Radio Tag Reader Phase Velocity Discrimination
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Solution Overview
Problem
Existing radio tag detection systems face challenges in accurately distinguishing between moving and stationary tags due to interference from moving objects and the need for reference tags, leading to erroneous detections and the requirement for additional infrastructure like fixed tags.
Innovation Solution
A radio tag reader system that uses a combination of phase measurement, distance change measurement, and velocity change measurement to determine the moving state of tags, eliminating the need for reference tags and reducing interference by analyzing the rate of velocity changes and phase bias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase measurement is used to detect moving tags, then detection capability is improved, but stationary tags may be erroneously detected as moving due to reflection from moving objects
Solution Approach 1:
The patent applies dynamics by analyzing the temporal characteristics of phase changes. It calculates the rate of change of phase differences over time and compares it against threshold values. Moving tags exhibit continuous phase changes above the threshold, while stationary tags show phase changes below the threshold even when reflected by moving objects, enabling reliable distinction between the two states.
Solution Approach 2:
The patent changes the parameter being measured from simple phase difference to the rate of change of phase difference. By deriving the time derivative of phase differences and analyzing its magnitude, the system transforms static phase measurements into dynamic velocity indicators, allowing it to distinguish moving tags from stationary tags based on velocity thresholds.
2Reliability
If reference tags are used to eliminate interference from moving objects, then detection reliability is improved, but device complexity and infrastructure requirements increase
Solution Approach 1:
The patent applies self-service by enabling the system to automatically distinguish moving tags from stationary tags using intrinsic characteristics of the tags themselves. The system analyzes the temporal behavior of phase changes from each tag and autonomously determines its movement state without requiring external reference tags or additional infrastructure, making the system self-sufficient.
Solution Approach 2:
The patent extracts the essential characteristic for movement detection - the rate of phase change - from the complex interference pattern caused by moving objects. By isolating and analyzing this specific parameter, the system eliminates the need for reference tags while maintaining detection reliability, effectively separating the useful signal from the noise.
3Reliability
If velocity change rate analysis is used to distinguish stationary tags, then false positive reduction is achieved, but calculation complexity increases
Solution Approach 1:
The patent applies partial action by implementing a tiered detection approach. It first calculates the rate of phase change for all detected tags, then applies velocity thresholds to quickly identify and filter out stationary tags. This partial processing approach handles the majority of cases efficiently without requiring complex analysis for every single tag, balancing computational load with detection accuracy.
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
The system effectively discriminates between moving and stationary tags with high accuracy, reducing false positives and eliminating the need for additional infrastructure, enabling real-time tracking of tag movements.
Implementation Method 1
a phase measurement section that uses the antenna to measure phases of response waves from the radio tag
Implementation Method 2
a distance change measurement section that measures change of distance from the radio tag to the antenna based on measurements of the phase measurement section
Data Source
AI summary
A configuration which can easily discriminate a moving wireless (radio) tag from a stationary wireless (radio) tag. The configuration uses an antenna to measure phases of response waves received from a wireless tag. Based on the measurements, the configuration measures changes in distance from the wireless tag to the antenna and detects travel of the wireless tag. Based on the measurements, the configuration measures changes in velocity of the wireless tag relative to the antenna. A wireless tag having a rate of changes in signs of the velocity, of not less than a predetermined value in the measured velocity changes, is detected as being a stationary tag.