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<div class="moz-cite-prefix">On 06/23/2014 02:35 PM, Gregory Taylor
wrote:<br>
</div>
<blockquote cite="mid:60245F3E-6C52-4A0B-B835-5C47BDE58596@unm.edu"
type="cite">
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Hi Frazer,
<div><br>
</div>
<div> The emission at 55.25 MHz is the video carrier for TV
channel 2.</div>
<div>We see this quite strongly with LWA1. At 60 MHz we see a
moderately</div>
<div>strong source to the North of LWA1 (see plot). We might be
seeing a VLA</div>
<div>antenna. The extended source in the NE is from power-lines.
They are better </div>
<div>following some mitigation earlier this month, but still
obvious. </div>
<div>Ciao,</div>
<div> - Greg</div>
</blockquote>
I had noticed the coincidence with 55.25 and channel 2. The
problem is that we don't see that signal, at least anywhere near as
strong, on the other two 4band antennas, just ea14. Unless ea14's
location at E8 allows it to see a channel 2 while the others are
blocked, then I don't understand why we just see 55.25 on ea14. That
signal is much stronger than anything else we see, including the
other TV channels. For the other antennas channel 5 is by far the
strongest of the clearly external signals. <br>
<br>
Not sure where 60 MHz is coming from. We should find out. <br>
<blockquote cite="mid:60245F3E-6C52-4A0B-B835-5C47BDE58596@unm.edu"
type="cite">
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<div><br>
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<div><img id="cfb151eb-2057-498f-9dd8-37f456e2ca8c"
apple-width="yes" apple-height="yes"
src="cid:part1.01020803.07000208@aoc.nrao.edu" height="461"
width="688"></div>
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<div>
<div>On Jun 23, 2014, at 9:40 AM, Frazer Owen <<a
moz-do-not-send="true" href="mailto:fowen@nrao.edu">fowen@nrao.edu</a>></div>
<div> wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite"><br>
We made a successful test of the the new 4band MJP
dipoles using <br>
antennas 12, 14, and 19. 14 is important for interference
tests because <br>
it has the new ACU. The autocorrelations on 12 and 19 show
the 5MHz <br>
clock comb that is thought to come from the old ACU. 60 MHz
is <br>
particularly strong and variable for test to test. The
autocorrelations <br>
for antenna 14 do not show the 5MHz comb. This seems to
confirm that <br>
that the 5 MHz comb is from the old ACU<br>
<br>
Antenna 14 also does not show interference at 64MHz,
which I <br>
understood was a possible frequency from the new ACU. It
does show a <br>
fairly strong spike at 55.25, much stronger than any else in
the 54-86 <br>
MHz band. The very narrow spike is clearly different from
the 55MHz <br>
spike on 12 and 19, which is part of the 5MHz comb. 12 and
19 don't show <br>
a spike at 55.25.<br>
<br>
Interestingly the 5MHz comb frequencies correlate on
baselines to <br>
14 (as they do on 12-19). Since the 5MHz clock is supposed
to be <br>
incoherent from antenna to antenna, there must be a general
source of <br>
the comb frequencies, especially 60MHz, which is being
broadcast around <br>
the site. Could this be one very bad antenna ?<br>
<br>
---Frazer<br>
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</blockquote>
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<br>
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</blockquote>
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