IoT Clock Calibration Using Dual-Tone Sine Wave Signals
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Solution Overview
Problem
Ambient IoT devices face inaccuracies in local clock frequency due to oscillators exhibiting frequency errors, jitter, or drift, leading to discrepancies in clock synchronization and increased power consumption for improved accuracy.
Innovation Solution
Calibrate the local oscillator of ambient IoT devices using the difference in frequencies of dual-tone sine waves received in a mixed signal, enabling enhanced clock synchronization and communication reliability without excessive power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the local clock accuracy is improved to satisfy clock synchronization requirements, then the clock synchronization is improved, but the power consumption increases excessively
Solution Approach 1:
The patent introduces an intermediary calibration signal transmitted by the reader that mediates between the reader's accurate clock and the tag's low-power oscillator. This calibration signal contains timing information that allows the tag to adjust its local clock without requiring a high-power accurate oscillator, thus resolving the contradiction between clock accuracy and power consumption
Solution Approach 2:
The patent replaces the mechanical/physical approach of using a high-precision hardware oscillator with a software/digital approach of calibrating a low-power oscillator using received calibration signals. This substitution allows the tag to achieve accurate timing through signal processing rather than relying on expensive high-power hardware oscillators
2Use of energy by moving object
If a low-power oscillator is used in the ambient IoT device, then the power consumption is reduced, but the clock synchronization accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the tag receives calibration signals from the reader, compares its local clock timing with the received signal timing, and adjusts its oscillator frequency accordingly. This closed-loop feedback allows the low-power oscillator to maintain accurate synchronization by continuously correcting its drift based on the reader's accurate timing references
Solution Approach 2:
The patent changes the operating parameters of the oscillator by adjusting its frequency based on the calibration information received from the reader. Instead of using a fixed high-precision oscillator, the system dynamically adjusts the oscillator parameters (frequency, phase) to maintain synchronization while operating at low power
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. Some aspects more specifically relate to using one or more clock synchronization signals comprising sine waves to calibrate a local clock at an ambient internet of things (IoT) device. In some aspects, the ambient IoT device may receive a mixed signal comprising a pair of dual-tone sine waves and calibrate the local clock using a difference in frequencies of the pair of dual-tone sine waves.