Not surprisingly, slap and ship is not a method endorsed by Wal-Mart. Langford won't say as much, but come Jan. The reputation of the world's biggest retailer has been tarnished of late with allegations of unfair wage practices, hiring illegal immigrants and discriminating against female employees. And now some industry experts are predicting that suppliers' failure to meet the RFID mandate could be more bad press for the retail chain.
Wal-Mart's biggest mistake, they say, was imposing a top-down mandate on its suppliers before the technology and business needs matured to where RFID-tagged inventory made good economic sense for suppliers, customers and Wal-Mart. The center proposed an electronic product code, or EPC, as the latest method for identifying products. The EPC would utilize radio frequencies to identify computer chips placed in tags. This technology would eventually replace bar codes, which require the scanner to "see" the UPC number to read it, with a device that requires no line of sight and little human intervention.
When applied in a controlled environment, RFID tags and the devices that "read" them work amazingly well. Essentially, the system is made up of two components. First, there's the tag, which varies in size and shape.
Some look like stickers and labels, and others like thin plastic wristbands. Tags are affixed to cases and pallets.
Each tag has an antenna and is embedded with a chip that contains a unique string of numbers that identifies each product. Tags can be passive or active. Active tags have a battery; passive tags, which get their energy from the antennal devices known as readers , are less expensive and more common. Readers identify the tags as they pass by. The magnetic field from the antenna wakes up the passive tags as the reader approaches, and the tags transmit their digital information, in the form of the electronic product code, from the reader into a computer system.
This essentially is the system that Wal-Mart and others, including the Department of Defense and Target Stores, believe will revolutionize the global supply chain. And indeed most supply chain experts predict that RFIDs will eventually take the black holes out of the retail supply chain, providing product shipment and inventory views of unprecedented detail.
No manual counting, no driving around, no question of mispicks, no order number mistakes. Once you get an accurate understanding of inventory position, that information becomes invaluable. Langford says the RFID payback for Wal-Mart's suppliers will be twofold: It will allow them to reduce their inventory, and because Wal-Mart will always have their product in stock, sales will improve. Wal-Mart's announcement in June of the January deadline caught many in the supplier community off guard. Some didn't even know what RFID stood for; others dismissed the announcement as grandstanding.
It operates at a relatively high radio wave frequency of Imagine your mission is to design an anti-shoplifting device using some old radio sets you found in the garage. You could build something a bit like a radar with a combined radio transmitter and receiver , sit it by the shop doorway, and point it at people passing by. Radio waves would pass out from your transmitter, bounce off people walking past, and then reflect back to your radio receiver.
The trouble is, this wouldn't actually tell you anything useful, because everyone would reflect the radio waves in exactly the same way! You wouldn't know whether people were shoplifting or not, because there would be no way to distinguish shoplifters from ordinary customers or people who hadn't bought anything at all. What you'd really need would be for shoplifters to reflect radio waves in a different way to everyone else.
But how? Photo: Look closely at this price and size label from a pair of shoes and you'll see it says "RFID" on the bottom. Peel it off, turn it over, and you'll find the tell-tale antenna pattern on the back. Anti-shoplifting devices have cracked this problem. As well as having a transmitter and receiver at the doorway, every item in the store contains a concealed RF "tag". In bookstores and libraries, you'll find very discreet "soft tags," stuck to one of the inside pages. In record stores, the plastic shrink-wrap may have an RF tag stuck onto it, or CDs may be locked into large plastic cases with RF tags built into them, which can be removed only be a special tool at the checkout.
In clothes stores, there is typically a "hard tag" a chunky, round, white plastic tag bolted onto each item with a sharp metal spike sometimes the tag has ink inside it so it spills all over you and spoils the item you're trying to steal if you attempt to remove it. Some of these tags are cleverly concealed so you can't spot them. Others are deliberately very obvious and easy to see—so they deter you from stealing. The gates on the doorway and the frequent alarms are another very visible deterrent to shoplifters. If you walk through the doorway without paying for something, the radio waves from the transmitter hidden in on one of the door gates are picked up by the coiled metal antenna in the label.
This generates a tiny electrical current that makes the label transmit a new radio signal of its own at a very specific frequency. The receiver hidden in the other door gate picks up the radio signal that the tag transmits and sounds the alarm. Why doesn't the alarm sound when you pay for something? You may have noticed that the checkout assistant passes your item over or through a deactivating device sometimes it's incorporated into the ordinary barcode scanning mechanism, and sometimes it's completely separate.
This destroys or deactivates the electronic components in the RF label so they no longer pick up or transmit a signal when you walk through the gates—and the alarm does not sound. It's all a bit more complex than I've made it sound so far because there are, in fact, two quite different types of RF tags and they work in a slightly different way.
Often the term "RFID" is loosely used to describe both, but there's a big difference between them: RF tags all send the same, simple signal and simply tell the receiver that something is present; RFID tags send more complex signals that uniquely identify whatever they're attached to. These are the simplest RF tags and they're used mainly in what's called electronic article surveillance EAS —the anti-shoplifting technique I've described above.
All the tags are exactly the same and none of them identify the articles to which they're attached. So in a store, RF tags set off the alarm when you try to steal something, but the alarm mechanism doesn't know what you're stealing, only that you're stealing something : there's no way of telling any one item from any another. One of the most popular RF technologies is called acousto-magnetic AM.
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A pulsed beam of radio waves from the transmitter strikes the tag, making it give off a precise frequency radio signal. The receiver picks up the signal, verifies that it's at the correct frequency, and then sets off the alarm. One big advantage of AM tags is that they can be scanned at quite a distance and at speed, making them popular in antitheft systems which have only seconds to pick up a signal from someone walking or running through a shop doorway.
These are more advanced and differ from simple RF tags in that they uniquely identify the article to which they've been attached: the radio signal that zaps from the article to the receiver contains a digitally encoded identifier. That's how self-checkout machines in libraries work: they beam radio waves into the RFID tag in the back of the book, receive the radio signal back from the book, and decode this to figure out a digital code that uniquely identifies which book you want to check out.
A computer attached to the scanner does the rest so in a library, the self-checkout machine communicates with the library's computer to update the main database whenever you check out or return a book.
Some actually have to be held right next to a reader device, while others operate at a distance of 10cm 4 inches or less. Simple RFID tags are described as passive. Instead of containing batteries , they work entirely by responding to the incoming radio waves from the scanner or transmitter.
There is just enough energy in those radio waves to activate the RFID chip. Passive tags typically send and receive signals only a few centimeters, but not much more. An alternative form of RFID technology, known as active tags, contain more advanced chips and tiny batteries to power them. They can send and receive signals over much greater distances. This is the sort of tag used in library self-checkout systems. As you can see from this photo, most of the space in an RFID tag is occupied by the antenna: the oval-shaped tracks around the edge.
The antenna needs to be this big both to pick up radio waves from the transmitter and because there are no batteries to convert them into energy to power the chip. The chip itself is tiny—sometimes as small as the point of a pencil.
Anti-shoplifting RF tags are often smaller and simpler than this: instead of needing a chip to generate a unique identifier code, all they have to do is receive the incoming radio waves and retransmit the same electromagnetic energy at a different frequency. Picture a shoplifter trying to steal a book from a store. What he doesn't realize is that the store's using electronic article surveillance EAS : the book has an RF tag stuck just inside the back cover. Here's the sequence of steps that triggers the alarm:. Here a military technologist is holding up some examples of RFID tags in front of a poster advertising the benefits of the technology.
You can't blame stores for wanting to install systems like this—especially when you hear that around 10 percent of all "shoppers" commit theft.