Clock Signal Correction Using Received Pulse Duration Variations
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Solution Overview
Problem
Contactless RFID tags face challenges in maintaining a constant clock signal frequency due to environmental and temperature variations, which affects synchronization with the reader's signal, especially since the reference signal is only transmitted once at the start of a communication session.
Innovation Solution
A method and device for regulating a clock frequency by taking measurements of characteristics in a received signal, specifically by comparing variations in pulse durations between reference and distinct events, and adjusting the clock signal frequency accordingly to maintain synchronization throughout the communication session.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a local oscillator is used to generate a reference frequency signal, then a clock signal with constant frequency can be produced, but the reference frequency varies due to environmental and temperature variations
Solution Approach 1:
The patent implements a feedback mechanism by measuring the duration of known-duration events in received signals and using these measurements to calculate correction factors that adjust the clock signal frequency. The system continuously monitors frequency drift through repeated measurements and applies corrective adjustments, creating a closed-loop control system that compensates for environmental variations affecting the local oscillator.
Solution Approach 2:
The patent changes the operational parameters of the clock generation system by adjusting the clock signal frequency based on measured deviations. Instead of relying on the fixed parameters of the local oscillator, the system dynamically modifies the clock frequency parameter using correction factors derived from signal measurements, thereby adapting to environmental conditions.
2Ease of operation
If the reference signal is transmitted only once at the start of a communication session, then the tag can initialize its clock frequency, but the tag cannot re-adjust its clock frequency during the session
Solution Approach 1:
The system establishes continuous feedback by repeatedly measuring the duration of known events throughout the communication session. Each measurement provides information about current frequency drift, enabling the tag to continuously monitor and re-adjust its clock frequency rather than relying solely on the initial reference signal.
Solution Approach 2:
The patent transforms the single-point initialization action into a continuous adjustment process. By continuously measuring event durations and recalculating correction factors throughout the communication session, the system maintains ongoing clock frequency optimization rather than performing a one-time adjustment at the start.
3Measurement precision
If measurements are taken using the first clock signal to determine event characteristics, then the clock signal frequency can be regulated, but the measurements may be inaccurate due to frequency drift
Solution Approach 1:
The system uses feedback to iteratively improve measurement accuracy. Initial measurements are used to calculate a first correction factor, which adjusts the clock frequency. Subsequent measurements taken with the corrected clock signal produce more accurate results, allowing for refined adjustment of the frequency throughout the communication session.
Solution Approach 2:
The patent applies preliminary correction by calculating and applying a first correction factor based on initial measurements before taking subsequent measurements. This preliminary adjustment improves the accuracy of later measurements by reducing frequency drift effects, creating a progressive refinement of measurement precision.
Data Source
AI summary
A method and device for generating a clock signal, the method including measuring, using a first clock signal, a characteristic of a reference event in a received signal, determining, using the first clock signal, a variation of a characteristic of a second event in a received signal, correcting the measurement according to the variation of the characteristic of the second event, and generating a second clock signal using the first clock signal according to the corrected measurement.