Radio frequency label and method for improving RFID (Radio Frequency Identification Devices) reader carrier modulation depth
A carrier modulation and radio frequency tag technology, which is applied in the field of radio frequency identification, can solve the problems that the modulation depth cannot meet the requirements of demodulation, the modulation depth cannot reach the modulation depth, and the impedance change of the submerged radio frequency tag can be improved, so as to improve the effective reading distance and decoding The reliability, good communication effect, and the effect of improving the modulation depth
Inactive Publication Date: 2012-12-26
PEKING UBIQUITOUS IC TAG TECH
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Problems solved by technology
[0003] When the radio frequency tag is in a conductive medium environment, such as the internal environment of a mobile phone, an additional vortex field will be generated in the alternating magnetic field generated by the reader, and its reflection impedance will affect the equivalent impedance of the reader antenna, which may be submerged. The impedance changes when the RF tag transmits data, so that the modulation depth cannot meet the requirements for demodulation; at the same time, when the antenna coil area of the RF tag is too small for some reason, the required modulation depth may not be achieved by simply using load modulation
Both of these situations will adversely affect the communication distance and communication effect
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[0022] Embodiments of the present invention will be further described below in conjunction with the accompanying drawings.
[0023] like figure 2 Shown is a schematic diagram of the overall structure of the radio frequency tag of the present invention. A radio frequency tag for improving the carrier modulation depth of an RFID reader, including a power supply, a radio frequency antenna, a reader carrier phase detection circuit, an additional alternating magnetic field generation circuit, and an additional alternating magnetic field phase control circuit; the power supply is connected to the reader carrier phase at the same time The detection circuit, the additional alternating magnetic field generation circuit and the additional alternating magnetic field phase control circuit, the carrier phase detection circuit of the reader is connected to the additional alternating magnetic field phase control circuit, the additional alternating magnetic field phase control circuit is con...
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The invention provides a radio frequency label and a method for improving RFID (Radio Frequency Identification Devices) reader carrier modulation depth. The radio frequency label and the method improve an effective reading distance of a reader and reliability in decoding under a conductive medium environment, so that a radio frequency recognition system coupled based on an inductance under the conductive medium environment has a better communication effect. The method disclosed by the invention comprises the following steps of: exciting an additional alternating magnetic field with the same frequency as that of an alternating magnetic field produced via a reader antenna on a radio frequency label antenna when the radio frequency label enters the alternating magnetic field produced via the reader antenna and returns data through an active mode; generating an additional induced electromotive force on the reader antenna by the additional alternating magnetic field, wherein the reader antenna can detect variation of a carrier signal voltage envelope caused via the additional induced electromotive force, so that modulation of a reader carrier is finished. The radio frequency label provided by the invention comprises a power supply, a radio frequency antenna, a reader carrier phase detecting circuit, an additional alternating magnetic field generating circuit and an additional alternating magnetic filed phase control circuit.
Description
technical field [0001] The invention relates to the technical field of radio frequency identification, in particular to a radio frequency tag and a method for improving the carrier modulation depth of an RFID reader. Background technique [0002] In the radio frequency identification system based on electromagnetic induction coupling, according to the law of electromagnetic induction, energy transfer and data transmission are realized between the radio frequency tag and the reader through inductive coupling. At this time, the radio frequency tag obtains energy from the electromagnetic wave emitted by the reader. And transmit data to the reader. The energy exchange method between the reader and the radio frequency tag, such as figure 1 As shown, when there is an alternating current of a certain frequency in the reader coil, an alternating magnetic field is generated in the area near the reader coil. When the radio frequency tag enters this space area, the changing magnetic f...
Claims
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IPC IPC(8): G06K7/00G06K19/07
Inventor莫宁
OwnerPEKING UBIQUITOUS IC TAG TECH