Not too long ago, people used pen and paper to manage information. In a very short time, however, electronic technologies have moved us to faster-and more efficient-ways of keeping track of things. Unlike pen and paper, radio-another old friend-has moved with the times. In fact, it’s pushed its capabilities to stay near the leading edge of new developments.
In this case, “radio” doesn’t mean that tabletop box that used to bring you the Top 40 hits. These days, you’re likely to encounter radio as a Band-Aid-sized chip imbedded in the heart of your cab, your trailer, or even your tires. This old friend in a new guise is RFID (Radio Frequency Identification). RFID had its beginnings in World War Two, in a system called Identification Friend or Foe (IFF). A radio on the ground transmitted a code to approaching aircraft. If the transmission was received and a signal returned, antiaircraft crews knew to hold their fire.
Today, RFID tags come in a variety of shapes and sizes.
Animal tracking tags, inserted beneath the skin, can be as small as a pencil lead in diameter and one-half inch in length. Tags can be screw-shaped to identify trees or wooden items, or credit-card shaped for use in access applications. The hard plastic anti-theft tags attached to merchandise in stores are RFID tags. The heavy-duty transponders used to track intermodal containers or heavy machinery, trucks, and railroad cars for maintenance and tracking applications are RFID tags.
A basic RFID system consists of three components-an antenna, a transceiver (or decoder), and a transponder (commonly called an RF tag). The antenna emits radio signals to activate the tag and read and write data to it. The transceiver controls the system’s data collection and communication.
In many applications, the antenna is packaged with the transceiver and decoder to become a reader (a.k.a. interrogator), which can be set up as either a handheld or fixed-mount device. When an RFID tag passes through the interrogator’s electromagnetic zone, it detects the reader’s activation signal. The reader then decodes the tag’s encoded data, and passes it along to a host computer for processing.
Supporters of RFID technology hope it will become as prevalent as the bar code. Shop managers could take inventory merely by walking down a parts aisle with an electronic data reader. Package operations could automate sorting to a degree now impossible. And those are only two applications that leap to mind.
ON THE ROAD
RFID tags are like bar codes, but they don’t have to pass under a scanner to be read. That means information can be viewed while the tag is on the fly. An example is PrePass, the weigh-in-motion system developed by Lockheed Martin IMS and Raytheon Highway Transportation Management Systems.
Started as a government-funded experiment in 1982, PrePass has grown to include 87 locations in 14 states since its commercial deployment four years ago. The number of trucks with a PrePass transponder now tops 61,500.
The advantage to PrePass is that participating trucks are pre-cleared to bypass roadside inspection stations. Interrogators located at weigh stations emit signals that prompt a reply from the transponder mounted to the truck’s windshield. That response identifies which fleet the truck belongs to and whether the carrier has an acceptable record of compliance with vehicle weight and safety rules. When the truck passes over a weigh-in-motion installation in the roadway, the transponder flashes a green light to the driver telling him he’s clear to pass the scale, or a red light telling him to stop. At some PrePass locations, a sensor in the roadbed can count, weigh, and measure the distance between axles, and calculate total gross vehicle weight.
The advantage of PrePass for jurisdictions is the ability to focus their enforcement away from pre-selected, quality carriers, and more closely monitor which truck has gone by, who owns it, and whether the appropriate taxes and duties have been paid.
In Canada, one of the most advanced RFID-aided systems is the automated toll-collection system on Hwy. 407 in Ontario.
When your truck enters the highway, an overhead reader recognizes the code embedded in the transponder mounted to the windshield and records where the trip began. When you exit under another overhead reader, the electronic sensor will log your vehicle off the highway and then forward a record of your trip to an automated billing system. Within about 30 days, you’ll receive an invoice for the amount of the toll, which is based on distance traveled.
IN THE YARD
RFID in yard applications offered by companies such as Raytheon, Synergistic Systems, and Randtec Inc., can smooth the way to more accurate monitoring and increased control of trailers. In these applications, the transponders on tractors, trailers, and straight trucks are read by interrogators at the company gate. Truck transponders can also be configured to provide odometer readings, reefer data, and trailer miles on anti-lock braking systems.
The advantages of RFID technology are obvious. Tags can be read through challenging conditions such as snow, fog, ice, paint, and crusted grime, and at high speeds (in most cases responding in less than 100 milliseconds). Because an active RFID system can both read and write data, it offers a significant advantage in such applications as work-in-process or maintenance tracking.
AROUND THE CORNER
Perhaps the biggest news in RFID technology is a read/write-capable tag called an Intellitag, developed by Intermec Technologies Corp.
Intellitag shatters two formidable technological barriers. First, most commercially available read/write RFID tags require local power, usually a battery. Tags without onboard power “reflect’ the power of the reading device, a technology known as “back-scatter.’ Until now, back-scatter tags have only been capable of read-only uses. Read/write capability without onboard power makes Intellitag valuable in more applications and reusable besides.
Second, these tags use an IBM technology called “anti-collision arbitration,’ a fancy way of saying they can deal with more than one tag at a time. If 20 tagged items are in a shopping cart, for example, a transponder can read them all correctly.
Intermec’s Intellitag may propel RFID as a stronger rival to bar code as the identification technology of choice. But the last barrier is cost. Intermec won’t say how much the new tags will cost, but it is rumored to be over $1 apiece (the least-expensive RFID tags now cost in the range of 50 cents). The price is far too high to seriously challenge bar codes, but still, this breakthrough technology will undoubtedly find applications in package delivery, cross-dock, and many private-carrier operations.
When you think about it, aren’t you glad radio (and its modern offspring) is still with us?
SIDEBAR: A lesson in reading and writing
When RFID came down from the skies in the 1980s, the price stayed high yet the technology was poor. Initially, for example, interrogators and transponders had to broadcast on two different radio frequencies, because the strong interrogator signal would often overwhelm the simultaneous, much weaker response from the transponder.
An early breakthrough chopped interrogator and transponder transmissions into tiny time blocks, allowing gaps for weaker transponder signals to pass on the same frequency, like sunlight through a picket fence.
As the cost of RFID dropped, interest picked up. In the 1980s, you could find small, cheap transponders at the department store in the form of electronic article surveillance tags, used to prevent shoplifting.
These simple magnetic-based RFID systems are called one-bit tags. That single bit conveys the “0” or the “1” of computer language, which can be read as “yes” or “no,” “on” or “off.” Or, in a retail setting, “paid for” or “stolen.”
More complex yet small read-only tags were used by scientists to track migratory fish. These tags-indeed, most RFID tags-are read-only tags in which a permanent string of data is programmed into the tag.
It usually represents an identifying code: anything from a stock number to a trailer number. Read-only or “passive” tags capable of returning one set message require no power to maintain memory. But even these passive tags may require power to transmit, depending on the application and distance from the interrogator.
Data stored on read/write tags can be changed or updated. These “active” tags require a power supply, though, which boosts the cost and complexity.
To put any tag to the best use, the information on it has to be quickly available up and down the supply chain to all the individuals who can use the input.
Unfortunately, most companies don’t have the computing capacity to manage all the data a tag can store.
When information about an item moves more slowly through the supply chain than does the item itself, that’s when it might be best to store data right on the moving item with a read/write tag so that it can be updated-and other people can take advantage of it locally.
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