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Author Topic: Looking for guidelines and help with locating and positioning motion sensors  (Read 4867 times)

JoKer

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I've been looking all over the forum for info about positioning multiple outdoor motion sensors so that they play nice together, but I am not finding much that seems applicable (other than one topic that looked like it was related but what I read of it just seemed to be a mutual dissing contest and not much help).   So in frustration, I'm just going to dive in and ask - and beg forgiveness if this is redundant to something already discussed elsewhere.

I have been trying to install several PR511 outdoor motion sensors in order to detect activity around my house and barns.  I am explicitly NOT using any of the wireless motion sensors due to some functional problems with those in my application.  I am using only the sensor portion of the PR511s and not the floodlights.  This is because I want the sensors to work 24/7 but I don't want the floodlights turned on during the daytime (wasteful), and in some of the locations, I don't even want floodlights to come on at night (causes disruptions).  So, I use only the motion sensor portions and have AHP to receive those triggers and deal with them as is applicable to the sensor location, time of day, and so forth.  Eventually I would like to trigger a camera and video recorder, at least for some of the locations, but that is future functionality.  For now, I just want to get the sensors to cooperate with each other.

I have installed a few PR511s, locating them where I THOUGHT they would cover the desired area(s) and would not interact with each other.  By interacting, I mean situations where two or more of the sensors trigger on motion in a particular spot when I want them to react only to their own areas.  Unfortunately, I run into not only that interaction problem, but there are also some places that are dead spots for no obvious reason.  I mean places that are within the range of a sensor but the sensor does not react to movements in those particular spots.  Because it takes a lot of work and materials to install PR511s in locations where there is no electrical fixture already existing, it makes it difficult to experiment with relocating the sensors to try to fix the problems.  So, before I do a lot of possibly useless fussing around, I wanted to ask these questions:

  • Are there any guidelines about locating and positioning PR511s that will help to prevent these problems?  (I have already followed all the recommendations in the instruction sheet and wiki literature, and I even swapped a few of the sensors to see if it was a problem with an individual sensor.  It was not, but I get the feeling that it does relate to the location or positioning of the sensor somehow).
  • Are there situations where it would help or even be necessary to have more than one sensor looking at the same area in order to get full coverage of the area?  If so, what are those situations?
  • How do I arrange the sensors so it avoids having two or more sensors react to spots that should trigger only one sensor?  (In other words, how do I create discrete sensing zones so I can tell where the motion is happening?)
  • Is there any more detailed info about the effects of physical factors such as mounting height, orientation of the sensor (i.e. - pitch and yaw), "dead air space" around the sensor, lighting levels in the area, etc. that would help me to pre-determine optimum mounting locations?
  • Any other helpful advice, tricks, workarounds, or whatever?

Sorry for the length of this.  I am totally frustrated by what a can of worms this simple job is turning into.
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dave w

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You may have been reading the thread where the OP could not get repeatable, consistent trigger points, and did not accept the fact that so many external factors influence the sensitivity of the detector.

My own experience with PR511 and xxxEye motion sensors has been: point in a downward direction as much as possible for more consistent triggers. Which means if you have a large area to cover, get the sensor mounted high to be able to point it downward. The detection field described in the X10 literature is accurate as long as you remember that external factors make the detector "range" very dynamic. Ambient temperature is probably most influential, but wind and sunlight also impact to a lessor degree. I don't think it possible to find a position where the sensor "boundaries" remain consistent from day to day, month to month.
$0.02
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JoKer

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Thanks for replying.

Do you know why it helps to angle the sensors downwards?  It is unfortunate if this is necessary to make them work properly because I have a couple locations where I need fairly long detection ranges (like 30' or more) and my understanding is that angling the sensors downwards will greatly reduce their range.  (Is that correct?)

Is there any good way to deal with the need to zone the sensors?  I would like (no, I need) to be able to tell where intrusion is occurring.  Is this feasible?

