PM7346 S/UNI-QJET
DATASHEET
PMC-960835
ISSUE 6
SATURN QUAD USER NETWORK INTERFACE FOR J2, E3, T3
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA INC., AND ITS CUSTOMERS’ INTERNAL USE
60
The E3-FRMR declares out of frame alignment if the framing pattern is in error
for four consecutive frames. The E3-FRMR is an "off-line" framer, where all
frame alignment indications, all overhead bit indications, and all overhead bit
processing continue based on the previous alignment. Once the framer has
determined the new frame alignment, the out-of-frame indication is removed and
a COFA indication is declared if the new alignment differs from the previous
alignment.
The E3-FRMR detects the presence of AIS in the incoming data stream when
less than 8 zeros in a frame are detected while the framer is OOF in G.832
mode, or when less than 5 zeros in a frame are detected while OOF in G.751
mode. This algorithm provides a probability of detecting AIS in the presence of a
10
-3
BER as 92.9% in G.832 and 98.0% in G.751.
Loss of signal is LOS is declared when no marks have been received for 32
consecutive bit periods. Loss of signal is de-asserted after 32 bit periods during
which there is no sequence of four consecutive zeros.
E3 Loss of Frame detection is provided as recommended by ITU-T G.783 with
programmable integration periods of 1ms, 2ms, or 3ms. While integrating up to
assert LOF, the counter will integrate up when the framer asserts an Out of
Frame condition and integrates down when the framer de-asserts the Out of
Frame condition. Once an LOF is asserted, the framer must not assert OOF for
the entire integration period before LOF is de-asserted.
The E3-FRMR can also be enabled to automatically assert the RAI/FERF
indication in the outgoing transmit stream upon detection of any combination of
LOS, OOF or AIS. The E3-FRMR can also be enabled to automatically insert
G.832 FEBE upon detection of receive BIP-8 errors.
9.3 J2 Framer
The J2-FRMR integrates circuitry to decode a unipolar or B8ZS encoded signal
and frame to the resulting 6312 kbps J2 bit stream. Having found frame, the J2-
FRMR extracts a variety of overhead and datalink information from the J2 bit
stream.
The J2 format consists of 789-bit frames, each 125μs long, consisting of 96
bytes of payload, 2 reserved bytes, and 5 F-bits. The frames are grouped into 4-
frame multiframes. The multiframe format is as follows: