New Sensations in Alarm Sensors

When I look back through the years, I think the application of alarm sensors was the No. 1 feature that got me hooked. In the beginning, it was simple devices such as door contacts, window foil and pull-traps. Next came acoustical glass-breaks, motion detection with microwave, ultrasonic and passive infrared. Today, digital signal processor technology has made sensors smarter and less false alarm prone.

I predict that in the near future we will see mainly one type of alarm sensor: the video camera. These cameras will be IP-based, high resolution, wireless and very intelligent at sensing both intrusion and fire. I am speaking of video analytics technology, which is already being deployed in commercial and Department of Homeland Security (DHS) applications.

Today’s security dealer and integrator must be versatile and a master of both old and new intrusion sensor technologies. You must understand not only the application but also the limitations of each available technology. Let’s take a closer look at some of my favorite intrusion sensor technologies and devices, as well as new sensor applications and what we can expect in the near future.

Sure Action Inc. (, the Pulsor – Some of the traits of a good intrusion sensor is that it be covert, can cover both large and very select areas, have good adjustable false alarm discrimination and work reliably for a long period of time. One such technology is stress or, as the engineers say, strain gauge motion detection. With the Pulsor system, strain gauge devices can be epoxied to the underside of floors, stairs or roof joists (this is particularly suited for new construction). Applications include detecting people walking on a roof and outside fire ladder, or even tied in to home automation and tripped as one walks up/down stairs. The sensors are also well suited for the decks of boats. I have also set them up to detect the removal of a valuable art object.

Protection Technologies Inc. (, Piramid Series – The challenge with motion sensors is to get one that can operate reliably in both an indoor and outdoor environment. Wouldn’t it also be nice if you could have a motion sensor that detected directional motion? Well there is a company that uses a technology called stereoDoppler microwave sensors. Using two receiving channels rather than one provides the ability to disregard vibration and objects that move periodically that cause false alarms.

Whereas most motion sensors today are paired with passive infrared to reduce false alarms, Protech’s uncommon microwave-only device can be concealed and detect intrusion motion covertly through walls. It’s a nice touch from the old school.

Honeywell (, FG- 1025Z – The use of digital signal processing (DSP) in intrusion sensors such as acoustical glass-breaks has been a big help in reducing false alarms. While there are many types in use, there is one design I consider special and representative of the performance commitment of its maker. Honeywell’s directional glass-break detector is differentiated by its two 180° pickup microphones. They allow the device to detect which direction sounds are coming from and ignore similar glass-break sounds that do not come from the protected glass area.

Be sure to use the appropriate manufacturer’s tester (see Tool Tip) when testing acoustical glass-break detectors. Take into account variables like sound-absorbing window coverings, furniture and carpeting. Remember that sound is very directional and can be easily blocked. Be very careful of 24-hour applications.

UTC / GE (, 5402 Learn Mode shock sensors; GRI, Shockgard 1 – Shock sensors have always been handy. In the early days they were nothing more than a contact on a metal reed that would vibrate when an object was shaken. I have seen inexperienced installers mount these devices on doors and, as you might guess, they would go off every time someone knocked on that door. Today’s shock sensors are electronically more intelligent and have pulse count adjustments. Some have learning modes that enable them to better adapt to their environments. I have always found these especially good on walls for blunt-type intrusions.

One of my all-time favorites is the little-known UTC (formerly GE/Sentrol) 5402 cabinet shock sensor. This UL-Listed device can turn a typical alarm enclosure into a box secured from drilling. In the old days these boxes would have to be foil lined for intrusion detection.

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About the Author


Bob is currently a Security Sales & Integration "Tech Talk" columnist and a contributing technical writer. Bob installed his first DIY home intercom system at the age of 13, and formally started his technology career as a Navy communication electronics technician during the Vietnam War. He then attended the Milwaukee School of Engineering and went on to complete a Security Management program at Milwaukee Area Technical College. Since 1976, Bob has served in a variety of technical, training and project management positions with organizations such ADT, Rollins, National Guardian, Lockheed Martin, American Alarm Supply, Sonitrol and Ingersoll Rand. Early in his career, Bob started and operated his own alarm dealership. He has also served as treasurer of the Wisconsin Burglar and Fire Alarm Association and on Security Industry Association (SIA) standards committees. Bob also provides media and training consulting to the security industry.

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