Symmetricom SDU-2000, User Manual

Page: 46 / 470

Product Overview
SSU-2000 Family of Modules
46 SSU-2000 User’s Guide 12713020-002-2 Revision D – April 2004
E1/2048 kHz Output Module
The E1/2048 kHz Output module can be installed in the SSU-2000 to generate and
monitor 20 independent E1/2048kHz output signals. If the module is inserted into an
SDU-2000 expansion shelf, a fourth 4 kHz clock (D clock) is available. If the input
signal PQL drops below a user-specified level, then the outputs can be squelched.
For more information, see
E1/2048 kHz Output Module , on page 185.
2048 kHz Output Module
The 2048 kHz Output module plugs into selected input/output slots in the SSU-2000
main shelf or one of the output slots on the expansion shelf. The module generates
and monitors 20 independent 2048 kHz signals that are referenced to a selected
clock module. The 2048 kHz Output module receives a set of three (four if installed
in an expansion shelf) 4 kHz clocks from the Clock modules and uses these clocks
to develop an 8.192 MHz phase-locked signal. This phase-locked signal is then
used to generate 20 sets of 2048 kHz clock outputs. For more information, see
2048
kHz Output Module , on page 192.
RS-422 Output Module
The RS-422 Output module generates 10 balanced square-wave outputs (TTIP and
TRING signal pairs) and 10 single-ended (Ring) square-wave outputs. Each output
can be turned off independently of other ports; relays on each output disconnect the
driver output from the output pins. A squelch feature turns off selected ports when
the input signal falls below predetermined quality levels. See
RS-422 Output
Module , on page 198.
Line Retiming Unit LRU
The LRU is comprised of a Line Re-timing Module (LRM) and a Cut-Through
Assembly (CTA). The LRU is available in both a two-port (Dual) and four-port
(Quad) version. For more information, see
Line Retiming Unit (LRU) , on page 204.
The DS1 LRU inserts DS1 signals on both sides of a DSX-1 panel in a Central
Office. Side 1 of the DS1 re-timer provides “3R” (Re-shape, Re-amplify, and
Re-time) for the DS1 signal to a client Network Element. When the LRU receives a
DS1 data stream, it re-times the data with the transmit clock signal. The clock signal
is inserted into the DS1 line route between two DS1 path-terminating elements.
Side one is the direction in which timing is applied. Side 1 contains the DS1 line
performance reporting and AIS generator. AIS is not generated when the port is set
to Unused/Off. Side 2 provides “2R”, which Re-shapes and Re-amplifies
(regenerates) the DS1 signal from the client Network Element. Side 2 does not
provide performance monitoring or AIS generation.
Configuring Redundant Output Modules
For an A/B pair of Output modules (in a redundancy configuration), it is possible to
connect all of the outputs of Module B to the corresponding outputs of Module A,
providing 1:1 output protection (1:1 redundancy).
Figure 1-10 shows the SSU-2000
input/output connectors.