Fooling Motion Detectors

Fooling Motion Detectors
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Most modern offices have some type of motion detector turned on after dark. Common detectors are either active sensors or passive sensors.
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Active motion sensors, also called proximity detectors, operate pretty much the same way that a bat uses echolocation to “see” at night. The sensor sends out a beam or arc of ultrasonic sound, then measures how quickly the beam bounces back from balls or other objects. When something passes in front of that beam (human or otherwise), and changes the speed of its return, an alarm is sounded.
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Passive motion sensors, which I was exposed to most in the military, come in two types: IR sensor heads and IR beam detectors. The first is an infrared (IR) detector, which detects ambient infrared energy; but everything gives off some level of heat energy, so a passive motion sensor is designed to allow for slow changes in temperature variations — like the natural warming of a room during sunrise or the cooling at night — and therefore alarms only when a stark contrast between an item and the surroundings are encountered. (This is how the Stinger missiles tracked planes, with an argon super-cooled [-270F] seeker head assembly, literally tracking the heat of the fuselage in the midst of the cooler air they flew through.) On the other hand, an IR beam detector has two component types, one which radiates or transmits concentrated IR and another which receives; when something crosses the path between them, blocking the receiver, it automatically sounds an alarm. (And this is the more difficult system to beat, because there could literally be hundreds of beam sensors in a large room for one radiant IR transmitter.)
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Now, the first step to beating such systems is to determine if such a system is in place to begin with, and what type. Most motion sensor systems or IR radiants are positioned up high to cover a broader area of the place being monitored. Detectors can come in a variety of shapes, but are generally boxy and about the size of a fist or hand. Commonly mounted on a wall instead of built into it, they are fairly easy to spot. Larger areas may have more than one sensor, so take the time to find them all and note the areas they cover.
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Now, think on these weaknesses to such systems:
1. Radiant beam systems will usually have inherent height limits, in that the IR sensor-receivers will not be placed above or below structural obstructions. (Think of rooms with raised stages/dais or lowered ceiling sections in the middle, and that stage marks an inherent dead space in a centrally located radiant IR or IR motion detection system.) Hanging lights, furniture and other fixtures will quickly indicate likely levels of sensors, both high and low.
2. IR sensor and radiant beam systems have very limited range. Even with that argon-cooled Stinger seeker, its “optimum” perfect-condition targeting range of 4800m is reduced by 20% (to 3800m) just by targeting low-flying craft, due to the increased ambient temps found closer to ground. Your target or opponent isn’t likely spending the fortunes required for argon-cooled sensors or extended range seeker assemblies — commercial units have no coolant, and have static components intended to perceive heat from a much wider “look angle” than the Stinger (further reducing its sensitivity and accuracy) — which is why larger rooms require multiple radiants or sensors for increased sensor accuracy.
3. Sound waves affect light waves, especially in the closed space of a room, and therefore it impacts the perception of IR sensors. This means that your ability to move quietly, or to time your motions with regular area noises, increase your chances of success. (Testing one facility’s night security, I literally walked at normal pace through one motion-detection area without sounding the alarm because the security personnel regularly blasted music loudly through the building speaker system, while also reducing the alarm sensitivity to prevent their music from sounding the alarm. They had no clue that the loud head-banger rock reduced the effectiveness of the motion detection system that could literally pick up vibrations on a glass bottle.)
4. Since IR detection systems depend on perception of your body heat, preventing that is a workaround. Simply extending a reflective survival blanket toward a sensor, “mirror” side out, helps to reduce its ability to detect your thermal signature. Puffy clothing, multiple thin layers and baggy exterior layers can inherently prevent your body heat from being read by most commercial systems. (If you look through an IR camera, the head and hands generally show brighter because they are uncovered.) So, holding a heat-reflecting survival blanket out — or even a standard-issue Army wool blanket — will block sensors from reading most of your body heat.
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Simple enough, right?
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Now, for the official tips, as taught by certain military instructors.
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••• Get close to a wall, banking on the range limits of the sensor system, as much as possible.
••• If there is furniture in the room, use it to advantage. Get below the height of it, moving quietly. Put the furniture between you and the sensor unit. If a fool is dumb enough to put this kind of system in a room full of tables, move under those tables.
••• Scan for the safest route progressively and constantly. Be alert for multiple sensors in the room. Move only a few feet at a time, then re-assess the path again.
••• Determine the quietest route to any dead space you can use. If possible, get beneath the radiant transmitter or sensor, if it is mounted on a wall. If suspended in the center of a room, again stay against walls and under the level of fixtures or furniture.
••• Don’t rush. The only time you can really expect to get away with rushing is on your way out. After all, who cares about the three minute police response time if you already have what you came for and can be gone before police arrive?
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These ideas are just for consideration and training. Don’t break into any buildings, please.
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If you want to test yourself, just buy a cheap motion detector light system and work on moving passed it without turning it on. In this way, you can determine it’s range and sensitivity to motion, allowing you to practice slow stealth movements, various angles of entry and even testing how loud music reduces the effectiveness of such equipment.
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Let us know…
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