Ultrasonic Distance Measurement Using Clock-Synchronized Audio
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Solution Overview
Problem
Existing methods lack an efficient, cost-effective, and secure way to accurately determine the proximity between devices, such as a wearable and a mobile phone, without requiring user action or additional hardware, while preventing false proximity detection.
Innovation Solution
A distance measurement system using clock-synchronized transmitter and receiver devices that emit and receive ultrasonic signals at predefined times, allowing for accurate distance calculation between the devices, potentially using chirp signals and symmetric cryptographic keys for security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing proximity detection methods are used, then device proximity can be determined, but the methods are not cost-effective, secure, or accurate enough
Solution Approach 1:
The patent replaces complex existing proximity detection systems with a simplified ultrasonic time-of-flight measurement system. By using ultrasonic signals and basic time measurement, the system achieves accurate distance measurement without requiring complex hardware or algorithms, thus improving measurement precision while reducing device complexity
Solution Approach 2:
The system uses the device's existing microphone and speaker components to perform distance measurement, eliminating the need for additional specialized hardware. The receiver device uses its own microphone to capture ultrasonic signals and its processor to calculate distance, making the system self-sufficient and cost-effective
2Measurement precision
If additional hardware is added for accurate distance measurement, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent makes the existing microphone and speaker components serve multiple functions: they are used for both audio processing and ultrasonic distance measurement. This multi-functionality eliminates the need for additional specialized hardware, maintaining measurement precision while simplifying manufacturing
Solution Approach 2:
The system uses the device's existing microphone and speaker components to perform distance measurement, eliminating the need for additional specialized hardware. The receiver device uses its own microphone to capture ultrasonic signals and its processor to calculate distance, making the system self-sufficient and cost-effective
3Ease of operation
If proximity detection is implemented without security measures, then ease of operation improves, but reliability decreases due to false detection
Solution Approach 1:
The patent implements preliminary authentication by verifying that the received ultrasonic signal contains the correct cryptographic key before accepting the distance measurement. This preliminary security check prevents false proximity detection while maintaining automatic operation, as the verification happens automatically as part of the signal processing
Solution Approach 2:
The system uses cryptographic verification as a feedback mechanism to confirm legitimate signals. The receiver device checks whether the decoded key from the ultrasonic signal matches the expected key, providing feedback that validates the signal's authenticity before accepting the distance measurement
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
Enables accurate proximity detection between devices, distinguishing distances within 2 meters and beyond 5 meters without additional hardware, and prevents false proximity detection, facilitating applications like intelligent personal assistants and device authentication.
Implementation Method 1
The transmitter device is configured to emit an ultrasonic signal at one or more predefined transmit times known to the transmitter and the receiver device
Implementation Method 2
The receiver device comprises a microphone configured to receive an ultrasonic signal emitted by a transmitter device
Data Source
AI summary
The present disclosure relates to a distance measurement system The system comprises a transmitter device and a receiver device. The transmitter device and the receiver device are clock-synchronized to each other. The transmitter device is configured to emit an ultrasonic signal at one or more predefined transmit times known to the transmitter and the receiver device. The receiver device is configured to receive the ultrasonic signal and to estimate a distance between the transmitter device and the receiver device based on the received ultra-sonic signal and the one or more predefined transmit times.