Combined FDX-B HDX RFID Tag Switchable Load Impedance
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Solution Overview
Problem
The proliferation of mutually incompatible RFID systems for animal identification has hindered the development of a standardized international identification system, leading to inefficiencies and compatibility issues in ISO 11785 compliant interrogators and transponders.
Innovation Solution
A combined FDX-B and HDX RFID tag that can respond to both FDX-B and HDX signal protocols, using a single ISO compatible identification code, and featuring a switchable load impedance for amplitude and frequency shift key modulation, enabling operation in various modes based on activation signal strength to optimize reading performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single RFID tag is designed to support both FDX-B and HDX protocols, then compatibility with multiple interrogator types is improved, but device complexity increases
Solution Approach 1:
The RFID tag is designed with universal functionality to support both FDX-B and HDX protocols through a single device. The tag includes circuitry that can operate in multiple modes: during the ON interval it can amplitude modulate the carrier for FDX-B communication, and during the OFF interval it can generate FSK modulated signals for HDX communication, making one tag compatible with multiple interrogator types
Solution Approach 2:
The tag employs dynamic switching between different operational modes based on the interrogator's protocol. A protocol detection mechanism identifies whether the interrogator uses FDX-B or HDX protocol, and the tag dynamically configures its circuitry accordingly - enabling amplitude modulation for FDX-B or frequency shift keying for HDX, thereby adapting its behavior to match the required protocol
2Reliability
If the tag uses amplitude modulation during ON interval and FSK modulation during OFF interval, then reading reliability is improved, but energy consumption increases
Solution Approach 1:
The tag utilizes the periodic structure of the interrogator's carrier signal, which alternates between ON and OFF intervals. During the ON interval, the tag performs amplitude modulation for FDX-B communication. During the OFF interval, the tag generates FSK modulated signals for HDX communication. This periodic switching allows the tag to support both protocols without requiring continuous operation of both modulation circuits simultaneously, thereby managing energy consumption more efficiently
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 enhances reading reliability and speed by exploiting frequency diversity, allowing the tag to be read by non-ISO compliant interrogators and maintaining equivalent reading distance performance to individual FDX-B and HDX tags, while adapting to insufficient power conditions.
Implementation Method 1
the tag circuitry is configured to receive power from electric current induced in the resonant antenna circuit by the activation signal
Implementation Method 2
the tag circuitry is configured so that the tag circuitry amplitude modulates the activation signal with a sequence indicative of the full-duplex identification data using a switchable load impedance
Implementation Method 3
the tag circuitry is configured so that the tag circuitry frequency shift key modulates an oscillator signal appearing at the resonant antenna circuit terminals with a sequence indicative of the half-duplex identification data
Data Source
AI summary
Transponders are disclosed that are configurable to operate in an HDX mode and/or an FDX-B mode and that use a switchable load impedance across the transponders' resonant antenna circuit to induce amplitude and/or frequency modulation. One embodiment of the invention includes an inductive antenna including two terminals connected to tag circuitry, where the inductive antenna forms a resonant antenna circuit tuned to resonate at the frequency of the activation signal. The tag circuitry and the resonant antenna circuitry are configurable as an oscillator, the tag circuitry is configured to be powered by electric current induced in the resonant antenna circuit, includes at least one switchable load impedance connected across the antenna resonant circuit, configured to amplitude modulate the activation signal appearing at the resonant antenna circuit terminals using a switchable load impedance, and to frequency shift key modulate the oscillator signal appearing at the resonant antenna circuit terminals.