Digital Persistence Filter for EMI Sensor Correction
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Solution Overview
Problem
Electronic devices equipped with sensors often face inaccurate measurements due to electromagnetic interference (EMI) from radio-frequency (RF) signals transmitted by the device's own RF signal transmitters.
Innovation Solution
The implementation of a digital filter, such as a digital persistence filter, to determine whether sensor measurements have been impacted by EMI. This filter generates a signal if the sensor measurement is high for a time corresponding with the known emission time of the RF signals, and can operate over single or multiple frames of sensor measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If RF signal transmitters are used to transmit radio-frequency signals, then communication functionality is improved, but electromagnetic interference with sensor measurements increases
Solution Approach 1:
A digital filter is introduced as an intermediary component between the RF transmitter and the sensor measurement system. The filter processes sensor measurements to identify and eliminate those corrupted by electromagnetic interference from RF signals, thereby enabling the device to maintain both communication functionality and measurement accuracy simultaneously
2Productivity
If sensor measurements are taken during RF signal transmission, then real-time monitoring capability is improved, but measurement accuracy deteriorates due to EMI
Solution Approach 1:
The system continuously monitors sensor measurements and uses feedback from the digital filter to identify when EMI is present. When interference is detected, the system discards affected measurements and waits for a clean measurement opportunity, thereby maintaining real-time monitoring capability while ensuring measurement accuracy through feedback-based quality control
3Measurement precision
If a digital filter is applied to remove EMI-affected measurements, then measurement accuracy is improved, but processing time increases
Solution Approach 1:
The digital filter applies partial processing by only analyzing sensor measurements during specific time windows corresponding to expected RF transmission periods. Rather than continuously processing all measurements, the system focuses computational resources on identifying EMI-affected readings during known interference intervals, thereby improving accuracy while minimizing processing time through targeted rather than comprehensive analysis
Data Source
AI summary
An electronic device may have a sensor and may have a radio-frequency signal transmitter. The sensor may be vulnerable to electromagnetic interference (EMI) from the radio-frequency (RF) signals. Therefore, circuitry in the device may determine whether measurements from the sensor have been impacted by EMI. To make this determination, a digital filter may be used. In particular, the digital filter may be a digital persistence filter that generates a signal if the sensor measurement is high for a time that corresponds with the known emission time of the RF signals. Alternatively, the digital filter may receive the sensor measurements in the digital domain and compare the sensor measurements to time-delayed sensor measurements to determine whether the sensor measurements have been impacted by EMI. Control circuitry may discard any of the sensor measurements, or measurements from one or more other sensors, in response to the sensor measurements being impacted by EMI.