Ultrasound Presence Sensor Interference Mitigation
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Solution Overview
Problem
Current active ultrasound presence detection systems face interference issues, leading to false positives and reduced sensitivity, as they cannot distinguish between their own signal and interfering signals during measurement periods.
Innovation Solution
A signal processing module that detects potential interference by listening for unwanted signals outside the frequency band of the echoes during measurement periods, adapting the detection threshold to reduce false triggers and adjust measurement timeslots to avoid interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensitivity of the sensor is increased to detect small genuine motions, then detection capability is improved, but false positives increase due to interference from other signal sources
Solution Approach 1:
The patent transitions from time-domain signal analysis to frequency-domain analysis by implementing a frequency scan that divides the spectrum into multiple channels. This dimensional change allows the system to identify and avoid frequency bands contaminated by interference while maintaining high sensitivity in clean frequency regions, thereby resolving the contradiction between detection capability and false positive rates
Solution Approach 2:
The system dynamically adjusts operating parameters by scanning through different frequency channels and selecting the optimal frequency band for measurement. By changing the operating frequency parameter based on environmental conditions, the sensor maintains high detection sensitivity while avoiding interference sources, thus resolving the contradiction between measurement precision and reliability
2Reliability
If the sensor operates continuously to detect presence, then occupancy detection is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic frequency scanning instead of continuous operation. The system performs frequency scans at intervals to identify suitable measurement channels, then operates continuously on the selected channel until conditions change. This periodic re-evaluation of operating parameters maintains reliable occupancy detection while significantly reducing energy consumption compared to continuous full-spectrum monitoring
3Area of stationary object
If multiple ultrasound sensors operate in the same space, then coverage is improved, but interference between sensors increases
Solution Approach 1:
The patent segments the frequency spectrum into multiple channels and assigns different sensors to operate on different frequency channels. This frequency-domain segmentation allows multiple sensors to coexist in the same physical space without interfering with each other, as each sensor operates in its designated frequency band, thus resolving the contradiction between coverage and interference
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 effectively reduces false positives while maintaining sensitivity to genuine presence detection, allowing for reliable control of lighting systems based on occupancy without unnecessary energy consumption.
Implementation Method 1
a receiver for receiving echoes of an emitted signal
Implementation Method 2
An active ultrasound presence detector sends out a signal in the form of a series of bursts of acoustic waves (or a continuous wave) at an ultrasonic frequency, e.g. 40kHz
Implementation Method 3
Different methods can be used for this, for example Doppler shift measurements
Data Source
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AI summary
A signal processing module for use with a receiver for receiving echoes of an emitted signal. The signal processing module comprises sensing logic for sensing presence of a being or object in a space using echoes of the signal as reflected from the being or object, wherein the echoes are received with an associated frequency band. The signal processing module further comprises control logic for detecting disturbance having potential to compromise said sensing, wherein the signal processing module is configured to detect this disturbance by listening for an unwanted signal in a region of the spectrum outside the frequency band of the echoes, and to adapt the sensing in dependence on the detected disturbance.