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AO-Note.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=windows-1252">
<TITLE>AO Setup Note</TITLE>
<META NAME="GENERATOR" CONTENT="OpenOffice 4.1.0 (Win32)">
<META NAME="CREATED" CONTENT="0;0">
<META NAME="CHANGED" CONTENT="20140814;7594031">
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</HEAD>
<BODY LANG="en-US" DIR="LTR">
<H1 ALIGN=CENTER>AO Setup Note</H1>
<P ALIGN=CENTER>Calin Culianu <[email protected]></P>
<P ALIGN=CENTER>Last Updated: August 14, 2014</P>
<DIV ID="Introduction" DIR="LTR">
<P ALIGN=LEFT STYLE="text-decoration: none"><FONT FACE="Verdana, sans-serif"><FONT SIZE=3><FONT COLOR="#222222"><SPAN STYLE="font-style: normal"><SPAN STYLE="font-weight: normal">AO
passthru works best when the AI and AO subdevices are using the same
clock source. So if you are doing “Straight AI” (no
INTAN hardware), and AI & AO are on the same DAQ card, then
setting the AO passthru clock to “OnBoard” is
acceptable, and any sample rate can be used for AO passthru.</SPAN></SPAN></FONT></FONT></FONT></P>
<P ALIGN=LEFT STYLE="text-decoration: none"><FONT FACE="Verdana, sans-serif"><FONT SIZE=3><FONT COLOR="#222222"><SPAN STYLE="font-style: normal"><SPAN STYLE="font-weight: normal">However,
when using the INTAN (MUX) modes for AI, then you may experience
problems if the AO device is using “OnBoard” as its
clock source. The problems are related to clock drift, and can
manifest themselves as a latency or delay in the AO data, or as
potential distortions in the AO passthru data.</SPAN></SPAN></FONT></FONT></FONT></P>
<P ALIGN=LEFT STYLE="text-decoration: none"><FONT FACE="Verdana, sans-serif"><FONT SIZE=3>The
best way to handle this scenario is to <B>wire the AO device's clock
(say, on PFI 2) to the INTAN board's clock output </B><SPAN STYLE="font-weight: normal">(and
select PFI2 as the AO clock)</SPAN>. Then, set the <B>AO samplerate
to match the INTAN clock sample rate</B> (say, on a 32 MUX INTAN
running at 20kHz per MUX channel, this would be approximately 640
kHz for the AO passthru output sample rate). In this way, the AO
passthru data is perfectly synched up to the incoming AI data, and
no clock drift is possible.</FONT></FONT></P>
<P ALIGN=LEFT><A NAME="Introduction"></A><FONT FACE="Verdana, sans-serif"><FONT SIZE=3><SPAN STYLE="text-decoration: none">Not
following the above advice may produce artifacts and/or delays in
the AO passthru data! </SPAN></FONT></FONT>
</P>
</DIV>
</BODY>
</HTML>