Unsynchronized Navigation Receiver TDOA Timing
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Solution Overview
Problem
Navigation systems using multilateration face inaccuracies when nodes are unsynchronized or experience clock drift, leading to unsuitable range differences for navigation applications.
Innovation Solution
A navigation system comprising unsynchronized anchored devices and a receiver unit that determines time difference of arrival (TDOA) between signals without requiring synchronization, using a specific timing scheme where each device transmits ranging signals at specified times, allowing the receiver to calculate TDOA based on measured time shifts and compensate for clock inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If nodes use unsynchronized internal clocks for signal transmission, then device complexity and synchronization requirements are reduced, but measurement precision of time difference of arrival deteriorates
Solution Approach 1:
The system performs preliminary actions by having anchored devices transmit signals at predetermined time slots before the receiver needs to calculate TDOA. This allows the receiver to capture signals from multiple anchors in a coordinated manner without requiring real-time synchronization, as the transmission timing is pre-planned and known to all devices
Solution Approach 2:
The patent introduces time slot indicators and signal timing information as intermediaries between unsynchronized devices. These intermediaries carry timing reference information that allows the receiver to correlate signals from different anchors despite clock differences, effectively mediating the synchronization problem without requiring actual clock synchronization
2Ease of operation
If anchored devices transmit signals at different times due to unsynchronized clocks, then ease of operation is improved, but reliability of navigation accuracy deteriorates
Solution Approach 1:
The system implements periodic action by having anchored devices transmit ranging signals at regular time slots according to their local clocks. This periodic transmission pattern ensures that signals are available for measurement while accommodating unsynchronized clocks, as the periodicity is consistent within each device even if out of phase with others
Solution Approach 2:
The patent changes the parameter approach from absolute time synchronization to relative time measurement. By measuring time differences relative to received signal timestamps rather than absolute synchronized time, the system maintains navigation accuracy while allowing operational flexibility with unsynchronized clocks
3Device complexity
If the receiver determines TDOA without transmitting signals to anchored devices, then device complexity is reduced, but measurement precision of range differences deteriorates
Solution Approach 1:
The patent inverts the traditional active-passive role by making the receiver a passive signal processor that calculates TDOA from received signals rather than an active device that transmits test signals. This inversion is enabled by the anchored devices transmitting comprehensive timing information, allowing the receiver to derive precise range differences without transmission capability
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 accurate navigation by overcoming synchronization and clock drift issues, allowing the receiver to determine its location relative to anchored devices despite lack of synchronization, and minimizing errors caused by device movement.
Implementation Method 1
determines a time difference of arrival between signals received from the first anchored device and the second anchored device
Data Source
AI summary
A system, device and method that enables at least two unsynchronized units with known locations and an unsynchronized unit having an unknown location to communicate with each other and to be a part of enabling navigation by the unit having the unknown location by determining time difference of arrivals of signals between the units.