OPTICAL SYSTEMS DESIGN
DOC ID: 10118101
OSD2512 OPERATOR MANUAL
PAGE 175
CLOCK SELECTION MODE AND STATE
The Clock Selector is only in one instance - the one who selects between the nominated clock sources.
Mode
The definition of the 'best' clock source is firstly the one with the highest (QL) and secondly
(the ones with equal QL) the highest priority.
Clock Selector can be in different modes:
Manual:
Clock selector will select the clock source stated in Source (see below). If this
manually selected clock source is failing, the clock selector will go into holdover state.
Manual To Selected:
Same as Manual mode where the pt. selected clock source will become
Source.
Auto NonRevertive:
Clock Selection of the best clock source is only done when the selected
clock fails.
Auto Revertive:
Clock Selection of the best clock source is constantly done.
Force Hold Over:
Clock Selector is forced to Hold Over State.
Force Free Run:
Clock Selector is forced to Free Run State.
Source
Only relevant if Manual mode is selected (see above).
WTR Time
WTR is the Wait To Restore timer value in minutes. The WTR time is activated on the falling
edge of a clock source failure (in Revertive mode). This means that the clock source is first
available for clock selection after WTR Time (can be cleared).
SSM Hold Over
This is the transmitted SSM QL value when clock selector is in Hold Over State.
SSM Free Run
This is the transmitted SSM QL value when clock selector is in Free Run State.
EEC Option
The ZL30xxx based Synce modules support both EEC1 and EEC2 option. The difference is:
EEC1=> DPLL bandwidth=3,5 Hz, EEC2=> DPLL bandwidth = 0,1 Hz.
State
This is indicating the state of the clock selector. Possible states are:.
Free Run:
There is no external clock sources to lock to (unlocked state). The Clock Selector
has never been locked to a clock source long enough to calculate the hold over frequency
offset to local oscillator. The frequency of this node is the frequency of the local oscillator.
Hold Over:
There is no external clock sources to lock to (unlocked state). The Clock Selector
has calculate the holdover frequency offset to local oscillator. The frequency of this node is
hold to the frequency of the clock source previous locked to.
Locked:
Clock selector is locked to the clock source indicated (See next).
