Real-time locating systems (RTLS) have been used for many years to track high-value assets. The technology behind them usually involves some sort of emission device on the object of interest, with multiple receivers located around a given area. Knowing the signal strength from the emitter to each receiver provides the approximate distance between them and, with enough collection points, a solid location value.
An RTLS can be expensive to deploy, given the cost of hardware and installation, as well as to support the infrastructure. And the environment in which you use an RTLS can affect how the system will function. RF systems will not perform well in highly metallic environments, and electronic components are sensitive to temperature and humidity.
Two fairly new technologies—Rubee and Ultra-Sonic—can make an RTLS cheaper to install and maintain. They can also be used for simple zone transition. It is important to understand where you would need each, and how to use it appropriately.
Rubee, or IEEE 1902.1, has combined old technology with new thinking. In the passive format, this technology employs two separate frequencies to operate, one serving as the powering wave (or carrier wave) and the other used strictly for data. This helps the technology work in noisy environments, where most passive technologies fall short due to the single frequency power transition for PIM (Pulse Interval Modulation) communication.
The antennas for this technology can be made out of speaker wire and cover the zone size needed, depending on what you are trying to achieve, which means they will be cheap. Reader cost is less than $100—again, cheap!—and the technology is extremely rugged: It will read objects in the trunks of cars, through metal briefcases or even immersed in water.
Still, this is not the "supply-chain killer" some originally thought it would be, and here's why: The communication speed of Rubee is such that only six items per second can be read reliably. So it's a fantastic technology for use in manufacturing, health care, site security, tool tracking and many other niche applications, but it won't do the job if you need to read thousands of items on a conveyor or at dock doors moving at high speeds.
Ultra-Sonic technology is based on the same non-audible (by the human ear) frequencies bats use to find out what is near them. The system consists of emitters (or tags—speakers emitting a high frequency), and receivers (or readers—essentially, microphones tuned to listen for such frequencies). The louder a receiver hears a tag, the closer it is. If you have enough receivers around, you can get an excellent location value for your tagged item. This technology is inexpensive compared to classic RF RTLS systems, and is currently finding huge traction in the health-care sector.
The downside, however, is that it will not work through metal or water, and you shouldn't try to use it in a veterinary clinic. There are a limited number of skilled implementers of this technology, but one who has rolled this out in real-life practice is RadiantWave. RFID and its many applications will still leave gaps, which can be addressed by examining the problem creatively and objectively to find the right solution.
Mark Brown is an independent consultant with vast experience in RFID solutions and creative design. He implements and teaches RFID technology worldwide, and continues to help customers, both domestic and internationally, realize the true potential this technology can offer real-world business needs. Brown and the team of consultants he works with speak regularly at trade shows and have authored many industry-recognized white papers, three best-selling RFID certification books and regular publications throughout the world, and are constantly delivering training to hundreds of organizations worldwide.
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