Sensor Phase Delay Compensation via Quadrature Demodulation
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Solution Overview
Problem
Sensors face challenges in accurately detecting the presence of objects due to phase delays in transducing circuits, which can obscure modulation signals and reduce signal-to-noise ratio (SNR) and signal-to-interference ratio (SIR), making it difficult to cancel out carrier signals effectively.
Innovation Solution
A system and method that apply orthogonal electrical signals to compensate for phase delays in transducing circuits using a quadrature demodulator, allowing for accurate extraction and compensation of signals to determine object presence, thereby improving data capture rate and SNR/SIR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor applies a carrier signal to detect object presence, then the sensor can detect the presence or position of objects, but the phase delay in the transducing circuit causes the carrier signal and measurement signal to be out of phase, making it difficult to accurately cancel or compensate for the carrier
Solution Approach 1:
The system performs preliminary characterization of the transducing circuit's phase response before actual measurement. By applying a known test signal and measuring the phase shift introduced by the transducing circuit, the system pre-calculates compensation parameters that are then applied during subsequent carrier cancellation, resolving the phase alignment issue before it affects measurement accuracy
Solution Approach 2:
The system dynamically adjusts the phase and amplitude parameters of the compensation signal based on the measured phase delay characteristics of the transducing circuit. By changing these parameters in real-time to match the actual circuit behavior, the system achieves accurate carrier cancellation despite variations in phase delay
2Reliability
If the sensor uses modulation to encode object information, then the sensor can improve signal detection capability, but the phase delay obscures the modulation signal and reduces signal-to-noise ratio and signal-to-interference ratio
Solution Approach 1:
The system implements a feedback mechanism where the output of the transducing circuit is fed back through a phase compensation path. The compensated signal is then subtracted from the original measurement signal, creating a feedback loop that continuously reduces the carrier component and improves the signal-to-noise ratio of the detected modulation
3Measurement precision
If the sensor applies orthogonal electrical signals to compensate for phase delays, then the accuracy of object detection is enhanced and signal-to-noise ratio is improved, but the device complexity increases due to the need for quadrature demodulator and multiple signal paths
Solution Approach 1:
The system designs the transducing circuit to serve multiple functions: it acts as both the signal path for object detection and the reference path for phase characterization. By making the same circuit perform dual roles, the system eliminates the need for separate reference circuits, reducing overall device complexity while maintaining measurement accuracy
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
The solution effectively compensates for phase delays, enhancing the accuracy of object detection and improving the signal-to-noise ratio and signal-to-interference ratio, leading to improved measurement sensitivity and reduced noise interference.
Implementation Method 1
extract the third electrical signal and the fourth electrical signal using a quadrature demodulator
Data Source
AI summary
Systems and methods for detecting a user's finger are provided. In some embodiments, a method may include applying a first electrical signal, applying a second signal, receiving a third electrical signal using a first electrode, receiving a fourth electrical signal using the first electrode, extracting the third and fourth electrical signals using a quadrature demodulator, and compensating for a phase delay between at least the first electrical signal and the third electrical signal.