Motion sensor wreaking havoc with wireless Internet?

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Old 02-15-08, 06:42 PM
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Motion sensor wreaking havoc with wireless Internet?

Our alarm guy installed a motion sensor yesterday, and since then, my wireless Internet access has gone nuts. When I move the laptop a few rooms away, itís fine. But in any room along the path of the sensor Ė not in its direct line Ė it wonít even recognize the network, or else it canít connect. This is happening even though that zone is ďshuntedĒ while Iím in the house.

Until now, the wireless on this computer has co-existed happily with everything else that should have interfered Ė cordless mice, microwave, baby monitor, 2.4 GHz cordless phones. But now it met its match and gave it up like a cheese-eating surrender monkey .

Is this common? Iím sure people who have motion sensors are able to use wireless Internet, so there must be a way to make them work in harmony. Does it happen with certain brands? Does the quality of the sensor make a difference? I didnít ask him what he was installing, but I can ask him to change it if I knew what to ask for.

I tried to Google, didn't get nada, maybe because I didn't know what to search for. I called the alarm guy, he'll get back to me Monday. Meantime I hope I'll find out more so I know what to ask him.

Thanks!
 
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Old 02-15-08, 07:06 PM
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Hmmm, that's odd.....

If it is a standard or even wireless passive infrared motion, the odds are radically against it being the problem. If it's a "dual tech" device that also use a microwave based sensor as well as the IR, then _maybe_.

The simple and most basic test is to simply disconnect the power (I'm assuming that the thing is hardwired). Open the cover and take one of the power wires off of it's terminal. (no, it won't trip the alarm, it'll just open a zone)

If your interference goes away, then you have found the problem, and you may need a different security solution.
 
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Old 02-15-08, 07:15 PM
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Yeah I'll say that's odd!

Ron beat me to it but I was going to ask if it was one of those microwave types like you see controlling automatic doors. (Those devices are great for setting off radar detectors by the way -- that would be one test if you have one.)

Even if the thing is wireless it shouldn't be interfering with your wireless network... way out of the band and not even close to a harmonic either.

It could be that the device is generating interference but NOT the 'detector' part of the device. (If that makes any sense?) In which case I'd call that defective.

It could also be that the alarm guy did something else that day which caused all this, not necessarily related to that detector.
 
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Old 02-15-08, 08:57 PM
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Even if it was microwave, which is very possible the way some dealers use dual tech's willy nilly, it shouldn't cause a problem. Maybe an old ultrasonic type. Is it about a foot tall and look like a 40 year old speaker?
 
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Old 02-15-08, 09:24 PM
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Originally Posted by Integrator97 View Post
Even if it was microwave, which is very possible the way some dealers use dual tech's willy nilly, it shouldn't cause a problem. Maybe an old ultrasonic type. Is it about a foot tall and look like a 40 year old speaker?
LOL, no, that sounds more like a description of me, if you add about 4 ft 3 in . The sensor is about the size of a nightlight! Thanks for the replies, guys!

I see the concensus is that the problem is most likely elsewhere. That's also why I didn't find anything in Google. I guess the timing is just coincidence, that it began just when the sensor was installed. Hmmm, back to the drawing board.

I gots bigger problems, anyway. I just found out that the sensor is sensoring just fine - it started whining when I didn't sneak out the door fast enough, but the alarm didn't dial the monitoring service. But at least that's an issue the alarm guy will know how to deal with.

Thanks for the quick replies. The system is hardwired, and he did a few things the same day, so it could be something else. I'll mention it to him, but it could be that my computer's wireless devices are finally conflicting with something else in the house that should have caused interference long ago - there are any number of devices around here that could be the cause. So I'll check those out too, one by one. Modern life, very complicated.
 
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Old 02-16-08, 07:29 AM
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Don't be surprised by that delay. Most systems are set to delay the dialer by about 30 seconds to prevent false dispatches.

I didn't think it was likely to be the device. Even if it was wireless, these things work in a very different frequency range from the current generations of wireless networking.
 
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Old 03-19-08, 04:07 PM
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OK, Iím bumping up my own question because the problem was never resolved and I have more information.

Turns out that yes, it is a microwave type of device. Here are the details from the box and info sheet:
ďOptex MX Series Passive Infrared And Microwave Combination Detector, Model MX-40PI.Ē

FWIW, on the side, among the features, it lists:
Easy MW sensitivity adjustment.

