Synchronized Ultrasonic Transmission for Multi-Device Interference
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Solution Overview
Problem
Acoustic tracking systems for electronic devices are prone to interference from other devices transmitting similar signals, leading to incorrect user input recognition, especially when multiple devices are in close proximity, as they struggle to distinguish between reflections from an object of interest and signals from other devices.
Innovation Solution
Implementing a method where devices synchronize their ultrasonic signal transmissions to avoid interference by defining a region-of-interest and an exclusion zone, ensuring that devices transmit signals at substantially the same time to prevent overlap and allow for effective distinction between direct and reflected signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If devices transmit acoustic signals at different times to avoid interference, then interference between devices is reduced, but the system scalability deteriorates when larger numbers of devices are within range and/or move relative to one another
Solution Approach 1:
The patent implements periodic transmission of ultrasonic signals at synchronized time intervals. Multiple devices transmit signals simultaneously at predetermined periodic intervals, allowing the system to maintain consistent timing patterns that facilitate interference management through exclusion zones while supporting dynamic device configurations and movements.
2Device complexity
If devices transmit acoustic signals at the same time, then system complexity is reduced and scalability is improved, but interference between devices increases and can swamp reflected signals
Solution Approach 1:
The patent segments the spatial environment into distinct regions: a region of interest where user interactions occur, exclusion zones around each device to prevent direct signal interference, and beyond zones. By transmitting signals simultaneously and defining these spatial segments, the system allows reflected signals from the region of interest to be distinguished from direct signals originating in exclusion zones, maintaining signal detection reliability despite simultaneous transmissions.
Solution Approach 2:
The patent transitions from temporal separation (transmitting at different times) to spatial separation (defining exclusion zones and regions of interest). By adding the spatial dimension to the solution, multiple devices can transmit simultaneously without interference, as the system distinguishes signals based on their spatial origins rather than requiring temporal sequencing.
3Adaptability or versatility
If acoustic tracking systems operate in environments with multiple devices, then device versatility is improved, but the ability to distinguish reflections from direct signals deteriorates due to signal overlap
Solution Approach 1:
The patent establishes exclusion zones around each device before signal transmission begins. These pre-defined spatial boundaries prevent direct signals from other devices from entering the region of interest, ensuring that when signals are transmitted simultaneously, any echoes detected within the region of interest must originate from user interactions rather than direct device-to-device signals, thereby maintaining measurement precision in multi-device environments.
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, enabling reliable touchless interaction by ensuring that signals from other devices are outside the exclusion zone, allowing for accurate user input recognition even in environments with multiple devices.
Implementation Method 1
track an object for touchless interaction with a computing device with an ultrasonic transmitter and a number of receivers using time-of-flight measurements
Implementation Method 2
sensitive to interference from echoes caused by other objects
Implementation Method 3
using time-of-flight measurements
Implementation Method 4
the direct path sound from the other device may be many times stronger than the reflection from the input object
Data Source
AI summary
In a method of operating at least first and second electronic devices, the devices are each arranged to transmit and receive ultrasonic signals, e.g. to operate a touchless user interface. Both devices, or at least two of the devices, are synchronised to transmit said signals at substantially the same time. The devices may, for example, listen to each other's ultrasonic signals or use a WiFi network access point for synchronization.