RF Proximity Detection Using Time-of-Flight Signals
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Solution Overview
Problem
Existing object location systems, such as RFID, GPS, and computer vision, are costly, complex, or inaccurate for determining the proximity of objects in large-scale settings, particularly when only proximity information is needed.
Innovation Solution
Radio frequency (RF) proximity detection devices using narrowband and wideband signals to detect passive RFID tags, determining proximity based on time-of-flight or time-of-arrival, and triggering user interfaces like LEDs or speakers when objects are within a threshold distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RFID tags are used for object location, then object identification capability is improved, but system cost and complexity increase
Solution Approach 1:
The patent extracts only the proximity detection function from the full RFID system, using simple passive RFID tags combined with time-of-flight measurement to achieve location awareness without requiring active RFID readers or complex tracking infrastructure. This selective extraction reduces system complexity while maintaining the core identification capability.
Solution Approach 2:
The patent replaces complex mechanical or optical tracking systems with electromagnetic field-based time-of-flight measurement. By using RF signals and measuring their travel time, the system achieves location detection without mechanical sensors, cameras, or complex tracking mechanisms, thereby reducing overall system complexity.
2Measurement precision
If active powered locator devices are used, then object tracking accuracy is improved, but power consumption and cost increase
Solution Approach 1:
The patent employs passive RFID tags that do not require their own power source. Instead, the tags utilize electromagnetic energy harvested from the RF fields of existing readers to perform their identification and proximity detection functions, eliminating the need for batteries or power consumption in the tracked objects themselves.
Solution Approach 2:
The system uses periodic time-of-flight measurements rather than continuous active tracking. By measuring the time of flight at specific intervals when objects are near detection zones, the system achieves accurate tracking without requiring continuous power consumption, maintaining accuracy while reducing energy usage.
3Reliability
If multiple sensors and systems are deployed for object detection, then detection reliability is improved, but installation complexity and cost increase
Solution Approach 1:
The patent makes existing RFID readers and detection systems multi-functional by enabling them to perform both traditional RFID identification and proximity detection through time-of-flight measurement. This universal approach allows a single system to serve multiple detection purposes, improving reliability without adding separate specialized systems.
Solution Approach 2:
The patent combines proximity detection capability with existing RFID infrastructure by integrating time-of-flight measurement into the same hardware and software platform used for RFID communication. This merging of functions eliminates the need for separate detection systems, reducing installation complexity while maintaining reliable detection through the combined capabilities.
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
Provides accurate, low-cost, and efficient proximity detection of objects by leveraging existing RFID infrastructure, reducing power consumption and installation complexity.
Implementation Method 1
determine a time value associated with the receiving of the second signal; determine that at least one of the time value or a distance value determined using the time value
Implementation Method 2
receive a second signal from a remote device in response to the first signal
Data Source
AI summary
A method includes: transmitting, by a first radio frequency transceiver of a first device, a first signal; receiving, by the first radio frequency transceiver of the first device, a second signal in response to the first signal; determining a time value associated with the receiving of the second signal; determining that at least one of the time value or a distance value determined using the time value is less than or equal to a first threshold value, wherein the first threshold value is associated with the first device; and triggering a first output by a user interface component of the first device based on at least one of the time value or the distance value being less than or equal to the first threshold value.