STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
Dual (transmit and receive) elastic stores for slip buffering and rate adaptation to
backplane timing are provided, as is a signaling extractor that supports signaling
debounce, signaling freezing, idle code substitution, digital milliwatt tone
substitution, data inversion, and signaling bit fixing on a per-channel basis.
Receive side data and signaling trunk conditioning is also provided.
In T1 mode, the COMET generates framing for SF, ESF and T1DM (DDS)
formats. In E1 mode, the COMET generates framing for a basic G.704 E1
signal. The signaling multiframe alignment structure and the CRC multiframe
structure may be optionally inserted. Framing can be optionally disabled.
Internal analog circuitry allows direct transmission of long haul and short haul T1
and E1 compatible signals using a minimum of external components. Typically,
only line protection, a transformer and an optional line termination resistor are
required. Digitally programmable pulse shaping allows transmission of DSX-1
compatible signals up to 655 feet from the cross-connect, E1 short haul pulses
into 120 ohm twisted pair or 75 ohm coaxial cable, E1 long haul pulses into
120 ohm twisted pair as well as long haul DS-1 pulses into 100 ohm twisted pair
with integrated support for LBO filtering as required by the FCC rules. In
addition, the programmable pulse shape extending over 5-bit periods allows
customization of short haul and long haul line interface circuits to application
requirements. Digital line inputs and outputs are provided for applications not
requiring a physical T1 or E1 interface.
In the transmit path, the COMET supports signaling insertion, idle code
substitution, digital milliwatt tone substitution, data inversion, and zero code
suppression on a per-channel basis. Zero code suppression may be configured
to Bell (bit 7), GTE, or DDS standards, and can also be disabled. Transmit side
data and signaling trunk conditioning is also provided. Signaling bit transparency
from the backplane may be enabled.
The COMET provides three transmit HDLC controllers. These controllers may
be used for the transmission of messages on the ESF data link (T1) or national
use bits (E1) and in any time slot. In T1 mode, the COMET can be configured to
generate in-band loop back codes and ESF bit oriented codes. In E1 mode,
transmission of the 4-bit Sa codewords defined in ITU-T G.704 and ETSI 300-
233 is supported.
The COMET provides optional jitter attenuation in both the transmit and receive
directions.
The COMET provides both a parallel microprocessor interface for controlling the
operation of the device and serial PCM interfaces that allow backplane rates
from 1.544 Mbit/s to 8.192 Mbit/s to be directly supported. Up to four COMET
devices can be multiplexed on a byte-interleaved basis on a common bus with
PROPRIETARY AND CONFIDENTIAL
15
PMC [ PMC-SIERRA, INC ]
