Acoustic Motion Tracking Interference Reduction
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Solution Overview
Problem
Acoustic tracking systems for touchless interaction with electronic devices are prone to interference from other devices transmitting similar acoustic signals, leading to incorrect user input recognition due to stronger direct path sounds overwhelming reflection echoes, especially in multi-device scenarios.
Innovation Solution
A method where the first device detects the presence of a second device by recognizing distinctive features in its acoustic signals and adjusts its transmission characteristics to reduce interference, using different signal characteristics to distinguish between reflections from the object and signals from the second device, thereby improving motion characterization and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If acoustic signals are transmitted for touchless interaction tracking, then user input recognition is enabled, but interference from other devices transmitting similar signals causes incorrect recognition
Solution Approach 1:
The system dynamically changes signal characteristics (frequency, time-of-flight patterns, modulation schemes) based on detected environmental conditions and presence of other devices. When interference is detected, the system adjusts transmission parameters to avoid conflicting with other devices' signals, maintaining reliable operation in multi-device environments
Solution Approach 2:
The system continuously monitors received acoustic signals to detect presence of other transmitting devices and adjusts its transmission strategy in response. By analyzing signal characteristics and timing patterns, the system receives feedback about environmental conditions and modifies its operation accordingly to maintain accurate input recognition
2Measurement precision
If acoustic signals are transmitted at high power to improve signal detection, then tracking sensitivity is improved, but direct path sound from other devices swamps reflection echoes
Solution Approach 1:
The system dynamically adjusts transmission power levels based on real-time detection of environmental acoustic conditions. When other devices are detected, the system modifies its power output and timing to optimize the signal-to-interference ratio, maintaining detection sensitivity while avoiding signal swamping
Solution Approach 2:
The system performs preliminary detection of other transmitting devices and predicts potential interference patterns before transmission. By anticipating interference conditions and pre-adjusting transmission parameters, the system prevents signal swamping while maintaining adequate detection sensitivity
3Adaptability or versatility
If multiple devices transmit acoustic signals simultaneously, then each device can provide touchless interaction, but signal interference increases and motion characterization fails
Solution Approach 1:
The system segments the acoustic time domain into distinct transmission windows and uses time-of-flight measurements to differentiate signals from different devices. By dividing the signal reception into discrete time segments and associating each with a specific transmitting device, the system maintains reliable motion characterization in multi-device environments
Solution Approach 2:
The system uses time-of-flight calculations as an intermediary mechanism to distinguish between signals from different devices. By measuring and comparing signal travel times, the system can identify and separate reflections from the user's hand from direct path sounds and other interference, maintaining accurate motion tracking
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 interference between devices, allowing for accurate characterization of object motion and reliable operation even in environments with multiple devices transmitting acoustic signals.
Implementation Method 1
an ultrasonic transmitter and a number of receivers using time-of-flight measurements
Implementation Method 2
receiving acoustic signals at the first device comprising reflections of the transmitted signals from an object
Data Source
Figure 1
Figure 2
Figure 3~6
AI summary
A first electronic device is operated in the presence of a second electronic device. Both are configured to transmit acoustic signals, the first being configured to transmit signals with a first characteristic. The first device determines the presence of the second device and thereafter transmits acoustic signals having a second, signal characteristic, different from the first characteristic, and giving a reduced interference between signals transmitted from the first and second devices respectively than the first signal characteristic. Acoustic signals comprising reflections of the transmitted signals from an object are received at the first device, and are used to characterise the motion of the object and thereby control a function of the first device.