<div dir="ltr">Hi All, <div><br></div><div style>As per the EVLA test discussion today, a modified ACU scientific test plan for EA21 is below. </div><div style><br></div><div style>Cheers,</div><div style>Deb</div><div style>
<br></div><div style>
<p class="">13jun13 – Thursday</p>
<p class="" align="center" style="text-align:center"><b>Draft ACU scientific test plan for the new VLA ACU to be installed on
EA21</b></p>
<p class="">The new and old ACUs use the same commands through the
executor so scientific testing will focus on comparing the performance of the
new ACU relative to the old ACU. </p>
<p class="">Before the new ACU is installed on EA21 (it goes into the
barn on 18 June) a number of baseline tests will be done to make sure we have
good measures of the performance of the old ACU:</p>
<p class="" style><span style="font-family:Symbol">·<span style="font-size:7pt;font-family:'Times New Roman'">
</span></span>PN3dB tracking test - this will be scheduled by
Vivek and Ken for 30min this weekend</p>
<p class="" style><span style="font-family:Symbol">·<span style="font-size:7pt;font-family:'Times New Roman'">
</span></span>30min pointing run with 50ms dumps at X and L
bands. X band is the standard band to do this but the steps are
larger at L band and may excite other problems that would be useful to catch.
Vivek and Ken will schedule this this weekend. </p>
<p class="" style="margin-left:1in"><span style="font-family:'Courier New'">o<span style="font-size:7pt;font-family:'Times New Roman'">
</span></span>Note that when we compare the pointing model
derived with the old and new ACUs there should only be collimation differences.
If there are any other differences then there is something wrong. </p>
<p class="" style><span style="font-family:Symbol">·<span style="font-size:7pt;font-family:'Times New Roman'">
</span></span>We should do beam cuts in both principle axes on
a very bright calibrator with fast dumps (100ms). Rick will do
this. He will use both X and L bands to look at the speed with which the
cut is made, look at how smooth the motion is and measure the oscillations at
the end and how fast they damp out. </p>
<p class="">After the new ACU is installed, the above 3 tests should be
repeated and results compared. In addition, we should:</p>
<p class="" style="margin-left:38.7pt"><span style="font-family:Symbol">·<span style="font-size:7pt;font-family:'Times New Roman'">
</span></span>Observe 2 sources that are relatively far apart
on the sky to check the slew times.</p>
<p class="" style="margin-left:38.7pt"><span style="font-family:Symbol">·<span style="font-size:7pt;font-family:'Times New Roman'">
</span></span>Do a reference pointing test at high frequency
and compare the results. We should be able to use the PL
output to check the reference pointing results or we can set up a quick high
frequency run to do a final verification that all is working properly. </p>
<p class="">Ken notes: the first real astronomical check is to verify
that the azimuth scale is consistent with all the other antennas. That is
something that the engineering tests could easily overlook; it is the first
thing to check if there are no fringes when this is first tried.</p>
<p class=""> </p>
</div><div style><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Jun 12, 2013 at 4:39 PM, Rick Perley <span dir="ltr"><<a href="mailto:rperley@nrao.edu" target="_blank">rperley@nrao.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> The monthly VLA 'science/engineering' Test meeting will be held at<br>
10AM tomorrow (Thursday), 13 June, in Rm 317. We have four items for<br>
discussion (so far):<br>
<br>
1) Initial results from new 4-band dipole feeds (Frazer).<br>
<br>
2) Temperature dependencies of VLA antenna gains (Rick)<br>
<br>
3) Concerns obout R-L phase stability at high frequencies (Rick)<br>
<br>
4) Antenna tests for ea21, prior to the ACU conversion (all).<br>
<br>
<br>
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<br>
</blockquote></div><br><br clear="all"><div><br></div>-- <br>Debra Shepherd <<a href="mailto:dshepher@nrao.edu" target="_blank">dshepher@nrao.edu</a>><br>National Radio Astronomy Observatory <div>1003 Lopezville Rd</div>
<div>Socorro, New Mexico 87801<br><a href="http://www.aoc.nrao.edu/%7Edshepher" target="_blank">http://www.aoc.nrao.edu/~dshepher</a><br> <br> </div>
</div>