We’ve had a setback with the Hum Map

It is with considerable regret, and out of a sense of duty and transparency, that I report that the World Hum Map is not reliable at the present moment. The latest upload of 1000 points has combined and shuffled data between map locations. As such, no statistics should be inferred or computed until I can rectify this problem. I may need to revert to a previous version.

Here is the schematic

Det Circuit - Copy

Corrupted data points in the recent upload

A sharp-eyed reader noticed that his data point seems to have combined his data with somebody else’s. If this is endemic in the latest upload, then this is bad news. I may need to roll back the Hum Map to the previous version. I would ask any readers whose map point was included in the recent update to take a good look at their listing and let me know if there are issues. I will audit, by hand, twenty or so random recent points, checking the raw live database against the Hum Map. This may be a single incident or a significant setback. I’ll keep you informed.

This is odd …

I went outside, about 30 feet away from house, turned on the device and turned in a slow circle. Look at the following screen shots of the resulting EM spectra. I’m wondering why the first strong line appears at 261 Hz. Also, note the transient but significant EM noise at around 10 Hz.

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Device testing continues…

I am slowly learning. After hearing back from George G. regarding some initial concerns, here is a screenshot that shows me turning on the unit at t=5 seconds, then approaching an active wall outlet and rotating the device a few times. You can see the vertical axis here. This makes more sense. I’m surprised that the mains don’t dominate the spectrum, given that I am surrounded by it in this room and in this house. I’ll keep you all posted.

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The Gear

20170722_184904A few of you have asked about my EM recording setup. Please see the photo below. On the left is George G.’s home-crafted EM receiving device (email me if you would like the schematic). On the right is my Zoom H4N Pro recorder. George’s device converts EM frequencies into their audio counterparts so that my Zoom can display them in audio software (Audacity in my case).

 

Initial baseline EM recordings

Finally, I had time to switch on George G’s EM device and make a few initial recordings. In the screenshot below, you can see that at the 10-second mark, I switched on the device. You can see the strong spectral lines at the odd harmonics of the power mains (60 Hz in North America). ┬áThis is a good sign. When I feel reasonably confident in my use of Audacity (OS X audio software), then I will establish once and for all whether VLF radio frequencies are not responsible for the Worldwide Hum. I’ll keep you posted.

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