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I decided that I wanted to see DSN receive the last bits of data from DSN Now. The last data was supposed to be received at about 7:55. The signal seemed to continue strong until about 10 minutes after, when I started seeing the signal seem to be received, and then disconnected, and then received again, in cycles of about 20 seconds. Any idea what was actually happening?

enter image description here

From what I've heard, the actual signal lasted about 30-40 seconds longer then expected, but still should have stopped well before this happened. Also, the signal did finally end about an hour later.

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  • $\begingroup$ I noticed that the signal continued for a while, but I did not watch long enough to see it cycling off and on. Is DSN Now not "real time" like its name implies? $\endgroup$ – JohnHoltz Sep 15 '17 at 16:28
  • $\begingroup$ I'm not really sure, it was strange, to say the least... $\endgroup$ – PearsonArtPhoto♦ Sep 15 '17 at 17:47
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    $\begingroup$ I asked on Twitter and got a conjecture that DSN is picking up noise at the correct frequency, mistaking it for a weak carrier, then giving up because it can't find any data frames in the noise, possibly exacerbated by an automatic gain control. If we don't get something more authoritative in a day or two I'll write that up as an answer. twitter.com/bofh453/status/908810578004779009 $\endgroup$ – Russell Borogove Sep 15 '17 at 22:19
  • $\begingroup$ Those look like extremely weak signals. I am guessing from the zero data rate this is just background noise at the carrier frequency. $\endgroup$ – honeste_vivere Feb 1 '18 at 14:11
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The best guess is that DSN is picking up noise at the correct frequency, and the DSN now web app puts up false data. They seem to frequently do this for spacecraft that can't be in contact, DSN Now isn't really accurate for such purposes. It is a PR tool, not meant to take any serious information from it.

https://twitter.com/bofh453/status/908810578004779009

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