Technology is only good if it solves a real problem or makes a solution better, faster or less costly. Wireless access control equipment solves two problems – making it a better, faster and less costly way to provide an access control system.
What exactly is wireless access control? It is not a proximity card reader. It is not a wireless transceiver that attaches to a card reader. It’s a lot more. It’s an integrated reader lock at the door and a panel interface module at the control panel. And it does a lot more for an integrator and its customers.
An integrated reader lock takes the place of everything needed at the door for online, real-time access control. The resultant benefit is that neither integrators nor their subcontractors need to spend three to six hours to install a strike and then hand wire up to six separate devices at the door, and then wire those all the way back to the control panel.
Since the electric door lock, card reader, door position switch, power supply, request-to-exit and request-to-enter functions are all built into the integrated reader lock, all that is needed is to remove the old lock, drill a few holes and then install the new integrated lock. There is no need for wiring anything at the door or from the door to the main control panel. That’s because there is a spread spectrum transceiver built into the integrated lock as well.
Such wireless access control solutions are opening up a wealth of opportunities for a myriad of applications as more and more security contractors and end users discover the scope of the technology’s capabilities and solutions.
Systems Installed in Days Not Weeks; Everything Is at Door
Think of it. Everything needed for access control at the door, all the way back to the control panel, can be installed in about 30 minutes. How much will this save integrators and their customers?
Door control modules no longer need to be placed near the door. They can be installed right next to the main panel. This saves time and hassle. The panel interface module then gets mounted next to the door control module and wired to it. Only a four-wire, RS-485 connection needs to be made to panels made by companies such as Nexwatch, Apollo and Maxxess. These panel interface modules can control up to 16 doors each and take just minutes to install.
Wireless access equipment is available that can be used with every brand of main control panel. Each panel interface module can control two to 16 doors. The panel interface modules come with Wiegand, magstripe or RS-485 connections, depending on the main control panel manufacturer. With an RS-485 connection, only four wires need to be connected to the panel interface modules.
These RS-485 panel interface modules can control up to 16 doors. If the brand of control panel selected does not have an RS-485 connection for wireless access, the panel interface module can be wired to the main panel or door control subpanel just as if it were a door using the Wiegand or magstripe protocol. Two doors can be controlled per panel interface module using the Wiegand or magstripe approach.
Systems can now be installed in days not weeks. Customers will appreciate that installers will be in and out of their premises quickly. This is especially true in university dormitories when the administration would like to finish an installation between semesters or during holiday breaks.
This was actually done at Biola University in La Mirada, Calif., with more than 250 integrated reader locks. Wireless access equipment also leads to gigantic savings on installation – typically 20 percent to 25 percent on a job.
In a recent installation at the University of New Hampshire, each suite in an entire dormitory was outfitted using wireless integrated reader locks. Bill Conk, senior manager of the school’s Housing Facilities department, says, “By using wireless access equipment, we probably saved about $50,000.”
Almost every integrator that has not used wireless yet usually believes it will not cost significantly less than a hardwired system. However, calculating the numbers is the only way to tell. On a recent bid for an 85-door, 77 monitoring-point job, one security contractor was able to lower its bid by $165,000.
Spread Spectrum Technology Creates Robust Communications
Electronic card readers, door position switches, request-to-exit and request-to-enter sensors are all cleverly packaged together with a transceiver and connected to an electric motor-driven lock to create the integrated reader lock. Both HID and Indala card readers and cylindrical and mortise locks are available.
The electronic signals that need to be sent back and forth between the lock and panel interface module are sent wirelessly. These wireless signals use spread spectrum techniques that help make the communications robust. For a truly reliable system, the receiver should have high sensitivity (+/-90dBm [decibels referenced to a milliwatt), while the transmitter should have high transmission power (greater than +20dBm), giving a dynamic range of at least 110dBm.
These dBms get used up as the two devices are separated from each other. For example, open air attenuation at 200 feet uses about half the dBms. Intervening walls use about 3dBm each, which further reduces the dBms available. Even with a large signal gain and heavy attenuation from distance and structure, there should be at least 25dBm left over to ensure reliable communications.
The range for controlling doors within buildings is usually a couple of hundred feet. The type of construction, like wood vs. concrete, will have an effect. But because of the penetration and bounce characteristics of spread spectrum at 900MHz, the effects are minimal if you stay within the manufacturer’s range specifications.
The panel interface module, which houses the antennae, needs to be located properly per the manufacturer’s instructions. If good communications aren’t obtained initially, overcoming communication difficulties is usually a simple matter of progressing to a remote antenna, then moving to a gain antenna and, lastly, using a RF repeater.
Manufacturers offer preinstallation test kits to quickly determine if the RF link will work adequately. Each door can be pretested in less than a minute. These tests are usually done at lower than normal power levels to ensure a signal surplus in normal use.
The security of the system is very important to users. Systems that employ spread spectrum technology coupled with pseudo-noise code algorithms and randomly generated addresses in their signal processing are very secure. The pseudo-noise algorithms make the transmitted information look like noise to a sniffer, while the randomly generated address is only known to the door-panel pair that uses it. So replicating is a monumental task.
Typically, in systems that use pseudo-noise algorithms, there are billions of permutations on every transmission. It’s easier to cut a hole in a wall than try to compromise the wireless electronics. As far as blocking a request to enter is concerned, it is only possible if there is another signal on the same frequency as the pair (integrated reader lock and panel interface module) trying to use it and the other signal is stronger than the pair’s. The possibility for this happening is remote.
But if it does occur, the solution to this problem is switching to a different channel automatically. This is called dynamic channel switching. Systems that have dynamic channel switching can avoid signal blocking.
Power is provided by a battery pack. The batteries will last longer than expected for a system that poles continuously to ensure communications are intact. Poling less than every 15 minutes is common. An excellent specification for the battery pack is that it will last for 60,000 swipes or up to five years, whichever comes first. A low batte
