Phase-Sensitive Sensor Demodulation for Same-Frequency Noise Separation
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Solution Overview
Problem
Existing capacitive sensors face challenges in distinguishing noise components with the same frequency as the driving signal, leading to incorrect noise detection and increased complexity in circuit structure due to the need for additional circuits to manage reference signals and potential changes in electrostatic coupling.
Innovation Solution
A sensor device with a demodulating unit that multiplies detection signals by both a reference signal with the same frequency and phase as the detection signal, and another with a shifted phase, allowing for the separation of signal and noise components, and a control unit that adjusts the driving frequency based on noise thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a detection signal is multiplied by a reference signal having the same frequency as a driving signal to extract a direct-current component, then noise components having a frequency different from the driving signal are removed, but noise components having the same frequency as the driving signal cannot be removed
Solution Approach 1:
The reference signal is segmented into two components: one with the same phase as the detection signal and another with a shifted phase. This segmentation allows the system to separately process signal components and noise components, enabling accurate noise detection while maintaining signal integrity.
Solution Approach 2:
A phase-shifted reference signal is introduced as an intermediary to differentiate between signal and noise components. By using this intermediate reference signal with a known phase relationship, the system can identify and measure noise components that would otherwise be indistinguishable from the main signal.
2Measurement precision
If additional circuits are added to manage reference signals and detect noise, then noise detection capability is improved, but circuit structure complexity increases
Solution Approach 1:
The reference signal creating unit is designed to generate multiple reference signals with different phase relationships, enabling it to serve both signal detection and noise detection functions. This multi-functionality reduces the need for separate dedicated circuits for each purpose.
Solution Approach 2:
The signal detection and noise detection functions are merged into a unified processing framework where the same demodulating unit processes both in-phase and quadrature components. This consolidation reduces overall circuit complexity while maintaining comprehensive detection capability.
3Measurement precision
If the driving frequency is adjusted to reduce noise impact, then detection accuracy is improved, but system adaptability to different operating conditions decreases
Solution Approach 1:
The system dynamically adjusts the driving frequency based on detected noise characteristics and operating conditions. This dynamic adaptation allows the system to optimize detection accuracy for each specific situation while maintaining the capability to operate across a range of frequencies.
Solution Approach 2:
A feedback mechanism is implemented where noise detection results are used to adjust the driving frequency. The system continuously monitors noise levels and automatically tunes the driving frequency to minimize noise impact, thereby maintaining high detection accuracy across varying operating conditions.
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 effective noise component separation and reduces circuit complexity by allowing for accurate noise detection and frequency adjustments, minimizing noise impact on the detection signal.
Implementation Method 1
a reference signal creating unit that creates a first reference signal of a sine wave, the first reference signal having a frequency equal to the frequency of the detection signal and also having a phase equal to the phase of the detection signal
Implementation Method 2
a demodulating unit that multiplies the detection signal output from the sensor unit by the first reference signal and creates, as a first demodulation signal matching the physical quantity to be detected, a signal matching a direct-current component included in a signal obtained as the result of the multiplication
Data Source
AI summary
A sensor device has: a sensor unit that outputs a sinusoidal detection signal having an amplitude matching a physical quantity to be detected; a reference signal creator that creates a first sinusoidal reference signal having the same frequency and phase as the detection signal; and a demodulator that multiplies the detection signal by the first reference signal and creates, as a first demodulation signal matching the physical quantity, a signal matching a direct-current component included in a signal resulting from the multiplication. The reference signal creator creates a sinusoidal second reference signal having the same frequency as the detection signal but being out of phase with the detection signal. The demodulator multiplies the detection signal by the second reference signal and creates, as a second demodulation signal matching a noise component superimposed on the detection signal, a signal matching a direct-current component included in a signal resulting from the multiplication.