DS26502_06 Datasheet, PDF (45/125 Pages) Dallas Semiconductor – T1/E1/J1/64KCC BITS Element

DS26502 T1/E1/J1/64KCC BITS Element
Table 8-1. T1 Alarm Criteria
ALARM
SET CRITERIA
Blue Alarm (AIS) (Note 1)
Yellow Alarm (RAI)
Over a 3ms window, five or
fewer zeros are received
CLEAR CRITERIA
Over a 3ms window, six or more zeros
are received
D4 Bit-2 Mode (T1RCR2.0 = 0) Bit 2 of 256 consecutive
channels is set to zero for at
least 254 occurrences
Bit 2 of 256 consecutive channels is
set to zero for less than 254
occurrences
D4 12th F-bit Mode (T1RCR2.0 12th framing bit is set to one
= 1; this mode is also referred to for two consecutive
as the “Japanese Yellow Alarm”) occurrences
12th framing bit is set to zero for two
consecutive occurrences
ESF Mode
Red Alarm (RLOS) (Also
referred to as Loss Of Signal)
16 consecutive patterns of
00FF appear in the FDL
192 consecutive zeros are
received
14 or fewer patterns of 00FF hex out of
16 possible appear in the FDL
14 or more ones out of 112 possible bit
positions are received, starting with the
first one received
Note: The definition of Blue Alarm (or Alarm Indication Signal) 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-ones signal. The Blue Alarm
criteria in the DS26502 has been set to achieve this performance.
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