periods or an input reference with excessive jitter will cause the phase error to be
high. The oscillator disciplining control will gradually reduce the phase error over
time. Alternatively, restarting the tracking manually (see "Restart Tracking" under
"Configuring the Oscillator" on page230), 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 dis-
ciplining system. The value is converted into a voltage that is used to discipline the
oscillator. A stable value over time is desirable and suggests steady oscillator per-
formance (see also the graph in the History Panel).
DAC Step: Step size for adjustments to the internal oscillator, as determined by the
oscillator 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 SecureSync’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 SecureSync believes it is aligned with its 1PPS input that is used to per-
form disciplining. If this estimated error is too large, it could adversely affect the per-
formance of oscillator disciplining. The available TFOM range is 1 through 15.
Max TFOM for Sync: Value, as set under "Configuring the Oscillator" on page230
Temperature(s): Three temperatures are displayed:
Oscillator temperature, which has an effect on oscillator accuracy, and there-
fore 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 His-
tory panel on the right, while graphs for board and CPU tem-
perature can be found under TOOLS > SYSTEM: System
Monitor.
Last Time Reference Change: [Timestamp: Last occurrence]
234
CHAPTER 3 • SecureSync 2400 User Manual Rev. 2
3.5 Managing the Oscillator
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