Stepped Frequency Radar Liquid Level Detection
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Solution Overview
Problem
Current radar-based liquid level measurement methods are inaccurate due to unreliability in measuring phase differences, leading to unreliable liquid level determination, especially with the presence of obstacles and interference.
Innovation Solution
A phase-based method using radar signals at different frequencies to determine the liquid level by calculating the frequency difference and phase shift between emitted and reflected signals, and deriving the actual phase difference using a wrapping factor to achieve high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-based radar signal processing is used to determine liquid level, then measurement precision is improved, but reliability deteriorates due to inability to measure actual phase difference directly
Solution Approach 1:
The patent uses stepped frequency modulation to change the frequency parameter of radar signals across multiple measurement cycles. By measuring phase differences at different frequencies (f1, f2, ...) and using the relationship between frequency difference and phase shift, the system can determine the wrapping factor and recover the actual phase difference, thereby resolving the reliability issue while maintaining high measurement precision
Solution Approach 2:
The patent implements a feedback mechanism where the measured phase difference is used to calculate a preliminary level value, which then feeds back to determine the wrapping factor. This wrapping factor is used to correct the phase difference measurement, creating an iterative feedback loop that resolves the ambiguity in phase measurement and improves reliability
2Device complexity
If traditional pulsed radar signals are used for liquid level measurement, then device complexity is reduced, but measurement precision deteriorates due to obstacles and interference
Solution Approach 1:
The patent transitions from static single-frequency radar signals to dynamic stepped frequency signals that change over time. This dynamic approach allows the system to distinguish between reflections from the liquid surface and reflections from obstacles by analyzing phase differences across multiple frequency steps, thereby improving measurement precision without significantly increasing device complexity
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
The method provides a highly accurate liquid level measurement with an error margin of less than 1 mm, independent of obstacles and interference, offering improved reliability and repeatability compared to traditional methods.
Implementation Method 1
a radar antenna disposed above the liquid for emitting radar signals to the liquid and receiving radar signals reflected from the liquid surface
Data Source
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AI summary
The invention relates to a method for accurately determining the level L of a liquid by means of radar signals emitted to the liquid surface and radar signals reflected from the liquid surface. The invention further relates to a device for accurately determining the level of a liquid by means of the method according to the invention, which device comprises at least a radar antenna disposed above the liquid for emitting radar signals to the liquid and receiving radar signals reflected from the liquid surface, as well as means for determining the liquid level on the basis of the emitted radar signals and the reflected radar signals.