RFID Basics: What is RFID, Why not just use Barcodes, How far can the tag be read, Is it dangerous to be around an RFID Reader, and frequently asked questions on EPC Standards.
Radio-Frequency Identification (RFID)
Q. What is RFID?
A. RFID stands for Radio Frequency Identification. In its simplest form, an integrated circuit, small silicon chip, is attached to a small, flexible antenna creating a tag. The integrated circuit provides data storage to record and store information. A reader sends a signal to the tag. The tag absorbs some of the RF energy from the reader signal and then reflects the RF energy as a return radio signal containing information from its memory.
Q. Why not just use barcodes?
A. Barcodes have been the primary means of identifying products for the past 25 years. However, there are some limitations with barcode technology that can be overcome using RFID. RFID does not require "Line of Sight" as long as in range of the reader; barcode scanners need to "See" to read the barcode. Standard barcodes only identify the manufacturer and product, not unique items. RFID allows for individual items to have a unique identifier and can identify many items at once.
Q. Is it dangerous to be around an RFID Reader?
A. They are similar in power levels to cordless phones that operate only within a short distance of their base stations. Alien's readers are certified under FCC Part 15 rules for unlicensed operation around people.
Q. From how far away can a tag be read?
A. EPC Class 1 UHF tags can be read at 1 meter (~3 ft) in any orientation, and up to 5 meters (~15 ft) if held in the optimum orientation. Battery-powered tags can be read reliably at up to 30 meters (~100 ft).
Q. Can the same tag be used for different frequencies?
A. Yes, if they are designed to do so. Tags can also be designed to operate in both the 915MHz and 2450MHz bands by incorporating a special antenna, however the peak performance of the tag may be slightly degraded.
Q. What is frequency hopping?
A. Frequency hopping is a technique used to improve performance of the RFID system and to allow multiple readers or other RF devices to work in the same area without interfering with one another. Frequency-hopping readers operate briefly at a particular frequency and then "hop" to another frequency within that ISM band. The 915MHz band actually runs from 902MHz to 928MHz. Thus, there are a lot of different frequencies to hop to when many readers are in the same area.
Q. Do RFID tags work on all products?
A. Not necessarily. Some products are more difficult to tag such as liquids and metals.
Q. How small are the RFID tags?
Alien's tags range from .5" x 3" to a 4" x 4" label for UHF tags. For 2450 MHz, the smallest tag is 2" x 1/8".
Q. Does RFID work in Europe and Asia?
Yes, at different UHF frequencies. Japan operates at 950 MHz and Europe operates at 868MHz. 2450 MHz works in most countries.
RFID Industry Standards
Q. Why are standards important in manufacturing and using RFID?
A. Standards define the fundamentals of how RFID systems operate, and are necessary for interoperability of equipment from different vendors. The key elements of standards are the RF air interface - how readers and tags talk to each other - and the structure and function of the command set and tag memory. Since the physics of RFID are fundamentally different at UHF and HF, different standards are called for at each of these frequencies.
Q. What is EPC?
A. EPC stands for Electronic Product Code. Like a bar code, the EPC is divided into numbers that identify the manufacturer, product, version, and serial number. The EPC however, uses an extra set of digits to identify unique items. The EPC is the only information stored on an RFID tag's integrated circuit and it enables an infinite amount of dynamic data that can be associated with an item.
Q. What is EPC compliance?
A. EPC compliance refers to adhering to the specifications set by EPCglobal (formerly AUTO ID, Inc.) for RFID. In order to realize the EPC vision of an "internet of things", RFID systems must be available from a variety of vendors and must work together and be interoperable.
Q. What are the EPC Standards?
A. The Auto ID Center (now administered by EPCglobal) has developed a Class 1 standard for UHF systems to act as the foundation for EPC hardware. The standard is necessary to address user requirements: low cost hardware, writable tags, solid range and speed, global application, and open to many hardware vendors. Class 1 tags are expected to be the most widely deployed of all, as they are the backbone of the EPC system. The Center started with Class 1 as the foundation for its standard-setting efforts because it is crucial to make the Class 1 system as simple and low-cost as possible, while still leaving a forward path to interoperable higher-functionality systems.
Q. How will the standards be enforced?
A. EPCglobal will assume responsibility for implementing the specifications as standards and certify EPC systems as compliant.
Q. What is Class 0?
A. The term "Class 0" was coined to describe a system where the chips that are later assembled into tags are irreversibly pre-programmed by the chip vendor with a unique code when they are manufactured. Class 0 was not part of the Center's initial vision because it is not well suited to EPC implementation, since it does not allow RFID tags to be programmed by users in the supply chain. To use a Class 0 system in an EPC application would require a user to order, inventory, and match pre-programmed tags to the proper SKU during product manufacturing and packaging. This is at best very challenging, and could create new supply chain challenges larger than the ones EPC is seeking to solve. The Class 0 "candidate" spec is not interoperable with Class 1, and would require different readers or a "multi-protocol" reader in order for customers to use both Class 1 and Class 0 tags in the same environment. Class 0 tags also do not operate legally in Japan or Europe.
Download a free white paper, which outlines EPCglobal Class 1 Gen 2 RFID Specifications and standards. This paper provides a brief explanation on how Class 1 Generation 2 improves on previous EPC protocols and the expected impact of these benefits.
SOURCE: Alien Technology