RFID Tag Read Range Extension via Continuous Interrogation
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Solution Overview
Problem
Conventional RFID scanners and interrogators have limited read range and sensitivity, requiring close proximity and repeated interrogation to accurately read RFID tags, due to insufficient signal delivery and dynamic range, making it difficult to locate and read tags efficiently.
Innovation Solution
The system enhances RFID tag read range by increasing signal power and dynamic range, allowing for continuous interrogation and improved signal processing to detect weaker responses, and includes a proximity indicator to aid in tag location, using a separated transmission and receiving coil configuration to enhance sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the RFID scanner is located in close proximity to the RFID tag, then the signal strength is sufficient to power the transponder, but the read range is limited and it is difficult to locate the tag
Solution Approach 1:
The patent changes the operating frequency parameter from the conventional 134.2 kHz to a higher frequency range (676.8 kHz to 1.4 MHz). This parameter change enables the system to achieve both sufficient signal strength for powering the transponder and an extended read range of at least 6 inches, resolving the contradiction between power delivery and read range limitation
Solution Approach 2:
The patent implements continuous interrogation mode where the scanner continuously transmits interrogation signals rather than using intermittent on/off cycles. This dynamic approach ensures continuous power delivery to the transponder while maintaining extended read range, eliminating the need for close proximity positioning
2Device complexity
If the RFID scanner uses conventional interrogation methods, then the system structure is simple, but the dynamic range is insufficient to detect weak responses
Solution Approach 1:
The patent separates the transmission and reception functions into distinct operational phases within the continuous interrogation cycle. The scanner transmits interrogation signals at higher power levels and then switches to a high-gain reception mode to detect the much weaker transponder responses. This segmentation allows the system to achieve the required 80 dB dynamic range without significantly increasing overall system complexity
Solution Approach 2:
The patent employs periodic switching between transmission and reception modes during continuous interrogation. The scanner alternates between transmitting high-power interrogation signals and listening for weak transponder responses in a rapid periodic cycle. This periodic action enables the system to maintain both simple structure and sufficient dynamic range for detecting weak signals
3Device complexity
If the RFID scanner uses intermittent interrogation cycles, then the system operation is simple, but the reading process is time-consuming
Solution Approach 1:
The patent implements continuous interrogation mode where the scanner continuously transmits interrogation signals without intermittent on/off cycles. This continuous operation maintains constant power delivery to the transponder and enables rapid, time-efficient reading of the tag data, eliminating the time loss associated with repeated interrogation cycles while keeping the interrogation method simple
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
The solution increases the read range of RFID tags to at least 6 inches, preferably up to 24 inches, facilitating rapid and accurate data retrieval while reducing noise interference, and enables efficient operation in applications like smart pet doors by providing a stronger carrier signal and improved signal detection.
Implementation Method 1
a transmission coil generates an electromagnetic carrier signal sufficient to energize a transponder
Implementation Method 2
a separated receiving coil detects a response
Data Source
AI summary
A system and method comprising an RFID scanner, a reader or an interrogator for interrogating a transponder of a desired RFID tag to be interrogated; a transmission device for transmitting a desired carrier signal toward the RFID tag to be interrogated; a receiving device for receiving an RFID signal from the RFID tag to be interrogated; a processing device for removing the carrier signal from the RFID signal and thereby leaving an encoded data field of the RFID tag to be interrogated and processing the encoded data field for determining a start bit sequence of the encoded data field for at least one scan; and an averaging device for averaging the encoded data fields of at least two scans with one another and facilitate reading the encoded data field of the RFID tag to be interrogated.