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I have a meter that will analyze limited RF spectrum in my area. One frequency that keeps coming up is 2.498 kHz. An FCC site listed that as the frequency used to communicate with underground mines. Is that correct, and if so, why would it be in my neighborhood?

There were a series of repeating frequencies, I'll list the most prominent, and hopefully you can tell me what most likely are producing them:

  • 2.502 GHz,
  • 672 MHz,
  • 640 and 624 MHz,
  • 72 MHz,
  • 2.623 MHz is a constant,
  • 550 kHz is a constant at -30 dbm,

then

  • 159,
  • 168,
  • 172,
  • 219,
  • 378, and
  • 471 kHz, all averaging -40 dBm.

That's a limited piece of data, but even that seems like alot. What are these coming from, and especially, is that 2.498 kHz really for communicating with mines? Thanks for your help.

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    $\begingroup$ What sort of antenna is it connected to? 2.4 kHz will not be easily detected by a small antenna. And if it's not detecting cellular phones at ~900 and ~1800 MHz, it's not working. $\endgroup$ – tomnexus Aug 20 '19 at 7:54
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    $\begingroup$ Isn't 2.5 GHz area where microwave ovens work? $\endgroup$ – Zeiss Ikon Aug 20 '19 at 12:23
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    $\begingroup$ Where is your "neighborhood?" There might be mines for coal, salt, minerals, etc. $\endgroup$ – Brian K1LI Aug 20 '19 at 12:58
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    $\begingroup$ Frequencies in the 3kHz range have been used to communicate with submarines. $\endgroup$ – Brian K1LI Aug 20 '19 at 12:59
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    $\begingroup$ Have you considered harmonics? You likely need to use a good bandpass, and know your rf spectrum analyzer well. $\endgroup$ – Jon Custer Aug 20 '19 at 20:44

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