PM4314 QDSX
DATA SHEET
PMC-950857
ISSUE 5
QUAD T1/E1 LINE INTERFACE DEVICE
9
FUNCTIONAL DESCRIPTION
Analog Pulse Slicer (RSLC)
9.1
The Analog T1/E1 Pulse Slicer function is provided by the RSLC block.The
Receive Data Slicer (RSLC) block provides the first stage of signal conditioning
for a G.703 1544kbit/s (DSX-1) or 2048 kbit/s (E1) serial data stream by
converting bipolar line signals to dual rail RZ pulses. Before an RZ output pulse
is generated by the RSLC block, bipolar input signals must rise to 50% (for E1) or
67% (for DSX-1) of their peak amplitude. This level is referred to as the slicing
level. The threshold criteria insures accurate pulse or mark recognition in the
presence of noise.
The RSLC block relies on an external network for compliance to the DSX-1 and
E1 input port specifications. The RSLC block is configured via an off-chip
attenuator pad to operate in one of four modes: DSX-1 normal mode, DSX-1
bridging mode, G.703 120 Ω twisted pair, or G.703 75 Ω coax.
According to G.703, the amplitude of a DSX-1 normal mode received pulse at
the 1:2 line-coupling transformer's primary should be in the range from 3.6V to
1.2V (depending on the length of the cable from the signal source). In this mode,
the QDSX can receive signal levels down to a typical squelching level of 227mV,
leaving a 14.5dB margin between the minimum expected signal level and the
typical minimum receivable signal level.
In DSX-1 bridging mode, the QDSX is connected to a monitor jack which bridges
across the line and attenuates the signal levels by 20 dB, so the expected pulse
amplitude at the 1:2 line-coupling transformer's primary should be in the range
from 360mV to 120mV (depending on the length of the cable from the signal
source). In this mode, the QDSX can receive signal levels down to a squelching
level of 50mV, leaving 7.6 dB margin between the minimum expected signal level
and the typical minimum receivable signal level.
In 120Ω E1 mode, the amplitude of a received pulse at the 1:2 line-coupling
transformer's primary can be in the range from 3.3V to 1.4V (depending on the
length of the cable from the signal source). In this mode, the QDSX can receive
signal levels down to a squelching level of 276mV, which means that there is
14.1 dB margin between the minimum expected signal level and the typcial
minimum receivable signal level.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
31
PMC [ PMC-SIERRA, INC ]
