DS2155 Datasheet, PDF (56/240 Pages) Maxim Integrated Products – T1/E1/J1 Single-Chip Transceiver

DS2155
Table 9-A. T1 Alarm Criteria
ALARM
Blue Alarm (AIS)
(Note 1)
Yellow Alarm (RAI)
D4 Bit 2 Mode
(T1RCR2.0 = 0)
SET CRITERIA
When over a 3ms window, five or
fewer 0s are received
When bit 2 of 256 consecutive
channels is set to 0 for at least 254
occurrences
CLEAR CRITERIA
When over a 3ms window, six or
more 0s are received
When bit 2 of 256 consecutive
channels is set to 0 for fewer than
254 occurrences
D4 12th F-Bit Mode
(T1RCR2.0 = 1; this mode is also
referred to as the “Japanese Yellow
Alarm”)
When the 12th framing bit is set to 1
for two consecutive occurrences
When the 12th framing bit is set to
0 for two consecutive occurrences
ESF Mode
When 16 consecutive patterns of
00FF appear in the FDL
Red Alarm (LRCL)
When 192 consecutive 0s are
(Also referred to as loss of signal) received
When 14 or fewer patterns of 00FF
hex out of 16 possible appear in the
FDL
When 14 or more 1s out of 112
possible bit positions are received
Note 1: The definition of Blue Alarm (or AIS) is an unframed all-ones signal. Blue Alarm detectors should be able to operate properly in the
presence of a 10E-3 error rate and they should not falsely trigger on a framed all-1s signal. Blue Alarm criteria in the DS2155 has been
set to achieve this performance. It is recommended that the RBL bit be qualified with the RLOS bit.
Note 2: ANSI specifications use a different nomenclature than the DS2155 does. The following terms are equivalent:
RBL = AIS
RCL = LOS
RLOS = LOF
RYEL = RAI
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