On Sat, 17 Dec 2011 09:03:30 -0500, Art Todesco
wrote:

On 12/17/2011 7:52 AM, Jim Elbrecht wrote:
I think I've got a problem with the motion detector that controls the
lights on the garage. It has always been 'odd'- but now it just
seems to *not* detect anything some days-- and on others seems to be
tripping when nothing is there. [though I can't rule out critters
tripping it]

It has been hanging there for 5-6 years& since day 1 it will let a
car drive right up to the garage [straight at it] and not trip until
the driver gets out of the car. It is supposedly a 180degree
sensor, but 120 would be generous, and the edges seem to wave back and
forth.

The way I have this set up, if it matters, is the sensor is mounted
above the door and operates carriage lights on either side of the
door.

The lights are switched-- but not 3-way.

So is there a *really* good detector that has a wide field of view,
and will detect objects coming straight at it up to about 100 feet
away? [minimum of 50']

Thanks
Jim
I use an X10 motion detector without any floods. Then when it detects
and sends and x10 signal, the program another box turns on the house
floods on that side of the house, if it's nighttime and sounds a chime
in the house. But, it will not detect a cold car or a car that is at
the ambient air temperature. So, if a car is running a a pretty high
speed and then pops in front of the detector, it probably sees no
difference and ignores it. However, if the car is really warmed up and
approaches slowly, allowing the hood, etc. to warm up, it detects as the
sensor sees a difference between the air temperature and the car.
Because I have a slow very steep road coming to my drive and then about
100' of drive, it usually detects. Although, at Halloween, I actually
put one of these sensors next to the road to fire off a Halloween
animation. It usually saw most cars, however, when I was testing with
my own car, cold out of the garage, it occasionally missed. Another
problem is that when the outside temperature gets to the upper 90s, it
won't detect a person, again because there is little difference between
the body and the ambient. The best way to reliably detect a vehicle
coming onto your driveway is either a pressure sensor or metal mass
detector, or a photo cell across the drive; the former probably won't
detect critters, the latter will if they are tall enough. Sorry for
rambling on.
The only "really good" motion detector I've ever seen is a video
camera with night vision running a pixel change comparator program on
a computer, controlling the lights. You set the percentage change rate
sensitivity on the program, and if, say, 10% of the pixels change over
a 15 second period, it triggers. This allows you to fine tune the
response to either respond or not respond to something the size of a
squirrel, or a racoon, or whatever.

A barn door moving at 1 foot per minute might be able to sneak in
where a running squirrel would be nabbed, depending on how you set it.

X10 has both the cameras and the software, as well as the
controllers, to set up this kind of system.

Again, to be 100% effective, 2 sensors with crossed field of vision
would work better by providing binaural vision