Motion Detector types

[suemarkp]

Since I seconded the request to create this group, I guess I'd better post a question. Does anyone know about the characteristics of different IR motion detector implementations? I bought a Voice Alert system that uses wireless outside motion detectors to detect cars or people coming up the driveway, and a second one to monitor the pool gate.

The motions work great with people. However, cars don't reliably trigger it. Are there IR motion detectors that work better for detecting people and animals, but not metal objects? I've got it pointed in such a way that it is about 90% reliable for cars coming up the drive and 60% for cars leaving the driveway. But in this position, cats trigger it too. It seems that a hot car (arriving) may be why I detect them better (plus, arriving cars show the exhaust to the sensor whereas leaving cars show the cooler front).

Any ideas for how to improve this? I really don't want to have to end up with a light beam across the driveway because it needs power and running a 100+ foot power cable won't be fun (expecially if I need it on both sides of the driveway).

[dkerr]

Is there any adjustments on your IR motion detector ?

If there is you may be able to adjust one or two things -
a) how rapid an IR (heat signature) change will triger it.
b) what intensity will cause itto trigger.

cars of course will be hotter coming into the driveway than leaving.

Other types of motion detectors will send out a radio signal, and will be able to detect changes in the reflected radio signal (motion - something moving to cause changes in that reflected signal), this type should detect a car coming or going. An infrared will need a heat signature change trigger.

Heavy rain can also give false triggers for certain types of motion detectors.

For cars most of heat is under the hood of the front of the car, exthaust in the back of course, only heat sourse would be the radiator, some of the headlights and exhaust, and will likley with some IR detectors need to look lower to read it than with people, which as you mentione will get the cats and dogs also.

Not sure what the solution is though, perhaps others may have some ideas to pass on.

Don

[Wgoodrich]

When using infrared you will always have issues with false and missed signals. I suggest you buy a pressure switch for closure switch and a hose agross driveway. This would sense any vehicle but not cats and dogs not carring anything except ice and thick snow packed causing this system to also fail.

Infrared light beam as you spoke of with a reflector on other side of drive beaming back the signal would work better. The do have low voltage light beam sensors for security system. You would need to create a hood to protect from weather. Same wiring would work for either a motion or a security low voltage light beam. Check with your security salesman that supplied the motion and ask for a beam and reflector. This beam low voltage looks like a receptacle will need an aiming device.

Good Luck

Wg

[Ron]

Here is a link to some good information.
http://www.smarthome.com/solution10.html
http://howstuffworks.lycoszone.com/question238.htm
I don't have any good solutions other than has been offered.

[suemarkp]

Thanks for the great answers. These motion detectors appear to have no adjustments, but I'll look to see if there's a potentiometer that can be adjusted on the board. I'll also see if I can get some tech support from the company that makes them.

Wg, the pressure sensor is the perfect solution -- requires no power and should plug right in to the contact closure switch on the detector/transmitter. I'll see if I can find something inexpensive that will work.

Ron, the links you provided were useful too. It explained something I noticed when adjusting the orientation of the detector. I had my car window down and was staring at the sensor which has an LED that goes off when it detects. I thought it was detecting my face, and sure enough when I closed the car window, the LED came on much less often. The lycos link explained that glass reflects most IR, so the detector could no longer detect the driver when the windows are up. Reliability improved when I realized that and aimed the sensor to detect hot exhaust instead of the car window area.

[Wgoodrich]

Look in the motion sensor for a jumper wire. ON many models this jumper wire can be moved to increase or decrease how often the sensor cycles for sensing. The motion sensors are normally made with this jumper wire adjustment for example a building being protected that has rats and mice such as pole storage building to reduce sensitivity a lot. Then for a minute adjustment such as for moths only move one space instead of the maximum adjustment.

Hope this helps

Wg

[Unregistered]

For detecting vehicles entering a driveway, you might also consider a device such as these:

http://www.automatedoutlet.com/customer/home.php?cat=82
http://www.smarthome.com/secvehicle.html

I have no prior experience with them, but I may eventually give one a try. If I do, and I have good results, I'll let you know.

Regards,
Don

[Unregistered]

For detecting vehicles entering a driveway, you might also consider a device such as these:

http://www.automatedoutlet.com/customer/home.php?cat=82
http://www.smarthome.com/secvehicle.html

I have no prior experience with them, but I may eventually give one a try. If I do, and I have good results, I'll let you know.

Regards,
Don

[Unregistered]

Oops. Sorry about the double post. Troublesome keyboard...

[suemarkp]

I first statrted with a product like the Smarthome #7171. It worked OK for a year or so, and then was unreliable. It also ate 4 D batteries about every 6 months. The other devices you posted require wires to be run or are rather expensive. I could use a loop system on my existing motion with the contact closure input, but they seem expensive to add to my already expensive wireless motion sensor.

The air break switch will be the next solution I add, as the parts are about $30. Finally found one online at a car wash supply site.

[Unregistered]

Thanks for the info Mark. Sounds like I should consider other alternatives as well then.

Regards,
Don