Radar Level Gauge Power Reduction via Discrete Frequency Segmentation
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Solution Overview
Problem
Conventional radar level gauge systems using frequency modulated continuous wave (FMCW) technology are power hungry, making them unsuitable for applications with limited power sources, and reducing the number of frequencies in the transmit signal to conserve power can lead to distorted intermediate frequency signals and false echoes, compromising the reliability of filling level determination.
Innovation Solution
The method involves transmitting two sequences of discrete and mutually different frequencies with different frequency ratios, where the second sequence has fewer frequencies to identify false echoes, allowing for reduced power consumption while maintaining reliable filling level determination by comparing the echo candidates from both sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of frequencies in the transmit signal is reduced to conserve power, then power consumption is reduced, but the intermediate frequency signal becomes distorted and false echoes are introduced
Solution Approach 1:
The patent divides the frequency spectrum into multiple discrete frequency steps rather than using a continuous sweep. Each frequency step provides a separate measurement opportunity, allowing the system to reconstruct the complete echo profile by combining results from multiple discrete measurements. This segmentation enables reduced power consumption (by transmitting fewer frequencies) while maintaining measurement reliability (through the combined analysis of multiple discrete frequency measurements).
Solution Approach 2:
The patent uses a limited number of discrete frequency steps (partial action) rather than transmitting all possible frequencies in the bandwidth. By strategically selecting a subset of discrete frequencies, the system achieves sufficient measurement accuracy without the full power consumption of a continuous or complete frequency sweep, thus resolving the contradiction between power consumption and measurement reliability.
2Use of energy by moving object
If the duration of the sweep is reduced to limit active time, then power consumption is reduced, but measurement accuracy may be compromised
Solution Approach 1:
The patent employs periodic discrete frequency steps rather than a continuous sweep. Each frequency step is transmitted for a specific duration, and the system accumulates measurements across multiple periodic cycles. This periodic action allows the system to achieve accurate measurements through cumulative data from multiple short cycles, reducing overall active time and power consumption while maintaining measurement precision.
3Reliability
If the bandwidth is increased to provide more robust measurement, then measurement reliability is improved, but power consumption increases
Solution Approach 1:
The patent segments the bandwidth into discrete frequency steps rather than transmitting the entire bandwidth continuously. This segmentation allows the system to achieve robust measurement coverage (by examining multiple discrete frequency points across the bandwidth) while consuming less power (by transmitting only a subset of frequencies at any given time). The discrete frequency steps provide sufficient spectral coverage for reliable measurements without requiring full bandwidth transmission.
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 effectively reduces power consumption while maintaining the reliability of filling level determination by distinguishing real echoes from false echoes through the use of two transmit signals with different frequency ratios, enhancing the tradeoff between power consumption and measurement accuracy.
Implementation Method 1
The transmitted signal is reflected by the surface of the contents in the tank (or by any other impedance transition) and an echo signal, which has been delayed a certain time, is returned to the gauge.
Implementation Method 2
The transmitted signal is reflected by the surface of the contents in the tank... an echo signal, which has been delayed a certain time, is returned to the gauge. The echo signal is mixed with the transmitted signal to generate a mixer signal.
Data Source
AI summary
A method of determining a filling level comprising transmitting a first transmit signal exhibiting a first ratio between bandwidth number of frequencies; receiving a first reflection signal; mixing the first transmit signal and the first reflection signal to form a first intermediate frequency signal; and determining a first data set indicative of a first set of surface echo candidates based on the first intermediate frequency signal. The method further comprises transmitting a second transmit signal exhibiting a second ratio between bandwidth and number of frequencies being different from the first ratio; receiving a second reflection signal; mixing the second transmit signal and the second reflection signal to form a second intermediate frequency signal; and determining a second data set indicative of a second set of surface echo candidates based on the second intermediate frequency signal. The filling level determined based on subsets of the first and second sets.