Beyond the problems I mentioned earlier, I also want to be able to detect animals and vehicles, not just humans.  I know the sensors are designed to avoid animal detections, but I am mainly concerned with larger animals, that is, the size of large dogs and bigger.  In that regard, there are a couple of things that really puzzle me about the response of my sensors:
  • During the daytime, they react fairly well to people and various animals, including fairly small ones, but quite often the sensors do not respond at all to people or animals at night.  I would expect the opposite to be true, because the background is cooler at night, so the warm bodies should cause more thermal differentiation at night, making them more detectable then, shouldn't they?  Any idea why the things don't work well at night?  Is it just me or does it seem really odd that FLOODLIGHT controllers don't work at night??
  • I am really surprised that the sensors often do not react to cars and trucks and tractors but they do react to humans and animals in those same areas.  I would expect the sensors to respond better to vehicles because of all the heat coming off of them from hot hoods, engines, radiators, exhausts, even lights.  But they do not, and I'm really puzzled about that.
Can anyone explain why the sensors react in these ways that seem counter-intuitive?  And more importantly, is there any fix for it?

Thanks!
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dave w

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Angling downwards seems to reduce sun's influence. My units trigger on quickly changing sunlight patterns. Angling down helps eliminate that. Yes pointing downwards will reduce range. Zoning is trial and error. I don't think there are shortcuts. Also The problem that I see in my application  is "today's zone" won't be "tomorrows zone". After two decades of playing with positioning I haven't found a solution.
As far as day and night detection, yes they should be more sensitive at night since it is cooler, but at night people tend to wear more clothing which acts as insulators. Don't know about the animals unless "insulation" is also a factor. In other word a beagle that triggers the 511 during the day at 20 feet should trigger the same 511 at night at the same distance or farther.  Some cars are pretty well insulated and more difficult to detect. I have a ActiveEye on front poach which "looks" out at our dead end street. one neighbor's car triggers the eye frequently (almost what one might call consistently  ;) , the other neighbors cars do not. I only speculate that the detected car has a greater heat signature. Y

our last sentence: I can't. I haven't come up with any.

Finally, and I'm sure your have read this and are aware: The motion detector does not do as good a job of detecting bodies, cars, dogs, moose, etc.  moving directly towards it, compared to bodies moving across it's field of vision.
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JoKer

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My units also trigger a lot during partly cloudy and windy weather, where cloud shadows are moving around a lot.  Makes the sensors go nuts sometimes.  Other than that, I haven't noticed any sunlight issues, but I have taken steps to make sure the lenses are not exposed to the sun at all, so maybe that is helping.

I really need to do zoning somehow.  It's sounding like it may not be feasible to use these sensors for that.  If that's the case, then are there any good alternative sensors?

The reaction of my sensors during the day is fairly consistent, and the non-reaction at night is also really consistent.  It puzzles me no end why they don't work most of the time at night.  Is there some setting that I've mucked up?  It is really unclear to me whether the various settings interact with each other, and if so how.  It leaves me wondering how to optimize the settings.

In regards to the motion towards the sensors not being very detectable, that reminds me of a couple other questions:

First, I believe the sensors are more sensitive to horizontal motion compared to head-on motion because horizontal motion causes the heat source to be focused on and off of the sensor, while head-on motion may not cause the heat source to change on the sensor.  If this is correct, I'm curious whether the sensors are sensitive to vertical motion as well as horizontal motion?

