Ultrasonic Flow Meter Transmitter Calibration via Digital Signal Simulation
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Solution Overview
Problem
Ultrasonic flow meters, particularly those using the transit time difference method, face challenges in calibration due to limitations in simulating continuous transit times and signal shapes, especially at high flow velocities, and require a flow calibration rig, which is invasive and costly.
Innovation Solution
The method employs an artificial simulation of the measurement path using two digital-to-analog converters to generate signals with continuous transit times and variable shapes, allowing for independent calibration of transmitters without the need for a flow calibration rig, using commercially available signal generators and achieving high resolution in transit time differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flow calibration rig is used to calibrate clamp-on acoustic transducers, then calibration accuracy can be achieved, but the non-intrusiveness advantage of clamp-on measurement is lost and costs increase
Solution Approach 1:
The patent creates an artificial measurement path that copies the essential characteristics of a real measurement path (transit time relationships) without requiring physical fluid flow or a calibration rig. Digital signals are processed to simulate the acoustic transit time behavior, allowing calibration while maintaining the non-intrusive nature of clamp-on measurement.
Solution Approach 2:
The patent replaces the mechanical/fluid-based calibration rig with an electronic/digital signal processing system. Instead of using physical fluid flow and acoustic transducers in a calibration rig, the invention uses digital signal generation and processing to simulate the measurement conditions, eliminating the need for invasive calibration infrastructure.
2Ease of manufacture
If delay elements are used to simulate transit times, then calibration can be performed, but the resolution is limited by the basic clock rate
Solution Approach 1:
The patent replaces hardware delay elements with digital signal processing. Instead of using physical delay lines limited by clock rates, the invention generates digital signals with precise timing control and processes them digitally, achieving much higher resolution in transit time simulation without being constrained by hardware clock frequencies.
3Device complexity
If the same signal shape is emitted in both directions, then calibration is simplified, but accuracy at high flow velocities is compromised
Solution Approach 1:
The patent applies different signal characteristics to different measurement directions based on the local conditions (flow velocity, direction). The signal processing is adapted locally for each direction to account for the asymmetry caused by fluid flow, allowing accurate simulation of high velocity conditions while maintaining manageable system complexity.
4Ease of manufacture
If commercially available signal generators are used, then costs are reduced and standards compliance is improved, but the ability to simulate continuous transit times is limited
Solution Approach 1:
The patent implements continuous transit time simulation through digital signal processing techniques. By generating and processing digital signals continuously with precise timing control, the system achieves high-resolution transit time simulation using commercially available equipment, eliminating the need for specialized high-cost calibration instruments.
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 calibration of ultrasonic flow meters, reducing measurement errors and costs by eliminating the need for a flow calibration rig, allowing for field calibration and improved compliance with national and international standards.
Implementation Method 1
two digital-to-analog converters, each of which is assigned to a terminal of the transmitter and one of which generates the signal in the flow direction, and the other generates the signal against the flow direction
Data Source
AI summary
The invention relates to a method for calibrating the transmitters of ultrasonic flow meters according to the transit time difference method. The object of the invention is to provide a method for calibrating the transmitters of ultrasonic flow meters, said calibration being able to be carried out independently of the other components of the meter, such as the acoustic transducers and the pipe in which the fluid flow being measured occurs. According to the invention, the measurement signals are generated by means of an artificial simulation of the measurement path. This allows the transmitter to be calibrated independently of the remaining components of the measuring apparatus, such as the measuring tube and the acoustic transducers.