22 TimeHub 5500 User’s Guide 097-55501-01 Revision M – January 2009
Chapter 1 Description
Overview
Overview
The TimeHub 5500, shown in Figure 1-1, is a building integrated timing supply
(BITS) redundant timing distribution system for 1.544 Mbps primary rate networks.
The system tracks incoming timing references, qualifies the signals against network
timing standards, then filters and distributes up to 140 precise timing signals. The
TimeHub 5500 system is suitable for installation in Network Telecommunication
Facilities.
The TimeHub 5500 clock uses precision timing references such as Primary
Reference Clocks (PRCs) (cesium frequency standards), GPS Primary Reference
Source (PRS) receivers, and DS1 input references from other nodes to generate
synchronized DS1 (1.544 Mbps) and composite clock (CC) (64 kbps) timing output
signals. These signals provide timing synchronization inputs to various network
elements. If a reference input is lost, the TimeHub 5500 provides SmartClock
holdover that exceeds Stratum 2 accuracy.
In addition to DS1 and CC output signals, the TimeHub 5500 can also provide
5 MHz outputs and carrier-class Network Timing Protocol (NTP) outputs.
TimeHub 5500 applications include providing timing synchronization for ATM,
SONET, and digital wireless networks.
The TimeHub 5500 supports up to four optional Expansion shelves. Each
Expansion shelf provides up to 320 additional output signals, for a maximum of
1420 outputs in a full system.
Figure 1-1. The TimeHub 5500
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