RFID Interrogators Grow Up

By Jill Gambon

The inability to pinpoint the direction in which tagged pallets or cases are moving, and the issue of unwanted tag reads, particularly vexing in crowded areas such as manufacturing floors or warehouses, have been "major pain points" for radio frequency identification users, says Toby Rush, president of Rush Tracking Systems, a Lenexa, Kan.-based systems integrator specializing in RFID and other auto-identification technologies. If solving these problems has been on the top of your "wish list," your wish may have been granted.

Tag direction detection and tag distance calculation are among the features being added to standards-based, off-the-shelf RFID interrogators, to provide more detailed location information about tagged goods and cut down on unwanted tag reads. These capabilities in readers increase the value of the RFID network, says Rush, because the data is more reliable and more specific.

Impinj's Speedway reader, which is certified by EPCglobal, features a new tag direction sensing capability.

One company that has an early lead in the area of tag direction detection is Seattle-based Impinj, which last October announced an upgrade to its UHF Gen 2 Speedway readers. With the upgrade, the company added an algorithm to its Octane firmware that can sense the direction in which pallets, crates or carts equipped with Gen 2 UHF tags are moving when they pass through an RFID portal. The interrogators sense the tags, and the algorithm calculates the direction in which up to 10 tags are moving at the same time. The algorithm reports tag direction via a Low-Level Reader Protocol (LLRP) response message. (LLRP is an EPCglobal standard that provides a common but extensible interface for linking EPC Gen 2-compliant readers to middleware or other types of networking software.) The algorithm running on the Speedway readers works with any compatible Gen 2 UHF tags and off-the-shelf Gen 2 reader antennas.

The ability to know tag direction creates a deeper level of information about the location of tagged assets, says Mendy Ouzillou, product line director for Impinj. For example, with that information, a retailer can track whether a pallet of goods has been moved from the stockroom to the retail floor. In a hospital, the medical staff can track whether carts of surgical equipment have been moved into the operating room. "This solves a real business problem," Ouzillou says. "Data without tag direction is fine, but there's not a lot that you can do with it."

To date, Ouzillou says, companies deploying RFID systems have tried a variety of methods to achieve tag direction detection, with varying degrees of success and at a range of costs. Some have tried installing motion sensors at portal doors, while others have used phased antenna arrays, and some have even used a combination of active tags and GPS technology.

The firmware upgrade has been in beta testing in recent months and is scheduled for general availability in January. Impinj declined to disclose the names of customers that had tested the product. The company is continuing to refine the tag direction technology and expects future releases to be more powerful, with the capability of determining the direction of larger populations of tags. In addition, Ouzillou says several middleware vendors have expressed interest in integrating the tag direction functionality into their software.