Understanding Manmade Frequency Events

In my suburban home-based basement station placement, and following other stations, I’ve routinely observe continuous manmade linear frequencies, e.g., at 39 Hz, or 19 Hz, and I’m trying to deduce what household devices are the cause. In addition, I observe linear rise & fall frequency events, e.g., 11 Hz rising linearly to 15 Hz one minute later, then decreasing back to 11 Hz over a 10 second interval.

Is there a need for a reference “library” of typical manmade activities which trigger linear features on Frequency graphics, to be populated by those who have got to the bottom of what is causing them, with possible remediation methods to lessen their impact?

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Hello MRT1953,

From my personal experience I have constant noise around 30 to 40Hz, due to the computer equipment always on in the same room where I have the Shake. Sometimes other frequencies remain busy, especially low non-audible ones, but I still haven’t found anything to what could be their source.

Does anyone else ere on the community have more info/insight on these ‘mysterious’ events?

Thank you for this feedback, Stormchaser. My Shake is on a hard surface on top of a concrete basement floor as far from footfalls and vehicles as is possible in a suburban home, BUT within six metres of a chest freezer, seven metres of a two-speed natural gas furnace, eight metres of a washer/drier, and nine metres of a fridge. But I have read of other Shakers concerned about inherent frequencies from their Raspberry Shakes. Would it be feasible for pre-assembled Shakes to be assembled and run under “favourable conditions” for “24 hours” in the assembly plant as part of a QC process, and for copies of the helicorder and frequency charts provided to the customer “in the box”? This would ensure both manufacturer and user can “see” any inherent frequency patterns before first use, and thus cease worrying about what they are viewing is an instrumentation issue?

Hello @MRT1953 (R6843)

Wonderful to hear from you. You are very engaged! Really digging in. It is good to see this.

I see from our database that you have a RS3D V5. This means that the unit does not have any inherent frequencies (idle tones) as that was minor issue was resolved in the move from V3 to V5 (Change log — Instructions on Setting Up Your Raspberry Shake).

Prior to shipment we do run the units in the lab but not under anthropogenic-free conditions. Once we determine that the units are operating to spec, we ship. I would compare our test data (if I still have it on disk - I would have to check as you bought your unit back in 2019) to your current data but your data is not entering the cloud (last connection was 2021-05-19 13:50:26.625837+00). Would you be interested in turning data forwarding on?

What you are viewing is likely cultural noise. To demonstrate this I would encourage you to install the Shake somewhere else like a friends house for a time and then compare the data between the two locations.



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Branden, thanks for your response. My RS3D is temporarily housed and will be moved to British Columbia when non-essential travel is permitted. This BC location should have less device disturbances, and more seismicity! As for data forwarding, our only cloud connection currently is an old 2G/3G cellular modem with poor connectivity to a distant tower. Hence my RS3D routinely disappears from the cloud, and stops running every couple of days or so, thus requiring frequent rebooting. PS: I bought the RS3D in December 2020, forty years after lusting after an old-school windup seismograph in an antique store in the UK.

“Good things come to those who wait.”

hahaha. That is a LONG time to wait!

Great to have you in the Community.


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