Motion sensor false alarm advice

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#1

[Sorry if this is a duplicate. I tried to subscribe to replies and appear to have deleted the original.]

My place gets broken into a lot, usually by breaking and climbing through the windows. At this point I stopped fixing the windows and just put boards or cardboard over them, which I know invites more break-ins, but I can’t fix a broken window every single week.

So… I thought motion sensors would be my best bet. Yesterday, I installed a bunch of Qolsys IQ S-line motion sensors. I set up my motion sensors high in the corners of my rooms, pointing at 45 degrees away from windows and slightly downwards. I placed them 8-9 feet off the ground, higher than the recommended 6.5, in the hopes that they would be harder for the intruders to damage. I tested them and they still triggered fine.

Today, one of the motion sensors triggered twice. The first time seems to have been a false alarm. The second time I haven’t investigated yet.

Last night someone did break in and ripped one of the sensors off the wall, but that sensor seems to be okay and work fine still. It is a different sensor that has triggered twice. That sensor is mounted slightly higher than the one they ripped down and appears not to have been touched by the intruders, though it’s of course possible they somehow sabotaged it. The intruders like to break in regularly, so are always looking for ways to make it easier to get back in.

Any suggestions on what might be causing false alarms? There are windows in the room, but the motion sensor is in the corner, angled diagonally away from them. The room is completely empty and isn’t especially sunny. There’s a gate about 25 feet away, so people shouldn’t be able to get that close from the street. It’s possible someone could be shining a flashlight or laser pointer into the room to trigger false alarms and discourage the police from responding, but the sensor is not directly visible from the window, being in the corner of the room.

Any other suggestions on how to deal with this? I thought about image sensors, but I would want to point those towards the windows to see who is climbing in, and that presumably would cause even more false alarms. Should I install two motion sensors in the same room and only consider it a real alarm if they both trigger?

I really want these people to stop breaking into my house, and I fear they will stop only once the sensors are accurate enough to send the police over every time the alarm triggers. The ordinary door/window sensors do nothing for people climbing through windows (or trigger only at the end when the intruders are leaving).

#2

One more point to add: This is a long room (about 20 ft) and on the wall opposite the motion sensor and windows, there is a closet with mirrored doors. Could the reflection of a pigeon outside the window 20 feet away trigger the alarm? Or could changing daylight from clouds and such cause this?

#3

There is a lot here, so we will try to address everything.

However, in general to get a better idea of what is going on, is this a home you are currently occupying? This sounds like a vacant property based on your description.

Based on your description there would be a huge number of possibilities for false alarms. I’d be very happy to help with suggestions but it would be important to get a better understanding of the property first. In general though false alarms on the motion detector are likely caused by something in the environment:

  • Is the property climate controlled via HVAC? PIR motion detectors detect disturbances in passive infrared radiation against the background (essentially the heat signature). If the location is not temperature controlled, standard indoor motion detectors would not be recommended. You would want to use outdoor models.
  • Motion Detectors should always be installed based on manufacturer instructions. Altering the height and angle will place a higher risk of false alarms.
  • Broken windows allowing drafts could cause false alarms.
  • Insects/Spiders crawling across the face may cause false alarms

Ultimately for standard indoor motion detectors, it sounds like you may be describing an unsuitable environment. They will still function to set off an alarm when an intrusion occurs, but there would be no real expectation that false alarms could be avoided.

Regular, repeated intrusion is a difficult problem, and one that the sensors are not necessarily designed to address. The detectors are designed to:

  1. Assume no disturbances occur regularly
  2. Catch any disturbance that occurs, against the intruder's efforts to mask the intrusion

In this case you would need to filter lots of possible disturbances that aren’t humans. For that it would be best to utilize a model of wired motion detector which uses dual PIR and Microwave to detect intrusion, probably outdoor models would be best.

Something like this might work well, which uses microwave and pir, with draft, vandal, and insect protection, has a variable mounting height, and can be set to require both PIR and Microwave to trip in order for an alarm to be reported. The detection circuit wiring can then be run to either a Hardwire 8/16 to wirelessly relay to the Qolsys IQ Panel 2, or can be individually wired to a sensor with a wired input, like the RE101, to act as a transmitter.

This video shows a similar concept, using the RE101 as a transmitter for a wired door contact. The motion detector would work similarly but would also require 12VDC power.

To some of the questions above:

There are windows in the room, but the motion sensor is in the corner, angled diagonally away from them. The room is completely empty and isn’t especially sunny. There’s a gate about 25 feet away, so people shouldn’t be able to get that close from the street.

If the glass here is intact, note that the infrared heat signature is not transmitted through glass. People walking by outside a closed window will not trigger a PIR.

If sunlight can hit the detector face it can cause false alarms, but the environment overall is a more likely factor.

