Timing modes
Timing units can be set in different modes:
• free running
• hold over
• locked.
Free running
In the Free running mode, the timing unit generates a clock signal from its own
oscillator. No timing signal from other equipment is used for the network element
synchronization.
Hold over
The Hold over mode will prevent a frequency step in case of a reference failure.
Therefore it uses a frequency memory of the last available frequency.
Locked
In the Locked mode, the timing unit locks the oscillator-frequency to one of the
external timing sources.
Schematic view of the timing modes
The next figure gives a schematic view of the three different timing modes.
Line signal Clock
Tributary signal
Line signal
Station clock input
Station clock output
Timing provisioning
NE timing
....................................................................................................................................................................................................................................
365-312-807R7.2
Issue 4, May 2007
Alcatel-Lucent - Proprietary
See notice on first page
7-5
To Next Page
Loading...
