Endace DAG 3.7D, User Manual

Page: 23 / 33

EDM01-06: DAG 3.7D Card User Guide
©2006 17 Version 1: March 2006
Chapter 5:
Synchronizing Clock Time
Introduction Overview
The Endace DAG range of products come with sophisticated time
synchronisation capabilities, in order to provide high quality timestamps,
optionally synchronized to an external time standard.
The system that provides the DAG synchronisation capability is known as
the DAG Universal Clock Kit (DUCK).
An independent clock in each DAG card runs from the PC clock. A card’s
clock is initialised using the PC clock, and then free-runs using a crystal
oscillator.
Each card's clock can vary relative to a PC clock, or other DAG cards.
DUCK Configuration
The DUCK is configured to avoid time variance between sets of DAG
cards or between DAG cards and coordinated universal time [UTC].
Accurate time reference can be obtained from an external clock by
connecting to the DAG card using the synchronisation connector, or the
host PCs clock can be used in software as a reference source without
additional hardware.
Each DAG card can also output a clock signal for use by other cards.
Common Synchronization
The DAG card synchronisation connector supports a Pulse-Per-Second
(PPS) input signal, using RS-422 signalling levels.
Common synchronisation sources include GPS or CDMA (Cellular
telephone) time receivers.
Endace produces the TDS 2 Time Distribution Server modules and the
TDS 6 units that enable multiple DAG cards to be connected to a single
GPS or CDMA unit.
More information is available on the Endace website at
http://www.endace.com/accessories.htm , or the TDS 2/TDS 6 Units
Installation Manual .