Power Line Signal Demodulation via Pulse Width Ratio
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Solution Overview
Problem
Conventional lighting control systems face challenges in real-time monitoring of operational parameters and are costly due to wired constructions and require additional signal lines, with power line communication methods prone to noise interference affecting digital control signals.
Innovation Solution
A method and system for demodulating signal packets using a controller that distinguishes between bit 0 and bit 1 pulses based on predefined pulse widths and threshold values, incorporating a digital pulse demodulation unit to correct command packets and prevent noise-induced errors in power line transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If power line communication is used to transmit digital control signals, then additional signal lines and installation costs are eliminated, but noise in the power line causes pulse width distortion that prevents correct demodulation of the digital control signal
Solution Approach 1:
The patent changes the parameter used for demodulation from absolute pulse width to pulse width ratios. By comparing the ratio of first pulse width to second pulse width against reference ratios, the system achieves noise-immune demodulation even when absolute pulse widths are distorted by power line noise
Solution Approach 2:
The patent implements feedback by measuring actual pulse widths, calculating their ratios, comparing against reference ratios, and using this comparison to determine bit values. This feedback mechanism allows the system to adapt to noise conditions and correct demodulation errors
2Device complexity
If conventional pulse width demodulation is used in noisy power line environments, then simple threshold comparison is sufficient, but parameter deviations cause incorrect bit detection
Solution Approach 1:
The patent transforms the demodulation approach from absolute threshold comparison to relative ratio comparison. By using the ratio of first pulse width to second pulse width, the system eliminates the impact of parameter deviations and noise on bit detection accuracy
Data Source
AI summary
A method of demodulating a signal packet includes steps of: determining whether a pulse width of each of pulses of one of bits of the signal packet is associated with bit 0 or bit 1; updating first counting data associated with a number of the pulses that define bit 0, and determining whether the first counting data is greater than a first threshold value; deciding that said one of the bits of the signal packet is a bit 0; updating second counting data associated with a number of the pulses that define bit 1, and determining whether the second counting data is greater than the second threshold value; deciding that said one of the bits of the signal packet is a bit 1.