DS2152
ALARM CRITERIA Table 4-2
ALARM
SET CRITERIA
CLEAR CRITERIA
Blue Alarm (AIS)
(see note 1 below)
when over a 3ms window, five
or less 0s are received
when over a 3 ms window, six or
more 0s are received
Yellow Alarm (RAI)
1. D4 bit 2 mode(RCR2.2=0)
when bit 2 of 256 consecutive
channels is set to 0 for at least
254 occurrences
when bit 2 of 256 consecutive
channels is set to 0 for less than
254 occurrences
2. D4 12th F-bit mode
(RCR2.2=1; this mode is
also referred to as the
when the 12th framing bit is set when the 12th framing bit is set to
to 1 for two consecutive
occurrences
0 for two consecutive occurrences
"Japanese Yellow Alarm"
when 14 or less patterns of 00FF
3. ESF mode
when 16 consecutive patterns of hex out of 16 possible appear in
00FF appear in the FDL
the FDL
Red Alarm (LRCL)
(this alarm is also referred to as received
Loss Of Signal)
when 192 consecutive 0s are
when 14 or more 1s out of 112
possible bit positions are received
starting with the first one received
NOTES:
1. The definition of Blue Alarm (or Alarm Indication Signal) is an unframed all 1s signal. Blue alarm
detectors should be able to operate properly in the presence of a 10-3 error rate and they should not
falsely trigger on a framed all 1s signal. The blue alarm criteria in the DS2152 have been set to
achieve this performance. It is recommended that the RBL bit be qualified with the RLOS bit.
2. ANSI specifications use a different nomenclature than the DS2152 does; the following terms are
equivalent:
RBL = AIS
LRCL = LOS
RLOS = LOF
RYEL = RAI
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DALLAS [ DALLAS SEMICONDUCTOR ]
