Endace Measurement Systems Limited
http://www.endace.com
EDM01.05-04r1 DAG 3.6GE User Manual
Copyright, all rights reserved.
23
Revision 7. 22 September 2005.
5.2.2 Two Cards no Reference Time Synchronization
, continued
Preventing
time-stamps
drift
To prevent the DAG card clocks time-stamps drifting against UTC, the
master can be synchronized to the host PC’s clock which in turn utilises
NTP. This then provides a master signal to the slave card.
The cards are locked together by connecting the synchronization
connector ports of both cards with a standard RJ-45 Ethernet cross-over
cable.
Configure one card to synchronize to the PC clock and output a RS-422
synchronization signal to the second card.
dag@endace:~$ dagclock –d dag0 none overin overout
muxin over
muxout over
status Synchronized 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.
5.2.3 Card with Reference Time Synchronization
Description
The best timestamp accuracy occurs when DAG card is connected to an
external clock reference, such as a GPS or CDMA time receiver.
Pulse signal
from external
sources
The DAG synchronization 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.
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