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Hi Frazer,
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<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>
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<div><img id="cfb151eb-2057-498f-9dd8-37f456e2ca8c" height="461" width="688" apple-width="yes" apple-height="yes" src="cid:50266521-6F65-4B8D-9860-0749349F0653@phys.unm.edu"></div>
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<div>On Jun 23, 2014, at 9:40 AM, Frazer Owen <<a 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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