Magnetometers

[Captain Winky]

So, ofcourse, in Night-ops, there's the ever-present nuisiance of electronic security measures. Some of the best known ones being Electromagnetic contact sensors.
Everything electronic in this world emits a small electromagnetic field. Computers, monitors, headsets, phones, even the fucking blow-drier for your pretty curly locks.

This is also the reason why, even if your phone is disconnected from those fancy-smancy airwave-carried services such as internet, GPS or phone services, sometimes a person can still be tracked by their phones because the clit has some way to detect electromagnetic fields. This is done through magnetometers. I will discuss two points on magnetometers in this topic. Which is 1: why they can fuck our shit up, and 2: how they can be usefull to us. To start off:

1: Why Magnetometers are bad for Night Oppers.
As I've stated before, the police is rumored to have some way to detect electromagnetic fields. These fields are pretty tiny and close by the device, so it is a pretty accurate data if it can be gathered from a distance. Most probably through some kind of amplifier like image intensifier tubes do on night vision goggles. If any of you has ever played Chaos Theory, the EMF-vision in that game is a pretty accurate way of describing modern electromagnetic fields if they ever could be seen, though a tad selective on what does and does not emit an electromagnetic field. But fuck it, it's a game. Now I am not sure if technology really is that far, it certainly is the most fantastic and ideal way of tracking electromagnetic fields. But remember: James Bond gave us the fantasy of being able to make photos with your cellphone, and so it happened.

This comes with problems for the police, naturally. If you are sneaking around a room full of electrical appliances or hell, run down the street, it's going to be very difficult to pinpoint your position regardless due to the enormous around of fields around you. If you're on a construction site with only building lights about a football field away from you, then things start getting diffirent. Or ofcourse, if you run into a forest with a smartphone, electrical pick gun, an electric drill or dremel, a radio or a GPS unit or your contact-less car keys in your pocket, you might as well lie down and pull your pants down off your ass, because you'd be fucked if these measures would be employed against you.

How likely this scenario is, however, I do not know.

2: Why Magnetometers are good for Night Oppers.
Let me introduce to you the most usefull, readily-available and safe and probably oldest magnetometer out there in the world: the compass.
Imagine the world has a giant fucking bar magnet buried inside it's center. The north pole of the magnet somewhere around the north pole, and the south pole of the magnet somewhere around the south pole. These, too, emitting electromagnetic fields. These poles is what the needles of the compass are drawn towards. This is because the north needle of the compass is magnetized as south, and sometimes the south needle of the compass is magnetized as north (yes, this does sound confusing, but remember: opposites attract).

This is also why a compass goes batshit insane near electronics or metal. One of the needles gets rejected by the field and hence it starts spinning like a motherfucker. If you have a double-magnetized needle (north AND south) usually the needle will stand still, but probably somewhere closest to the field it attracts. What allows compasses to function normally in urban settings, however, is because these electromagnetic fields are extremely small and close to the object in question.

If you've all been reading around the boards and sources, this should now give you a clue on why compasses are so damn handy on finding electronic or magnetic security measures. Slide it around the edge of a door and if there's an electromagnetic switch or sensor there, it will go insane. So as you may realise by now: Compasses are a huge plus so far. But the question comes along: if the compass needles are polarised, does that may mean they may also emit an electromagnetic field, which may in turn be detected by other magnetometers, now that I think about it.

There's another way to find magnetometers: Nowadays, most smartphones have compasses in them. This is either a Gyroscopic compass (most smartphones used to use those, but in newer models, the only phones that really still use those are iPhones. iPhone 5 still uses a gyroscopic compass, as the SE Xperia, Sony Xperia, One X, and GSIII use the following) or a magnetometer for a compass.
I have been experimenting with this, I have downloaded a small android app that can detect electromagnetic fields up to the thousandth of a microtesla. But there also has to be some way to detect fields other than just intensity. Otherwise the maps compass wouldn't work from my chair. So I am going to have to experiment with this a little more, perhaps open up eclipse and perhaps snoop out a few of the properties. So in andvance, I'll just supply the android documentation here on the sensor to see what can be done with it.

http://developer.android.com/reference/ ... ensor.html

As the following documentation, sensorevent, as lead from the source above, states. The electromagnetic values are returned over 3 axis': X, Y, and Z. Allowing for a three-dimensional detection of electromagnetic fields.

http://developer.android.com/reference/ ... ETIC_FIELD

[Xanatos]

If they have developed EMF sensors to the standard as Fisher's goggles in Chaos Theory I don't think your standard police units would be kitted out with that kind of stuff. Do they even get thermals?

It's important to note that life forms - including us - emit an EMF signature as well ('bioelectromagnetism'). Depending on the sensitivity of their equipment, they may be able to detect you even if you don't have any electronics on you except for the complex computer between your ears. Some Russian scientists have developed a camera that can capture the bioelectricity of life forms, some of the images are pretty amazing. However, if you happen to be hiding in a forest or some other shrubbery then magnetometers would be about as useful as using thermals to detect ice cubes in a freezer.

[Urgon]

AVE...

Bad science-fiction, Winky. Not enough science and lots of fiction...

I'll make it into list of facts and fiction:
Fact - we can detect even the faintest EM fields in RF bands with special devices.
Fiction - but not in any practical manner for even special forces to have one of those devices.
Those devices are used by radioastronomers, and require constant liquid nitrogen cooling. Also multi-channel receivers, size of 40U server rack, and at least one big computer to operate it all.
Fact - we can pin-point the location of those signals.
Fiction - not in suburbs.
Those receivers are so sensitive, that on few occasions SETI had detected alien signals, because someone used microwave oven. That's why radiotelescopes are on deserts, not in cities...
Fact - your cellphone emits signals even when you disable GSM, Wi-Fi, Bluetooth and NFC modules.
Fiction - range of those signals is so small, that I had to make special pick-up coil to measure current with oscilloscope.
And if you are afraid then put your phone in metal box or wrap in aluminum foil...

[Captain Winky]

Xanatos, I was not aware of biomagneticism, that has been eye opening to me.

Also Urgon, thanks for clearing that up.
As I stated I was not aware of how far this technology was. I knew that the presence of these devices implied all these things could be possible, what I did not know is if we were at that point just yet technologically, nor how likely it was to be used.

This does not mean that with technology getting smaller and smaller, and more and more devices obtain more and more sensors, which are used in more and more creative ways that this may not be possible ten to twenty years from now, but that is an entirely diffirent story.

I too think it is highly unlikely the police will be using any of these devices anytime soon, so I would just as happily disable signals and just take my phone with me turned on.
I have, however, purposefully left the reach of this 'power' blank because I did not know anything about this, so that the indivual opper with perhaps more in-depth knowledge could decide for his or herself.

[Psychlonic]

-cleaned-

[Xanatos]

True. For instance, I know the local police force in my city has helicopter support on quick standby. I know it's got a visible spotlight but I'm not sure about IR.

[Urgon]

AVE...

Nightvision IR cameras are now so cheap, that every police force can buy tons of them. The drawback is they need IR lights to work, and thus can be blinded with some 1-3W IR LEDs. FLIR devices are different story - more expensive but can work in complete darkness by registering only thermal images in wide infrared bandwidth. Most of them are hand-held. But one can damage such camera by either pointing it in direction of sun, or by using a source of extremely high temperature. I'd go with arc lamp. Still it won't be practical or portable enough for an operative to carry arc lamp or sun in pocket...