Inductive RFID Transponder Timing Calibration via Reference Duration
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Solution Overview
Problem
Existing contactless RFID systems with inductive coupling face challenges in ensuring error-free data transmission due to parameter-dependent timing variations, particularly when transponders lack calibration mechanisms, leading to interference and incorrect decoding of character sequences.
Innovation Solution
The method involves transmitting a carrier signal with field gaps to encode character values, with transponders determining durations between gaps for decoding, and using a reference duration for calibration in some protocols, allowing for downward compatibility and error-free data exchange across different transponder and base station protocol types, even without internal clock generators or calibration mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the quality of the parallel resonant circuit is increased to enable power supply at greater distances, then the supply range is extended, but the timing precision of detected field gaps deteriorates
Solution Approach 1:
The patent applies preliminary action by transmitting a reference duration before the actual data transmission. This reference duration allows the transponder to pre-calculate a calibration value that compensates for timing variations caused by high-quality resonant circuits. The calibration value is stored and used to adjust subsequent duration measurements, thereby maintaining timing precision even when the resonant circuit quality is increased for extended supply range.
2Measurement precision
If a reference duration is transmitted for calibration, then timing accuracy is improved, but protocol compatibility complexity increases
Solution Approach 1:
The patent implements universality by designing the data transmission protocol to universally support both transponders with and without calibration mechanisms. The base station automatically adapts its transmission by including or excluding the reference duration based on the transponder's capabilities. This allows a single protocol implementation to serve multiple device types, maintaining timing accuracy for calibrated devices while ensuring compatibility with non-calibrated devices.
3Adaptability or versatility
If downward compatibility is ensured for transponders without calibration mechanisms, then device versatility is improved, but timing variation interference increases
Solution Approach 1:
The patent applies segmentation by dividing the data transmission into distinct segments: an optional reference duration segment for calibration, and a data segment for actual information transfer. This segmentation allows the system to provide calibration information to devices that need it while maintaining compatibility with devices that process data segments directly. The base station can selectively include or exclude the reference duration segment based on transponder capabilities, thereby managing timing variation interference while preserving device versatility.
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 approach ensures interference-free data transmission by compensating for timing variations and enabling communication between transponders and base stations with different protocol support, ensuring both downward and upward compatibility and reliable data exchange.
Implementation Method 1
Passive transponders draw the power necessary for their supply from the electromagnetic field emitted by the base station
Implementation Method 2
an antenna coil of the base station and an antenna coil connected to the input circuit of the transponder form a transformer
Implementation Method 3
the quality of a parallel resonant circuit, which is formed here by the antenna coil and a capacitor connected parallel thereto, is increased
Data Source
AI summary
In one embodiment, a method includes receiving a carrier signal transmitted by a base station according to either a first data-transmission protocol or a second data-transmission protocol; detecting a first field gap in the carrier signal indicating initiation of a data transmission by the base station; and determining whether a reference duration is present in the carrier signal after the first field gap. The method includes, if the reference duration is present in the carrier signal after the first field gap then, according to the first data-transmission protocol, determining a calibration value for the data transmission based on the reference duration and decoding the data transmission by measuring durations between successive subsequent field gaps and determining whether each duration as measured is a binary 1 or binary 0 based on the calibration value.