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Pir Choice


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  • 3 months later...
Posted

Let's just break it down for you:

All PIRs have a pyroelectric element.

Most modern PIRs have a dual pyroelectric element which is divided in half. One half gives a positive trigger if a signal is detected, while the other half gives a negative trigger if a signal is detected. These normally cancel each other out in the event of a false alarm. (+1 + -1 =0).

A quad detector's pyroelectric element is divided into four sectors, with two positive and two negative sectors, which are normally diagonally opposed. Which make the detector even more immune to false alarms.

A PIR with two dual pyroelectric elements is often only used in pet friendly detectors and can be quite effective in reducing false alarms in an environment when pets are present.

Most manufacturers also use their own patented algorithms to further reduce false alarms with the above technologies.

A Dual Tech Detector uses two different technologies to detect an intruder. Both of these technologies have different vulnerabilities in terms of false alarm immunity and even further reduce the possibility of false alarms in most instances. The most popular technologies used are PIR and Microwave, but could also use a number of other technologies.

Most PIRs use Fresnel lenses which are generally less expensive to manufacture. Some mirror optic lenses (depending on design) have the advantage to determine size vs distance and can reduce false alarms in this manner.

If you are not going to use a detector with a mirror lens, I suggest that you choose one with a spherical Fresnel lens as this normally focuses better than a flat or bent Fresnel lens, this can define the target better and reduce false alarms. How well would you see an intruder if you had flat or curved flat eyes?

One of the most effective ways of reducing false alarms is a well designed and installed system. You can have the best HiFi system and the best speakers, but if you use cheap or badly installed wiring, your sound will be lacking.

In the same manner a poorly designed and installed system with great detectors will often give you more problems than a professionally installed installation using standard detectors.

Regards

NitroN

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