Fill Level Sensor Signal Resolution via Phase Shifted Excitation
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Solution Overview
Problem
Existing methods for increasing the resolution of scanning signals in measuring devices, such as capacitive filling level measuring devices, are limited by the fixed sampling rate and memory constraints of analog-to-digital converters, which restrict the ability to enhance signal resolution beyond a certain point.
Innovation Solution
The electronics unit applies two excitation signals with an adjustable phase to the sensor element, shifting the signal to be processed in time rather than shifting the sampling points, allowing for higher resolution excitation and measurement signals by digitizing the same signal multiple times with a time offset, resulting in increased sampling points without altering the fixed sampling points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sampling rate of the analog-to-digital converter is increased to improve signal resolution, then the measurement precision is improved, but the device complexity and memory requirements increase
Solution Approach 1:
The patent applies periodic action by repeatedly applying the same excitation signal to the sensor element multiple times with a time offset between each application. This periodic repetition allows the system to achieve higher resolution by processing multiple signal cycles rather than requiring a single high-rate sampling operation, thereby avoiding the complexity increase associated with higher sampling rates.
Solution Approach 2:
The patent implements preliminary action by pre-establishing the time offset between successive excitation signals. This time offset is set in advance to create a phase shift that enables the analog-to-digital converter to sample the signal at different points in the periodic cycle, effectively increasing resolution without requiring the converter itself to operate at a higher rate.
2Measurement precision
If the number of sampling points is increased to improve resolution, then the measurement precision is improved, but the memory available for storage is reduced
Solution Approach 1:
By using periodic action with repeated excitation signals at a fixed sampling rate, the system achieves higher resolution through the time offset between repetitions rather than increasing the number of simultaneous sampling points. This allows the same memory capacity to store multiple resolved signal components that would otherwise require proportionally more memory.
3Device complexity
If the sampling rate is fixed to simplify the converter design, then the device complexity is reduced, but the resolution of the scanning signal cannot be increased
Solution Approach 1:
The patent resolves this contradiction by using periodic action to generate multiple excitation signals with a time offset. This allows the fixed sampling rate to effectively resolve finer details through the phase shift between repeated signals, achieving higher resolution without requiring a more complex high-rate converter.
Solution Approach 2:
The patent applies parameter changes by modifying the time offset between successive excitation signals. This parameter change creates a phase shift that enables the fixed sampling rate to access different portions of the signal cycle, thereby increasing resolution without changing the sampling rate or converter complexity.
Data Source
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AI summary
The invention relates to a device for determining and/or monitoring a process variable, comprising a sensor element (1) and with at least one electronic unit (2) applying an electric excitation signal (AS1, AS2) for a measurement of the process variable to the sensor element (1). The electronic unit receives an electric measuring signal (MS1, MS2) for the measurement of the process variable from the sensor element (1) and evaluates the measuring signal (MS1, MS2) in relation to the process variable. In the electronic unit (2), an analog-digital-converter (3) is provided. A first excitation signal (AS1) and a second excitation signal (AS2) is applied to the sensor element (1) by the electronic unit (2) for each measurement of the process variable in close temporal succession, such that the first excitation signal (AS1) and the second excitation signal (AS2) comprise an adjustable phase (j) to each other.