By Mary Catherine O'Connor
June 19, 2006—Aside from being "people who work late at night and have great respect for Maxwell's equations," engineers at
Visible Assets, a Miami-based company that sells product and asset-tracking solutions, are also Rolling Stones fans, according to Chairman John Stevens. It's no mystery, then, that they named their latest
tag technology "
RuBee," after the Stones' 1967 hit song, "Ruby Tuesday."
The
protocol RuBee is based on, however, has recently earned a much more workaday moniker: P1902.1. That's the
Institute of Electrical and Electronics Engineers' (IEEE) candidate specification, based on Visible Assets' RuBee protocol, under which the standards group is beginning work to standardize the technology. Tags based on the P1902.1 specification can be either active or passive, and all operate at a low
frequency, 132 kHz, rather than the
high-frequency (13.56 MHz) or ultrahigh-frequency (916 MHz) ranges used in the most widely deployed
RFID systems.
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John Stevens, Visible Assets
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Conventional HF and
UHF RFID tags, whether active or passive, primarily use the radio portion of electromagnetic induction to transmit a signal. RuBee tags, however, use "99.9 percent magnetic waves and 0.01 percent radio waves," Stevens explains—and because magnetic waves are not attenuated by water, as radio waves are, RuBee tags can be used in the presence of liquids. Low frequencies are also less affected by metal, which significantly impacts radio signals. Thus, RuBee tags can be much more easily
read around, in or on metal or water than HF or UHF tags. "You can take a [active] RuBee tag and put it inside a sealed steel can and read the tag from 2 feet away. Take the lid off, and that range should grow to about 8 feet," says Stevens.
Some makers of passive UHF tags are starting to design tags optimized to reflect signals using the magnetic field when the tag is close to an
interrogator, and the radio field (which gives a greater read distance at ultrahigh frequencies) when the tag is located farther from the interrogator. These tags are being built for use at the item level since they would make items easier to singulate at close range (such as at the point of sale), and because any metal and water content in the product would not impact the transmission in the magnetic field. (See
Wal-Mart Seeks UHF for Item Level.)
Stevens says that while RuBee is not an appropriate protocol as an alternative to the ones used by conventional RFID tags, the technology excels in applications where HF or UHF RFID fails. Plus, he says,
low-frequency technology "is in widespread use all over the world—and in using lower frequencies, the chips we use are also significantly cheaper."