Loud low frequency noise, then harmonic silence

The above image shows what happens on my EHN channel on my 3D (RC4B2).

I get normal signal, then a buildup of low frequency noise, then everything changes to silence and strong harmonic overtones for very long periods of time (days) or plain blank signal.

Has anyone seen anything like this before? Am I running into a shielding issue?

The Z channel and EHE channel are unaffected.


Hello, and welcome back to the community!

This is an interesting phenomenon. Have you noticed if the “build-up” happens at regular intervals, or at the same time every hour/day/week? Any other detail you could provide could be helpful to understand what is happening with the EHN sensor (also curious that only that one is experiencing this issue, it could be a clue).

I think I remember seeing something akin to this in relation to my radio ham equipment, but a bit (a long time) ago, so I don’t recall the specifics.

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There’s no obvious interval, and sometimes the results are backwards: silence with strong harmonics and then a snap of loud low frequency noise and the sensor returns to “normal”

I moved the unit today to see if a different position would change anything and the result was near silence, where previously we were in a state of strong harmonics.

The other two sensors are still functioning normally.

I’m going to build an aluminum foil cage/box for it and see if I get any reduction in noise, but I might also reseat the geophone too.

I’ve attached the reversed phenomenon as well as the results after moving.


Thanks for the update!

I wonder what external source (or particular positioning) was the reason for what you saw, especially with randomized intervals, as you said.

If you want to share pictures of the box you’ll be building with us, feel free! I’m sure that the community will find the process very interesting.

So… umm…


…I solved my problem.


The mystery has been solved!

Thank you for the pictures. I wouldn’t have imagined something like this to be responsible for what you are seeing, but it’s a good learning experience for me, too.

Happy to hear that your Shake is now working fine!

@SouthLewisHighSchool an additional question for our records. Did you buy a Turnkey solution or a DIY kit?


Ha! that sort of problem is SO hard to find. Congratulations!!


This was a kit that I put together. However, this issue showed up after I replaced the pi board a while back. I was missing a lock washer then and figured it was lost forever during the second assembly. Surprise! It was bridging the contacts and shorting out the geophone!


You know what’s really awesome is that me looking at the device was literally all I needed to do. Here I was designing elegant grounded faraday cages in my head and watching YouTube videos of Linus tech tips testing out fake shielding boxes for his wi-fi routers, when really all I needed to do was walk over and just look.

And this was the second thing stuck in a thing that I fixed on that day. The other was a Lego stuck in the rollers of my printer. That repair made me bleed.