Phase Ranging RFID Location System Using Steerable Phased Array Antennas
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Solution Overview
Problem
Existing RFID location systems face challenges in achieving high precision distance ranging of RFID tags due to obstructed scanning areas and high costs associated with multiple antenna configurations, with alternative methods offering less than satisfactory accuracy for precise location.
Innovation Solution
The implementation of phase ranging technology, which analyzes the phase of the received signal over multiple interrogation frequencies to calculate the distance of RFID tags from the antenna along the interrogation signal beam, utilizing intelligent steerable phased array antennas and phase detection circuits to enhance location precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple SASL (steerable phased array antenna modules) are used to provide high precision triangulation data for RFID location calculations, then location precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent segments the location determination process into two independent components: angular position determination (using beam steering and direction finding) and distance determination (using time-of-flight measurement). This allows a single SASL to perform both functions by separating the measurement tasks, eliminating the need for multiple antennas while maintaining high precision location capability.
Solution Approach 2:
The patent introduces time-of-flight measurement as an intermediary method to determine distance between the SASL and RFID tag. By measuring the time for the RF signal to travel to the tag and back, the system obtains accurate distance data without requiring multiple antennas for triangulation, thus resolving the contradiction between precision and complexity.
2Reliability
If multiple SASL are deployed to ensure unobstructed scanning coverage, then reliability of location determination is improved, but ease of operation and maintenance deteriorate
Solution Approach 1:
The patent segments the location determination process into angular position determination (using beam steering and direction finding) and distance determination (using time-of-flight measurement). This allows a single SASL to perform both functions by separating the measurement tasks, eliminating the need for multiple antennas while maintaining high precision location capability.
3Device complexity
If alternative methods such as RSSI or signal timing are used for range location with a single SASL, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent introduces time-of-flight measurement as an intermediary method to determine distance between the SASL and RFID tag. By measuring the time for the RF signal to travel to the tag and back, the system obtains accurate distance data without requiring multiple antennas for triangulation, thus resolving the contradiction between precision and 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 approach enables precise three-dimensional location of RFID tags with reduced processing times and improved noise immunity, while minimizing the need for multiple antenna configurations, thus lowering costs and enhancing system reliability and maintenance.
Implementation Method 1
a plurality of data set(s) are gathered by scanning a volume with an intelligent steerable phased array antenna module
Implementation Method 2
The phase of the reply signal is measured and the distance along the beam to the RFID tag is determined from the measured phase
Data Source
AI summary
A method and apparatus for phase ranging the distance an RFID tag is from an RFID location system antenna along the interrogation signal beam, based upon the phase readings included in data sets obtained from monitoring reply signals corresponding to interrogation signals at multiple frequencies and a common interrogation signal beam direction; by comparison of measured phase and frequency data sets with theoretical phases calculated with respect to the same frequencies over a range of positions corresponding to a beam extent of the interrogation signal.