Maxim DS33R11 T1 Alarm Criteria, 10.4.3 T1 Receive-Side Digital-Milliwatt Code Generation

DS33R11 Ethernet Mapper with Integrated T1/E1/J1 Transceiver

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)	When over a 3ms window, five or	When over a 3ms window, six or
(Note 1)	fewer 0s are received	more 0s are received
Yellow Alarm (RAI)	When bit 2 of 256 consecutive	When bit 2 of 256 consecutive
D4 Bit 2 Mode	channels is set to 0 for at least 254	channels is set to 0 for fewer than
(TR.T1RCR2.0 = 0)	occurrences	254 occurrences
D4 12th F-Bit Mode	When the 12th framing bit is set to 1	When the 12th framing bit is set to
(TR.T1RCR2.0 = 1; this mode is	for two consecutive occurrences	0 for two consecutive occurrences
also referred to as the “Japanese
Yellow Alarm”)
ESF Mode	When 16 consecutive patterns of	When 14 or fewer patterns of 00FF
	00FF appear in the FDL	hex out of 16 possible appear in
		the FDL
Red Alarm (LRCL)	When 192 consecutive 0s are	When 14 or more 1s out of 112
(Also referred to as loss of signal)	received	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

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