Motion sensors are now a mainstay of intrusion detection, but, back in the day, traditional devices were obtrusive, prone to false triggering and difficult to program. It usually took two installers, and all bets were on the contractor being called back for weather or environmental disturbances in the future (including a rogue rat or lumbering pet). There was no way to tell if it was operable, or at what point the battery would fail, adding to truck rolls and frustrated security installers. They got a bad rap, and false alarms were often blamed on the devices.


That has changed. Detectors now incorporate multiple sensing technologies and LEDs to indicate trouble (red), caution (yellow) and operation (green). There are various mounting options, sensitivity settings and selectable optics. One installer can walk-test the unit to confirm its operation, and intelligence and interference immunity has increased with advanced signal processing.


Detectors of yesteryear were generally based on single technologies, such as passive infrared (PIR), microwave or ultrasonic. PIR sensors look for heat emitted by the person entering the field of view. Microwave sensors detect motion through the principle of Doppler radar. Ultrasonic sensors detect a wave of sound at a frequency higher than human hearing. A major breakthrough years ago was to incorporate two detection principles or dual technologies, often PIR/ultrasonic or PIR/microwave. This has resulted in a more stable device, as both technologies must trigger in sequence or within a preset time to engage an alarm.


In addition, many detectors boast sophisticated, advanced signal processing and pet alleys or virtual detection pathways that prevent false alarms. Antimasking features address vandalism and attempts to disable devices or cover optics, sending a trouble signal to the central monitoring facility.


Stability and reliability


Additional cotegories of specification have emerged with this newfound reliability and stability. In the commercial environment, detectors are more robust and can penetrate concrete walls and operate among heavy machinery or manufacturing locations without additional signal repeaters. Increasingly, sensors are used to detect occupancy and trigger heating, ventilating and air conditioning systems and regulate energy management controls. Detectors are also part of integrated security solutions; for example, they trigger video surveillance and video verification of alarms.


Neil Evans, senior product manager—hybrid systems, Tyco Security Products, Toronto, said detectors now incorporate multichannel, frequency hopping spread spectrum, so the signal can navigate between wireless channels, ensuring seamless, secure communications between device and control panel. They also feature longer read ranges and can communicate reliably up to 1.24 miles line-of-sight, reducing the cost of installing repeaters. In addition, 128-bit AES encryption offers high-level protection against device signal compromise.


Evans said Tyco’s PowerSeries Neo from DSC incorporates PowerG, a technology the company acquired when it purchased Visonic several years ago. 


“PowerG is one of the strongest transmission protocols for residential and commercial applications, using full encryption and two-way communications,” he said. “It operates over multiple frequencies and is extremely intelligent. If there is interference with the detector’s signaling, it finds the next available channel.”


Intelligent data gathering


The technology and its range, distance and redundancy make it well-suited to new vertical markets. For example, one receiver can cover up to eight floors of a condominium building without a repeater. 


“In addition, with the full two-way protocol, devices can be engaged remotely and used in environmental monitoring, with the ability to pull more info and data into the central station from temperature sensors, low temperature alarms and even server rooms,” Evans said.


Increased intelligence and processing power has also provided visual and sequential detection for alarm verification. That means events are qualified by technology before an alarm, but devices also assist the installer with an easier and more robust installation, said Tom Mechler, product marketing manager, Intrusion Products, Bosch Security Systems, Fairport, N.Y.


“With a lot of detectors, you see a raw circuit board and exposed mechanics,” he said. “We house all critical components in a chassis. Terminal strips are in the base of the unit and everything’s fixed, so it’s easy to wire. A lift gate design reduces loose wires and potential problems. A good quality terminal strip makes for a higher quality installation.”


While there have been news reports of hacking into wireless signals, Bosch detectors address that through superior manufacturing, Mechler said. 


“Our wireless detectors include antijamming technology and additional supervision,” he said. “Hardwired detectors include antisabotage technology and safeguards to alert if someone tries to compromise the unit.”


When a detector is reliable and easier to install, it adds to its stability, Mechler said.


“Installers have to think about buying quality products,” he said. “You can get inexpensive detectors, but consider the cost of a service call. Spend a little more upfront and install a quality product to avoid all that.”