Endace DAG 5.2X, Руководство пользователя

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EDM01-33v1 DAG_7.5G4_Card_User_Guide
©2008 Endace Technology Ltd. Confidential - Version 1 - November 2008 41
Synchronizing Clock Time
Overview
DAG cards have sophisticated time synchronization capabilities. This allows for high quality
timestamps and optional synchronization to an external time standard.
The core of the DAG synchronization capability is known as the DAG Universal Clock Kit
(DUCK).
A clock in each DAG card runs independently from the computer clock. The DAG card’s
clock is initialized using the computer clock, and then free-runs using a crystal oscillator.
Each DAG card's clock can vary relative to a computer clock, or other DAG cards.
DUCK Configuration
The DUCK (DAG Universal Clock Kit ) is designed to reduce time variance between sets of
DAG cards or between DAG cards and coordinated universal time [UTC].
You can obtain an accurate time reference by connecting an external clock to the DAG card
using the time synchronization connector. Alternatively you can use the host computer's
clock in software as a reference source without any additional hardware.
Each DAG card can also output a clock signal for use by other DAG cards.
Common Synchronization
The DAG card time synchronization connector supports a Pulse-Per-Second (PPS) input
signal, using RS-422 signaling levels.
Common synchronization sources include GPS or CDMA (cellular telephone) time receivers.
Endace also provides the TDS 2 Time Distribution Server modules and TDS 6 expansion
units that enable you to connect multiple DAG cards to a single GPS or CDMA unit.
For more information, please refer to the Endace website at
https://www.endace.com/support , or the EDM05-01 Time Distribution Server User Guide .