RFID on the Production Line
发表时间:2005-12-05
al RFID concepts are described by U.K.-based Pelican Control Systems Ltd. on its 'General RFID System Definition' Web page at www.pelicansystems.co.uk. Here are some of Pelican's most useful definitions:

RFID tags/labels/transponders are identifiers fixed to items that need to be monitored or processed. Transponders differ in size, memory capacity, physical construction, and range.

Readers/scanners act as the monitoring and/or processing interface between transponders and the data environment.

Readers manage the data communications process with transponders and then temporarily store or transmit the information to the data environment.

Operating frequency, typically below 1 MHz, 13.56 MHz and over 800 MHz, determines an RFID system's design characteristics, such as material penetration, data transfer rates, required energy, and operating distances.

Passive RFID systems use transponders energized by an external source, such as the antenna or reader. Passive transponders are usually cheaper than active ones, but their operating distance and data transfer capabilities are limited.

Active RFID systems overcome passive RFID limits by driving their logic circuitry with onboard energy via batteries or wired connections.

Induction, e-field disturbance (also known as backscatter or field disturbance modulation), and radio data communication are the three methods that allow RFID communication coupling between the tag and reader. Induction systems typically operate at low frequency (approximately 125 kHz) with few regulatory requirements, or at 13.56 MHz, where normal radio and spectrum allocation regulations apply. E-field is based on radio energy emitted by the reader, which is collected and reflected by the transponder. Radio data communication occurs when both the reader and transponder communicate using radio signal emissions.

Anti-contention communications protocol. If a system does not use an anti-contention communications protocol, it can only communicate with on

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