Short distance active radio frequency identification system

Abstract

The invention discloses a short distance active radio frequency identification system, comprising an electronic tag and a reader-writer. The electronic tag works in a passive working mode, and is suspended under a sleep mode; if a receiving circuit of the electronic tag receives an amplitude modulation signal transmitted by the reader-writer when approaching the reader-writer, a micro controller of the electronic tag is waken up; the awaken micro controller of the electronic tag receives command codes transmitted by the reader-writer and modifies a coupling coefficient of an antenna by means of adjusting antenna impedance of the receiving circuit and returns data to the reader-writer; the reader-writer is in an interval working state, namely searching cards at intervals and getting into sleep state thereafter. The electronic tag and the reader-writer of the invention are small in size and capable of long distance communication and long time of continuous work without replacing batteries or charging.

Description

[technical field] [0001] The invention relates to short-distance radio frequency identification technology, in particular to a short-distance active radio frequency identification system. [Background technique] [0002] The electronic tags in the traditional short-range radio frequency identification system are generally passive, and the commonly used frequencies are 125KHz and 13.56MHz. The electronic tag obtains energy and works through the carrier wave emitted by the reader. The emission power of the reader generally exceeds 50 milliwatts, and the recognition distance is generally within 10 cm. There are also those that can recognize more than 1 meter, but require the reader to transmit power up to 1 watt, and use a large loop antenna. [0003] In the existing short-range radio frequency identification system, the electronic tag does not have a power supply, and relies on the electromagnetic waves emitted by the reader to obtain energy, which requires a relatively large ...

AI Technical Summary

Problems solved by technology

Under some working conditions that require the reader to be powered by batteries, but cannot perform battery replacement or charging operations, the existing passive RFID systems cannot meet the application requirements

However, when the recognition distance is required to be tens of centimeters, the traditional reader cannot meet the needs of small and portable applications, and the power consumption is also greater.

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