Sophisticated sensors tackle false alarm problem

Sunday, May 1, 2005

While false alarm reduction remains the primary focus for manufacturers in the sensor and detector marketplace, other factors are influencing product development, from ease of installation to aesthetics.
The incorporation of microprocessors has made sensors "work faster, smarter and cleaner," explained Therry Brunache, sales manager for Crow Electronics Engineering in Fort Lee, N.J.
Crow is in its fourth-generation of ASIC, application-specific integrated circuit technology, said Brunache. In terms of false alarm reduction, he said, the microprocessor "allows us to incorporate information on anything than can go wrong," such as programming in certain wavelengths that would likely trigger alarms.
Smarter sensors can adapt to their environments, scaling their sensitivity to mask out false alarms but still detect intruders. Conventional passive sensors typically fall into one of two camps, said Judy Jones, director of marketing for Napco Security Group, Amityville, N.Y. Either they appear too sluggish to catch an intruder, or they are too "hot," which makes them prone to false alarms.
Jones said the microprocessors in its units include "algorithms for analyzing signatures of false and valid alarm sources," identifying each by features such as size/amplitude, sequence and characteristics.
Through such means, she said, sensors can determine whether a target is human, animal or some other option such as a blowing heater or a moving window blind.
Steve Connor, product marketing manager-sensors for GE Infrastructure, Security, said the addition of range-controlled radar to its dual-technology PIR/microwave sensors provides a third line of defense against false alarms by enabling installers to set a range beyond which the microwave operates.
Digital technology reduces false alarms, said Pascal St-Cyr, regional sales manager for Paradox Security Systems Ltd. in western Canada, by ensuring multiple sensing beams are triggered before sounding an alarm.
Another way false alarms are reduced, he said, is by having microwave signals confirm the results of the PIR sensor before sounding an alarm. And having companion sensors outside and inside a building both activated before sending an alarm signal, St-Cyr noted, can be yet another way to guard against false alarms.
If false alarms go unchecked, he said, users of the systems become frustrated and turn them off completely, so they are unprotected. And law enforcement also begins levying fines, which may force people not to use their security system as well, he said.
Pets have long been a challenge for sensor developers. "Pet immunity is still a big issue," noted GE's Connor, who said the company's RCR product has a pet immune version for dogs up to 80 pounds. The challenge is the heat given off by short-haired dogs of a certain weight versus their long-haired, same size counterparts. "It's very difficult to build that in," he said.
"Our PIRs today are 80-pound pet immune," explained John Kovach, director of the global sensors business for Honeywell.
The sensors are able to ignore an 80-pound pet, but a lesser weight person will be detected, he said. "Early generation pet immune sensors had problems," he acknowledged, "but the way we are developing optical arrays, we aren't having the same problems."
Pet owners continue to seek versions that will detect pets up to 120 pounds, said St-Cyr of Paradox, but the reliability just isn't there yet. Paradox, he said, has detectors for smaller pets, 40 pounds and less, as well as a digital sensor that is true to dogs up to 90 pounds.
Crow's Brunache said there is a trade off between achieving large animal immunity and detecting intruders. Crow, which has produced pet immunity sensors since 1995, can detect pets in the 50- to 60-pound range, he said.
Napco's 50-pound, pet-immune detector "is really catching on," noted Jones.
Wireless is another sector catching on among end users because of its functionality in specific settings, such as historical homes, museums or other buildings where wiring is difficult or inappropriate. "The biggest catch phrase is wireless," said Crow's Brunache. "There's a lot of R&D going into it."
Wireless provides a "fantastic labor and time-saving element," said Connor, and has come a long way in its technological improvements.
One argument for wireless, he said, is the ease of installation it provides for integrators both from a time and technical standpoint.
Napco's Jones said wireless does address the need for faster installations and products now encompass those features available in hard-wired models, such as PIRs, pet-immune detectors and dual-technology wireless.
As wireless addresses the changing face of the industry, so do products that integrate with other components in a security system. Connor said products need to function well as part of a larger system, such as motion detectors which, when activated, can drive cameras toward a certain spot.
This is especially critical, he said, as more communities require video verification before sending authorities to respond to an alarm.
Aesthetics are also increasingly important to installers and end users alike, said Brunache. As a result, he said, manufacturers are focused on making sensors and detectors "smaller, user friendly and not as noticeable."
"People don't like that thing on the wall," he explained, so smaller, sleeker designs are becoming the norm."