PIR (Passive Infra-Red) alarms are used in certain types of motion detectors. Infrared imaging technology is used in military applications for night vision, surveillance, homing and tracking. It is also used in weather forecasting and short-range wireless communications. In astronomy it is used on telescopes for penetrating regions in space clouded by dust particles. There are many other uses for the infrared technology, but the one most people are familiar with is a PIR alarm. In this application, a sensor is triggered (and an alarm sounds or a light comes on) when an object with one temperature (such as an animal) crosses between the PIR sensor and another object (like a wall) of a different temperature.
Not all PIR alarms are made alike and some are better than others. There are some key differences when comparing the low price models to the high end. As with all products up for consideration when the market is saturated with options, which you choose depends on how you want to use it and how much you want to pay for it. Another important consideration may be the difficulty level of installation. To give you an idea of the overall scope of usage, popular areas of PIR alarm application are driveway, entrances, windows, back gardens, and interior point alerts.
Since this type of alarm uses radiant heat to detect motion, the motion sensor has the unfortunate characteristic of potentially tripping with the movement of every 4-legged creature that passes by. This was in the past a real nuisance especially after several false alarms in the middle of the night have gone off so if you were planning to install a PIR motion device on the exterior of a building, they were best for use in areas wherein few animals, if any, will ever pass. Now though, many models have a built in sensitivity control which allows small moving bodies such as the family pet to pass without the alarm triggering, whereas a human will trip the alarm.
Two different lens-styles can make one PIR sensor alarm less expensive than another. A low-end motion detector typically uses a Fresnel lens, which is fine for those areas where nothing should technically trip the alarm. These areas are the exact place you need to be warned if someone is venturing into an off-limits area. The affordability of these models makes them highly popular. A PIR sensor alarm with a mirrored optic lens is more reliable because it requires less signal power in the electronic circuitry that follows the IR sensor. This makes the unit less likely to trigger from lightning, static electricity, or radio waves. While these alarms cost more, they can save you from the hassle of false alarms.
There are also combination alarms utilizing passive infrared and microwave and both. These units must be precisely installed in order to take advantage of the dual sensing features; otherwise, it will be a waste to pay the higher price and not get your money’s worth. Alarm units of this type are the most logical if you intend to have a security system hard-wired into your electrical grid. The advantage of a wired system is never having to replace batteries.
Wireless PIR alarms are simple for do-it-yourself installation. They require periodic maintenance of the batteries, but are the ideal choice for areas without a ready electrical supply. Some of these units have a GSM alert system that calls your cell phone when the alarm is triggered. Storage units, boats, barns, and other otherwise unmonitored areas you need to protect are a few of the applications for this type of unit. Professionally monitored home alarm systems are the most expensive; however, most of the big name companies offer deep discounts on equipment and installation in exchange for a contract spanning a number of years of monthly monitoring fees. This set-up is great for those who do not have the time or inclination to worry about their home or business security.
Prices begin very low for a simple wireless model with a range of 100-feet. One of these may be a good choice for monitoring a backyard gate or a baby climbing out of a cot. Prices and models rise from there on in but the variation across the internet for the same product can be massive, so definitely shop around. It is always important to comparison shop for the security system that is the right choice for your particular needs. The top models have a combination of state of the art features, but there is a plethora of similar models and it is difficult to say which the absolute best is. Customer reviews and word of mouth are the two best ways to discover which alarms truly come out with a 0-star rating and which have 5-star reviews.
There are many Internet retail websites devoted exclusively to home and business security. Understanding exactly how different monitors operate is the key to selecting one model over another. Pay attention to manufacturer warranties and save all receipts. If you find the wireless or portable PIR alarm you have purchased does not perform as stated by the manufacturer, take advantage of the store’s return policy.