RFID Read Area Definition Device Preamble Jamming
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Solution Overview
Problem
RFID systems face challenges in defining a specific read area to record tags passing through while avoiding accidental reads of tags near the area but not passing through, leading to inventory management inaccuracies and spillover issues.
Innovation Solution
The implementation of a system using RFID Read Area Definition Devices (RADD) that transmit a modulated carrier to block interrogation signals from RFID readers during the preamble period, allowing only tags within the defined area to be read, while allowing other RFID readers to function normally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RFID reader energy is set at maximum allowed EIRP to achieve greatest penetration and read range, then the RFID reader can read the greatest amount of RFID tags at the greatest range, but spillover into adjacent areas occurs where items near the exit but not actually leaving are accidentally read
Solution Approach 1:
The system applies preliminary anti-action by transmitting a jamming signal in advance during the preamble period before the actual RFID interrogation. This jamming signal pre-occupies the communication channel and prevents tags outside the intended read zone from responding to subsequent interrogation signals, thereby eliminating spillover reads while maintaining accurate reads within the defined area
Solution Approach 2:
The jamming signal acts as an intermediary element that mediates between the RFID reader and tags. By introducing this intermediate signal during the preamble period, the system controls which tags can be read (only those within the intended zone that are not affected by the jamming) without directly modifying the reader's maximum power output or the tags' response capabilities
2Object-affected harmful factors
If jamming is used to prevent accidental reads of nearby tags, then reads are confined to the intended zone, but nearby tags cannot be read at all which prevents proper inventory management
Solution Approach 1:
The system uses periodic action by applying the jamming signal only during specific time intervals (preamble periods) rather than continuously. During these brief preamble periods, the jamming signal prevents unintended reads. However, during normal interrogation periods when no jamming is present, RFID readers can properly read nearby tags for inventory management, thus resolving the contradiction between preventing spillover and maintaining inventory accuracy
Solution Approach 2:
The jamming signal is applied in advance during the preamble period before the actual tag interrogation occurs. This preliminary action selectively blocks tags that would otherwise be accidentally read due to spillover, while allowing the main interrogation process to proceed normally for proper inventory management of tags within the intended read zone
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively confines reads to the intended zone, reducing unintended reads by up to 50 feet and enabling accurate inventory management without interfering with other RFID readers, maintaining compliance with FCC regulations and minimizing spectral load on the ISM band.
Implementation Method 1
controlling the at least one RFID transmitter to transmitting a modulated carrier in an area adjacent to the specified read area during a preamble transmission of the at least one RFID reader
Data Source
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AI summary
Defining a radio frequency identification read area includes a radio frequency identification (RFID) reader operable to read RFID tags within a specified read area. An RFID transmitter is coupled with the RFID reader and is operable to radiating a modulated carrier in an area adjacent to the specified read area. The RFID reader controls the RFID transmitter to transmit the modulated carrier during a preamble transmission of the RFID reader to prevent any RFID tags in the adjacent area from recognizing an interrogation signal from the RFID reader.