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Pulsed power method for increased read range for a radio frequency identification reader

A technology of radio frequency identification and radio frequency identification tags, which is applied in the field of power output of radio frequency identification readers, and can solve problems such as limiting the power level of RFID readers

Inactive Publication Date: 2009-08-12
TYCO FIRE & SECURITY GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, restrictions on RF radiation limit the power levels at which RFID readers can operate

Method used

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  • Pulsed power method for increased read range for a radio frequency identification reader
  • Pulsed power method for increased read range for a radio frequency identification reader
  • Pulsed power method for increased read range for a radio frequency identification reader

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Embodiment Construction

[0013] Regulations in the United States and Europe limit the transmit power levels of RFID readers. For example, at 2450 MHz, these regulations limit RFID emissions to 500 milliwatts continuous or 4 watts measured at a 15% duty cycle for 200 milliseconds. A continuous transmission of 500 mW can only provide a read range on the order of 10-20 inches. According to these regulations, transmissions can be pulsed at a time of 30 milliseconds up to 4 watts in order to increase the read range. Thirty milliseconds is not enough to execute a multi-label algorithm. During the off-time between 30 millisecond pulses some tags may reset so that the reader may read some tags many times but never others.

[0014] refer to figure 1 , one solution to this problem is to simultaneously transmit a continuous interrogation signal and a pulsed interrogation signal. Continuous transmission keeps the tags "active" so that they are not reset between pulses. A pulsed signal increases the read rang...

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PUM

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Abstract

A method to power a radio frequency identification (RFID) reader to increase multi-tag reading capability and increase the reading range of a passive tag without maximizing the continuous transmitted power level is provided. The RFID reader transmits a pulsed interrogation signal until an RFID tag response is received, and then switches to a continuous and pulsed power scheme. The continuous power emitted maintains the power supplied to the RFID tags so the tags will not reset due to loss of power. The pulsed signal permits reading the tags at longer ranges, especially when there is a plurality of tags in the area.

Description

technical field [0001] The present invention relates to radio frequency identification (RFID) reader power output, and more particularly to pulsed and continuous power output methods for RFID readers. Background technique [0002] The use of RFID systems is increasing in a variety of applications including inventory control and item monitoring. In an RFID system, an RFID reader transmits an RFID interrogation signal, and an RFID tag or tag receives the transmitted RF interrogation signal and responds with a reply signal containing identification information and other data known in the art. The RFID reader receives the RFID tag's reply signal and reproduces the relevant information contained in the signal. In order for an RFID reader to detect and retrieve data from an RFID tag's reply signal, the RFID tag must be located within a predetermined maximum radius of the RFID reader. If the RFID reader does not receive a reply signal, the RFID reader will continue to send an RFI...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04Q5/22G06K17/00G06K7/00H04B1/59
CPCG06K7/0008G06K7/10019G06K7/10217
Inventor 休伯特·A·帕特森飞利浦·A·腊祖
Owner TYCO FIRE & SECURITY GMBH