Ultrasonic Flow Meter Phase Modulation Noise Reduction
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Solution Overview
Problem
Ultrasonic flow meters face challenges in accuracy due to noise interference from echoes and transducer ringing-on, as well as external noise sources like cyclic components in fuel circuits, leading to measurement errors and aliasing effects.
Innovation Solution
The method involves transmitting successive pairs of periodic signals in opposite directions along a common path, with controlled phase alterations to counteract noise effects, ensuring that noise tends to average towards zero over a series of measurements, thereby minimizing measurement errors and allowing for higher sampling frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic signals are transmitted through fluid to measure flow rate, then flow rate measurement is achieved, but noise from echoes and transducer ringing-on interferes with signal detection and reduces measurement accuracy
Solution Approach 1:
The patent applies periodic action by transmitting ultrasonic signals at specific intervals and using phase modulation across multiple successive signals. The phase of each signal is altered relative to previous signals, allowing the system to average out noise effects over multiple measurements while maintaining periodic transmission for continuous flow monitoring
Solution Approach 2:
The patent changes the phase parameter of successive ultrasonic signals to counteract noise effects. By varying the phase of each transmitted signal and processing multiple phase-altered signals, the system reduces the impact of consistent noise patterns from echoes and transducer ringing, thereby improving measurement accuracy
2Measurement precision
If delay between successive ultrasonic signals is increased to allow echoes to decay, then noise interference is reduced, but the rate of flow rate measurements decreases
Solution Approach 1:
The system uses periodic ultrasonic signal transmission with optimized timing. By transmitting signals at regular intervals and using phase modulation, the system achieves sufficient signal separation to reduce echo interference while maintaining a high measurement rate that satisfies productivity requirements
Solution Approach 2:
The patent maintains continuous flow measurement capability by transmitting ultrasonic signals in rapid succession with phase modulation. This allows the system to continuously monitor flow rate without significant delays, ensuring uninterrupted measurement while still managing echo interference through phase-based noise reduction
3Measurement precision
If phase of successive ultrasonic signals is altered to counteract noise effects, then measurement accuracy is improved, but signal processing complexity increases
Solution Approach 1:
The patent modifies the phase parameter of transmitted ultrasonic signals in a systematic manner. By altering the phase of each successive signal and processing multiple phase-varied signals through correlation or averaging techniques, the system reduces noise impact while maintaining manageable processing complexity through algorithmic efficiency
4Reliability
If ultrasonic transducers are used for flow measurement, then non-contact measurement is achieved, but aliasing effects from cyclic components in fuel circuits cause measurement errors
Solution Approach 1:
The patent uses periodic ultrasonic signal transmission with phase modulation to distinguish actual flow signals from cyclic interference. By varying the phase of transmitted signals and analyzing the response over multiple periods, the system can differentiate between genuine flow variations and periodic aliasing effects from fuel circuit components
Solution Approach 2:
The system employs feedback mechanisms where the received signals are processed to determine flow rate, and this information is used to adjust subsequent signal transmission and processing. The phase modulation and multi-signal processing create a feedback loop that helps identify and eliminate aliasing effects, improving overall measurement accuracy while maintaining reliability in harsh environments
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 enhances the accuracy of flow rate measurements by reducing the impact of noise from echoes and transducer ringing-on, while also mitigating aliasing effects, enabling more frequent and reliable data collection, particularly in applications like motorsport where high resolution is crucial.
Implementation Method 1
transmitting successive pairs of periodic signals through the fluid, the respective signals of each pair being transmitted in opposite directions along, and from opposite ends of, the path
Implementation Method 2
the propagation time of ultrasonic signals travelling through a fluid between two fixed points varies depending on whether the signal travels in the direction of flow or against the direction of flow
Implementation Method 3
the velocity of the fluid can be determined based on a difference in propagation times of ultrasonic signals travelling with and against the flow
Data Source
AI summary
A method of measuring a flow rate of a fluid flowing along a path, the method comprising: transmitting successive pairs of periodic signals through the fluid, the respective signals of each pair being transmitted in opposite directions along, and from opposite ends of, the path; determining a difference in propagation times of each signal of each pair along the path; and determining a flow rate of fluid along the path based on the difference in propagation times of the signals of each pair along the path; wherein a phase of each signal is altered with respect to a phase of at least one other signal transmitted along the path.