Functional Overview; Rear View Of The Sdu-2000 Expansion Shelf - Symmetricom SSU-2000 User Manual

Chapter 1 Product Overview
SDU-2000 Synchronization Distribution Unit
Figure 1-13. Rear View of the SDU-2000 Expansion Shelf

Functional Overview

Figure 1-14 shows a simplified functional block diagram of the SDU-2000
Expansion shelf. The SDU-2000 interfaces with the SSU-2000 main shelf in
two-way communications through the SSU/SDU interface cables and receives
synchronization clocks that are buffered and used to produce the differential output
signals at the connector panel, as shown in Figure 1-14. A second interface cable
supplies the SDU-2000 Expansion shelf 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 shelf 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-2000 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.
12713020-002-2 Revision F.01 – January 2007 SSU-2000 User's Guide 53