Acoustic Measuring Apparatus Transit Time Estimation
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Solution Overview
Problem
Existing acoustic measuring devices face challenges in achieving high measuring accuracy for fluid flow and fluid composition analysis, particularly in determining transit times of sound signals with sufficient precision without requiring high-speed analog/digital converters.
Innovation Solution
The method involves using a sound transducer to emit and receive sound signals, recording echo signals, and determining a time profile, which is then cross-correlated with a reference sine signal to find the frequency and phase values that maximize the cross-correlation function, allowing for precise estimation of transit time without needing high sampling rates or fast converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high sampling rates are used to determine sound signal propagation time accurately, then measurement precision is improved, but device complexity and cost increase due to requiring fast analog-to-digital converters
Solution Approach 1:
The patent replaces the mechanical/electronic approach of using fast analog-to-digital converters with a signal processing approach using cross-correlation of echo signals with reference signals. This substitution allows accurate transit time measurement without requiring high-speed hardware converters, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent introduces cross-correlation processing as an intermediary method between the raw echo signal and the final transit time measurement. By correlating the echo signal with reference signals at different frequencies and phases, the system extracts precise timing information without directly requiring high-speed digitization, thus mediating between the need for accuracy and the constraint of simpler hardware.
2Measurement precision
If high sampling rates are used to accurately determine transit time, then measurement precision is improved, but computational effort and processing time increase
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing reference signals at multiple frequencies and phases before actual measurement. During measurement, the system only needs to correlate the echo signal with these pre-prepared references, significantly reducing real-time computational effort compared to processing raw high-rate sampled data, thus maintaining precision while reducing processing time.
Solution Approach 2:
The patent extracts the essential timing information from the echo signal through cross-correlation with reference signals. By extracting only the critical phase and frequency components needed for transit time calculation, the system avoids processing the entire high-rate sampled waveform, thereby reducing computational load while preserving measurement precision.
3Device complexity
If simple signal processing is used to reduce computational effort, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent changes the parameters of the reference signals by varying frequency and phase to create multiple correlation patterns. This allows the simple cross-correlation operation to extract precise timing information through the interaction of these parameter variations, achieving high measurement precision without complex signal processing or hardware requirements.
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 enables precise determination of sound signal propagation time with reduced computational effort and sampling rates, allowing for accurate fluid flow and composition analysis using ultrasonic transducers.
Implementation Method 1
The transit time of the sound pulses allows conclusions to be drawn about the fluid's velocity in the fluid line
Implementation Method 2
an echo signal of the output signal is received by the at least one sound transducer
Data Source
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AI summary
The invention relates to a method and an apparatus for operating an acoustic measuring apparatus (10). At least one sound transducer (12) in the acoustic measuring apparatus (10) is provided. The at least one sound transducer (12) is designed to send and receive sound signals. An output signal (40) is emitted by the at least one sound transducer (12), and an echo signal (42) for the output signal (40) is received by the at least one sound transducer (12). A time profile for the echo signal (42) is recorded. The time profile of the echo signal (42) is used to determine a first estimate (T_sig_1) of a delay for the sound signal from the beginning of the output signal (40) to the beginning of the echo signal (42). Cross‑correlation between the echo signal (42) and a reference sinusoidal signal (44) is used to ascertain a profile for a cross‑correlation function (R) on the basis of a frequency and a phase of the reference sinusoidal signal (44). A value (f_0) for the frequency of the reference sinusoidal signal (44) and a value (phi_0) for the phase of the reference sinusoidal signal (44) are ascertained for which a maximum value for the cross correlation function (R) is achieved. Depending on the value (f_0) of the frequency of the reference sinusoidal signal (44) and the value (phi_0) of the phase of the reference sinusoidal signal (44) for which the maximum value of the cross correlation function (R) is achieved, and of the first estimate (T_sig_1) of the delay in the sound signal from the beginning of the output signal (40) to the beginning of the echo signal (42), an updated estimate (T_sig_2) of the delay in the sound signal from the beginning of the output signal (40) to the beginning of the echo signal (42) is determined.