RF Tracking Calibration Using Time of Arrival Measurements
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Solution Overview
Problem
Current RF tracking systems face challenges in achieving high accuracy and efficient receiver setup, particularly in applications requiring sub-millimeter precision and fast calibration, as they rely on signal amplitude detection which is inadequate for demanding environments like virtual reality and surgical applications.
Innovation Solution
A calibration system that uses an RF transmitter to send signals from multiple locations, with multiple receiver antennae receiving these signals and a processing unit computing time of arrival measurements to determine the relative positions of the antennae, allowing for dynamic positioning of RF-transmitting devices with high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If signal amplitude detection is used for tracking, then the system is simple and economical, but the tracking accuracy is insufficient for high precision applications
Solution Approach 1:
The patent changes the measurement parameter from signal amplitude to time of arrival (TOA) of RF signals. By measuring the time it takes for signals to travel from the tracked device to multiple receivers, the system achieves high precision positioning (inch or sub-millimeter accuracy) while maintaining a relatively simple system architecture. The TOA measurements are used to calculate distances and determine position through trilateration.
2Ease of operation
If multiple receivers are placed throughout the tracked area for amplitude-based tracking, then the system can operate without complex calibration, but the position accuracy cannot meet high precision requirements
Solution Approach 1:
The patent transitions from amplitude-based to time-based measurement, where receivers record the arrival time of signals from known reference points. This parameter change enables the system to achieve high precision positioning without requiring complex calibration procedures. The receivers use the time stamps and known reference point locations to calculate their own positions and the positions of tracked devices through mathematical computations.
Solution Approach 2:
The patent replaces the mechanical/amplitude-based detection system with a time-based electromagnetic measurement system. Instead of measuring signal strength which is affected by environmental factors, the system measures the time of arrival of RF signals, which provides more precise and reliable position information. This substitution enables sub-millimeter accuracy while maintaining operational simplicity.
3Ease of manufacture
If receivers are located at predetermined positions on a mapped layout, then the system setup is straightforward, but the accuracy is limited to rough range measurements in feet or meters
Solution Approach 1:
The patent changes the fundamental measurement parameter from signal amplitude (which provides only rough range estimates) to time of arrival measurements. This parameter change transforms the system's capability from meter-level to sub-millimeter level precision. The receivers use TOA measurements combined with the speed of light to calculate precise distances, enabling high accuracy positioning without requiring predetermined receiver positions on a mapped layout.
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
Enables precise and efficient calibration of RF receiver positions, enabling sub-millimeter accuracy in tracking devices within complex environments, such as virtual reality and surgical applications, by using time of arrival measurements to determine the relative positions of the antennae.
Implementation Method 1
an RF transmitter to send signals from multiple locations, with multiple receiver antennae receiving these signals
Implementation Method 2
a processing unit computing time of arrival measurements to determine the relative positions of the antennae
Data Source
AI summary
Position tracking systems and methods for tracking a physical location of a radio frequency (RF) transmitter include an RF transmitter transmitting an RF signal from a plurality of known locations. At least three RF receiver antennae are disposed at undetermined locations within range of the RF transmitter to receive the RF signals transmitted from the plurality of known locations. A receiver station in communication with the at least three RF receiver antennae initially calibrates a relative position of each RF receiver antenna with respect to the other RF receiver antennae based on the plurality of known locations and on information acquired in response to the RF signals received at the at least three RF receiver antennae.