Symmetricom TimeProvider 500, Руководство пользователя

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098-00172-000 Revision A – December, 2009 TimeProvider 500 2.0 User’s Guide 67
Chapter 3 Operations
Frequency Locked Loop
Frequency Locked Loop
The TimeProvider 500 drives a state sequence that allows the operational status of
the Frequency Locked Loop (FLL) to be observed. These can be viewed via the
show status CLI command query. Table 3-2 lists the FLL states, transition
conditions, and SYNC LED impact. The possible sequential flow of frequency
locked-loop states is shown in
Figure 3-8 .
Table 3-2. Frequency Locked-Loop State
TimeProvider
500 State
Current FLL
State
Typical
Duration
SYNC LED Comment
FREERUN Warm-up ~2-3 minutes OFF initially and
then may blink.
Amber if flow is
established during
warm-up. Unit is getting ready
for operation.
No SYNC
Flow None OFF and may
blink Amber prior
to exit state. No Sync packets
have been received
from master. Will
remain in this state if
there is no flow from
master clock
.
Acquiring ~20 minutes Blinking Green TimeProvider 500 is
receiving sync
packets from
grandmaster and
performing coarse
frequency
adjustment.
NORMAL Fast FLL ~90 minutes Blinking Green Performance margins
are being improved,
but steady-state not
yet attained.
Normal FLL Continual Green Performance margins
are stable
Bridging 420 seconds, but
depends on
bridge-time
setting.
Green Abnormality such as
significant load
change or loss of
sync flow has been
observed.
HOLDOVER Holdover Varies depending
on how long it
takes to correct
the reason for
holdover. Red TimeProvider 500 is
no longer using sync
flow from
grandmaster to
control the outputs.