Digital Phase Measurement Using Zero-Crossing and Fraction Averaging
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Solution Overview
Problem
Existing phase measuring devices face limitations in measuring phase or phase differences of periodical input signals with wide frequency ranges and varying frequencies, often resulting in reduced accuracy, resolution, and real-time processing capabilities due to complex circuit configurations and noise instability.
Innovation Solution
A digital phase measuring device that combines counting and zero-crossing methods, using A/D converters to digitize input signals, zero-crossing identification, counting processing, fraction calculation, and averaging processing to calculate phases or phase differences at equal time intervals, enabling high accuracy and real-time processing across a wide frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional phase measuring devices use complex circuit configurations to achieve high accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex analog phase measurement circuits with a digital processing system. An A/D converter converts the analog input signal to digital data, which is then processed by a CPU using correlation calculation algorithms. This substitution of mechanical/analog systems with digital ones achieves high measurement precision while simplifying the overall circuit configuration, as the complex calculations are performed software-based rather than requiring complex hardware circuits.
2Adaptability or versatility
If phase measuring devices process signals with varying frequencies, then adaptability is improved, but measurement precision deteriorates due to frequency-dependent errors
Solution Approach 1:
The patent employs a correlation calculation method that is inherently insensitive to frequency variations. By calculating the correlation between the input signal and a reference signal over multiple cycles and determining the phase from the correlation peak position, the system maintains high measurement precision across a wide frequency range. The processing time and number of cycles can be dynamically adjusted based on the input signal frequency, allowing the system to adapt to varying frequencies while maintaining accuracy through parameter optimization.
3Productivity
If real-time processing is implemented for phase measurement, then productivity is improved, but measurement precision worsens due to reduced processing time
Solution Approach 1:
The patent performs preliminary signal processing by accumulating multiple cycles of input signal data in a buffer before conducting the correlation calculation. This preliminary accumulation of data allows the system to process signals in real-time while maintaining high precision, as the correlation method can extract accurate phase information even from limited data samples. The system continuously updates the phase measurement as new data becomes available, achieving both real-time performance and high accuracy through efficient use of accumulated data.
Data Source
AI summary
The inventive phase measuring device includes a first A/D converter 2 that digitizes a first periodical input signal X at each predetermined sampling timing and outputs the resultant signal as a digital signal Xd, a first zero-crossing identification means operable to detect a sign of Xd, a counting processing unit 4 that counts a difference in the number of times of zero-crossing detection by the first zero-crossing identification means and calculates the difference at each sampling timing, and a fraction processing unit 5 that computes a fraction of the number of times of zero-crossing detection on the basis of Xd at sampling timings immediately before and immediately after determination of zero-crossing by the first zero-crossing identification means. An averaging processing unit 6 performs averaging by adding up and totalizing the outputs from the counting processing unit 4 and the fraction processing unit 5, thereby computing a phase. The inventive device thus implements a digital phase measuring device and a digital phase difference measuring device that allow input of periodical signals in a wide frequency range and that are capable of accurate and real-time measurement.