
pre-locked
wait for up to 100s
(state 110)
locked
keep ref
(state 100)
holdover
select ref
(state 010)
(2) all refs evaluated
&
at least one ref valid
(5) selected ref
phase locked
(3) no valid standby ref
&
(main ref invalid
or out of lock >100s)
(14) all refs evaluated
&
at least one ref valid
pre-locked2
wait for up to 100s
(state 101)
(10) selected source phase
locked
(6) no valid standby ref
&
main ref invalid
free-run
select ref
(state 001)
(1)Reset
Reference sources are flagged as ’valid’ when
active, ’in-band’ and have no phase alarm set.
All sources are continuously checked for
activity and frequency.
Only the main source is checked for phase.
A phase lock alarm is only raised on a
reference when that reference has lost phase
whilst being used as the main reference. The
micro-processor can reset the phase lock
alarm.
A source is considered to have phase locked
when it has been continuously in phase lock
for between 1 and 2 seconds
Lost phase
wait for up to 100s
(state 111)
(7) phase lost
on main ref
(8) phase
regained within
100s
(12) valid standby ref
&
(main ref invalid
or out of lock >100s)
(13) no valid standby ref
&
(main ref invalid
or out of lock >100s)
(11) no valid standby ref
&
(main ref invalid
or out of lock >100s)
(9) valid standby ref
&
[ main ref invalid or
(higher-priority ref valid
& in revertive mode) ]
(15) valid standby ref
&
[ main ref invalid or
(higher-priority ref valid
& in revertive mode) or
out of lock >100s]
(4) valid standby ref
&
[ main ref invalid or
(higher-priority ref valid
& in revertive mode) or
out of lock >100s]
5(