Indoor Geolocation Using Audio Time of Flight
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Solution Overview
Problem
Existing geolocation technologies, such as GPS and cellular tower-based systems, lack sufficient accuracy and reliability for indoor environments, making it difficult to provide precise location services in large retail spaces or other indoor settings.
Innovation Solution
A method using audio signals transmitted between devices, where a smartphone generates a geolocation request signal and receives a reply signal from a beacon, allowing for the calculation of time of flight and subsequent sub-centimeter accurate distance measurement, enabling geolocation without the need for clock synchronization or calibration, and utilizing machine learning for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS or cellular tower-based systems are used for geolocation, then outdoor positioning can be achieved, but indoor geolocation accuracy deteriorates significantly
Solution Approach 1:
The patent replaces traditional electromagnetic-based geolocation systems (GPS, cellular towers) with an acoustic-based system using audio signals transmitted through air. This substitution enables reliable indoor positioning by utilizing sound wave propagation characteristics that work effectively in indoor environments where electromagnetic signals fail.
Solution Approach 2:
The patent introduces audio signals as an intermediary medium for distance measurement between devices. Instead of directly using electromagnetic signals for positioning, the system uses sound waves that travel through air as a mediator, allowing accurate time-of-flight measurements and subsequent geolocation calculations in indoor spaces.
2Adaptability or versatility
If traditional geolocation systems are used, then infrastructure coverage can be maintained, but measurement precision deteriorates in indoor environments
Solution Approach 1:
The patent changes the fundamental parameter used for geolocation from electromagnetic signal characteristics to acoustic signal characteristics. By measuring the time of flight of audio signals and using the known speed of sound, the system achieves precise distance measurements indoors without relying on satellite or cellular infrastructure.
3Measurement precision
If audio signal transmission is used for indoor geolocation, then sub-centimeter precision can be achieved, but device complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where each device independently generates audio signals, records the time of flight, and calculates its own geolocation. The system uses the device's own speaker and microphone to create a self-contained positioning mechanism that doesn't require external infrastructure or complex coordinated systems between multiple devices.
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 provides a reliable and accurate indoor geolocation service with sub-centimeter precision, allowing for personalized navigation within indoor environments without the need for extensive infrastructure changes or continuous deep learning model updates.
Implementation Method 1
generating a geolocation request audio signal by a speaker of a first device
Implementation Method 2
receiving by a microphone of the first device a reply audio signal from a second device
Implementation Method 3
calculating a first time of flight (TOF) using the first point in time and the estimated receipt time for a second audio signal
Data Source
AI summary
A method for geolocating a mobile computing device within an indoor environment. One embodiment may comprise generating a geolocation request audio signal by a speaker of a first device starting at a first point in time, receiving, by a microphone of the first device, a reply audio signal from a second device, and extracting, by one or more processors of the first device, information encoded in the reply audio signal. The method may further comprise estimating, by the one or more processors, a receipt time by the first device for the reply audio signal and calculating a first time of flight (TOF) using the first point in time and the estimated receipt time for a second audio signal. The first device may comprise a smartphone and the second device may comprise a beacon located at a known location in an indoor environment.