From the specs:
Microwave Frequency is 2.45GHz.

Now does it make more sense that itís blocking the network signal? Because since then, we havenít been able to even see the network when we plug in the laptop in any of the rooms beyond where the motion detector is installed, in a part of the house where we had great signal reception previously. Also, the wireless signal works perfectly Ė even through walls and floors Ė as long as itís nowhere near the path of the motion detector.

If this device is indeed the culprit, is there anything we can do to get it to play nice with the network, short of dismantling it?

Many TIAs
 
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Old 03-19-08, 04:24 PM
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The simple and most basic test is to disconnect the motion. If your network issue goes away, then you need to either swap it for an IR only device, or relocate it to a space that doesn't paint your network work area.
 
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Old 03-19-08, 06:03 PM
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I think 2.45 GHz is one of the frequencies

used for wireless networking. The sensor operates on that frequency, probably blocking the signal near it, since the network signal is not designed to be very high-power.

Have you tried changing the channel your router is using? Linksys routers default to channel 6, not sure about others. It may help. I think the laptop will automatically switch to the new channel, as long as the SSID is broadcasting, if not, you'll need to adjust the network settings. Give it a try.

Can you move the router, preferably into the problem area? Even as just a test? The extra signal boost may help.

If changing the channel or moving the router doesn't work, then you're kind of stuck. You'll have to power down the sensor, making it useless; replace it with a PIR only model, if possible; or find one that operates on a different frequency.

Your last option is to accept the situation as is.

Dumb question, but would it be possible to use a wired connection where you're looking to use the laptop or device? Running a wire between the location and your router may not be too hard and eliminate the problem.

I hope this helps!
 
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Old 04-08-08, 09:04 AM
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Update: Thanks so much for all your help! In some ways, I get a more useful education here than I ever got in school.

The alarm guy switched the sensor for an infrared-only one. The wireless network works perfectly, as before, and we're surfing happily ever after.

Just for the record and anyone who might be reading this in future, lesson learned is that evidently, a microwave motion detector can in fact interfere with a wireless network, even a network that has never had problems with interference from cordless phones or microwave ovens.

We tried a lot of other solutions first. Changing the channel the network was using (to Channel 8), moving the router around, changing the router, changing the modem and router to a new modem/router combo, moving the computer around, trying to get a signal with three laptops, 2 network cards, and 2 USB network adapters, enabling (and then disabling) static DHCP. Nothing helped. But as soon as the computers were taken out of the area covered by the motion detector, they got the wireless signal perfectly.

And the second the alarm guy pulled the motion sensor out – while he was still standing on the ladder - the wireless signal on the computer we were using as a test was already blinking. So it was quite apparent that this was the source of the problem, even though I hadn’t been able to find a lot of info about it previously.

Once the wireless network was broadcasting throughout the house, all the previous configuration settings worked perfectly again. Essentially, at no time was there a problem with the wireless network itself, as long as we stayed away from the area covered by the motion detector.

I don’t know the details of the infrared-only motion detector he installed as a substitute, but will check if I can and edit this post. He did not mention that there would be any change as far as how it is expected to function. I don’t know what the benefits are of a motion detector that combines infrared and microwave, but in our case, where we need a wireless network to function in the same space, the infrared-only seems to be a better choice.

Thanks again. I would never have been able to get to the bottom of this without your help, especially since apparently this is not a common problem, even according to some of the comments in this thread.
 
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Old 04-08-08, 08:52 PM
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The dual tech motions are a good bit less prone to false trips than IR only (both the microwave and IR have to agree that there is motion), but if it's interfering with the network signal, then all you can do is go to the IR only unit.

Functionally, there really is no practical difference.
 
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Old 04-08-08, 09:40 PM
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Curious. What brand and model motion detector is it?
 
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Old 04-19-08, 01:56 PM
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Originally Posted by Integrator97 View Post
Curious. What brand and model motion detector is it?
The one with the interference problem (combination PIR/Microwave) was the Optex Motion Detector MX-40PT.

The replacement (infrared only) - I don't know. I only know the first one because by chance the installer left the box behind, which luckily gave me the first clue what I might be dealing with.


