17. Anonymity advanced: electromagnetic waves record in your audio

When you post audio, or video with audio, especially in original quality - remember that the power grid even far away from you can be heard in it and the sound waves from the video can be analyzed!!! If they are after you - remember to consider it.

That is because they can look in great detail for the frequency of your nearby powergrid. In most countries it is 50 or 60hz. If they see 60 peaks in a second of audio - then you cannot be in Europe for example. If they know your country they can see logs from power grids and look at an exact frequency in your audio at different times of your recording and deduce more things from that.

For example: it is 50hz on paper in France but at the time of recording your mic captured 49.94hz. They can deduce what places in the world had that exact frequency at what times. Frequency changes by tiny bits as electrical companies try to aim for the perfect frequency or the load changes and frequency along with it.

Then they will move your audio forward, look at freqency at a different point in time, for example a minute later it is 49.99hz now and now the amount of places and times you could be standing in shrinks exponentially because what is the likelyhood of electrical grid's freqency chaning in this particular way in this particular time in other places? They will take more and more measuring points and attribute your general location to fit what power lines in your proximity behaved like over particular timeframe. They will learn what was the time of the recording.

Once they have your approximate location and time - then they will look at the peak power and how peak power changed from hertz to hertz and depending on it - they will approximate how far away you were from the nearest power source. Now they can draw a circle on the map on whose outer range you were. If you were at home it will include your home and it will be used as evidence. Besides it gives up your anonymity. Even if they do not find you - they will know to expect somebody in a very particular area. It is crucial to consider.

In would guess that in some places power logs are public knowledge. Anyone with brain and time can stalk you in that case.