Distance Estimation Using Multi-Frequency Phase Combinations
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Solution Overview
Problem
Conventional methods for estimating distance between a portable terminal and a communication device using radio wave propagation time are prone to errors due to interference and multipath delays, leading to inaccurate distance measurements.
Innovation Solution
A distance estimation device that utilizes phase determination based on radio wave phases at multiple frequencies, generating multiple sets of combinations and adopting the estimated distance only when the differences between calculated distances are within a predetermined range, thereby improving accuracy and security by using a generating rule to shift phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radio wave propagation time is used for distance estimation, then the measurement process is simple, but the measurement precision deteriorates due to interference and multipath delays
Solution Approach 1:
The patent changes the measurement parameter from propagation time to phase information at multiple frequencies. By measuring phase differences at multiple frequency points and using combinatorial calculations, the system achieves higher distance estimation accuracy while avoiding the limitations of single-frequency or time-based methods susceptible to interference and multipath effects.
2Measurement precision
If multiple measuring data at different frequencies are used, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent segments the distance estimation process into multiple independent frequency measurements. Each frequency point provides a separate phase measurement, and these segmented measurements are then combined through systematic pairing to produce the final distance estimate. This segmentation allows for improved accuracy while maintaining manageable processing complexity through structured combination.
Solution Approach 2:
The patent transitions from single-frequency measurement to multi-frequency measurement space. By introducing the frequency dimension and measuring phase at multiple frequency points, the system creates additional measurement dimensions that can be combined to eliminate errors and improve accuracy, effectively using dimensional expansion to resolve measurement limitations.
3Reliability
If phase shift amount is determined from reference phase following generating rule, then the reliability improves against unauthorized access, but the device complexity increases
Solution Approach 1:
The patent uses a predetermined generating rule that both the communication device and portable terminal possess as copies. This rule enables them to independently determine expected phase shift amounts and verify each other's authenticity. The copying principle allows secure verification without requiring complex cryptographic protocols, as both parties have identical reference information to validate the phase relationship.
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
Enhances distance estimation accuracy by reducing errors and securing the communication process against unauthorized access by ensuring the generating rule is unknown to unauthorized devices.
Implementation Method 1
a phase acquisition unit, when the terminal communication unit receives measuring data for distance estimating purpose, acquiring a phase of a radio wave from the received measuring data
Implementation Method 2
a data generating unit determining a phase shift amount from a reference phase following a predetermined generating rule and generating the measuring data by applying the determined phase shift amount
Data Source
AI summary
A distance estimation device includes: a portable terminal; a communication device; a distance estimation unit estimating a distance between the portable terminal and the communication device; and a phase determination unit. The communication device determining a phase shift amount from a reference phase following a predetermined generating rule and generates measuring data by applying the determined phase shift amount. The phase determination unit determines a distance estimation phase for distance estimating purpose. The distance estimation unit adopts an estimated distance when a difference between the estimated distances respectively calculated based on at least two sets of combinations of the distance estimation phases is within a predetermined range.