Originally Posted by MrRonFL View Post
The dual tech motions are a good bit less prone to false trips than IR only (both the microwave and IR have to agree that there is motion), but if it's interfering with the network signal, then all you can do is go to the IR only unit.

Functionally, there really is no practical difference.
Now this all leads me to the obvious question (a rhetorical one, in absentia, to my alarm guy): Why not install this in the first place, when I told you that I was having problems with the network from the minute you installed this device? He kept telling me that since the alarm system itself is wired (not wireless), that couldn't be the source of the problem.

He didn't tell me that you could get an infrared-only motion detector, and that functionally it was just about the same as the combo one, and he didn't make the switch until I specifically pressed him to do it. If we wouldn't have a relationship with this guy that's older than some of our children...

P.S. The replacement (infrared only) has been working without any glitches since it was installed. No false trips, and I know it works, because when I stand in its path, I can see it detecting me by the lights on the alarm panel. And needless to say, I'm posting wirelessly right now .
 
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Old 04-19-08, 07:08 PM
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Interesting. I may have to experiment with that. Also, what kind of wireless router are you using, and is it b/g?

Alot of dealers use dual tech's all the time, which is not necessary. Just a way to prevent false alarms when you don't know what your doing as an installer, don't know what to look for.
 
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Old 04-19-08, 07:43 PM
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He went with the dual tech because motion detectors are the largest source of false alarm trips, and those devices cut the incident of false trips by a lot.

The interference of the microwave with the WiFi was a sheer dumb luck thing.
 
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Old 04-19-08, 08:31 PM
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Well, Ron, I didn't think I'd ever be saying this, but I partially disagree with you. I know what you guys are all thinking. Who woulda thunk it?

Yes, most environmental false alarms are probably motion detectors. But that's because so many installers, as I said, don't know what they're doing. Oh, also they want to use the cheapest thing they can find. You get what you pay for.

I use hundreds upon hundreds of PIR's with no microwave, and have no false alarm issues, except when one fails. I have rarely used dual techs. I even use PIR only in warehouse & auto repair shops, with no problem (I use the Crow Genius dual element PIR, have never had a false even with birds and mice). But I make sure to always use a good detector, placed in the right locations.

If you have a PIR that falses due to the environment, you might just as well put in a microwave only, because the PIR part will still be falsing all the time. So why bother with a dual tech, just go to the microwave. Assuming it's already been properly placed.
 
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Old 04-20-08, 02:24 PM
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For the most part, you are very correct. With a little bit of knowlege of _how_ PIR devices actually work, and 5 minutes of actually _reading_ the install instructions, most false alarm issues are easily avoided.

The problem often found here in N. FL, especially in places like commercial offices is that the desired coverage areas are often places like glass walled lobbys where you have the problem of sunlight generated hot spots suddenly appearing on days when such offices are closed (not an issue on normal weekday schedules), or the HVAC system suddenly sending a blast of cold air into the space.

That's the differenced between a simple installer, and a real technician: Knowing the proper application for a given piece of hardware and system configuration.

Bluntly, many of the mass market installing companies tend to default to the most "idiot proof" package they can sell, because they, most of all, are feeling the heat from the false alarm ordinances that their own practices engendered.
 
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Old 04-20-08, 02:59 PM
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Originally Posted by MrRonFL View Post
For the most part, you are very correct. With a little bit of knowlege of _how_ PIR devices actually work, and 5 minutes of actually _reading_ the install instructions, most false alarm issues are easily avoided.

The problem often found here in N. FL, especially in places like commercial offices is that the desired coverage areas are often places like glass walled lobbys where you have the problem of sunlight generated hot spots suddenly appearing on days when such offices are closed (not an issue on normal weekday schedules), or the HVAC system suddenly sending a blast of cold air into the space.

That's the differenced between a simple installer, and a real technician: Knowing the proper application for a given piece of hardware and system configuration.

Bluntly, many of the mass market installing companies tend to default to the most "idiot proof" package they can sell, because they, most of all, are feeling the heat from the false alarm ordinances that their own practices engendered.
Well, we're not that far apart after all.

BTW, have you used the microwave with the 4 distance settings? 9, 18, 27 & 36 feet. You can put it above a ceiling or behind a wall, or control a roped area. Pretty cool.
 
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