STANDARD PRODUCT
PM5365 TEMAP
DATASHEET
PMC-1991148
ISSUE 3
HIGH DENSITY VT/TU MAPPER
AND M13 MULTIPLEXER
000233 Section 5.3.14.1 recommends compatibility with non-compliant existing
equipment, the two other loopback command possibilities are also supported. As
per TR-TSY-000009 Section 3.7, the loopback request must be present for five
successive M-frames before declaration of detection. Removal of the loopback
request is declared when it has been absent for five successive M-frames.
DS2 payload loopback can be activated or deactivated under software control.
During payload loopback the DS2 stream being looped back still continues
unaffected in the demultiplex direction to the DS2 Framer. All seven
demultiplexed DS2 streams can also be replaced with AIS on an individual basis
under register control or they can be configured to be replaced automatically on
detection of out of frame, loss of signal, RED alarm or alarm indication signal.
9.13 DS2 Framer (DS2-FRMR)
The FRMR DS2 Framer integrates circuitry required for framing to a DS2 bit
stream and is directly compatible with the M12 DS2 application. The FRMR can
also be configured to frame to a G.747 bit stream.
The DS2 FRMR frames to a DS2 signal with a maximum average reframe time
of less than 7 ms and frames to a G.747 signal with a maximum average reframe
time of 1 ms. In DS2 mode, both the F-bits and M-bits must be correct for a
significant period of time before frame alignment is declared. In G.747 mode,
frame alignment is declared if the candidate frame alignment signal has been
correct for 3 consecutive frames (in accordance with CCITT Rec. G.747 Section
4). Once in frame, the DS2 FRMR provides indications of the M-frame and M-
subframe boundaries, and identifies the overhead bit positions in the incoming
DS2 signal or provides indications of the frame boundaries and overhead bit
positions in the incoming G.747 signal.
Depending on configuration, declaration of DS2 out-of-frame occurs when 2 out
of 4 or 2 out of 5 consecutive F-bits are in error (These two ratios are
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
register. In G.747 mode, out-of-frame is declared when four consecutive frame
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-
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PMC [ PMC-SIERRA, INC ]
