RF Distance Estimation via Multi-Frequency Phase Ambiguity Resolution
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Solution Overview
Problem
RF-based distance estimation is challenging due to small time-of-flight for RF waves, signal absorption or reflection, and multiple copies of distorted signals with different gains and phases, making it difficult to accurately measure distance between objects.
Innovation Solution
A system and method that measures phase differences at different frequencies, calculates normalized and corrected phases to resolve ambiguities, and uses these phases to obtain a characteristic curve for estimating distance based on the corrected phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If simple time-of-flight measurement is used for RF-based distance estimation, then the measurement process is simple, but the accuracy is insufficient due to very small time-of-flight values
Solution Approach 1:
The patent replaces direct time-of-flight measurement with phase difference measurement. Instead of measuring the actual time delay directly (which is too small to measure accurately), the system measures the phase shift of continuous wave signals at multiple frequencies and uses these phase differences to calculate distance, thereby achieving high precision without directly measuring the extremely small time interval
Solution Approach 2:
The patent changes the measurement parameter from direct time measurement to phase difference measurement at multiple frequencies. By measuring phase differences at several different frequencies and using the relationship between phase shift and frequency, the system can resolve the ambiguity and achieve accurate distance estimation that would be impossible with simple single-frequency or direct time measurement
2Adaptability or versatility
If RF signals are transmitted through different media, then the measurement can be performed in various environments, but the signals get absorbed or reflected causing measurement errors
Solution Approach 1:
The patent uses periodic continuous wave signals at multiple frequencies instead of single pulse transmission. By transmitting continuous periodic signals and measuring phase differences across multiple frequency cycles, the system can average out the effects of random absorption and reflection, and the multi-frequency approach helps distinguish between systematic errors and environmental interference
Solution Approach 2:
The patent measures phase differences at multiple frequencies and uses the relationship between these measurements to resolve ambiguities and correct for environmental effects. The system uses the feedback from multi-frequency phase measurements to iteratively refine the distance estimate, compensating for signal absorption and reflection effects that vary with frequency
3Loss of information
If multiple copies of transmitted signal are received with different gains and phases, then the received signal contains useful distance information, but the distorted signals make accurate measurement difficult
Solution Approach 1:
The patent segments the received signal analysis by measuring phase differences at multiple distinct frequencies. Instead of trying to analyze a single distorted signal, the system divides the measurement into multiple frequency components, each providing independent phase difference information that can be combined to resolve the total distance while filtering out distortion effects
Solution Approach 2:
The patent adds the frequency dimension to the measurement process. By measuring phase differences across multiple frequencies rather than at a single frequency, the system transforms a one-dimensional problematic measurement into a multi-dimensional problem that can be solved using the relationships between measurements at different frequencies, thereby extracting accurate distance information from distorted signals
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 enables accurate distance estimation by resolving phase measurement ambiguities and accounting for signal distortions, improving the precision of RF-based distance measurement.
Implementation Method 1
a transmitter for transmitting RF signals from a location of an object
Implementation Method 2
measuring a plurality of phase differences at different frequencies between the transmitted RF signals and the corresponding received RF signals
Data Source
AI summary
A system, method, and computer program product are provided for estimating a distance to an object. The system includes a transmitter for transmitting RF signals from a location of an object. The system further includes measurement equipment, including a receiver, for receiving the transmitted RF signals as corresponding received RF signals and measuring a plurality of phase differences at different frequencies between the transmitted RF signals and the corresponding received RF signals. The system also includes a processor. The processor is configured to calculate normalized phases from the plurality of phase differences. The processor is further configured to calculate corrected phases by resolving one or more ambiguities from the normalized phases. The processor is also configured to obtain a characteristic curve using the corrected phases. The processor is additionally configured to provide an estimate of the distance based on the characteristic curve and the corrected phases.