Multi-Frequency Phase Ranging for Indoor Distance Estimation
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Solution Overview
Problem
Existing indoor positioning systems face challenges in accurately determining device location due to high precision requirements for time measurement in distance estimation between devices, often necessitating sophisticated hardware, which can lead to errors and inaccuracy, especially in environments with obstacles or indoors where GPS signals are weak or absent.
Innovation Solution
A distance estimation system that uses phase differences between signals of different frequencies to determine distances between devices, reducing the complexity and hardware requirements for precise distance measurement, and enabling more accurate location estimation by adaptively selecting signals of various frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time measurement is used to determine distance between devices, then distance measurement can be performed, but high precision time measurement hardware is required and measurement accuracy is difficult to achieve
Solution Approach 1:
The patent replaces the mechanical/time-based measurement system with a phase-based measurement system. Instead of measuring the time of flight of signals which requires precise timing hardware, the system measures the phase difference between transmitted and received signals at the same frequency. This substitution of measurement methodology eliminates the need for sophisticated time measurement hardware while achieving accurate distance measurement.
Solution Approach 2:
The patent changes the measurement parameter from time to phase. By measuring phase difference rather than time duration, the system achieves distance measurement without requiring precise time measurement capabilities. The phase difference can be measured with standard hardware, and the distance is calculated based on the relationship between phase difference, signal frequency, and propagation distance.
2Adaptability or versatility
If GPS system is used for location estimation, then outdoor positioning can be achieved, but signal reception fails in indoor or obstructed environments
Solution Approach 1:
The patent creates a universal positioning system that can operate in both outdoor and indoor environments. By using wireless communication signals that can penetrate obstacles and work without line-of-sight requirements, the system replaces GPS with a method that functions reliably in diverse environments including indoors, urban canyons, and areas with obstructions.
Solution Approach 2:
The patent introduces anchor devices as intermediaries between the target device and the positioning calculation. These anchor devices receive signals from the target device, measure phase differences, and facilitate distance calculation. This intermediary approach enables positioning in environments where direct GPS satellite reception is not available.
3Device complexity
If phase difference measurement is used instead of time measurement, then hardware complexity is reduced, but distance measurement precision must be maintained
Solution Approach 1:
The patent replaces the time measurement system with a phase measurement system, achieving the same distance measurement function with simpler hardware. Phase measurements can be performed using standard signal processing capabilities without requiring specialized time-to-digital converters or high-precision clocks.
Solution Approach 2:
The patent changes the measurement parameter from time to phase, allowing distance measurement to be performed with less sophisticated hardware while maintaining accuracy. The phase difference measurement approach uses the periodic nature of wireless signals to encode distance information in a manner that can be decoded with standard communication hardware.
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 allows for more precise and accurate distance measurement between devices with less sophisticated hardware, improving location estimation accuracy in various environments, including those where GPS signals are weak or absent, by leveraging phase differences rather than time measurements.
Implementation Method 1
enable the second device to determine a distance between the first device and the second device based at least in part on a phase difference between the first signal and the second signal
Data Source
AI summary
A first signal generated from a signal generator may be synchronized with a local clock of a first device at a first time, and sent to a second device, the first signal having a first frequency. A second signal generated from the signal generator may be further synchronized with the local clock of the first device at a second time, the second signal having a second frequency different from the first frequency, and a difference between the second time and the first time being within a predetermined range of a predetermined time difference. The second signal may then be sent to the second device to enable the second device to determine a distance between the first device and the second device based at least in part on a phase difference between the first signal and the second signal.