Single Receiver Beacon Tracking via TDOA and DSSS
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current navigation systems require multiple receivers to determine the location of a radio beacon, which is impractical for search and rescue operations, especially in situations like Man overboard incidents where fast and accurate location is crucial, and existing technologies are limited by the need for directional antennas and complex equipment.
Innovation Solution
A method using a single receiver to determine the location of a radio beacon by measuring the time difference of arrival (TDOA) of periodic signals, employing Direct Sequence Spread Spectrum (DSSS) communication to enable accurate TDOA and TOA measurements without the need for directional antennas, and using a portable device with a GNSS receiver to calculate the direction and location of the beacon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple receivers are used to determine the location of a radio beacon, then the accuracy of location determination is improved, but the device complexity and cost increase
Solution Approach 1:
The patent inverts the traditional approach by using a single moving receiver instead of multiple stationary receivers. The mobile device moves through different locations and uses TDOA measurements at each position to triangulate the beacon's location, effectively reversing the roles of the receiver array and the target object.
Solution Approach 2:
The patent employs dynamic movement of the receiver to achieve what would otherwise require a static array of multiple receivers. By moving the single receiver through space and collecting TDOA measurements at multiple positions, the system dynamically creates the geometric diversity needed for accurate location determination.
2Measurement precision
If directional antennas are used to track a radio beacon, then the direction finding accuracy is improved, but the ease of operation and equipment simplicity deteriorate
Solution Approach 1:
The patent replaces mechanical directional antennas with an electronic signal processing approach. Instead of physically orienting antennas to determine direction, the system uses TDOA measurements and computational algorithms to calculate the beacon's location and direction, eliminating the need for complex mechanical directional antenna systems.
3Device complexity
If a single receiver is used to determine beacon location, then the device complexity is reduced, but the measurement precision and reliability worsen
Solution Approach 1:
The patent incorporates preliminary actions to ensure reliable measurements: the mobile device first determines its own location coordinates using GNSS before performing TDOA measurements, and the system pre-processes signals to accurately extract transmission time information. These preliminary steps ensure that even with a single receiver, the location determination is reliable.
Solution Approach 2:
The system uses feedback by continuously updating the beacon location estimate based on sequential TDOA measurements as the mobile device moves. Each new measurement refines the previous estimate, and the system can detect and correct for errors in signal propagation speed or clock synchronization through iterative calculation.
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 efficient and accurate location of radio beacons, such as Cospas-Sarsat beacons, using a single, simple, and affordable receiver, even in extreme conditions, improving response times in search and rescue operations and reducing equipment complexity.
Implementation Method 1
at said radio beacon transmitting periodic signals
Implementation Method 2
a receiver calculates its distance to a transmitting beacon based on the time it takes a signal to travel between the transmitter and the receiver, and multiplying this time interval by the signal propagation speed, typically the speed of light
Data Source
AI summary
A method and devices are disclosed, for tracking a radio beacon from a moving device, while the beacon transmits periodic signals, which the device detects at least at two different locations, and the device provided with information enabling determining the time difference between transmissions of these periodic signals. The method discloses a formula for estimating the angle between the course of the moving device and the beacon: arccos [c*(TDOA12−TDOT12)/baseline12]; wherein the moving device detects signal 1 and signal 2 respectively at location 1 and location 2, the distance between these locations defined as baseline12, TDOA12 is the Time Difference of Arrival of the signals at the two locations, TDOT12 is the time difference between transmission of these signals, and c is the speed of light.