Apr 20, 2006In a project set for completion by the end of the year, Post Danmark—the Danish postal service—will tag all of the 25,000 roll cages at its facility. These wheeled containers are used to move mail around its mail-distribution network.
The mail carrier believes tagging its roll cages will help reduce the loss of such cages, as well as improve the security of mail during transport and track roll-cage usage. The carrier also expects to reduce supply chain inefficiencies and improve workflow. For the purpose of this project, Post Danmark plans to use semi-active RFID technology—battery-powered tags programmed to transmit only when requested. The carrier is already using semi-active tags to monitor its international mail operations. The decision to expand the use to roll cages has not been a speedy one.
"We initially completed a trial of a few hundred tagged cages more than a year ago as a proof of concept," says Claus Jensen, area sales manager at Lyngsoe Systems.The Danish RFID company will supply the hardware and install the new RFID system at Post Danmark.
The initial trial deployment used Lyngsoe's semi-active tags and interrogators. "Post Danmark then looked for an alternative, passive RFID solution," Jensen recalls, "but they couldn't find one to meet their read-rate requirements. That's why the decision [to deploy Lyngsoe's semi-active system] took a year."
According to Lyngsoe, Post Danmark sought a passive-tag solution for roll cages. That way, if it ever adopted a passive-tag system to track letters, trays, parcels and other items, the carrier could use a single system to track both the mail and the cages. For cage-tracking, Post Danmark demanded the rate of successful read attempts be at least 98 percent—and as close to 100 as possible. Without such a high performance level, the system would not be able to provide sufficient data for load control, volume forecasting and tracking and tracing. According to Lyngsoe, the passive solution did not reach this target.
Post Danmark's failed effort involving passive tags stands in contrast to Finland Post's success in using passive tags to track its own roll cages. This past summer, Finland's national mail carrier tagged 200 of the 200,000 roll cages it uses to store and transport packages and letters. The 200 roll cages were fitted with passive 856 MHz UHF tags made with Philips Semiconductors' U-Code HSL chips (see Finland Post Finds RFID Can Deliver ROI). However, the two roll-cage types are not identical. Finland Post's cages have three closed metal sides (the fourth side is open), whereas Post Danmark's have all four closed.
The deployment is scheduled to start in June, using Lyngsoe's CT21 semi-active tags. Measuring 100mm by 150mm by 2mm and weighing 12 grams, each tag carries 256 bits of memory, used to store the ID number. When the tag enters a read field, a 125 kHz signal transmitted by an RFID reader wakes up the tag's transponder. Once powered up, the tag's processor starts running, utilizing the high-frequency 433.92 MHz band to transmit the tag's ID to the reader. After this, the transponder will shut down once more, awakening again only when the transponder enters another read field.
Post Danmark can already read these tags as part of its Automatic Mail Quality Measurement (AMQM) infrastructure system, also supplied by Lyngsoe. Readers installed at key Post Danmark distribution hubs measure RFID-tagged parcels and letters as part of the International Post Corp.'s (IPC) quality-of-service measurement system. This system is used to monitor postal services in more than 50 countries (see Big Blue Puts Stamp on RFID).
For the new roll-cage tracking deployment, Post Danmark's existing interrogator antennas will be upgraded to support individual gate allocation, automatic load control on all gates and automatic in-and-out registration on all gates. It will also handle automatic registration of handling time in hubs and sorting centers, Lyngsoe reports. The carrier's existing RFID system, installed in selected distribution offices, and its existing middleware and back-end applications, will be retained and upgraded with all these new features.
Initially, Post Danmark will not be using the new RFID system to track which customers have which roll cages. Instead, it will track cages as they leave for a specific delivery area—which can include more than one customer—and as they return to Post Danmark's facilities. However, according to Lyngsoe, the postal carrier hopes to install RFID interrogators on its delivery trucks and link those readers to its system via a cellular phone connection. In that way, it can record the drop-off and pickup of individual cages at customer sites.
