AOA-TDOA Location Synchronization for Asynchronous Stations
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Solution Overview
Problem
Existing methods for locating multiple transmitters in the presence of reflectors using multiple receiving stations are not robust, especially when dealing with asynchronous stations and multi-paths, as they require prior knowledge of signal types and system operations, and are not effective in separating transmitters from obstacles without synchronous signals.
Innovation Solution
A method that identifies a reference transmitter, estimates angles of arrival and time differences of arrival using spatial filtering and inter-correlation of signals across stations, corrects for synchronization errors, and determines the orientation of the network to accurately locate transmitters and reflectors, even in asynchronous scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If asynchronous receiving stations are used to increase coverage and flexibility, then adaptability is improved, but measurement precision deteriorates due to synchronization errors in TDOA estimation
Solution Approach 1:
The patent applies preliminary action by performing synchronization calibration using a reference transmitter before conducting TDOA measurements. The method pre-determines synchronization parameters and correction factors when the reference transmitter is detected, so that subsequent TDOA estimations can be performed with corrected time differences, eliminating the need for real-time synchronization adjustments and maintaining measurement precision across asynchronous stations.
2Reliability
If spatial filtering and inter-correlation techniques are used to separate transmitters from reflectors, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the signal processing into distinct functional modules: spatial filtering to separate signals from different directions, inter-correlation to identify direct paths versus reflected paths, and TDOA estimation for location calculation. This modular approach improves reliability by addressing each aspect separately while managing complexity through organized processing stages.
Solution Approach 2:
The patent uses inter-correlation as an intermediary technique between spatial filtering and final TDOA estimation. The inter-correlation process acts as a mediator that analyzes the filtered signals to distinguish direct transmitter paths from reflected paths by comparing signal characteristics, thereby enabling reliable separation of transmitters from reflectors without requiring direct observation of physical properties.
3Measurement precision
If joint AOA-TDOA estimation is performed to accurately locate transmitters, then measurement precision is improved, but calculation time increases
Solution Approach 1:
The patent performs preliminary AOA (Angle of Arrival) estimation using spatial filtering before conducting TDOA calculations. By pre-determining the directions of transmitters and separating direct paths from reflected paths in advance, the system reduces the computational burden of the joint AOA-TDOA estimation, as the subsequent location calculation only needs to process already-filtered and organized data rather than performing full joint optimization.
Data Source
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AI summary
Method and system for locating one or more transmitters Ei in the potential presence of obstacles Rp in a network comprising at least one first receiving station A and one second receiving station B asynchronous with A, characterized in that it comprises the identifying of a reference transmitter E0 by estimating its AOA-TDOA pair direction of arrival (θref,ΔTref) from the knowledge of the position EO of the reference transmitter and of those of the stations of A and B, estimating the direction of arrival of the transmitter or transmitters and reflectors (or estimating the AOA) on the first station A, the correcting of the asynchronism errors between station A and station B using the reference transmitter E0 and the location of the various transmitters on the basis of each pair (AOAi, TDOAi).