Carrier Compensation Reader for RFID EMI Immunity
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Solution Overview
Problem
Radio-frequency identification systems face challenges with low sensitivity and electromagnetic interference, limiting read distance and mechanical flexibility due to high costs and zero amplitude modulation issues in car immobilizer systems.
Innovation Solution
A carrier compensation reader system that uses a digitized low bandwidth and high dynamic range direct conversion receiver to generate a compensation signal, allowing for higher EMI immunity and sensitivity, enabling longer read distances and reduced system costs by positioning the reader base station farther away from the coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the reader base station is placed very close to the reader coil to improve read distance, then the read distance is improved, but the system cost increases and mechanical flexibility is reduced
Solution Approach 1:
The patent replaces the mechanical solution of placing the reader base station close to the coil with a signal processing solution. By using carrier compensation techniques and digital signal processing to enhance signal quality and immunity to electromagnetic interference, the system achieves long read distance without requiring physical proximity between the reader base station and coil, thus avoiding increased system cost and reduced mechanical flexibility.
2Object-affected harmful factors
If a separate reader coil exclusively is used for immobilizer function to improve EMI immunity, then EMI immunity is improved, but device complexity and cost increase
Solution Approach 1:
The patent enables a single reader coil to serve multiple functions (passive entry, passive start, and immobilizer) by implementing carrier compensation signal processing. This multi-functional approach eliminates the need for separate dedicated coils for each function, reducing device complexity and cost while maintaining high EMI immunity through digital signal processing techniques.
Solution Approach 2:
The patent replaces the physical separation of reader coils with digital signal processing to achieve EMI immunity. By using carrier compensation and digital filtering, the system can distinguish and process signals from the transponder even in the presence of electromagnetic interference, eliminating the need for separate dedicated coils and reducing overall system complexity.
3Device complexity
If carrier signal is used for immobilizer function to reduce system cost, then system cost is reduced, but sensitivity and EMI immunity deteriorate
Solution Approach 1:
The patent replaces simple carrier signal processing with advanced carrier compensation techniques and digital signal processing. By implementing compensation circuits that dynamically adjust for phase and amplitude variations, and using digital filtering to enhance signal quality, the system achieves high sensitivity and EMI immunity while maintaining cost-effectiveness through a single coil design.
4Object-affected harmful factors
If zero amplitude modulation is used in backscattered signal to reduce EMI sensitivity, then EMI sensitivity is reduced, but signal demodulation becomes difficult
Solution Approach 1:
The patent replaces simple zero amplitude modulation with carrier compensation techniques that maintain signal amplitude information. By dynamically compensating for phase and amplitude variations in the carrier signal, the system preserves signal quality for accurate demodulation while maintaining immunity to electromagnetic interference, thus avoiding the demodulation difficulties associated with pure phase modulation.
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 system achieves higher EMI immunity and sensitivity, allowing for increased read distances and reduced costs, while eliminating zero amplitude modulation issues, enabling new mechanical designs and broader application in identification and tracking.
Implementation Method 1
Some passive transponders (e.g., with no battery) are powered and read within the read distance via magnetic fields (e.g., electromagnetic induction) from the reader base station
Implementation Method 2
a resonant circuit including an antenna... the resonant circuit transforms electrical energy to electromagnetic energy
Data Source
AI summary
A carrier compensation reader compensates a carrier signal. The carrier compensation reader transmits, via an antenna, a first carrier signal and obtains a second carrier signal based on the first carrier signal. The carrier compensation reader configures a compensation circuit to receive a receiver output signal based on the second carrier signal and generate a compensation signal based on the receiver output signal to compensate the second carrier signal. The carrier compensation reader obtains a carrier compensation signal summing the second carrier signal and the compensation signal.