Data Intelligence:HF vs. UHF: Lies, Damned Lies, and Marketing

May 1, 2006
Is HF or UHF best for item-level tagging? The answer is 'yes,' and 'no,' and 'neither of the above.'

Mark Twain's original observation was, "There are three types of lies. Lies, Damned Lies, and Statistics." By selecting the right set of parameters, statistics can be used to support nearly any view— even conflicting ones. Today, marketing pronouncements and news releases on RFID can be considered in much the same light as Twain's view of statistics.

I'm going to digress for a moment and talk about "the multiplicity of truth," a concept I first encountered in a college Shakespeare class (don't worry, this won't be painful). The only thing I remember verbatim from that class was, in the middle of a heated discussion on the significance of some point, the professor smiling, leaning forward and very quietly saying, "That's true. And it's not true. And that's true too." (Hence, the "multiplicity of truth.")

Oh joy. What did that mean? Let me paraphrase his explanation.

I say, "It's a beautiful day. The sun is shining, the birds are singing and the tempera-ture's just delightful." You look outside and see dark, ominous thunderclouds. It's raining frogs, grapefruit-size hail, and the occasional Volkswagen. Your immediate conclusion is that either I'm lying or delusional.

Two days later, it's a beautiful day; the sun is shining, etc. So, was my statement a lie, delusional or just premature? It could be "none of the above." I might have been speaking of the weather in Sri Lanka or Sydney, Australia. In other words, without a specific point of reference, my statement is actually meaningless. Do you see where this is headed?

By now, you may have seen various news releases touting either HF (13.56 MHz) or UHF (860-960 MHz) as THE solution to item-level tagging. A recent test proclaims HF the clear winner. Tesco (UK) and Metro (Europe) both use HF for various tagging applications because it works well and because European UHF regulations are very restrictive. This latter point suggests that HF is the only global solution.

On the other hand, a major retailer has proclaimed that UHF has been shown to work just fine, even on metal and liquids. Advances in near-field reading of UHF tags promise increased ability to singulate items (read a single tag) as well as batches—essential for item-level tagging. UHF proponents suggest European (and other countries') UHF regulations will soon be relaxed.

Thus, for each group of advocates, it's obvious that experience and trials "prove" that, for item level tagging: a) HF is the only solution b) UHF is the only solution.

The multiplicity of truth strikes again
So, how's the weather in Sri Lanka? Or, more importantly, how does RFID work on Procter & Gamble's Pantene shampoo (shown to be one of the more RF-hostile consumer products) or jars of pickles (with a very strong electrolyte solution)? More importantly, do we care?

There is, at the moment, a limited number of products worth tagging. And, yes, both HF and UHF have been shown to be viable approaches (note my choice of wording). In the real world, however, there are lingering concerns about performance and costs of both current technologies.

In health care, there are concerns that pharmaceuticals, particularly cold chain products, exposed too long to UHF are at risk. On the other side of the argument, the Steel Recycling Institute has just issued a statement that copper from RFID tag antennas (typically used in HF) would be harmful to steel recy-cling.

So, is HF or UHF "best" for item-level tagging? The answer is, "yes," "no," and "neither of the above." More testing and development needs to be done. And possibly a new version of either HF or UHF developed.

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