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Thread: How do you do outdoor presence detection without nuisance tripping

  1. #1
    Automated Home Jr Member
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    Lightbulb How do you do outdoor presence detection without nuisance tripping

    The council has installed new networked dimming LED street lighting (leafnet), which is great :-)

    The beam angle on them (by design) is so tight it only lights the pavements and road and not our private gardens.

    This leaves me needing to put "pathway" lighting in the garden as the entrance way is in shadow anyway.

    What I don't want to do however is leave lights on for extended periods.

    This leads me to have triggered lights, but I don't want to have nuisance triggering as you can see on some PIR sensors, I only want it to light when someone actually starts down my path.

    How have others in my situation done it? One idea I have had is a beam-break detector but don't want to have to keep cleaning it!
    Last edited by back_ache; 19th November 2013 at 03:23 PM. Reason: tidy up embarrassing typo's

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    Moderator toscal's Avatar
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    The most reliable is to install a multiple beam break system. These are normally 50cm to 1.5m in length and have multiple beams, and normally you have to break at least 2 of the beams for it to trigger. So small animals or falling leaves shouldn't trigger it.
    This link is non UK but should give you an idea of what I mean. You can also download the manual as well from the link. In Spain they cost about 72 Euros for a 57cm one right upto about 350 Euros for a 2m high one.

    I have used these on entry ways for a client and they have 2 cats and 2 Jack Russels, and no false alarms.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
    www.casatech.eu Renovation Spain Blog

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    Automated Home Legend TimH's Avatar
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    In wonder whether those security sensors at shop doorways could be adapted to fit (i.e. be hidden) by gate posts?
    IIRC some of them count the in/out movements so could alert to someone walking in/out through the gate?
    Don't know if you could make your own sensors but if you had a rose arbour over the gate you could probably disguise it pretty effectively (are they hall effect sensors?).

    Or, a few other suggestions:
    # pressure sensor under a paving slab/step,
    # micro-switch/sensor on self-closing gate,
    # "pet-proof" PIRs like you'd get for internal security alarms,
    # multiple PIRs so the lights only activate if >2 PIRs have been triggered,
    # motion detection on CCTV - many systems will provide a physical trigger signal from the DVR box if they detect motion

    Some gardens I was in at a wedding reception had the lighting and fountains controlled by "simple" PIRs...

    All of the above can be conditioned against a light sensor so that your lights only come on if it is dark enough.

    HTH,
    Tim.

  4. #4
    Moderator toscal's Avatar
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    Pressure sensor won't work if you have pets or animals roaming around. You may get to many false triggers.
    There are pet proof external sensors, Visonic do them as do a few other manufacturers.
    The motion sensor via a cctv system can work. As many of the more upmarket systems allow you to define the areas where motion needs to be, and can be more than one area. But this will be expensive, the more complex the motion trigger the more you will need to spend have a look at Mobotix
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
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  5. #5
    Automated Home Legend TimH's Avatar
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    Quote Originally Posted by toscal View Post
    Pressure sensor won't work if you have pets or animals roaming around. You may get to many false triggers.
    Yes, I was thinking more of an analogue sensor (e.g. strain gauge) where you could set the threshold above the weight of a cat/dog/fox but would still trigger if a child/person stepped on it. Perhaps starting to get complicated, and also issues consider with it being an outside install with water, dust, sand, leaves and other crud...
    There was that pathway in the news a while ago which generated electricity while people walked over it. Likely to be too expensive in this application but similar principles should/could apply.

    Quote Originally Posted by toscal View Post
    The motion sensor via a cctv system can work. As many of the more upmarket systems allow you to define the areas where motion needs to be, and can be more than one area. But this will be expensive, the more complex the motion trigger the more you will need to spend
    Zoneminder is free and looks very comprehensive being able to set different zones for triggering (and ignoring) and also being able to adjust the sensitivity within those zones. It also claims to work with USB, IP and analogue cameras (via a capture card).
    See http://www.zoneminder.com/ for more info

    I haven't used it, but the motion detection part looks much more detailed than my dedicated CCTV DVR box!

    Cheers,
    Tim.

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    Automated Home Legend Karam's Avatar
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    Never get the feeling that video based motion detection is a reliable way to go. We have this facility in the IDRATEK Cortex software, with more parameters than you can shake a stick at (though why you'd want to shake a stick ...). But have to say I've not yet personally succeeded to get zero false triggers in most applicatons. Which is not to say that you can't in certain conditions but clearly not straightforward. It really does depend on the area of the image that is of interest to you and what else might happen there of same size and shades. I've had setups thwarted simply by fast moving clouds on a sunny day. Doesn't matter so much if you are just triggering recording of clips and maybe even tolerable for some LED lighting when the scene is initially lit using IR (beware of re-triggering when light goes off), but I'd hesitate to control something more critical on that basis.

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    Automated Home Legend TimH's Avatar
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    Quote Originally Posted by Karam View Post
    Never get the feeling that video based motion detection is a reliable way to go. We have this facility in the IDRATEK Cortex software, with more parameters than you can shake a stick at
    Yes, I do agree. It's trees in the wind that give false triggers for me, plus spider webs over the lens.
    Clouds and quick changes in sunlight haven't been an issue for me but each installation is unique
    Conditioning the cctv motion with another sensor, such as a PIR will allow more accurate detection I'm sure. A finer detection grid on my cctv box would help (currently 12x12 squares) and would allow me to permanently ignore some areas...

    Cheers,
    Tim.

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    Automated Home Legend chris_j_hunter's Avatar
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    for us, outdoor presence detection is also tricky to get right because the garden & yard are in-between ...

    ie: sometimes they are part of the house (as in summer), sometimes a sort of protective zone around the house ...

    in the first instance, presence there indicates the house is occupied; and in the second that the house may be under attack ...

    difficult to handle - but maybe door-sensors + other logic could be used to switch between modes ... ??

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