ACS8515REV2.1T SEMTECH [Semtech Corporation], ACS8515REV2.1T Datasheet - Page 31

• Manufacturer Part Number: ACS8515REV2.1T
• Description: Line Card Protection Switch for SONET or SDH Network Elements
• Manufacturer: SEMTECH [Semtech Corporation]

the alarm is cleared depends upon the decay
rate and the alarm-clearing threshold. On the
alarm-setting side, if several events occur close
together, each event adds to the amplitude
and the alarm will be triggered quickly; if events
occur a little more spread out, but still
sufficiently close together to overcome the
decay, the alarm will be triggered eventually. If
events occur at a rate which is not sufficient to
overcome the decay, the alarm will not be
triggered. On the alarm-clearing side, if no defect
events occur for a sufficient time, the amplitude
will decay gradually and the alarm will be cleared
when the amplitude falls below the alarm-
clearing threshold. The ability to decay the
amplitude over time allows the importance of
defect events to be reduced as time passes
by. This means that, in the case of isolated
events, the alarm will not be set, whereas, once
the alarm becomes set, it will be held on until
normal operation has persisted for a suitable
time (but if the operation is still erratic, the
alarm will remain set). See Figure 9.
Revision 2.01/December 2005 Semtech Corp.
ADVANCED COMMUNICATIONS
The time taken to raise an inactivity alarm on a reference source that has previously been fully active (leaky
bucket empty) will be:
where N is the number of the relevent leaky bucket configuration. If an input is intermittently inactive then
this time can be longer. The default setting of cnfg_activ_upper_threshold is 6, therefore the default time is
0.75 s.
The time taken to cancel the activity alarm on a previously completely inactive reference source is calculated
as:
where N is the number of the relevent leaky bucket configuration in each case. The default settings are shown
in the following:
Leaky bucket timing
Leaky bucket timing
Leaky bucket timing
Leaky bucket timing
Leaky bucket timing
2
(cnfg_decay_rate N)
(cnfg_activ_upper_threshold N)
8
2
1
x ((cnfg_bucket_size N) - (cnfg_activ_lower_threshold N))
x (8-4)
8
8
31
The
programmable for size, alarm set & reset
thresholds and decay rate.
monitored over a 128 ms period. If, within a
128 ms period, an irregularity occurs that is
not deemed to be due to allowable jitter/wander,
then the accumulator is incremented. The
accumulator will continue to increment up to
the point that it reaches the programmed
bucket size. The ‘fill rate’ of the leaky bucket
is, therefore, 8 units/second. The "leak rate"
of the leaky bucket is programmable to be in
multiples of the fill rate (x1, x0.5, x0.25 and
x0.125) to give a programmable leak rate from
8 units/sec down to 1 unit/sec.
between trying to ‘leak’ at the same time as a
‘fill’ is avoided by preventing a ‘leak’ when a
‘fill’ event occurs.
Disqualification of a non-selected reference
source is based on inactivity, or on an out of
band result from the frequency monitors. The
currently selected reference source can be
= 1.0 s
ACS8515 Rev2.1 LC/P
secs
‘leaky
bucket’
accumulators
Each source is
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A conflict
FINAL
secs
are