By crawling under it ? Thats why I say multiple beams.
Provide link to seismic detectors.
Provide a link to what a wired alarm screen is.
Please provide a link to these.
Its a generic term, could be a PC that sends you an MMS or SMS. Or somebody in India that manually inspects a beam break if there are to many false alarms.
A-A-hahahahahahahahahahahahahaha! Priceless!
Just so you'll understand, the reason Frank laughed is that idea is a fable.
I'm a little late to this thread but I don't believe this is a fable. I was experimenting with this earlier in the week and I can walk right past my motion detectors by wearing a winter jacket and hiding my face or by holding a blanket up.
Doug
Yeah? What's the make and model of the detector? How is it mounted? Without getting into ways of defeating motions, you have to understand how they work. PIR's utilize a faceted lens. In order to sense "motion" you have to walk across the face of the lens (perpendicular to the detection zones). Old style ultrasonic and any microwave type motion sensor depends on the doppler shift of a target moving TOWARDS the detector. A PIR has a difficult time picking up motion when you move towards it. A microwave detector would have a hard time picking you up if you walked across it's field of view whilst maintaining your distance from it. There are "combo" units made up of a microwave element and a PIR. In most instances both detection methods have to be tripped for a valid motion "event". If you walk slowly enough, you could fool most of the cheaper detectors (and even some of the more expensive "pet proof" ones). I run into customers that have to "test" the "quality" of the sensor by using the "shuffle across the floor with your head down and back bent" method all the time. I can assure you that the average thief isn't going to be doing an "old man" impression when he breaks into your house to try and fool your motion sensors. Besides, in a properly set up perimeter type security system the motion sensors are there as a "backup" (or to protect a special area) and you'll get an alarm generated *BEFORE* he even sets foot in the house.
It's a DSC alarm system, professionally installed a few months ago. The invoice lists the motion detectors as "ISMBLP1P - 40LB Motion Detector" They are installed in the corners of the rooms, about 6.5 or 7" from the floor.
I wasn't trying to make any comment about whether motion is a first line of defense or not, or about how patient a theif might be. I was mearly pointing out that it is not a myth that insulation can be used to fool a PIR motion detector. I'm aware that PIRs are most effective at picking up perpendicular motion and I moved perpendicular to the detectors at distances ranging from 4 to 20' and was able to fool it every time, even moving rapidly.
If you know all this and were just trying to keep the secret out of the hands of the bad guys, then I can only say, oops, sorry. :)
Doug
Bosch Blue Line ISM-BLP1-P ?? Never used them, but I can tell you now it's mounted too low. The manufacturer recommends a mounting height of 7.5'-9'.
Oops, typo. I meant they are 7 feet from the floor not, 7 inches.
Doug
This is confusing the issues. What you say is true but PIR works on the difference in heat no matter from what direction you are moving. If the crook puts on a thermal insulating suite he will get past because the PIR can't detect the heat, heat is the issue. With IR leds and microwave it isn't heat.
You are somewhat correct but still don't quite understand the concept of how a PIR works. A PIR looks at the "difference" in heat. A thief wearing a "reflective suit" is still going to change the heat signature of the room as he moves through the protected space. Some PIR's have a difficult time determining a motion event if you walk directly towards them (depending upon the size of the lens facets you could successfully traverse the entire room and stand right under the sensor without it ever detecting you). If the sensor isn't responding as it should, I would suggest the OP have the units changed to something a bit more "responsive". Paradox makes excellent motion sensors (both PIR and Micro-wave). The DG-65 is "aces" in my book. It has quite a wide viewing field at 110 degrees (for a wall mounted detector) and is available through most distributors in the US. I have no experience with Bosch products so can't offer any insight into the OP's situation.
They may not be properly set up. Most detectors have a height adjustment and you can also make horizontal adjustments to the lens. In order to set up a motion sensor properly you have to adjust the unit and make sure the detection pattern is optimized for the room and the height of the sensor. This involves rather extensive "walk testing" and could take between 15 and 30 minutes to "get right". I've also learned (through experience) that some sensors "fall asleep" after extended periods of inactivity in the room. The Rokonet 6000 in particular was prone to this even though it had one of the best detection patterns I'd ever seen.
Yes and no. Certainly if we were to develop a heat signature accurate to a fraction of a degree at every point in the room, this is true. However at a lower level of accuracy, this suit could be at the same temperature as the objects the their is walking in front of. The more "accurate" the heat signature is the greater the chance of a false alarm. So would it be possible to build a sensor that wouldn't have excessive false alarms but could still not be fooled? I don't know. What I do know is that I can fool my motion detectors this way, and I bet there are a huge number of other motion detectors installed that can also be fooled in the same way. So to laugh at the premise or to call it a myth is unfair. It *can*, in fact, be done, although perhaps not with all PIRs or all installations.
Doug
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