but coarser adjustments. The step size is
mainly determined by the type of oscillator.
TFOM: The Time Figure of Merit is VersaSync’s estimation of how accurately 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 Ver-
saSync 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 page172
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.
Last Time Reference Change: [Timestamp: Last occurrence]
Last 1PPS Reference Change: [Timestamp: Last occurrence]
Last TFOM Change: [Timestamp: Last occurrence]
Last Sync State Change: [Timestamp: Last occurrence]
Last Holdover State Change: [Timestamp: Last occurrence]
The Oscillator History Panel
The Oscillator History Panel offers real-time graphical monitoring of VersaSync’s internal timing.
The following graphs plot key oscillator-relevant data over time::
Phase Error Magnitude: See 1PPS Phase Error
Frequency Error: See 10_MHz_Frequency_Error
Scaled DAC Value: See DAC Step
Oscillator Temperature, which has an effect on oscillator accuracy, and therefore can be
used to interpret oscillator performance.
3.4 Managing the Oscillator
CHAPTER 3 • VersaSync User Manual Rev. 6.0
177
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