Vehicle NFC Reader Presence Detection via Supply Signal Amplitude
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Solution Overview
Problem
Existing near-field communication systems in automobiles face inefficiencies and high energy consumption due to the need to wait for timeout errors when no modulated return signal is received from a radio-frequency transponder, especially when the transponder moves out of range during the communication process.
Innovation Solution
A method that detects the presence of a radio-frequency transponder by measuring the amplitude of the radio-frequency supply signal and comparing it with a predetermined threshold, allowing for rapid and energy-efficient confirmation of the transponder's presence or absence without requiring additional signal transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the radio-frequency reader waits for the entire predetermined duration of the radio-frequency supply signal (FWI frame) to detect timeout errors, then the system can confirm the absence of a transponder, but the detection process becomes slow and consumes excessive energy
Solution Approach 1:
The system performs preliminary presence detection by measuring the amplitude of the radio-frequency supply signal during its transmission, rather than waiting for the entire FWT duration to elapse. This allows the system to detect transponder absence early in the communication process, significantly reducing the detection time while maintaining reliability through continuous amplitude monitoring throughout the FWT frame transmission
2Reliability
If the radio-frequency reader transmits additional interrogation signals to confirm timeout errors, then the system can verify transponder absence, but the energy consumption increases significantly
Solution Approach 1:
The system uses the radio-frequency supply signal that is already being transmitted for communication purposes to simultaneously perform presence detection by measuring its amplitude. This self-service approach eliminates the need for separate detection signals, as the supply signal itself provides the detection function, thereby confirming transponder absence without additional energy-consuming transmissions
3Measurement precision
If the radio-frequency reader continuously monitors for modulated return signals throughout the entire FWT duration, then the system ensures accurate transponder presence detection, but unnecessary signal transmissions continue occurring
Solution Approach 1:
The system continuously measures the amplitude of the radio-frequency supply signal during transmission and uses this feedback to determine transponder presence. When the amplitude indicates absence (no modulation detected), the system can immediately terminate further transmissions for that FWT frame, preventing energy waste while maintaining detection accuracy through continuous amplitude feedback monitoring
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 method reduces power consumption and speeds up the detection process by leveraging the influence of the transponder's presence on the amplitude of the supply signal, minimizing unnecessary signal transmissions and promptly detecting transponder movements.
Implementation Method 1
transmitting a radio-frequency interrogation signal... transmitting a radio-frequency supply signal... measuring an amplitude of the radio-frequency supply signal
Data Source
AI summary
A method implemented in a near-field communication system (100), for detecting the presence of a radio-frequency transponder (110) by means of a radio-frequency reader (120) on board a motor vehicle, said radio-frequency transponder (110) being carried in use by a user located outside the vehicle, and said radio-frequency reader (120) being intended to communicate with the radio-frequency transponder (110) so as to control access to the motor vehicle, the method comprising the following steps implemented by the radio-frequency reader:transmitting a radio-frequency interrogation signal; thentransmitting a radio-frequency supply signal, intended to be received then modulated by the radio-frequency transponder;detecting the presence of the radio-frequency transponder (110) by measuring an amplitude of the radio-frequency supply signal and comparing it with at least one predetermined threshold.