Hi-Tech-Consulting

Biometrics is a term used in access control to mean a type of reader which utilizes some unique charactoristic of a human to identify them to the system.

Common types are Retinal scan, Hand geometry and fingerprints. Rentinal scan are effective but expensive and users often are hesitant to place their eyes near the scanner.

So called Hand Geometry actually uses an infrared scanner to “measure” the hand. They are very large and not user friendly.

Fingerprint readers are probably the best solution but still have several drawbacks: they are not really suited to outdoor use and often require a separate computer for “enrollment” and / or a card reader or keypad to narrow down the selection:

One of the better solutions is : http://www.bioscrypt.com/

Modern, well designed intrusion alarms are 99.9% impossible to defeat. The TV show MYTHBUSTERS recently devoted an entire show http://dsc.discovery.com/fansites/mythbusters/episode/episode.html

trying to defeat several types of alarms. Despite what you see in the movies- detection beams (active infrared) are invisible and nearly impossible to detect or avoid if properly installed and designed.

There is no doubt most false alarms (90% or more) are caused by the user- human error. Sometimes this is poor training of the user, often it is human error caused by poor system design. For example: placing a motion detector near the keypad where the person arming the system will trip it. Or setting the entry / exit delay too short or at the wrong door— the entry exit delay should be programmed for the door the employees actually use.

Equipment is the next big offender but generally only responsible less than 10% of the time. Usually though when equipment is faulty it will account for a large number of false alarms in a short period of time until fixed- so rapid response is necessary before fines kick in.

Some examples of equipment caused false alarms are

(1.) loose door contacts (or loose fitting doors which move excessively in the wind). 

(2.) motion detectors which are frequently set of by heaters, moving signs or plants- and pets or rodents- even birds.

90% of  motion detection devices used in intrusion alarms are PIRs. A PIR is in effect a sensitive thermometer. PIRs do not actually detect motion at all. PIRs detect a change in temperature within the range of it’s “lens” or sensor. Some PIRs divide the area into zones and detect the temperture change between zones to try to avoid false alarms caused by temperture changes from heaters, the sun, and even bright lights.

PIRs usually operate in a small range of 1 degree or less of change. Since they detect temperature they can be less effective when ambient temp hovers around 98-100 degrees (body temperature). PIRs are most effective around 70-80 degrees..

PIRs can be a major source of false alarms. They are frequently very cheaply made. Installed improperly (they should always be installed at the correct height and so that they detect motion across the field of view- not coming towards them), they will be a source of problems.

ANY heat source near 98 degrees will cause PIRs to alarm. These include pets, birds, rodents, fans, and heaters.