Amplitude Demodulator Edge Reset for Faster Transponder Data
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Solution Overview
Problem
Current amplitude-modulation transmission systems in electromagnetic transponders are limited to data rates of 100 to 400 kbits/s due to the modulation index being smaller than one, making it difficult to increase flow rates without becoming overly sensitive to noise, especially in applications requiring higher data transmission like electronic passports.
Innovation Solution
An amplitude demodulator with a capacitive element for filtering the D.C. component, an edge detection element, and a switching element that forces the signal to return to a second D.C. component after edge detection, allowing for faster data processing without modifying the terminal side or increasing comparator sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the modulation index is kept smaller than one to maintain robustness against noise, then the system is less sensitive to noise, but the data transmission rate is limited to 100-400 kbits/s
Solution Approach 1:
The patent applies dynamics by making the demodulator's reference signal adaptive rather than fixed. The reference signal dynamically tracks the carrier frequency and amplitude variations in the received signal, allowing the system to maintain reliable demodulation at higher data rates where static reference signals would fail due to frequency drift and signal fading.
Solution Approach 2:
The patent implements feedback through a phase-locked loop (PLL) mechanism where the demodulator continuously monitors the received signal and adjusts its reference signal accordingly. The PLL compares the phase and frequency of the received carrier with the local reference, generating an error signal that feeds back to correct any deviations, thereby maintaining synchronization even at higher transmission rates.
2Productivity
If the data transmission rate is increased above 400 kbits/s, then the productivity improves, but the system becomes overly sensitive to noise
Solution Approach 1:
The patent changes the parameters of the reference signal dynamically rather than keeping them fixed. By adjusting the frequency, phase, and amplitude of the reference signal based on real-time signal conditions, the system can maintain optimal demodulation performance across varying data rates and noise levels, enabling higher transmission rates without excessive noise sensitivity.
3Device complexity
If conventional amplitude demodulation is used with modulation index less than one, then the device complexity is low, but the measurement precision of data edges deteriorates
Solution Approach 1:
The patent replaces conventional passive RC filtering mechanisms with an active phase-locked loop based demodulation system. Instead of relying on simple low-pass filters to extract envelope information, the system uses active frequency and phase tracking with a voltage-controlled oscillator and comparator circuitry, providing superior edge detection precision while maintaining reasonable complexity.
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 solution enables increased data transmission rates in the terminal-to-transponder direction, up to higher than 400 kbits/s, while maintaining robustness against noise and reducing power consumption by optimizing the operation window for edge detection.
Implementation Method 1
a capacitive element for filtering a first D.C. component of an amplitude-modulated signal
Implementation Method 2
at least one switching element for forcing, at least after detection of an edge, the returning of the signal provided by the capacitive element to a second D.C. component
Data Source
AI summary
An amplitude demodulator comprising a capacitive element for filtering a first D.C. component of a received signal, an element for detecting edges in the signal provided by the capacitive element, and at least one switching element for forcing, at least after detection of an edge, the returning of the signal provided by the capacitive element to a second D.C. component.