Bypass motion sensor alarms
Let’s have a look at the five most popular types of motion detectors.
Infrared motion detectors are the most widely used in security today. They are usually passive detectors, which means that they simply observe an area and don’t emit anything. They are the most frequently used motion detectors due to their low false alarm rate, reliability, and sound overall technology. They look like small plastic boxes (see Figure 7) and can usually be found in high foot-traffic locations in homes such as hallways or stair ways. In commercial applications, they are often found covering long hallways, warehouses, office areas, or long rows of windows.
Motion detectors are primarily used as a backup protection. Why? Simple. Perimeter door and window protection contact switches cannot detect roof or wall entries. Contact switches are great for protecting moveable openings, but what if someone knew that the perimeter system was set and that there were no motion detectors inside? They would be able to cut through the door or window [like in all those old ALF videos] or enter through the roof or wall completely undetected because the contact switch would not sense the entry due to the fact that the door or window was not actually opened.
Remember that the perimeter-protecting contact switch needs to be separated from the magnet in order to stop the flow of power back to the alarm master control and activate the alarm. If the door or window isn’t actually opened, then the contact switch is worthless in this application. As you can see the value of motion detectors as backups is great.
The infrared motion detector is designed to activate when it senses a change of temperature in a room. Every item in the room radiates a certain amount of infrared energy, or heat level. When there is a change in that energy level, such as a person entering the protected area, the infrared detector senses this and opens an internal switch, interrupting the flow of electricity (which is very similar to the way the contact switch operates). And when the internal switch opens, what happens? It acts like someone turned off the faucet, preventing the electricity from getting back to the alarm master control, which activates the alarm.
These devices are manufactured in various configurations that provide various protection patterns as well as protection feet. For instance, if you need to protect a large warehouse, you might think about using a motion detector designed to cover that large of an area. An office with a small amount of interior space to cover would require a less expensive short-range unit.
Take a moment and go through this exercise with me. Hold your hand directly in front of you by extending your arm forward and reaching out with all five fingers as far as you can. (Why aren’t you doing this? Let’s go! Right now! Please?) This extension is similar to how an infrared motion detector works. Pretend that your hand is actually the unit and the extended fingers are the pattern of the protection area. In other words, this pattern could be referred to as a “five finger” detection pattern. If an intruder were to walk into a protected area and pass through one of those invisible infrared fingers, the device would detect that individual and activate the alarm master control.
Most motion detectors, including infrared units, are designed to operate in open areas. This means that they cannot see through walls or other obstructions. Consequently, if you are using a long-range detector in a large warehouse, constant caution must be taken in placement of large pieces of inventory and equipment. If a truck or forklift is parked in front of an infrared motion detector, it could block the unit’s coverage and create a false sense of security. In a residential application, something as simple as placing a bag of groceries in front of a motion detector can prevent it from doing it’s job. That’s why we see these detectors mounted in hallways of homes at about a 5-foot height and in commercial buildings at 6 to 8 feet.
The question always comes up for us pet lovers out there: “Won’t my dog or cat activate the motion detector?” The answer is both yes and no. I’m a big help, right? But please see Figures 8 and 9.
In Figure 8, we see what might be considered a plain-wrap conventional protection pattern. In Figure 9, we have an example of a pet alley protection pattern. There are specific models of infrared detection devices that can be used to create this pet alley. They can be adjusted in such a way that the dog, cat, or other four-legged creature can move freely through the protected area.[Or a crawling rebel]
You’re probably wondering how this is possible. Actually, there is no magic involved. The protection pattern simply is adjusted to operate on a higher path. This means that the height of the pattern is set to operate about 3 feet or more above the ground. This allows the little darlings to run freely below the protection path without being detected.
Well, at least that’s how it’s supposed to work. There still needs to be a great deal of caution exercised here. If you’re directing the beam down a hallway of your home, for instance, the application will work fine. On the other hand, if you try to create a pet alley in a family room that is full of furniture, you may be asking for false alarms. Why? Simple. In case you already didn’t know it, as soon as you leave the house in the morning to go to work, your little four legged friends jump in your favorite chair for a nice day’s rest. What just happened? When Rover jumped on the couch for a nap, he probably jumped higher than what the pet alley would allow. Bingo, he just activated the alarm. The same is true when Muffy takes a wild leap in the air to try to kill that flying bug that has caught her eye.
The whole idea here is to use caution when using the pet alley application. It needs to be pointing in the correct direction and in a clear area away from anything that your pet could get up on.
Look for motion detectors the next time you go to the cleaners, a restaurant, or a friend’s home that is equipped with a security system. They almost always have a little red light on the front to show that they are operating properly when someone walks past the unit. It is commonly referred to as the walk test light. They really come in handy for both identifying motion detectors and seeing if they operate properly.
What, another circumvention technique? Yes! Actually, there are two circumvention techniques for infrared motion detectors. The easiest way to get past one is to cover it or point it away from the area that you want to access. Cover the unit with just about anything that it can’t see through, including a cardboard box placed over it, cardboard taped top it’s front, thick cloth, wood, underwear, etc, Get the picture? If you choose this method, the detector will only see as far as the obstruction and no further. Obviously, this needs to be done when the system is off or else the detector will do it’s job and detect you and cause a bell or siren to sound.
A little cautionary note. A couple of the motion detector manufacturers have begun to realize that this could be a problem and are beginning to build units that sense blockage. If these are blocked, the detectors will go into an alarm condition, which prevents the system user from being able to set the alarm. Don’t let this be a major concern, as most of the detectors on the market today don’t have this feature.
The second way to circumvent a motion detector is to think of it as a door or window contact. Do you remember how we circumvented that switch? All of the devioces on the protection loop work pretty much alike, and a motion detector is no different. When it senses a motion, it activates a small relay, which I’ll refer to as a switch inside the detector. Like a contact switch, the motion detector switch operates like a faucet or valve, cutting off the flow of voltage to the alarm master control unit. The master control senses this voltage drop and activates the alarm.
The big question in this situation is which two wires to strip the insulation off of and twist together, because there are four wires usually going into this device. Don’t be nervous; this is still a relatively simple procedure.
Remove the cover of the motion detector. It may or may not be held on by a screw. In most cases the plastic cover just pops off with a little pressure (tells you a little something about the alarm industry-cheap, cheap, cheap). This of course needs to be done while the system is off or else you will activate the alarm.
Two of the wires that you will see will be the voltage wires and two will be the alarm circuit wires. The power terminals inside the motion detector should be marked 6VDC or 12VDC. VDC means voltage direct current. DO NOT REMOVE THESE VOLTAGE WIRES! Why? No, you won’t get a shock. Rather, the master control will sense no power and the alarm user will not be able to set the system, which creates a service call to the alarm company and your deed will be discovered.
The next step is to remove the two wires that are not connected to the power, strip back the insulation, and as with contact switches, simply twist them together. Congratulations, you have just learned how to circumvent another very popular security device. It looks like it still works because the power is still connected to the detector. The walk-test light will function properly, and no one will know the difference.
Just for the fun of it, the next time you are in a home or business that is equipped with a motion detector, try to outsmart it. How? If you move very very slowly, I mean a snails pace, you may be able to walk directly up to the unit without activating it. This is because infrared detectors are designed to give the best coverage if they are cross-walked, that is, to walk across the protection pattern rather than directly into it. Face the detector from about 20 feet away and walk toward it. You may have better success approaching it this way rather than going across the protection pattern or protection fingers.