NUDET (GPS L3 at 1381.05MHz)

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Marcus D. Leech

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Sep 11, 2024, 6:22:35 PM9/11/24
to Society of Amateur Radio Astronomers
I've been spending some time today tuning around our pass-band looking
for any strong signals that might possible
  drive later stages into compression, and thus screw up our baseline.

I paused, quite randomly, at 1381MHz.  I was about to tune away from it,
when I saw a "burst" of signal at 1381.05MHz,
  with a distinct SINC-like spread pattern. Hmmmmmm.

That turns out to the GPS L3 (NUDET) frequency that is used to alert of
atmospheric nuclear detonations.  I'm going to go ahead
  and assume that they send out test signals from time to time, as
would be necessary operationally.

Anyone else seen these from time to time?  1381.05Mhz, with the primary
spectral lobe being about 1MHz wide, and obvious,
  much smaller, SINC-like lobes coming out from it?

It was only a few dB above background, so not strong enough to drive us
into compression or anything...


Don Latham

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Sep 11, 2024, 6:39:41 PM9/11/24
to sara
fantastic...our very own furby...
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Don Latham
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