Second, I have a challenging installation in one spot.  The situation is a driveway that runs along side the 50' length of a barn.  The driveway is about 12' wide, and about 20' beyond that is the edge of a parking lot where trucks are likely to be active.  My need is to detect any activity in the driveway beside the barn, but ignore the activity of the trucks in the nearby parking lot.  I tried putting a sensor high on one corner of the barn, where it was aimed a little wide of being parallel to the driveway.  This is sort of contradictory to the need to avoid head-on motion because the sensor is sort of looking down the length of the driveway.  In any case, it does not do well for detecting movements in the driveway, but does manage to react fairly well to the motion in the parking lot next door.  (It figures!)  This isn't really surprizing because the motion in the parking lot is more horizontal in relation to the sensor, while the motion in the driveway is more head-on to the sensor, although both motions are well below the plane of the sensor.  Anyway, my question is whether there is any way I can set up sensors so they will detect motion in this driveway but not in the parking lot?  I was thinking it might work to mount a sensor under the eave of the barn about at the midpoint, and angle it almost straight down, so that it would be shielded from the motion next door, and all motion in the driveway would be essentially along its horizontal plane.  Or, is there some better approach?

Thanks again!
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dave w

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The vertical vs horizontal is an interesting question. I haven't played with the detectors in that respect. The front fresnel lens has gradations denser near the top of lens vs the gradtions at the bottom. Obviously X10 did it for a reason. maybe an "optical guy" can explain the effects the fresnel lens as far as focusing the IR on the IR pick-up in the unit.

Maybe you could use the xxxxEye to find the best position for the 511s. I believe they use the same IR pick-up. I'm not sure if the fresnel lenses are the same. Not much help....sorry.
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JoKer

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The vertical response question came from that idea to aim a PR511 straight down so that it would only react to sideways motion, that is, along the driveway, which would be now in the horizontal aspect in respect to the sensor's normal orientation.  The vertical question came up because I was wondering whether a sensor oriented down like that would be able to react to motion across the whole width of the driveway, which would now be in the formerly vertical relationship to the sensor.  I'd like to test the idea somehow before going to the trouble of installing wiring for it, or maybe someone has some applicable experience to draw on?

In regards to using the wireless motion sensors to test for PR511 locations, I don't think that would work out because the main reason why I don't use any of those wireless sensors is that when I tried them (before getting PR511's) they reacted constantly outdoors.  That is, they were triggered almost all the time during the day, and so they were practically useless.  The PR511s suffer from some bogus triggering, but at least they do react to some real events.  In any case, I don't think the wireless sensors would give any sort of realistic comparison, although it may be that I configured them wrong somehow.  I don't know;  they worked OK indoors, but not outdoors.

I suppose I could put a plug on the wires from a PR511 and hang it up with an extension cord for testing, but with my luck it probably would flop in the breeze and give false results.  In fact, I really never have found a good way to test those sesnors before installing them, and that has come back to bite me in a couple of cases.

Oh well;  I guess it is all going to be trial and error.  It really makes me wonder if there is some better way to detect people, larger animals, and vehicles, because these sensors are being a royal pain in the behind!
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JoKer

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Just an update - and maybe a question:

I mounted my driveway PR511 sensor high on the side of the barn (under the eave), about in the middle of the length, facing more or less downwards, so it is about 14' from the ground to the lens face of the sensor.  I angled it slightly outwards so that an imaginary line parallel to the "bottom" of the sensor housing extends to the ground at far side of the driveway, which is about 10' from the wall of the barn.  My theory was that angling it this way should allow it to "see" the entire width of the driveway, while blocking its ability to react to anything much beyond that distance.  What I was concerned about is how far along the driveway the sensor could detect things.  (My hope was that it would detect anything along the full length of that side of the barn - about 40' total).

Well, the results were a little mixed:  It does seem to be able to detect along the full 40' length, and then some, but not very consistently.  What I mean is that it seems to depend a lot on where across the width of the driveway the warm body moves.  That is, if the body moves parallel to the wall along a line either 8'-9' away from the wall OR about 2'-3' away from the wall, then it gets detected well beyond the ends of the barn.  But, if the body moves more or less along a line down the middle of the driveway (about 5' from the wall), then it may not be detected at all!  This was rather unexpected, not to mention very undesirable!

