Doppler-Compensated Phase-Based Ranging in Channel Hopping
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Solution Overview
Problem
Existing phase-based ranging methods are biased by Doppler shift during movement, especially in pseudo-random channel hopping scenarios, which are not compliant with regulatory requirements such as US FCC regulation 47 CFR § 15.247.
Innovation Solution
A Doppler-compensated phase-based ranging method that calculates relative speed between devices based on two-way phase measurements at the same frequency, allowing for accurate distance calculation even in pseudo-random frequency hopping scenarios, using equations such as vˆ=cΔϕ-4πfvΔT for relative speed and ϕˆdoppler=-2πfvˆc(tA+tB) for Doppler compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear frequency sweep is used for phase-based ranging, then Doppler compensation can be achieved, but the method cannot comply with pseudo-random channel hopping regulations
Solution Approach 1:
The patent segments the frequency measurements into pairs performed at the same frequency, allowing Doppler compensation to be calculated independently for each pair. This segmentation enables the system to work with pseudo-random frequency hopping patterns while still achieving Doppler compensation, as each frequency pair can be processed independently to extract Doppler information.
Solution Approach 2:
The patent changes the approach from requiring a continuous linear frequency sweep to using discrete frequency pairs at the same frequency. This parameter change allows the system to adapt to pseudo-random channel hopping regulations while maintaining the capability for Doppler compensation through phase difference measurements at matched frequency pairs.
2Measurement precision
If Doppler compensation is applied using existing methods, then range estimate bias is removed, but the method depends on linear frequency sweep and cannot be used with pseudo-random channel hopping
Solution Approach 1:
The patent creates a universal Doppler compensation method that works with both linear frequency sweeps and pseudo-random channel hopping patterns. By using frequency pairs at the same frequency rather than requiring a continuous linear sweep, the method becomes multi-functional and can adapt to different frequency sequencing requirements including regulatory-compliant pseudo-random hopping.
Solution Approach 2:
The patent introduces dynamic adaptability by allowing the frequency sequencing to vary according to different patterns (linear sweep or pseudo-random hopping) while maintaining the core Doppler compensation functionality. The system dynamically adjusts to the available frequency measurements rather than requiring a fixed linear sweep sequence.
3Measurement precision
If two-way phase measurements are performed at multiple frequencies, then range estimation can be improved, but Doppler shift introduces bias in moving devices
Solution Approach 1:
The patent uses feedback by calculating Doppler compensation from phase differences at the same frequency and applying this compensation to correct the range estimation. The system measures the Doppler effect through phase differences, feeds this information back into the calculation, and uses it to compensate for the bias in the final range estimate.
Solution Approach 2:
The patent converts the harmful Doppler shift bias into a beneficial measurement by using the phase difference at the same frequency to calculate Doppler compensation. Instead of treating Doppler shift as purely detrimental, the system extracts useful Doppler information from the phase measurements and uses it to correct the range estimation, turning the harmful effect into a corrective mechanism.
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 phase-based ranging in pseudo-random channel hopping scenarios while ensuring regulatory compliance, using FFT or super-resolution algorithms for distance calculation, effectively mitigating Doppler-induced errors.
Implementation Method 1
In the presence of Doppler shift, e.g., during movement of one or both of the devices, the range estimate will be biased
Data Source
AI summary
A method of phase-based ranging between a first device and a second device, comprises receiving a plurality two-way phase-measurements between the first device and the second device performed at a plurality of frequencies; identifying a first measurement and a second measurement of said plurality of two-way phase measurements, said first measurement and said second measurement having been performed at a same frequency; calculating a relative speed between said first device and said second device based at least on said first measurement and said second measurement; doppler compensating a plurality of measurements of said plurality of two-way phase measurements based on the calculated relative speed; and calculating a distance between said first device and said second device based on the doppler compensated measurements.