Range Measurement Using Round-Trip Phase at Multiple Frequencies
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Solution Overview
Problem
Current range measurement techniques, such as RTT-based methods, are inaccurate in band-limited systems like Bluetooth due to clock drift and multipath effects, leading to complex and inaccurate range determination between devices.
Innovation Solution
The method involves obtaining multiple round-trip phase (RTP) measurements using wireless tone signals transmitted at different carrier frequencies to resolve ambiguities and achieve higher spatial accuracy, enabling sub-meter range measurements with reduced sensitivity to timing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RTT-based range measurement is used in band-limited systems, then the measurement can be obtained, but the accuracy deteriorates due to clock drift and multipath effects
Solution Approach 1:
The patent changes the measurement parameter from time-based RTT to phase-based RTP measurements. By measuring the phase of wireless tone signals at different carrier frequencies, the system achieves higher precision range measurements that are less sensitive to clock drift and timing errors inherent in band-limited systems like Bluetooth.
Solution Approach 2:
The patent introduces frequency diversity by performing RTP measurements at multiple different carrier frequencies. This adds a frequency dimension to the measurement process, allowing the system to resolve ambiguities and achieve sub-meter accuracy by combining phase measurements from multiple frequency channels.
2Measurement precision
If single frequency RTP measurement is used, then the measurement process is simple, but measurement ambiguity cannot be resolved
Solution Approach 1:
The patent resolves measurement ambiguities by introducing frequency diversity. By performing RTP measurements at multiple different carrier frequencies, the system can disambiguate phase measurements and achieve higher precision range determination, accepting increased processing complexity as a trade-off for improved accuracy.
3Measurement precision
If conventional RTT method is used, then the implementation is straightforward, but the spatial accuracy is limited
Solution Approach 1:
The patent achieves sub-meter spatial accuracy by changing from time-based RTT measurements to phase-based RTP measurements of wireless tone signals. This parameter change enables centimeter-level precision in multipath-free environments, significantly improving spatial accuracy despite requiring multiple frequency measurements.
Data Source
AI summary
Disclosed are systems, devices and methods for determining a range between devices based, at least in part, on measurements of wireless tone signals transmitted between devices. In particular, two devices may measure tone signals transmitted between the two devices for determination of a round-trip phase measurement. Obtaining multiple round-trip measurements from tone signals transmitted at different carrier frequencies may enable resolving at least some range ambiguities.