Endace DAG 3.8S, User Manual

Page: 43 / 48

EDM01-09v7 DAG 3.8S Card User Guide
©2005 38 Version 9: May 2006
Using 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 synchronization.
When the time reference source is connected to the DAG synchronization
connector, the card automatically synchronizes to a valid signal.
dag@endace:~$ dagclock –d dag0
muxin rs422
muxout none
status Synchronized Threshold 596ns Failures 0 Resyncs 0
error Freq 30ppb Phase -15ns Worst Freq 2092838ppb Worst
Phase 33473626ns
crystal Actual 100000023Hz Synthesized 67108864Hz
input Total 225 Bad 0 Singles Missed 1 Longest Sequence
Missed 1
start Thu Apr 28 14:55:20 2005
host Thu Apr 28 14:59:06 2005
dag Thu Apr 28 14:59:06 2005
Connecting
time
distribution
server
The TDS 2 module connects to any DAG card with a standard RJ-45
Ethernet cable and can be placed some distance from a DAG card.
Existing RJ-45 building cabling infrastructure can be used to cable
synchronization ports.
CAUTION: Never connect DAG and/or the TDS 2 module to active
Ethernet or telephone equipment.
Testing signal For Linux and FreeBSD, when a synchronization source is connected the
driver outputs some messages to the console log file
/var/log/messages
.
The
dagpps
tool is used to test a signal is being received correctly and is
of correct polarity. To perform the test, run:
dagpps –d dag0
.
The tool measures input state many times over several seconds, displaying
polarity and length of input pulse.
Some DAG cards have LED indicators for synchronization (PPS) signals.