Endace DAG 3.8S, Руководство пользователя

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EDM01-09v7 DAG 3.8S Card User Guide
©2005 37 Version 9: May 2006
Preventing
time-stamps
drift
To prevent the DAG card clocks time-stamps drifting against UTC, the
master can be synchronization 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.
6.2.3 Card with Reference Time Synchronization
Description 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
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.