X-band motion sensor vs. PIR

Larry Molter

Traditionally, PIR sensors have been used to detect motion in paranormal investigations. Stop. If you're shaking your head about the mention of 'ghost hunting', please read something else. Some of us are trying to correlate various events in an attempt to scientifically define the makeup of a paranormal event. Motion detection is one of those events. Combined with EMF fluctuations and temperature drops, we can try to correlate the evidence and start to gain an understanding of what exactly happens during an paranormal event. Having an EMF meter spike alone or a cold spot appear by itself is not enough to define paranormal activity. You need a combination of events. This is where the scientific investigators are heading.

The PIR sensors are somehow able to detect IR from whatever is there. I'm wondering if the X-band detector will detect anything at all? Especially since I don't really don't know what the PIR sensor is detecting in these cases. Maybe an area of low temperature air? I don't know. Nonetheless, will a mass of cold air or whatever produce any reflection at all of GHz energy? I suspect not. Maybe the X-band can only be used for solid objects.

What I plan to do is combine the X-band and the high-power PIR in the same case and output them separately to my Linux data acquisition box. After placing the data logger in an area of known paranormal activity, I can compare the results to see if either sensor 'saw' more than the other did.

Sorry if I got preachy.

mindrobots

Go for it! In the era of the Internet of Things, who are we to question the Internet of Non-things??

Larry Molter

I think your cat is possessed. Mine are, too. Anyway, what's cool about this sensor is that it's more sensitive to motion coming towards and going from. D'oh! That's Doppler! And that's a good thing because the PIR sensor is more sensitive to motion across its plane. So... combining them both in one case makes a lot of sense (to me, at least). And they seem to be equally sensitive at the edges of their range.

I didn't scope the output of the X-band sensor, but I did hook an LED up to it. Little blips if little motion. Steady stream of blips if a lot of motion. Can't tell if the pulse width changes, though. No matter. I'll build a retriggerable one-shot with a period of .25 seconds or so.Well, maybe .5 seconds. I'm sampling at 4Hz. Might miss one.

I'm stoked to put these in a box. Right now I'm on a breadboard for proof of concept.

Larry

ElectricAye

If temperature or density variations in air are what you're after, consider developing sensors based on the Schlieren effects.

[video=youtube_share;_gKNhGbsEf4]


http://en.wikipedia.org/wiki/Schlieren

If that doesn't work out, try wiring up the skin response of cats. As annoying as cats are, I think they pick up things your instruments will fail to see.