Not too many years ago, we saw the first surge in the sale of laptop computers. The portability factor, along with their ability to extend the workday, made them an almost instant hit. Along with that popularity came a wave of laptop thefts that caused most industry security directors to go looking for solutions. The widespread availability of Electronic Article Surveillance systems in the retail world made it seem like there should be an easy fix to the laptop problem. Well, it turned out the problem was a lot more difficult that any of us imagined, and the solutions that entered the marketplace fell short in effectiveness and cost.
While these technologies faded from the scene in the security industry, you may be interested to know that the technology to track high-value assets has continued to evolve and grow. These systems are now being sold to track assets in environments such as hospitals, where there is a real ROI on knowing where the infusion pumps, vital sign monitors, x-ray equipment, wheelchairs and even patient beds are at any given moment. This technology, now known as RTLS (Real Time Locating System), is also gaining interest for supply chain applications to locate entire pallets of goods in a warehouse, as well as other applications such as research labs, where expensive equipment needs to be inventoried or located without spending the time to do expensive searches.
So, is there a security application after all? Perhaps — especially if there is also a good operational reason, like the hospital example, to justify such a system. At the very least, security departments need to keep an eye on emerging technologies like this one that have real potential to solve the thorny loss problems that we just seem to put up with today.
What’s Important?
Looking back over our experience with these products, several key factors jump out as being important to the success of the system:
Tracking — We made a mistake with the early systems by making them portal-based. Sensing an asset passing through a doorway is just not good enough. Instead, we need to track the whereabouts of an asset anywhere in the building. Why? First, portals rarely serve any purpose other than security and so they are much harder to justify than a system that provides location. Second, a system that only senses passage through a portal has too many security shortcomings. Take the asset out through an unprotected window or remove the tag in the lunchroom, and the system provides no further protection.
Accuracy — If you are going to track assets, the system needs to be reasonably accurate when it provides locations. A system that says a monitor is on the second floor when it really is on the third floor will do more to frustrate than inform. Frustrating systems get turned off.
Reliability — The same is true for reliability. Assets cannot just disappear from view because the electric forklift puts out a lot of interference, or because the new metal supply cabinet seems to somehow be upsetting the system.
Battery Life — Active systems require batteries in their tags and the life of those batteries varies significantly. In addition to looking for products with a long battery life, any good system needs to help track the life of and manage the maintenance of those wear items.
There are wide variations in cost for these systems. In particular, system design and installation can be significantly different due to the complexity of the required infrastructure. Evaluation of any system or technology must go beyond the raw equipment cost.
How do these systems work?
The technology behind these systems has changed significantly since we first started talking about RTLS. Right now, there are seven basic types of systems, each with their own advantages and disadvantages.
Infrared: Traditionally, one of the most precise ways to get room-level accuracy has been to use a system that combines traditional RF technology to identify the asset, while using an IR signal (like that of your TV remote) to provide location information. IR works in this application because it does not go through walls or floors, thus enabling a sensor in each room to provide the exact room-level location of the tag. On the other hand, that inability to go through solid objects also means the signal is easily blocked by a nurse’s uniform, a work glove or any other misplaced object. While the cost of these tags is reasonable, the IR power requirements often make for short battery life and the cost of placing a receiver in each room can be high.
Ultrasound: Like IR-based systems, ultrasound systems provide room-level location accuracy. They work by using small tags with speakers that emit ultrasound at around 40kHZ, which is above the range of human hearing. Once again, ultrasound does not go thru walls in any real way, so placing a sensor in each room provides a high degree of positional accuracy. Ultrasound has the additional benefit of being much harder to shield with clothing or misplaced objects. Maximum distance is fine for a hospital environment, but can be an issue for larger rooms and is likely not a good application for warehouse space. The largest downside to these systems tends to be the cost of “gridding” the building with enough receivers to cover each room.
Conventional Active RFID: When RFID first started being used for asset tracking, this was the technology employed. There were and are a lot of tradeoffs, however, because of the laws of physics. Pick a low frequency like 125KHz and the signal easily passes through objects made of metal and containing fluid, like the human body; however, power requirements go up and maximum distances tend to drop. At the other end of the spectrum, the use of 900MHz signals provides distance and reasonable battery life, but placing a hand over the tag will block all output.
