Radar Fill Level Measurement Using Phase-Processed FMCW Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Guided wave radar measurement devices face challenges in achieving accurate and precise fill level measurements, particularly when the material has a small dielectric constant, as increasing signal strength to compensate for weak reflections reduces measurement resolution.
Innovation Solution
The use of a frequency modulated continuous wave (FMCW) radar signal processed with phase information, combined with a coaxial waveguide probe, allows for accurate fill level determination independent of signal strength, avoiding dispersive effects and enabling precise measurements to within +/- 0.5 mm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the signal strength is increased to compensate for weak reflections from materials with small dielectric constants, then the detectability of the reflected signal is improved, but the measurement resolution deteriorates due to increased pulse breadth
Solution Approach 1:
The patent applies frequency modulation to the continuous wave signal, changing the frequency parameter over time according to a predetermined law. This allows the use of frequency differentiation to obtain distance information without requiring narrow pulse widths, thus maintaining both signal strength and measurement resolution. The frequency modulated signal enables accurate measurement of materials with small dielectric constants while preserving fine resolution capabilities.
2Device complexity
If traditional pulsed radar methods are used to measure fill level, then the measurement process is simpler, but the measurement accuracy deteriorates when signal strength varies due to material dielectric properties
Solution Approach 1:
The patent replaces the traditional pulsed radar mechanical/time-domain approach with a frequency-modulated continuous wave approach processed in the frequency domain. Instead of using time-domain pulse reflection methods that are sensitive to signal strength variations, the invention uses frequency differentiation of the phase of the frequency modulated signal, providing measurement accuracy independent of signal strength while maintaining practical system 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
This approach significantly enhances measurement accuracy and precision, reducing processing complexity and cost, while maintaining high resolution, outperforming traditional methods by a factor of 10 in measurement accuracy.
Implementation Method 1
A measurement device can be viewed as comprising a transducer and a transmitter, wherein the transducer serves to convert a process variable, such as the fill level of a material in a tank, into an electrical signal
Implementation Method 2
said received signal containing a reflected portion of the transmission signal, said reflected portion being reflected from a surface of the material
Implementation Method 3
The use of a frequency modulated continuous wave (FMCW) radar signal processed with phase information
Implementation Method 4
wherein the electronics unit comprises a signal generator to generate a frequency modulated transmission signal
Implementation Method 5
wherein the radar device comprises a coaxial waveguide probe, wherein said coaxial waveguide probe serves for guiding the transmission signal and received signal
Implementation Method 6
At the material interface, there is a sudden change in the dielectric constant - the change being proportional the the difference between the dielectric constant of the material and the dielectric constant of a transmission medium
Data Source
Figure 1
Figure 2a~3
AI summary
The invention relates to a radar based fill level measurement device (1) for measuring the fill level (10) of a material (9) in a container (8), comprising an electronics unit (2), wherein said electronics unit (2) serves to generate a transmission signal, wherein said electronics unit (2) serves to process a received signal, said received signal containing a reflected portion of the transmission signal, said reflected portion being reflected from a surface (10) of the material (9) whose distance is to be measured, wherein the electronics unit comprises a signal generator (3) to generate a frequency modulated transmission signal, wherein the electronics unit (2) comprises a processor to process the received signal using phase information comprised in the received signal, and wherein the radar device (1) comprises a coaxial waveguide probe (7) arranged in the container (8), wherein said coaxial waveguide probe (7) serves for guiding the transmission signal (TX) and the received signal (RX).