Garage Security

[Albert25 0]

I want to increase the security for my garage after our neighbor have lost their car.I already install security system in my car.So now i installed the alarm system in my garage or installed any other security system in my garage?

[the toss 0]

Most "name" brand security systems will do the job you want , the main difference being the ease of programming. Depending on the amount of clutter in your garage you may need 2 or 3 detectors for decent coverage with no blind spots. The important thing here is not to go cheap on the PIRs. Most garages are not airtight & are likely to suffer from warm/cold air movement which will result in false alarms. Use good quality tri tech PIRs. A sure sign of a cheap PIR is if it incorporates a "sensitivity" or "range" adjustment.

[Kawboy12R 0]

A sure sign of a cheap PIR is if it incorporates a "sensitivity" or "range" adjustment.

 

???

 

http://www.optexamerica.com/security-products/lx-402

 

Opinions?

[the toss 0]

A sure sign of a cheap PIR is if it incorporates a "sensitivity" or "range" adjustment.

 

???

 

http://www.optexamerica.com/security-products/lx-402

 

Opinions?

 

 

OK , I'll try to keep this from being too complicated. Kawboy - notice on the link you provided that it is recommended for " Lighting or Camera " NOT for alarms.

The success of any electronic design is to establish a set of operational parameters which the design will address. So , what is the basic operational parameter of a PIR? If you said to detect a moving IR signature in a defined area then you would be correct. Now there are many other design parameters such as white light rejection , anti masking , temperature compensation , adaptive IR compensation etc but lets just restrict ourselves to detecting a moving IR signature in a defined area. Unless you design you analytics for a defined area you will have trouble determining if you are seeing a human signature at 20' or an elephant at 80'. The defined area is set by - the mounting height (recommended by the manufacturer) , the lens (radial limits) and the floor. All the grey areas for detection are eliminated. There is no need for adjustable sensitivity or detection angular adjustment.

Now generally the cheaper detectors have poorly defined design parameters. Their marketing strategy is to boast about their range (at the expense of analytics) They get this range by increasing the sensitivity of the IR detection circuitry. But this in itself won't increase the range. It only increases the potential range , the lens still limits the angular detection area (ie it is still looking down towards the floor) So they then put in a vertical adjustment for the pcb (or sometimes the lens) Now by moving the pcb downwards the detecgtion area moves upwards (through inverting lens) The result is that the designers have handed over one of the most important design parameters to the end user (installer) That in itself would not be a problem if the PIR was set up properly for the environment it is in but do you think an installer is going to spend 30 min setting every PIR up to suit its location? What they end up doing is winding up the sensitivity to maximun thereby decreasing its ability to discriminate between real & imagined events. It would probably detect a fart.

 

Tritech PIRs will always have a "range" adjustment" but this serves an entirely different purpose.

Tritech PIRs are a combination of IR & microwave detection elements. Both the IR & MW are needed to initiate an alarm. That being said , the range will be set by the lowest denominator

( always the IR ). The adjustment is always on the microwave section for a couple of reasons. One is that MW will penetrate walls , windows etc which is not desireable. The other most used feature is to enable discrimination of physical size ( useful for pet immunity). Microwave motion detection is most usually through two methods. Doppler (as in radar) and standing wave patterns (the amplitude of which are proportional to the size of the detected object) By utilising both these detection methods you can start to build some pretty good analytics into your PIR. So now your design parameters can include volumetric detection area, size , speed , IR mass as well as anti masking & anti cloaking etc.

 

So to cut to the chase - the existance of a sensitivity or range adjustment usually indicates a lack (laziness) of design effort.

 

I am a big fan of optex PIRs and none of the ones I use have this adjustment. As I've pointed out , the one in your link is recommended for lighting or cameras where false tripping is not a big deal

[Kawboy12R 0]

So, almost by definition, the only outdoor Optex PIR worth a damn is the HX-40DAM because it is their only outdoor PIR with microwave technology?

[the toss 0]

I am not a fan of ANY outdoor PIR. I just don't see how they can reliably discriminate in such an environment. Maybe the technology is leaving me behind. It is very hard to get any proper info other than sales talk now days