SAW Sensor Signal Processing Undersampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high cost and instability of analog-to-digital converters (ADCs) and complex circuitry in ball SAW sensors for temperature compensation in gas sensing applications, leading to expensive systems and potential phase drift in long-term measurements.
Innovation Solution
Implementing an electrical signal processing device that uses undersampling with a specific ADC sampling frequency and band-pass filters to extract and process aliasing frequencies, reducing the need for expensive ADCs and complex conversion circuits, while achieving precise temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oversampling with high sampling rate ADC is used to achieve precise temperature compensation, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the sampling rate parameter from high (oversampling) to low (undersampling), and uses digital signal processing to extract the required temperature compensation information from the undersampled signal, thereby reducing ADC complexity while maintaining measurement precision
Solution Approach 2:
The patent replaces the hardware-based high-performance ADC system with a software-based signal processing approach, using digital filtering and frequency analysis to achieve the same measurement precision with simpler hardware
2Measurement precision
If two-frequency measurement is implemented using heterodyne detection, then temperature compensation precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the temperature compensation information directly from the undersampled signal through digital filtering and frequency analysis, eliminating the need for complex heterodyne detection circuits while maintaining the ability to measure at two frequencies
Solution Approach 2:
The patent creates a digital copy of the signal processing function that normally requires analog heterodyne detection circuits, implementing the same functionality through software-based frequency analysis and phase detection
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 allows for precise temperature compensation in ball SAW sensors, simplifying the system and reducing costs, while maintaining measurement accuracy comparable to oversampling or two-system low-frequency conversion methods.
Implementation Method 1
band-pass filters whose center frequencies are f1 and f2 and whose band widths are equal to or less than 20% of the center frequencies so as to process a received signal from the SAW sensor and to extract components of f1 and f2
Implementation Method 2
an ADC which samples a signal from a delay line type SAW sensor that can transmit and receive two frequencies f1 and f2 (f2>f1), and a sampling frequency fS of the ADC is lower than twice the frequency
Implementation Method 3
by use of a sensitive film which is formed on the propagation path of the SAW device and a SAW sensor which measures an acoustic velocity variation caused by reaction of the sensitive film with gas molecules
Implementation Method 4
A ball SAW sensor is the sensor utilizing this phenomenon which brings multiple roundtrips of the SAW on an equator with respect to the Z-axis cylinder of a piezoelectric crystal sphere
Data Source
AI summary
When frequencies used in the two-frequency measurement of a SAW sensor are represented by f1 and f2 (f2>f1), an electrical signal processing device is provided without use of oversampling at a frequency higher than twice the frequency f2 or a two-system low-frequency conversion circuit, in which temperature compensation with the same accuracy as the case where these are used can be realized. Narrow band frequency filtering is applied to a waveform after roundtrips in a delay line type SAW sensor capable of transmitting and receiving multiple frequencies, the two frequencies f1 and f2 (f2>f1) are extracted, and a delay time is determined utilizing an aliasing obtained by applying undersampling at a frequency lower than twice the frequency f1.