PM8313 datasheet(51/192 Pages) PMC

51 / 192 page

PM8313 D3MX

DATA SHEET

PMC-920702

ISSUE 5

M13 MULTIPLEXER

recommended in TR-TSY-000009 Section 4.1.2) or when one or more M-bit

errors are detected in 3 out of 4 consecutive M-frames. The M-bit error criteria

for OOF can be disabled via the MBDIS bit in the DS2 Framer configuration

alignment signals are incorrectly received (in accordance with CCITT Rec. G.747

Section 4). Note that the DS2 framer is an off-line framer, indicating both OFF

and COFA. Error events continue to be indicated even when the FRMR is

indicating OOF, based on the previous frame alignment.

The RED alarm and alarm indication signal are detected by the DS2 FRMR in

9.9 ms for DS2 format and in 6.9 ms for G.747 format. The framer employs a

simple integration algorithm (with a 1:1 slope) that is based on the occurrence of

"valid" DS2 M-frame or G.747 frame intervals. For the RED alarm, a DS2 M-

frame (or G.747 frame, depending upon the framing format selected) is said to

be a "valid" interval if it contains a RED defect, defined as the occurrence of an

OOF event during that M-frame (or G.747 frame). For AIS, a DS2 M-frame (or

G.747 frame) is said to be a "valid" interval if it contains AIS, defined as the

occurrence of less than 9 zeros while the framer is out of frame during that M-

frame (or G.747 frame). The discrepancy threshold ensures the detection

algorithm operates in the presence of bit error rates of up to 10-3. Each "valid"

DS2 M-frame (or G.747 frame) causes an integration counter to increment; "non-

valid" DS2 M-frame (or G.747 frame) intervals cause a decrement. RED or AIS

is declared if the associated integrator count saturates at 53, resulting in a

detection time of 9.9 ms for DS2 and 6.9 ms for G.747. RED or AIS declaration

is deasserted when the associated count decrements to 0.

The DS2 X-bit or G.747 remote alarm indication (RAI) bit is extracted by the DS2

FRMR to provide an indication of far end receive failure. The FERF status is set

to the current X/RAI state only if the two successive X/RAI bits were in the same

state. The extracted FERF status is buffered for 6 DS2 M-frames or 6 G.747

frames before being reported within the DS2 FRMR Status register. This buffer

ensures a virtually 100% probability of freezing the FERF status in a valid state

during an out of frame occurrence in DS2 mode, and ensures a better than

99.9% probability of freezing the valid status during an OOF occurrence in G.747

mode. When an OOF occurs, the FERF value is held at the state contained in the

last buffer location corresponding to the previous sixth M-frame or G.747 frame.

This location is not updated until the OOF condition is deasserted. Meanwhile,

the last four of the remaining five buffer locations are loaded with the frozen

FERF state while the first buffer location corresponding to the current M-frame/

G.747 frame is continually updated every M-frame/G.747 frame based on the

above FERF definition. Once correct frame alignment has been found and OOF

is deasserted, the first buffer location will contain a valid FERF status and the

PM8313 Datasheet(PDF) 51 Page - PMC-Sierra, Inc

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