Should I install two motion sensors in the same room and only consider it a real alarm if they both trigger?

No, but you’re on the right track. You should probably use a detector which uses both PIR and Microwave to determine if an alarm occurs. It is not recommended to create a situation where you ignore certain alarms, and traditional cross-zoning is normally used with multiple types of sensors or multiple rooms. Two nearby motion detectors would be susceptible to the same false alarm hazards.

I really want these people to stop breaking into my house, and I fear they will stop only once the sensors are accurate enough to send the police over every time the alarm triggers. The ordinary door/window sensors do nothing for people climbing through windows (or trigger only at the end when the intruders are leaving).

Door/Window sensors have the benefit of few false alarm concerns when installed per instructions, so if they are tripped you can be certain of activity. Yes, if the windows are not opened and just climbed through they would not be tripped though.

One more point to add: This is a long room (about 20 ft) and on the wall opposite the motion sensor and windows, there is a closet with mirrored doors. Could the reflection of a pigeon outside the window 20 feet away trigger the alarm? Or could changing daylight from clouds and such cause this?

The reflection of an object outside does not impact infrared radiation being emitted. The sensor only “sees” the mirror itself. Sunlight reflected directly on the detector face might have an impact, but the environment has more likely false alarm hazards.

#4

Thanks for all of the advice. Indeed, the house is currently empty. However, there is no HVAC. The climate is pretty temperate here, so inside/outside is about the same temperature. One of the windows is broken and boarded up, which could be letting in a draft. However, there are no insects or spiders that I have seen.

What’s puzzling, however, is that I have another room (also with a broken window, boarded up even worse), with a similarly installed motion sensor also angled 45 degrees away from windows facing the same direction (though effectively perpendicular, as both are in opposite corners of the house). The other room also has more sunlight, but it has never given a false alarm. (Fortunately that’s the room through which people have been breaking in more recently, so being able to count on that motion sensor is good.)

I did notice something yesterday: Across the street from me is an opaque, outdoor, giant industrial roll-up garage door that is accessed 24x7. It’s at least 40 feet from the room in question. Nonetheless, I got a false alarm exactly when that door was opened. The door is clearly visible in the mirrored closet doors, though it’s 20 feet from the sensor to the mirror and 60 feet from the mirror back to the window and on to the neighbor’s garage door. Yesterday I thought the garage door might explain the problem, but based on your explanation that the sensors use IR, I’m less sure. I should say I get more false alarms during the day, but got one at 10pm, so exposing a bunch of hot pavement that has been baking in the sun when the roll-up door opens can’t be the only explanation.

I guess I’m considering two courses of action: 1) swapping the two sensors in similar rooms, just to make sure that the problem doesn’t follow the sensor (in which case I probably got a bad or sabotaged sensor), and 2) just re-positioning the problematic sensor so it faces perpendicular to the windows and mirror. Is #1 worth it? Is #2 okay even though the sensor might “see” the windows out of the corner of its view?

#5
It’s at least 40 feet from the room in question. Nonetheless, I got a false alarm exactly when that door was opened. The door is clearly visible in the mirrored closet doors, though it’s 20 feet from the sensor to the mirror and 60 feet from the mirror back to the window and on to the neighbor’s garage door. Yesterday I thought the garage door might explain the problem, but based on your explanation that the sensors use IR, I’m less sure.

Well, I will clarify and say that IR can be reflected. IR is light radiation, but does not have the same properties as visible light. It can be reflected by mirrors.

What you are describing though is a situation where an object outside a window is reflecting on a mirror inside the home. Glass will block and actually reflect some of the IR spectrum used by PIRs. This is part of the reason you should not aim them toward glass windows.

There is actually an interesting service bulletin I just saw from the past few days for Qolsys. There were corrective measures placed in IQ Panel 2 firmware version 2.2.0 for a false alarm issue caused by the way IQ S-Line Motion detectors shipped from Qolsys to distribution between May and July of 2018. Apparently there is an issue caused by the way the sensors report supervision to the panel which causes an alarm. 2.2.0 addresses this.

Ultimately if drafts are possible I would recommend the dual PIR and Microwave detector. But you might check the date codes on the PIRs to see if any fall within 1820-1825. Those are the ones affected. The date code will be the first four digits in the middle of the SN.

To update the firmware:

1- Swipe down from the top of the screen and touch “Settings"
2- Touch “Advanced Settings”
3- Enter a valid installer code (default is 1111)
4- Touch “Upgrade Software”
5 -Touch “Patch Tag” and enter the patch iqpanel2.2.0 then touch OK
6- Touch “Upgrade Using Network” (panel must be connected to Wi-Fi). Update will download and install
7- Once complete touch “OK” to reboot the panel. DO NOT TOUCH THE SCREEN. The update process will
take approximately 5 minutes. After the panel reboots the home screen will appear and the LED will turn green.