Thinking the angle of the sensor probably affects this, I tried several different angles, and even tried "twisting" it a little one time.  These adjustments did alter the detection patterns (I think), but it looks like the original position actually produces the best results overall (except for that distinct "dead zone" down the middle of the driveway).  And it does provide better results for desired detection (along the driveway) and inhibiting unwanted detections (from the area beyond the driveway) than it did when it was mounted in a "conventional" orientation near one end of the barn.  So, overall, it seems to work a lot better, but I'm hoping there might be some way of fixing that miserable dead zone down the middle of the driveway.  Any ideas?

Note:  When I adjusted the sensor angle "in" or "out", I think the dead zone "tracked" the angle of the sensor, but I could not move it entirely out of the driveway without opening the sensor up to undesirable detections out beyond the other side of the driveway.  And when I angled it almost parallel the wall that it was mounted on, the sensor could not detect more than about 1/3 of the way out into the driveway.

I can't help but think it would be nice if there was some way to "diffuse" the detection pattern so it would be more random and would not be these bands of dead zone that are fairly predicatable.  I mean, it did not take me long to figure out where I could walk and be totally ignored by the sensor:  I simply walked down the middle of the driveway on my first pass!   So, I imagine intruders would be able to do the same.  I'd like to make it a little bit more difficult for them to duck the sensor!  As I said, any ideas?

Thanks in advance.
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dave w

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Not sure if I undersatnd from your description, but, the detector is most sensitive to movement ACROSS it's field of view. It is least sensitive to movement directly towards, or directly away from it's field of view. The defraction grating of the lens trys to compensate for this. I don't know of a fix other than changing position or using multiple detectors. 
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JoKer

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Not sure if I undersatnd from your description, but, the detector is most sensitive to movement ACROSS it's field of view. It is least sensitive to movement directly towards, or directly away from it's field of view. The defraction grating of the lens trys to compensate for this. I don't know of a fix other than changing position or using multiple detectors. 

Well, I guess it is a matter of perspective:  In a normal (near-horizontal) sensor orientation, "across" would constitute any side-to-side direction of movement, while "towards" would constitute any movement (from any angle) directly towards the sensor.  Apparently, the geometry of the sensor and the lens causes the IR to be imposed on the sensor momentarily as the source moves "across" the lens, but likely would not change the intensity of the IR on the sensor as a sources moves directly at (or away from) the sensor.  If this is correct, then the "perspective" changes a bit when the sensor is mounted in a more vertical orientation:

In a near-vertical orientation, almost any direction of movement along the ground (within the viewable area) would move the IR source across the lens in some way or another, and about the only way to move the source directly towards (or away from) the lens along a single axis would be if it "levitated" off of the ground and towards the sensor by some means.

I suspect the reason for "dead band(s)" (I've only definitely observed one deadband) is that the deadband area occurs at the "edge" between the rows of sub-lens "segments", and thus any IR occurring along that line never even reaches the sensor.  Obviously, this is just speculation, but it seems plausible, and I don't see any other explanation.  The thing that kind of shoots down this theory is that when I rotated the sensor head a bit (so that it is not parallel to the side of the building), this did not seem to alter the location of the "dead zone".  To hold with the theory, skewing the lens segment line in this way should have caused the dead zone to fall more diagonally across the driveway, so detections would occur somewhere along any parallel track that the IR source might follow.  However, this did not seem to occur, and I'm not sure why.

Anyway, what I'm observing is that the sensor detects (or does not detect) more or less along "stripes" running parallel to the plane of the bottom of the sensor housing, or in my near-vertical installation, roughly parallel to the side of the building where the sensor is mounted.  If I test by walking along "tracks" that are parallel to the side of the building, at various distances from the building, there are some tracks where the sensor will detect movement almost anywhere along the length of the building, while there is another (central) track where detection does not occur anywhere, from one end of the building to the other.  (This is a case where a picture would be worth a thousand words, but I hope this gets the image across).  The bottom line is that it is entirely possible to walk the full 40'+ down the middle of the driveway, without ever triggering the sensor, but if I walk a couple feet either side of that, the sensor will detect me from one end of the driveway to the other.  Pretty strange!
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