Location finding is also a problem. Since these signals move through walls, they either need another technology like IR to provide location information, or they need to compute the location using multiple receivers. This computing process measures either relative signal strength to multiple receivers or the time the signal takes to arrive at multiple receivers. The latter is becoming the preferred technology, but is complex and can still be affected by signals reflecting off nearby objects and producing multiple ghost signals that the receiver has to find a way to ignore. Overall, newer technologies find ways to offset one or more of these issues in ways that make these systems less popular at this point.
Wi-Fi: Wi-Fi-based systems are radio-based and use the common technology invented to provide wireless connections for laptops. The key advantage of these systems is the ability to take advantage of the existing Wi-Fi infrastructure that many companies already have in place to lower the cost of the installation.
Unfortunately, there are some counterbalancing issues. In most cases, the Wi-Fi equipment already in a building was not selected or positioned with location finding in mind; therefore, location accuracy can be poor unless you add or relocate the Wi-Fi infrastructure — which raises the cost substantially. Tag cost also tends to be higher than competing technologies and battery life shorter. Still, this is a technology worth considering if your accuracy needs are low or you have happen to have the right infrastructure in place. For more information about WiFi-based systems, visit Ekahau (www.ekahau.com).
Ultra Wide Band (UWB): Ultra Wide Band is an intriguing technology. By using very short pulses of RF spread across a very wide spectrum, UWB systems avert some of the shortcomings of conventional RF systems. Short pulses make the tags much easier to reliably find in spite of reflections from nearby objects (think of listening for a hand clap in the middle of a noisy room and you start to get the idea). The wide spectrum also makes the technology relatively immune to interference.
Put all of this together and you get a reliable system with long battery life that can locate assets down to 2-foot accuracy. The downside is the cost, which can be among the highest — owing to the need to use a large number of precisely installed receivers to get that accuracy. Time Domain Corp. (www.timedomain.com) is a source of UWB systems.
ZigBee: ZigBee is a relatively new standard for wireless communications. It allows the tags and receivers to automatically form a “mesh” of communications, in which tags can talk to other tags as well as receivers. The advantages are significant in that if a tag cannot see a receiver, it can still send a signal to it by passing through another nearby tag. Beyond reliability, this has the effect of dramatically reducing installed cost, since fewer receivers are required and placement and installation is less critical. In fact, the receivers are often just plugged in to outlets in each room.
While location is often determined computationally using signal strength, it is possible for the system to periodically calibrate itself by measuring the signal between each receiver. This can result in good positional accuracy and resilience to changes in the environment. Because ZigBee was designed with battery operation in mind, battery life is also good. For an example of a ZigBee system, see Awarepoint (www.awarepoint.com).
Passive RFID
All of the above systems are “active” systems. That means the tags contain a battery which provides the power for long-distance communication, and, in some cases, assisting to compute location. Of course, the downside of this is cost, size and maintenance headaches. The other option has been passive systems. The best-known example of this technology in the security would be our proximity ID badges, where the reader on the door sends power to the tag in the badge and no batteries are required. The downside historically has been very short read distances in a passive system.
This is changing, however. Over the last year, tags and handheld readers have emerged for retail and supply chain applications that can read up to 40 feet away. Called “UHF Gen2” technology, they are part of a large project to replace printed barcodes on all retail packaging with an RFID device. They are already priced well under a dollar and are headed much lower as volume grows.
Even with this tempting price, however, no one thought there was any possibility of doing RTLS applications with them over any great distance. That was until a company called Mojix (www.mojix.com) demonstrated a reader system last year that could read these tags at 300 feet away and has the technology to locate the tags within a 3-foot radius. They claim the reader will be specified to a 600-foot distance. This will be a great system for the retail environment with the potential for inventory and loss prevention in one.
Are We Ready?
Is it time for security to think about asset management again? It’s still not an easy decision — there are lots of choices, and while costs have dropped, they still can be tough to justify. The good news is there are also a large number of system choices now available which makes finding the right system for your needs more likely. If your company could benefit from the operational efficiencies of asset location, you could easily find that today’s technology could be just what you need.
Rich Anderson is the president of Phare Consulting, a firm providing technology and growth strategies for the security industry. A 25-year veteran of high tech electronics, Mr. Anderson previously served as the VP of Marketing for GE Security and the VP of Engineering for CASI-RUSCO. He can be reached at [email protected].
