Connection to the Network
33
Output clock Enables the user to choose between different clock reference
outputs.These outputs could be used to synchronize an
external equipment, including a second xGenius, with the
test unit. The available outputs depend on your hardware
configuration and the current operation mode.
Internal reference
status
Displays information about the internal clock reference when
it is free running, locked to an external reference or in holdo-
ver.
• Free run: The clock reference input is internal and the
oscillator is free running without any external disci-
pline.The oscillator will exhibit a frequency offset that will
depend on the oscillator type, aging, last calibration date
and temperature. A free running oscillator may still be suit-
able to run some frequency tests but it will generally
unsuitable to perform measurement related with time /
phase.
• Do not use: The oscillator has been configured to be disci-
plined to an external clock reference but the locking pro-
cess is still starting. When the reference reports the “Do
not use” status large variations in phase or frequency may
happen and therefore the equipment is not yet ready for
any test requiring accurate synchronization.
• Not sync: The internal oscillator is in the process of acquir-
ing the frequency and phase from the external clock refer-
ence. Large variations in the internal oscillator phase and
frequency may happen during this period and the equip-
ment is not ready for any test for this reason.
• Locking: The internal oscillator is in the last phase of the
locking process. No sudden phase changes are expected
in this state. In this status, the unit becomes ready for all
tests not requiring the maximum accuracy degree.
•Holdover: The unit has been previously locked to an exter-
nal time or phase reference but now the reference input is
not being used. The unit keeps an accurate reference fre-
quency and phase for a limited period of time. When the
unit is operating in holdover mode it is still ready for testing
even if no external clock reference is available.
• Error reference: For some reason, the local oscillator is not
able to finish with the locking sequence. This message
should never be displayed under normal operation.
Table 2.8: Reference Clock Panel
Result Description
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