Help on alarm

With modern dual technology detectors this is not a problem.

You may find corner mounting more effective. Aim the detectors across the middle of the room but don't allow the PIR zones (fields of view) to see the windows themselves. This will further reduce the likelihood of false alarms.

That may help. There's another way to protect basement windows which may, depending on the way the windows are framed (inset or flush), prove useful to you. There's a device called a BB-1GS Barrier Bar which looks from the outside like it's a metal window bar. In fact, it's a pressure sensitive switch that will trip the alarm if someone tries to dislodge it. I've used a number of these for many years and they hold up well.

The bar functions whether the window is open or shut. The cable is covered in a BX-like, flexible sheath to resist tampering. With a bit of effort these can do a decent job of protecting basement openings. However, nothing is 100% so consider backing them up with a motion detector or two.

I haven't tried those though I've sold well over a thousand of the wired DG-75 models. They rarely cause any problems.

If it truly is bullet proof, contact the door against opening and don't worry about the glass itself. Besides, if you back it up with motion detection they're not likely to get by the system.

I wonder how much that slider cost. Attack resistant glass is expensive stuff.

Use a wide gap, magnetic "contact" (door sensor) to detect movement of the door itself.

Might be, but from your description of the door it's probably a wasted expense.

Just angle the detectors slightly down so they don't see past the fence. I've used plenty of DG85 detectors and they work well, even during some of the storms that hit south Florida.

We planted jasmine along our fence. The plants were about 18" tall from the nursery. It took year and a half to fill in. Now the fence is completely hidden by green leaves and in the spring the air fills a wonderful jasmine aroma.

Regards, Robert L Bass

Angelo, with regard to pointing two dual-tec motion detectors at one another, I'd be sure to check with the manufacturer first, just to be sure whether they recommend this. The Microwave device in many dual tech motion detectors will cause another dual tech detector, within range .... to activate erratically or worse case, even constantly. This, in itself wont cause an alarm condition, but it negates the purpose of using dual tech detectors. What is usually the case with dual tech motions, is that the manufacturer makes the PIR portion very sensitive to motion. What this results in is ..... if you've activated the microwave portion constantly with the other unit from across the room, now you've got only a very sensitive PIR between you and a false alarm. You might find that you'd be better off using two passive infra red detectors with pulse count or sensitivity control rather than dual-techs where the microwave detectors are always activated and leaving only 2 super sensitive PIRs.

Oh and by the way ........ Robert Bass is not an installer of alarms and wouldn't think of warning you about things like this. He's only interested in selling equipment to people who don't know what kind of unscrupulous person he is. He's got a long long record of deceiving people, stealing information from people, lying about his experience and backgroud and has a very bad record with the Better Business Bureau.

Beware of him and what he says.

JoeRaisin ha scritto:

Thank you very much for your help, My previous description was not accurate. Actually, the room is L shaped, it is long about 9 meters, the top side with the sliding door, is 4 meters, the bottom side is about 7 meters. There are three windows, one on the long side and two on the bottom side. There are also a door to the garage and stairs up; on the top of the stairs, there will be another detector. I was planning to put one sensor at the top right corner and another at the lower left.

--W--*-W-- SlidingDoors, Windows, Door, Stairs up, *Detectors, Stairs

How long is this room? I would try to stick to one detector. Less expense and unless you plan on cross zoning your protection won't be compromised.

.. of space between each bar. Anyway, I am planning to cover

Sorry, actually this is it:

SlidingDoors, Windows, Door, Stairs up, *Detectors, Stairs

I added some symbols to your drawing.

My first choice would be one motion at location *1, that covers everything you are covering now... unless there is going to be something in the area not protected, either of high value or that could compromise the rest of the system, then I would place the upper in the location you picked out but would move the lower one to location *2. That location gives you full coverage of the basement and better protection on your stairs. Most motions, when mounted in a corner will look down both walls. With location *1 you avoid looking directly at any windows and have your stairs well protected.

Good luck

Joe, are you recommending dual tec's in this configuration or just PIR's?

I wouldn't ...... unless the mfg of the dual-tec's have designed the units to be used in close proximity to one another.

JoeRaisin ha scritto:

Thanks, I will do as you suggest. BTW, the detector I want to install is the DGP2-70 by Paradox. Do you recommend it?

Not real familiar with Paradox, but I think they are PIR's. But my layout was with dual tech's in mind. A single unit at location *1 or dual units, one at the * in the upper left hand corner and one at location *2 would avoid the units seeing each other.

I'm not familiar with it, some of the other folks here could probably give a more informed endorsement.

Hi Joe,

If I'm seeing it right in your drawing, the "array" of each unit will still be in view of each other. The units don't actually have to be in "sight" of each other. It's the beat frequency of the slightly different outputs of each unit that will cause, what looks like a doppler shift to either or both of the units, that will cause the false alarms. With some manufacturers, they don't recommend that units be within "range" of each other ( ie you must consider penetration of walls etc) nor do they recommend units be mounted "back to back" either. It's the "arrays" overlapping each other, even if they're not within in the line of sight, that can cause the problems. And, for example, you have to keep in mind that even in large areas like warehouses, with, we'll say 2 units with 35 foot range, they *still* should not be looking at one another closer than ..... say 90 feet or more. Just because a unit is rated at 35 feet doesn't mean that it's microwave array doesn't extend further. It just means that the unit can detect movement of a body at that distance. The array can extend much further than that.

Which is why you adjust the microwave sensitivity down to the minimum need for the application. I would be confident in the layout I proposed. But let me restate that I would prefer the single unit at the *1 location. Only if he really needs that small area at the bottom protected would I go to the double unit arrangement. As I look at the drawing the two corners appear to overlap so the units won't see each other. If you can see past the corners (from the upper left to the lower right then a single unit in the upper left or lower right may do or move the lower unit to the left side of that area.