Functional Overview - Symmetricom SSU-2000e User Manual

Functional Overview

The SDU-2000e interfaces with the main shelf in two-way communication through the
SSU/SDU interface cable. The SDU-2000e receives buffered synchronization clock
signals that are used to produce the differential output signals at the connector panel,
as shown in the functional block diagram in
supplies the SDU-2000e chassis with a backup clock (D Clock) which can sustain the
expansion shelf even if the main cable is accidently disconnected. An address switch
on the connector panel of the expansion shelf identifies each additional shelf to the
main shelf for status and firmware downloading purposes.
Each expansion shelf extends the expansion bus and D clock to the next chassis in
the daisy chain. The last expansion shelf uses a set of termination plugs on the
Expansion Bus Connector and the Backup-Clock Connector.
Each expansion shelf can support any combination of up to ten 2048 kHz,
Composite Clock (CC), or framed 2048 kbit/s (E1) or DS1 modules, each capable of
generating 20 output signals for distribution to large networks. Each Output module
generates a phase-locked signal of 1.544 Mbps (DS1) or 2048 kbit/s (E1) using one
of three 4 KHz clocks supplied by the clock oscillators in the SSU-2000e main shelf.
The phase locked clock signal is buffered and summed with a companion Output
module in redundant pairs to generate a set of 20 independent output clock signals
for distribution to large networks.
Output modules are available to support the following formats:
2048 Kbit/s (E1)
DS1, SF (D4) and ESF
2048 kHz
Composite Clock (64/8 kHz)
RS-422
Expansion Shelf Features
The SDU-2000e expansion shelf consists of the following major components and is
shown in Figure
Expansion chassis
One or two Buffer Modules; where two provide a more robust system
Up to 10 Output modules, which can be a combination of Output module types
Connector panel with five groups of output connectors, SDU interface connector
group, dual power connectors, dual frame ground connectors, and a shelf
address switch
12713140-002-2 Revision E – October 2006
1-14.
Chapter 1 Product Overview
SDU-2000e Synchronization Distribution Unit
Figure 1-13. A second interface cable
SSU-2000e User's Guide 51