How to Work With Wireless Technology in Difficult Settings
There’s nothing as frustrating as a wireless device that works one day but not the next. Over the past few years we’ve talked about a variety of security options for the home and business. Among them are intrusion alarms, video surveillance, and access control. The low-power wireless technology that fuels them usually works fine in residential and some office settings, but where it comes to commercial and industrial environments, there’s often a sizable challenge connected with the endeavor.
If you observe the manufacturer’s instructions to the letter, in most cases you shouldn’t have a problem. However, if you decide to go it alone, without reading and following the product’s installation manual, then it’s almost certain that you’ll run afoul.
This is one of the reasons why it’s advisable that you routinely sit down and read the manufacturer’s instructions. Take the installation manual home with you and read through it the night before a job, just in case the manufacturer has changed something. Hey, you never know.
In this Locksmith Ledger article we’ll discuss the use of wireless technology in industrial and commercial spaces as well as large residential applications. Our goal is that this paper will assist you when you install your next wireless system in a difficult setting.
Commercial Wireless and the “Difficulty Factor”
Commercial and industrial settings are truly more demanding than residential where it involves wireless low-voltage systems. The incentive to do them centers on the higher dollar figure you realize when compared to residential. To realize those extra earnings, you must build a “difficulty factor” into your proposals.
For example, although most of us have worked with WiFi, in a commercial/industrial setting, there can be issues that spell trouble if you’re not aware of them.
“One of the big problems we’re having with WiFi, especially in industrial buildings is the metal in them. It causes ther [radio] signals to bounce around. Unless you know how to work with it in this type of setting, you’re going to have problems,” says Nick Markowitz, owner and chief tech of Markowitz Electric & Integration of Verona, PA. “I’ve seen some real WiFi horror stories out there.” Markowitz also is chief engineer of an AM radio station in Pennsylvania.
Adding a “difficulty factor” to a job is part of an estimation system where a given number of “labor units” are assigned to each item within each system category. In turn, labor units are assigned a dollar value based on your own current labor rates.
“Let’s say it takes an hour to replace an electronic lock in a common, ordinary circumstance. When you evaluate the job on a RFP (Request for Proposal), you have the option of adding a ‘difficulty factor,’” says John Larkin, Senior Partner of Electric Systems Consultants of Columbus, Ohio. “Based on the amount of trouble involved, you can assign 1-½, 2, 2-½, or 3 times each ordinary labor unit.”
In other words, when you count the labor units for each element, you can multiply the sum of those that were more difficult by one of the above numbers.
Larkin goes on to say, “When installing cable, there’s a labor unit assigned per C, or every 100 feet, assuming the usual degree of difficulty. Each hanger, every screw, and every other item is assigned a labor unit as well.”
For more difficult jobs, where the cable looks like it will take longer, you can assign a difficulty factor to it as well. We’ll cover more of the labor unit method of job quoting in another article another time.
Signal Attenuation in Metallic Structures
There are several reasons why wireless installs easier in residential settings than in commercial and industrial. Understanding these differences assures that you have a better understanding of the problems so you’re always on the lookout for adverse situations. First of all, the distances that radio signals must travel from the wireless network’s edge to the receiver at the center is usually greater in commercial settings due to the larger size of the structures involved. Second is signal attenuation.
According to a Wikipedia article entitled Path Loss, “Path loss (or path attenuation) is the reduction in power density (attenuation) of an electromagnetic wave as it propagates through space. This term is commonly used in wireless communications and signal propagation. Path loss may be due to many effects, such as free-space loss, refraction, diffraction, reflection, aperture-medium coupling loss, and absorption. Path loss is also influenced by terrain contours, environment (urban or rural, vegetation and foliage), propagation medium (dry or moist air), the distance between the transmitter and the receiver, and the height and location of antennas” (http://bit.ly/2Ls9am5).
Attenuation itself is due in part to things in the environment that the radio waves from our electronic lock, for example, happens to encounter. For one, the type of wall material that a low-power wireless signal has to pass through is a key component. In modern residential construction it’s common for our radio signals to pass through drywall, or sheetrock. Thus, far less signal is absorbed and converted into heat than with solid, masonry walls with metal rebar in them. Of course, some homes have plaster lath with metal mesh, which can cause real problems as well.
“Radio signals are forced to travel through walls, cabinets, you name it. In homes these obstacles are usually made of wood and other materials that do not cause significant attenuation where in industrial [and commercial] they are often made of metal,” says Markowitz.
The frequency of our wireless signals also is a factor that needs to be considered. A good example that most of us can relate to is that of our cell phones. In most 3G cell networks there are two basic frequency ranges that cell carriers use: 850 MHz and 1.9 GHz, or 1900 MHz. The preferred frequency band when operating in a building is 850 MHz. This is basically because the lower the frequency, the less attenuation that occurs. WiFi frequencies include the usual 2.4 GHz and that of 5 GHz, which serve the newer 802.11ac standard for wireless routers. Compare this to wireless alarms that often use a frequency range of 300 to 400 MHz.
Remember, the higher the frequency, the more attenuation that takes place and it’s this loss of signal that we have to contend with. You’ll find the operating frequency of your system in the instruction manual in the specifications section.
Solutions to Signal Attenuation
Wireless equipment manufacturers are well aware of the issue of signal attenuation. Those who engineer these products, in conjunction with service techs in the field, have come up with a variety of solutions designed to provide worry-free installation and ongoing service. In a residential environment there are several rules of thumb to adhere to in order to avoid the issues involved with attenuation, and they can be applied to commercial as well:
Evaluate the environment around the geographic location, looking for sources of radio interference such as a nearby radio station, a cell tower, as nearby airport, or an industrial plant where there is large electrically charged equipment.
- Install the receiver, also referred to as an “access point,” above ground level.
- Install the receiver as close to the middle of the structure as possible.
- Avoid installing wireless transmitters on metal doors. Instead, install a plunger switch in the jamb and hard wire it to the transmitter, which should be mounted to or next to the trim.
- Don’t fasten the receiver (access point) down until the system has been tested for signal strength and general operability, then fasten it down.
- If the manufacturer has a survey feature, use it to test the location of the panel/receiver with that of the proposed location of the head-end.
There are other things you can do to provide quality and reliable wireless service. One of them is to install wireless extenders, remote receivers, and repeaters, whichever ones are available with the line of products that you happen to use.
An extender is pretty much the same as a remote receiver, but you will find both terms in practice. Smaller burglar alarm lines will allow up to two receivers on a single alarm panel. Others will allow many more. Eight is the limit with some electronic locking systems as well. It’s going to vary so you have to review your product information to find out what’s going to work in your case. Repeaters are also common when they support the frequencies used with the line of products you have settled on.
One more thing, “Because of the electromagnetic interference encountered in some buildings, it may become necessary to use special cable to connect remote access points to the main system head-end,” says ESC’s Larkin.
Markowitz agrees, “Use Category 6 cable instead of Category 5e when connecting extenders and receivers. CAT 6 helps with the noise factor in factories and in airports,” he says. “In some applications we have to install fiber for the same reason.”
One place you can always turn to is the manufacturer’s support team. Another is the distribution house whom you purchase your equipment from. There is usually one or two resident experts who can help you engineer job so you can minimize the chances of trouble.
