ADC Phase Synchronization Using Redundant Signal Paths
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Solution Overview
Problem
Commercially available analog-to-digital converters (ADCs) used in Coriolis mass flowmeters suffer from phase drift issues due to input signal amplitude changes, power supply voltage variations, electromagnetic compatibility (EMC) effects, temperature changes, and noise content, which affect the accuracy of mass flow rate measurements.
Innovation Solution
The implementation of a phase synchronization method using four or more switches and ADCs to generate redundant digitized signals and phase drift values, allowing for concurrent compensation of digitized signals to mitigate phase differences between ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple ADCs are used to digitize analog signals from pickoff sensors, then the digitized signals can be processed to determine phase difference and mass flow rate, but phase drift between ADCs degrades measurement accuracy
Solution Approach 1:
The patent creates redundant copies of the analog signals by routing each pickoff sensor signal to multiple ADCs simultaneously. Specifically, the left pickoff signal is copied to both the first and second ADCs, and the right pickoff signal is copied to both the second and third ADCs. This copying approach allows phase drift measurement and compensation by comparing results from multiple ADC paths
Solution Approach 2:
The patent implements a feedback mechanism where phase drift values are continuously measured by comparing redundant digitized signals from different ADCs, and these measured phase drift values are then used to compensate the digitized signals. The processing device calculates phase drift based on differences between redundant signals and applies compensation to correct the measurements, creating a closed-loop system that actively counteracts phase drift
2Device complexity
If commercially available ADCs are used without phase synchronization, then device complexity is reduced, but phase drift performance deteriorates due to manufacturing variations and environmental factors
Solution Approach 1:
The patent performs preliminary phase drift measurement and compensation operations before the final mass flow rate calculation. The system continuously measures phase drift values from redundant ADC outputs and applies compensation to the digitized signals before they are used for phase difference determination. This preliminary action ensures that phase drift is corrected in advance, maintaining measurement precision without requiring specially matched ADCs
Data Source
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AI summary
An analog-to-digital conversion stage (300) includes three or more ADCs (303, 305, 307) that receive two or more analog signals, generate a first digitized signal from a first analog signal, generate at least a second digitized signal from at least a second analog signal to create two or more digitized signals, and generate one or more redundant digitized signals from the two or more analog signals. The one or more redundant digitized signals are generated substantially in parallel with the two or more digitized signals. A processing device (330) generates a phase drift value from a phase difference between a redundant digitized signal of the one or more redundant digitized signals and a corresponding digitized signal of the two or more digitized signals and compensates the corresponding digitized signal using the one or more phase drift values.