Operating In Revertive, Non-Revertive, Or Manual Mode; Setting Up Input Reference Controls - Symmetricom TSG-3800 Series User Manual

Best Mode
In the Best mode, the TSG-3800 uses Input priority, SQL, input stability, and
position to automatically determine the best input signal as the reference signal.
Input stability refers to measuring input signal noise and choosing the best input
signal based on this noise measurement (the best signal has the least noise). To
prevent excessive reference input switching, which is caused by changes in input
signal noise levels, the software uses 20 percent hysteresis, or lagging. This means
an input signal must have the least noise for a certain amount of time before it is
used as the reference signal. All signal characteristics are weighted and the input
with the highest weighted average is selected as the input reference.

Operating in Revertive, Non-Revertive, or Manual Mode

When the Auto Return mode is set to the default mode of ON, the reference
automatically reverts to the highest selectable input available for the assigned
provision or mode of operation at all times. Therefore, when a failed input of higher
priority than the current selection is restored to a valid state, it is immediately
reselected as the reference input. For example, if the preferred signal fails, the
system switches to the second in priority. When the preferred signal becomes good
again, the selected input switches back to the preferred signal immediately.
With Auto Return set to OFF, the current reference selection remains selected until
it fails by some fault condition. In Best or SSM mode, this option has no effect and
the highest quality input is always selected. For example, if the preferred signal
fails, the system switches to the second in priority. When the preferred signal
becomes good again, the selected input does not switch back until another input is
of better quality than the current input.
When the Auto Switch option (default ON) is set to OFF, then selection is done
manually only, and a fault on the selected input will cause a switch of Clock
operating mode to Holdover. When using manual selection of the reference, Auto
Return mode should be OFF to force the unit to remain on the selected input.

Setting Up Input Reference Controls

You can control the input reference signals using the following:
Selection of the input reference in use
Enabling or inhibiting automatic switching of references
Enabling or inhibiting automatic return to a higher-priority input
Selecting Input Reference Selection Mode
Assigning fault modes for violation of operating limits
Setting the number of faulted time intervals necessary to cause an alarm
12778474-002-2 Revision F – March 2004
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Operating the TSG-3800
Setting Up Input Reference Controls
TSG-3800 User's Guide 87