STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
For payload conditioning, the RX-ELST may optionally insert a programmable
idle code into all channels when the framer is out of frame synchronization. This
code is set to all 1's when the RX-ELST is reset.
9.12 Receive Jitter Attenuator (RJAT)
The Receive Jitter Attenuator (RJAT) digital PLL attenuates the jitter present on
the RXTIP/RXRING or RDAT inputs. The attenuation is only performed when the
RJATBYP register bit is a logic 0.
The jitter characteristics of the Receive Jitter Attenuator (RJAT) are the same as
the Transmit Jitter Attenuator (TJAT).
9.13 Signaling Extractor (SIGX)
The Signaling Extraction (SIGX) block provides channel associated signaling
(CAS) extraction from an E1 signaling multiframe or from SF and ESF T1
formats. With external logic the Signaling Extraction (SIGX) block extracts the
nine bit signaling format from SLC®96 T1 formats.
The SIGX block provides signaling bit extraction from the received data stream
for T1 ESF, SF, SLC®96 and E1 framing formats. It selectively debounces the
bits, and serializes the results onto the BRSIG output. Debouncing is performed
on individual signaling bits. This BRSIG output is channel aligned with BRPCM
output, and the signaling bits are repeated for the entire superframe, allowing
downstream logic to reinsert signaling into any frame, as determined by system
timing. The signaling data stream contains the A,B,C,D bits in the lower 4
channel bit locations (bits 5, 6, 7 and 8) in T1 ESF and E1 framing formats; in SF
and SLC®96 formats the A and B bits are repeated in locations C and D (i.e. the
signaling stream contains the bits ABAB for each channel).
The SIGX block contains three superframes worth of signal buffering to ensure
that there is a greater than 95% probability that the signaling bits are frozen in
the correct state for a 50% ones density out-of-frame condition, as specified in
TR-TSY-000170 and BELL PUB 43801. With signaling debounce enabled, the
per-channel signaling state must be in the same state for 2 superframes before
appearing on the serial output stream.
The SIGX block provides one superframe or signaling-multiframe of signal
freezing on the occurrence of slips. When a slip event occurs, the SIGX freezes
the output signaling for the entire superframe in which the slip occurred; the
signaling is unfrozen when the next slip-free superframe occurs.
The SIGX also provides control over timeslot signaling bit fixing, data inversion
and signaling debounce on a per-timeslot basis.
PROPRIETARY AND CONFIDENTIAL
51
PMC [ PMC-SIERRA, INC ]
