Time-Domain Signal Synchronization via CPSD Phase Slope
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Solution Overview
Problem
Computer systems face challenges in accurately synchronizing time-domain signals from different data acquisition devices with varying sampling rates and unsynchronized clocks, leading to phase discrepancies that hinder the analysis of relationships between operational parameters like power and CPU utilization.
Innovation Solution
A method that transforms time-domain signals into frequency-domain signals, computes cross-power-spectral-density to determine phase alignment, and iteratively adjusts the phase difference to synchronize the signals, using the slope of the phase angle versus frequency graph to achieve phase coherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If different data acquisition devices with different clocks and sampling rates are used to collect system variables, then the quantity and variety of collected data increases, but phase coherence between signals is lost
Solution Approach 1:
The patent introduces cross-power spectral density (CPSD) as an intermediary tool to analyze and determine the phase relationship between signals from different data acquisition devices. The CPSD function serves as a mediator that quantifies phase coherence, enabling the system to identify and correct phase discrepancies while maintaining the use of multiple independent measurement devices.
2Device complexity
If clocks of different data acquisition devices are allowed to operate independently, then device complexity and synchronization overhead are reduced, but phase discrepancies between signals increase
Solution Approach 1:
The patent performs preliminary phase coherence analysis using CPSD before conducting data analysis. By calculating the CPSD function and identifying phase relationships in advance, the system can pre-adjust or pre-correct phase discrepancies, eliminating the need for complex real-time synchronization mechanisms during data collection and analysis.
3Measurement precision
If sampling rates of different devices are made uniform, then phase coherence is improved, but the flexibility and adaptability of the measurement system decreases
Solution Approach 1:
The patent changes the parameter of interest from sampling rate uniformity to phase relationship characterization. Instead of forcing all devices to sample at the same rate, the system allows each device to operate at its optimal sampling rate while using CPSD to analyze and correct phase relationships, thereby maintaining both precision and flexibility.
Data Source
AI summary
Some embodiments of the present invention provide a system that accurately synchronizes signals related to the operation of a computer system. During operation, the system receives a first time-domain signal associated with a first system variable and a second time-domain signal associated with a second system variable from the computer system. The system then transforms the first and the second time-domain signals into a first frequency-domain signal and a second frequency-domain signal, respectively. Next, the system computes a cross-power-spectral-density (CPSD) between the first and second frequency-domain signals to obtain a phase angle versus frequency graph between the two frequency-domain signals. The system subsequently extracts the slope of the phase angle versus frequency graph, and uses the value of the slope to synchronize the first time-domain signal and the second time-domain signal.