Alarm systems that use wireless transmissions between sensors and the control panel can cover greater distances today than ever before. And while wireless continues to be limited by some factors, numerous advances in technology have enabled it to overcome many previous hurdles. That technology is also allowing alarm dealers to maximize their wireless installations in many ways.
MAKING SENSE OF PRODUCT SPECS
Comparing the range of wireless alarm systems from different manufacturers is a mixed bag, in part because it’s impossible to predict the range that any system will have in each individual installation.
“Every environment is different,” says John Kovach, global market leader for sensors for Melville, N.Y.-based wireless manufacturer Honeywell. “Every building has different ways of attenuating the signal.” Concrete and metal, for example, can be difficult for signals to penetrate.
Another issue, Kovach notes, is that some sensors transmit over greater distances than others. Devices with smaller batteries, such as pendant alerts, may have less range than motion detectors â€” a tradeoff that a manufacturer may be willing to make to minimize the size of certain devices. “But the overall system range is only as great as the weakest link,” Kovach explains.
Because of these uncertainties, some manufacturers, including Honeywell and Inovonics, avoid publishing specific range data for their products. Other companies talk about their “open-air” range but are quick to add that range will be reduced in real-life environments. GE Security is somewhat unique in stating both an open-air range and an obstructed range for some its products.
The frequency at which a system operates is one important factor in determining the range of the system. Companies offering systems that operate in the 300 to 400 MHz frequency bands, including Bosch, GE and DSC, claim open air ranges of anywhere between 400 and 1,000 feet. In contrast, companies operating in the 900 MHz band, including Bosch and DMP, claim open-air ranges between 1,200 and 3,000 feet. In addition, DMP offers a high-power system with a stated open air range of 1.7 miles.
DIFFERENT FREQUENCIES FOR DIFFERENT NEEDS
The tendency of 900 MHz systems to have greater range is the result of several factors, including federal regulations that allow manufacturers using that frequency band to transmit at higher power levels. “We transmit at 40 milliwatts at 900 MHz versus 10 milliwatts at 300 MHz,” explains Michael Reimer, product manager for Fairport, N.Y.-based Bosch Security Systems.
The wavelengths generated by a system operating at 900 MHz are considerably shorter than those of a 300 to 400 MHz system, and that also contributes to the greater range of 900 MHz systems, notes Craig Dever, national sales manager for Inovonics of Louisville, Colo., a manufacturer of a 900-MHz system. “The longer the wave-length, the less ability you have to penetrate commercial buildings that are made with a lot of concrete and metal,” he explains.
Manufacturers of systems operating in the 300- to 400-MHz range note, however, that their systems tend to be less costly than 900-MHz systems and that the range they provide is more than adequate for most residential installations, as well as some commercial installations. David Nark, intrusion product marketing manager for Bradenton, Fla.-based GE Security, notes that according to census data, the average U.S. home measures 2,400 square feet.
“That translates into roughly 60 feet by 40 feet,” Nark says. “When you think of wireless range, even obstructed range of 150 feet for the majority of homes, we’re more than adequate.”
Another advantage of operation in the 300- to 400-MHz range, some manufacturers say, is that not many other devices operate at that frequency. In contrast, the 900 MHz band is shared by a variety of consumer electronics devices that could cause interference, reducing the range of wireless systems operating in the vicinity.Manufacturers of 900 MHz systems, however, have addressed interference concerns, allowing signals to hop among multiple channels within a given frequency range.
Government regulations virtually ensure that interference is not a problem for products operating at 900 MHz, notes Mark Hillenburg, product architect for Springfield, Mo.-based Digital Monitoring Products (DMP). “To operate at that frequency, you have to accept interference any other system gives you, and there are certain things you can’t do,” he explains. For example, he says, “You can’t lock onto one channel and talk on it all day long.”
Virtually all manufacturers agree on one thing:. The range of today’s systems is better than it used to be. Nark points to three factors that have contributed to GE’s progress â€” a “secret sauce” that enables the company to maximize signal strength, improved antenna placement within each sensor, and improvements in battery technology. “We’ve moved to larger or lithium batteries to boost signal strength and provide more power,” Nark says.
Advances in components also have played a role, some manufacturers say. “There have been improvements in electronic components on transmit power and receive sensitivity,” says Mike DeMille, director of product management for Toronto-based DSC. Components involved include both chipsets and discrete components, he adds. Some advances in wireless range have led to the creation of new products. Honeywell, for example, offers a wireless motion detector designed for outdoor use that has extended range.
But despite all of these advances, some things haven’t changed. To get sufficient range, alarm dealers still need to avoid installing sensors in locations where their signals could be blocked by metal or concrete. And in a few rare instances, such as inside a bank vault, wireless alarms may not be an appropriate solution.
The best way to ensure that a system will provide sufficient range is to avoid obvious potential blockages and to test system range prior to installation. Some manufacturers sell hand-held receivers and transmitters designed especially for testing purposes. By placing those devices in the same locations where permanent devices are planned, installers can ensure signal strength will be sufficient. Other manufacturers have a test function built into each receiver.
Even with careful planning, however, installers sometimes find they have to return to a customer site to address range issues, often because the home or business owner remodeled or changed something in the environment. Such problems can sometimes be addressed by moving a transmitter. Where that isn’t feasible, most manufacturers offer repeaters, which receive signals from transmitters and boost them for retransmission to the receiver.
In the future, expect to see additional gains in wireless alarm system range. Although manufacturers generally are reluctant to discuss future plans for their product lines, Reimer hinted at some new developments in the works. “We’re looking at different frequencies and different systems for getting the message back to the control panel from the device,” he says.
Hybrid Systems Are Here to Stay
Improved range is just one of several reasons wireless systems are finding their way into more homes and businesses today. Enhancements in how the systems communicate, greater reliability and longer battery life also have played a role. Wireless equipment still costs more than equivalent wired products, though, which means that many alarm dealers still opt to use wired equipment, especially if wiring is already in place. Wireless still has a role in that situation, however.
Many of today’s panels support a mixture of wired and wireless sensors, enabling installers to use wireless where wiring does not exist or cannot easily be installed. Manufacturers offer a wide range of wireless sensors today, including some that work outdoors, making them suitable choices for adding protection to outlying areas. And certain sensors, such as pendant alerts, are inherently wireless.
Improved communication adds to the appeal of wireless add-on sensors, which today can be individually identified by the control panel.