STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
9.17 E1 Transmitter (E1-TRAN)
The E1 Transmitter (E1-TRAN) generates a 2048 kbit/s data stream according to
ITU-T recommendations, providing individual enables for frame generation, CRC
multiframe generation, and channel associated signaling (CAS) multiframe
generation.
In concert with Transmit Per-Channel Serial Controller (TPSC), the E1-TRAN
block provides per-timeslot control of idle code substitution, data inversion, digital
milliwatt substitution, selection of the signaling source and CAS data. All
timeslots can be forced into a trunk conditioning state (idle code substitution and
signaling substitution) by use of the master trunk conditioning bit in the
Configuration Register.
Common Channel Signaling (CCS) is supported in time slot 16 either through the
internal HDLC Transmitter (TDPR) and the Transmit Channel Insertion (TXCI)
block. Support is provided for the transmission of AIS and the transmission of
remote alarm (RAI) and remote multiframe alarm signals.
The National Use bits (Sa-bits) can be sourced from the E1-TRAN National Bits
Codeword registers as 4-bit codewords aligned to the submultiframe.
Alternatively, the Sa-bits may individually carry data links sourced from the
internal HDLC controllers, or may be passed transparently from the BTPCM
input.
PCM output signals may be selected to conform to HDB3 or AMI line coding.
9.18 Transmit Elastic Store (TX-ELST)
The Transmit Elastic Store (TX-ELST) provides the ability to decouple the line
timing from the backplane timing. The TX-ELST is required whenever the
BTCLK and TCLKO clocks are not traceable to a common source. The elastic
store function is in effect (with a nominal one frame delay) when:
1. BTCLK is an input (CMODE = 1) and the transmitter is loop timed to the
receive recovered clock (PLLREF[1:0] = ‘b10, OCLKSEL1 = 0, OCLKSEL0 =
0).
2. BTCLK is an input (CMODE = 1) and the transmitter is clocked by TCLKI
(OCLKSEL1 = 0, OCLKSEL0 = 1) or a jitter attenuated version of TCLKI
(PLLREF[1:0] = ‘b11, OCLKSEL1 = 0, OCLKSEL0 = 0).
3. BTCLK is an output (CMODE = 0) referenced to the receive recovered clock
(PLLREF[1:0] = ‘b10) and the transmitter is clocked by TCLKI (OCLKSEL1 =
0, OCLKSEL0 = 1).
PROPRIETARY AND CONFIDENTIAL
53
PMC [ PMC-SIERRA, INC ]
