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DS33R11 Ethernet Mapper with Integrated T1/E1/J1 Transceiver
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10.4.3 T1 Receive-Side Digital-Milliwatt Code Generation
Receive-side digital-milliwatt code generation involves using the receive digital-milliwatt registers
(TR.T1RDMR1/2/3) to determine which of the 24 T1 channels of the T1 line going to the backplane should be
overwritten with a digital-milliwatt pattern. The digital-milliwatt code is an 8-byte repeating pattern that represents a
1kHz sine wave (1E/0B/0B/1E/9E/8B/8B/9E). Each bit in the TR.T1RDMRx registers represents a particular
channel. If a bit is set to a 1, then the receive data in that channel is replaced with the digital-milliwatt code. If a bit
is set to 0, no replacement occurs.
Table 10-2. T1 Alarm Criteria
ALARM SET CRITERIA CLEAR CRITERIA
Blue Alarm (AIS)
(Note 1)
When over a 3ms window, five or
fewer 0s are received
When over a 3ms window, six or
more 0s are received
Yellow Alarm (RAI)
D4 Bit 2 Mode
(TR.T1RCR2.0 = 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 fewer than
254 occurrences
D4 12th F-Bit Mode
(TR.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
When 14 or fewer patterns of 00FF
hex out of 16 possible appear in
the FDL
Red Alarm (LRCL)
(Also referred to as loss of signal)
When 192 consecutive 0s are
received
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 device 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 this document. The following terms are equivalent:
RBL = AIS
RCL = LOS
RLOS = LOF
RYEL = RAI