Fill Level Measurement Using Undersampling ADC
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Solution Overview
Problem
Current fill level measuring devices, particularly those using ultrasonic and radar technologies, face challenges in achieving accurate and reliable measurements while minimizing cost and energy requirements, often relying on expensive high-speed analog to digital converters and narrow-band band-pass filters.
Innovation Solution
The proposed solution involves a fill level measuring device that employs an analog to digital converter with a sampling frequency lower than the expected signal frequency, utilizing undersampling and a broadband band-pass filter to filter frequencies, eliminating the need for precise tuning and active filtering components, and integrating the analog to digital converter within a microprocessor for cost and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-speed analog to digital converters are used to sample the intermediate frequency signal, then measurement accuracy and reliability are improved, but device cost and energy consumption increase
Solution Approach 1:
The patent changes the sampling frequency parameter from conventional high-speed sampling (at least twice the intermediate frequency) to a lower sampling frequency that is less than the expected signal frequency. This parameter change enables the use of lower-cost, lower-power analog to digital converters while maintaining measurement accuracy through subsequent digital signal processing techniques such as decimation and filtering.
2Measurement precision
If narrow-bandwidth band-pass filters are used to filter noise components, then measurement precision is improved, but device complexity and cost increase due to required precise tuning
Solution Approach 1:
The patent uses a broadband band-pass filter that copies a wide frequency range instead of precisely filtering only the expected signal frequency. This approach eliminates the need for precise tuning and active filtering components, reducing device complexity while maintaining measurement precision through digital signal processing of the broader frequency spectrum.
3Manufacturing precision
If high-speed analog to digital converters with high sampling rates are employed, then signal sampling accuracy is improved, but production cost and energy requirements increase
Solution Approach 1:
The patent applies partial sampling by using a sampling frequency that is less than the expected signal frequency, which is below the conventional Nyquist rate. This partial sampling approach, combined with digital decimation and filtering, achieves sufficient sampling accuracy for fill level measurement while dramatically reducing the cost and power requirements of the analog to digital converter.
4Loss of information
If conventional sampling rates (at least twice the signal frequency) are used, then complete signal information is captured, but energy consumption and device cost increase
Solution Approach 1:
The patent extracts only the essential signal information needed for fill level measurement by using a sampling frequency lower than the expected signal frequency. Through digital signal processing techniques including decimation and filtering, the system extracts the necessary measurement data while discarding redundant information, thereby reducing energy consumption without sacrificing measurement capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate and reliable fill level measurements while reducing power consumption and production costs, enabling more measurements per unit of energy and achieving high accuracy at lower monetary costs through averaging techniques and digital signal processing.
Implementation Method 1
an analog to digital converter is provided that serves to subsequently sample the intermediate frequency signal, said analog to digital converter employing a sampling frequency less than the expected signal frequency of intermediate frequency signal
Implementation Method 2
a band-pass filter that serves to pass the predetermined frequency range and filter frequencies greater than a measurement signal frequency of the measurement signal
Implementation Method 3
a fill level measuring device for measuring a fill level of a material in a container based on the time of flight principle
Implementation Method 4
The present invention especially relates to fill level devices that employ ultrasonic and/or electromagnetic measuring signals
Implementation Method 5
The present invention especially relates to fill level devices that employ ultrasonic and/or electromagnetic measuring signals, such as radar based measuring devices
Data Source
Figure 1
Figure 2a~3
AI summary
The invention relates to a measuring device (1) for measuring a fill level (11) of a material in a container (12) based on time of flight principles, comprising components (2-9) that serve to generate, transmit and receive a measurement signal (S) and further serve to convert said measurement signal (S) into an analog intermediate frequency signal (SIF) having an expected signal frequency within a predetermined frequency range, said intermediate frequency signal (SIF) comprising information corresponding to the fill level (11) of the material in the container (12), wherein an analog to digital converter (16) is provided that serves to subsequently sample the intermediate frequency signal (SIF), said analog to digital converter (16) employing a sampling frequency (fs) less than the expected signal frequency of intermediate frequency signal (SIF).