Endace DAG 3.7D, Руководство пользователя

Страница: 27 / 33

EDM01-06: DAG 3.7D Card User Guide
©2006 21 Version 1: March 2006
dag@endace:~$ dagclock –d dag0 none overin
overout
muxin over
muxout over
status Synchronised Threshold 11921ns Failures 0
Resyncs 0
error Freq -691ppb Phase -394ns Worst Freq
143377ppb Worst Phase 88424ns
crystal Actual 49999354Hz Synthesized 16777216Hz
input Total 87464 Bad 0 Singles Missed 0
Longest Sequence Missed 0
start Wed Apr 27 14:27:41 2005
host Thu Apr 28 14:59:14 2005
dag Thu Apr 28 14:59:14 2005
The slave card configuration is not shown, the default configuration is
sufficient.
Card with
Reference
Overview
The best timestamp accuracy occurs when a DAG card is connected to an
external clock reference, such as a GPS or CDMA time receiver.
Pulse Signal from External Source
The DAG synchronisation connector accepts a RS-422 Pulse Per Second
[PPS] signal from external sources.
This is derived directly from a reference source, or distributed through the
Endace TDS 2 [Time Distribution Server] module which allows two DAG
cards to use a single receiver.
More cards can be accommodated by daisy-chaining TDS-6 expansion
units to the TDS-2 unit, each providing outputs for an additional 6 DAG
cards.
Using an External Reference Source
To use an external clock reference source, the host PC’s clock must be
accurate to UTC to within one second.
This is used to initialise the DUCK.
The external time reference allows high accuracy time synchronisation.
When the time reference source is connected to the DAG card
synchronisation connector, the card automatically synchronises to a valid
signal.