Flow Measurement Using Enhanced Phase Difference Detection
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Solution Overview
Problem
Conventional transit-time flow meters require complex and power-consuming circuitry for precise time or phase measurement of ultrasonic signals, which is inefficient and generates significant heat.
Innovation Solution
A flow measurement system using enhanced phase difference detection based on the ratio of amplitudes of summations of two oppositely propagating acoustic signals, allowing for compact, low-power analog circuitry with improved accuracy by calculating phase difference without direct time measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional time measurement techniques are used to achieve 100 picosecond resolution, then measurement precision is improved, but device complexity and power consumption increase significantly
Solution Approach 1:
The patent replaces direct time measurement circuitry with phase measurement circuitry. Instead of using a gated counter operating at 10 GHz to directly resolve 100 picoseconds, the system measures the phase of the signal. A 10 MHz carrier has a 100 nanosecond period, and 100 picosecond resolution corresponds to measuring phase to 0.36 degrees, which can be achieved with simpler circuitry including a local quadrature oscillator and mixers.
Solution Approach 2:
The patent changes the measurement parameter from direct time measurement to phase measurement. By measuring the phase difference between transmitted and received signals instead of directly measuring time of flight, the system achieves the same 100 picosecond resolution with less complex circuitry that consumes less power and generates less heat.
2Measurement precision
If conventional phase measurement techniques are used to achieve 100 picosecond resolution, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces complex conventional phase measurement circuitry with a simplified analog circuit implementation. The system uses a local quadrature oscillator operating at 10 MHz and a pair of mixers to produce a complex baseband signal, which is then sampled to determine the phase of the incoming signal. This approach achieves 0.36 degree phase resolution (equivalent to 100 picosecond time resolution) with significantly reduced power consumption compared to direct time measurement methods.
3Measurement precision
If high-speed logic is used to achieve 100 picosecond time resolution, then measurement precision is improved, but heat generation and power consumption increase
Solution Approach 1:
The patent substitutes high-speed logic circuits with lower-speed analog phase measurement circuits. Instead of using a gated counter operating at 10 GHz that generates significant heat, the system uses a 10 MHz local quadrature oscillator with mixers and analog-to-digital converters. This frequency reduction from 10 GHz to 10 MHz dramatically reduces power consumption and heat generation while maintaining the required 100 picosecond measurement precision through phase measurement.
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 simplifies circuitry requirements, reducing size and power consumption while maintaining high accuracy in fluid flow measurement, enabling efficient and precise flow rate determination.
Implementation Method 1
an ultrasonic signal is propagated between a pair of opposed transducers positioned upstream and downstream from each other, so that the signal travels with the flow in one direction and against the flow in the other direction
Implementation Method 2
The flow modifies the transit time of the acoustic signals slightly, and can be observed as a change in the signal phase
Implementation Method 3
The phase of a signal traveling in the direction of flow is advanced, while the phase of a signal traveling against the direction of flow is delayed
Data Source
AI summary
A flow measurement system and method uses enhanced phase detection based on a ratio of amplitudes of summations of two oppositely propagating acoustic signals. A need for direct time measurement and extensive difference calculation is consequently avoided so that in some implementations compact, simple, low power analog circuitry can be used.