Doppler Flow Meter Zoomed Spectral Analysis for Wide Velocity Range
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Solution Overview
Problem
Conventional Doppler flow velocity instruments face challenges in accurately measuring a wide range of velocities due to limitations in measurement range, computation time, and signal processing, where high velocities require rapid sampling rates, precluding analysis of low velocities, and vice versa, leading to excessive memory and processing requirements.
Innovation Solution
The Doppler measurement instrument employs a zoomed spectral analysis architecture that simultaneously processes samples at multiple sample rates, enabling a wide velocity measurement span with high resolution at lower velocities, using a single-phase hardware signal path and successive decimation to generate multiple frequency resolution versions of the measurement signal, allowing for accurate measurement of both low and high velocities without complex hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rapid sampling rates are used to measure high velocities, then velocity measurement range is improved, but computation time and memory requirements increase excessively
Solution Approach 1:
The signal processing is segmented into multiple stages with different sampling rates. A first stage processes at a high sampling rate to capture high velocity signals, while a second stage processes at a lower sampling rate for low velocity signals. This segmentation allows the system to handle a wide velocity range without requiring all processing to occur at the highest sampling rate, thus reducing overall computation time and memory requirements.
Solution Approach 2:
The system dynamically adjusts the sampling rate based on the detected velocity range. When high velocity signals are detected, the system uses rapid sampling; when low velocity signals are present, it switches to slower sampling. This dynamic adaptation allows the instrument to optimize computation time and memory usage according to the actual measurement conditions while maintaining the ability to measure across the full velocity range.
2Measurement precision
If high sampling rates are used to capture high velocities, then measurement accuracy for high velocities is improved, but the system cannot accurately analyze low velocities due to excessive processing requirements
Solution Approach 1:
The processing system is divided into separate stages: a first processing stage handles high velocity measurements with high sampling rates, while a second processing stage handles low velocity measurements with lower sampling rates. This segmentation allows each stage to be optimized for its specific velocity range, maintaining measurement precision without requiring the entire system to operate at maximum processing complexity.
Solution Approach 2:
Different processing qualities are applied to different velocity ranges. High velocity signals receive high-rate sampling and processing appropriate for capturing rapid changes, while low velocity signals are processed at lower rates suitable for their slower variations. This local optimization of processing quality ensures accurate measurement across all velocity ranges without uniformly applying high complexity processing to all signals.
3Speed
If a single high sampling rate is used for all velocity ranges, then high velocity measurement capability is improved, but low velocity measurement resolution deteriorates
Solution Approach 1:
The sampling rate is dynamically adjusted based on the velocity range being measured. For high velocity measurements, the system uses high sampling rates to accurately capture rapid signal changes. For low velocity measurements, the system transitions to lower sampling rates that provide sufficient resolution for slow variations without the excessive processing overhead of continuously high sampling rates. This dynamic adjustment maintains both high velocity capability and low velocity resolution.
Solution Approach 2:
The system changes the sampling rate parameter according to the detected velocity range. When high velocity conditions are detected, the sampling rate parameter is set to a high value to capture fast-moving targets. When low velocity conditions are detected, the sampling rate parameter is reduced to provide appropriate resolution for slow-moving targets. This parameter adaptation allows optimal measurement precision across the full velocity range.
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 accurate and reliable measurement of target velocities across a large range, reducing computational time and memory requirements, while maintaining high accuracy at both low and high velocities, and avoiding aliasing, thus improving Doppler flow measurements.
Implementation Method 1
measuring fluid velocity by frequency based measuring (Doppler), for example by emitting an ultrasonic or microwave carrier signal that echoes off targets such as particulate matter, air bubbles, etc., carried in a flowing liquid and returns with its mean frequency shifted by the Doppler Effect
Data Source
AI summary
A fluid flow measurement instrument is provided. The measurement instrument includes a sensor producing a time domain signal representative of reflections of an emitted signal; and a meter being coupled to the sensor and configured to: receive the time domain signal; create two or more spectral estimates for the time domain signal, wherein said two or more spectral estimates have different frequency ranges and resolutions; determine a frequency offset value using one or more of the two or more spectral estimates; and convert the frequency offset value into a fluid velocity. Other aspects are described and claimed.