Wireless Tag Reader Phase Analysis for Region Detection
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Solution Overview
Problem
Existing wireless tag reading apparatuses face challenges in accurately distinguishing between signals from tags within and outside a predetermined region, especially when goods are stacked or made of metal, leading to deteriorated reading accuracy due to signal interference.
Innovation Solution
A wireless tag reading apparatus that includes input control, extraction, and determination means, where the antenna moves to read the tag from multiple positions, extracts the phase of the radio wave, and determines the tag's location based on phase changes, storing this information to differentiate between tags inside and outside the region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the RSSI threshold value is increased to improve reading accuracy, then the reading accuracy is improved, but the apparatus may read information from wireless tags located outside the predetermined region
Solution Approach 1:
The patent introduces phase information as an intermediary parameter to mediate between RSSI threshold settings and region determination. By using phase changes of radio waves as the antenna moves, the system can accurately determine tag location without needing to adjust RSSI thresholds, thus resolving the contradiction between reading accuracy and region determination accuracy
Solution Approach 2:
The patent changes the parameter used for region determination from RSSI value to phase information. By monitoring phase changes of the radio wave signal as the antenna moves to different positions, the system can determine whether a tag is inside or outside the predetermined region without adjusting the RSSI threshold, thereby maintaining both reading accuracy and region determination accuracy
2Area of stationary object
If the RSSI threshold value is decreased to read tags outside the predetermined region, then the reading coverage is improved, but the reading accuracy for tags inside the region deteriorates
Solution Approach 1:
The patent uses phase information as an intermediary to separate the functions of reading coverage and reading accuracy. The RSSI threshold can be set for adequate reading coverage while phase information provides accurate distance measurement to ensure only tags within the predetermined region are processed, resolving the contradiction between coverage and accuracy
3Measurement precision
If multiple reception positions are used to determine tag location, then the region determination accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent makes the antenna serve multiple functions: it both reads the wireless tag information and measures the phase of the radio wave signal. By utilizing the same antenna for both information reading and phase measurement, the system achieves accurate region determination without adding separate measurement devices, thus resolving the contradiction between determination accuracy and device complexity
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 method improves reading accuracy by correlating commodity codes with phase changes, allowing the apparatus to accurately determine if the tag is within the predetermined region, thereby preventing false readings from external tags.
Implementation Method 1
an antenna (60) which receives a radio wave from the wireless tag (20)
Data Source
AI summary
A wireless tag reading apparatus includes an input control means, an extraction means, a storage control means, and a determination means. The input control means receives an input of a signal obtained by converting the radio wave received by an antenna that receives a radio wave from a wireless tag. The extraction means extracts the phase of the radio wave received by the antenna from the signal received by the input control means. The storage control means causes the storage medium to store the phase of the radio waves extracted by the extraction means for each reception position at which the antenna received the radio waves. The determination means determines whether the wireless tag that transmitted the radio wave is inside a predetermined region based on the amount of change of phase stored in the storage medium.