Power Line Communication Protocol Using Three-Level Voltage Encoding
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Solution Overview
Problem
Existing power line communication methods for lighting systems face inefficiencies and signal distortion due to high EMI and long transmission times, particularly when transmitting signals to lighting devices far away, as they require multiple switching events and prolonged low-level voltage signals.
Innovation Solution
A power line communication protocol using alternate first and second level voltage signals, where each bit is represented by the time period of either signal, reducing the need for quick switching and ensuring sufficient power delivery, allowing for efficient data transmission with reduced signal distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple short timed switching events are used to transmit each bit (as shown in FIG. 4), then the proportion of high level voltage signal is sufficient to provide stable power to LED devices, but high EMI and signal distortion occur making it difficult to transmit signals to lighting devices far away
Solution Approach 1:
The patent changes the parameter of voltage level from two levels (0V and high level) to three levels (0V, intermediate level, and high level). This allows the transmission of bit information through voltage magnitude differentiation rather than through multiple switching events, thereby reducing EMI and signal distortion while maintaining power stability.
2Reliability
If low level voltage signal time period is used to define bit value (as shown in FIG. 5), then power transmission is sufficient to drive lighting devices, but transmission time is doubled reducing efficiency and frames per second
Solution Approach 1:
The patent introduces an intermediate voltage level that allows bit information to be encoded in the voltage magnitude itself rather than in the duration of low voltage periods. This eliminates the need for doubled transmission time while maintaining sufficient power delivery to lighting devices.
Solution Approach 2:
The patent uses periodic voltage transitions between high and low levels, where the intermediate level is used to encode bit information. This periodic structure maintains power sufficiency for driving lighting devices while reducing the time required for bit transmission compared to the FIG. 5 approach.
3Loss of time
If high speed switching is used to transmit bits quickly, then transmission time is reduced, but signal distortion and EMI increase particularly for distant lighting devices
Solution Approach 1:
The patent changes the encoding method from time-based (requiring high-speed switching) to voltage-magnitude-based (using three distinct voltage levels). This allows bit transmission without rapid switching, thereby reducing transmission time losses while minimizing signal distortion and EMI effects.
Data Source
AI summary
A power line communication sender generates a command signal that comprises a series of alternate first level voltage signals and second level voltage signals, while the time periods of each first level voltage signal and each second level voltage signal are determined according to the value of each corresponding bit in a command information. A power line communication receiver is connected to the sender through power lines to receive power and command signals. When the receiver receives the command signal, the time periods of each first level voltage signal and second level voltage signal is calculated to record each bits of the command signal. Since the information is carried in every first level voltage signal and second level voltage signal, it requires only half the time and requires no quick switching in every binary bit of the transmitted signal, therefore efficiency is improved and signal distortion is lowered.