Satellite Linear Array Interferer Geolocation
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Solution Overview
Problem
Existing geolocation techniques for interferers are limited, particularly when the interferer is stationary, as they rely on time difference of arrival (TDOA) or frequency difference of arrival (FDOA) signatures, which do not work without movement, and require complex antenna arrays for array signal processing techniques.
Innovation Solution
A method and system using a linear array on a satellite to determine the location of an interferer by generating a first curve from TDOA or FDOA signatures between two satellite locations and a second curve from direction of arrival information, with the location determined at the intersection of these curves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If array signal processing techniques (MUSIC or ESPRIT) are used to determine interferer location, then location accuracy is improved, but device complexity increases due to requiring relatively complex antenna arrays and associated signal processing components
Solution Approach 1:
The patent segments the complex 2D location determination problem into two separate 1D curve intersections: a first curve from TDOA/FDOA measurements and a second curve from DOA information. This segmentation allows each curve to be determined independently using simpler measurements, avoiding the need for complex antenna arrays while maintaining location accuracy through the intersection of these two simplified curves.
2Device complexity
If TDOA or FDOA techniques are used for interferer location, then device complexity is reduced, but the technique fails when the interferer is stationary as no TDOA or FDOA signature is created
Solution Approach 1:
The patent merges two different measurement approaches: TDOA/FDOA signatures (which work for moving interferers) and direction of arrival information (which provides angular information). By combining these two independent measurement types, the system creates two curves whose intersection uniquely determines the interferer location, enabling the system to work with both moving and stationary interferers while maintaining relative simplicity.
3Device complexity
If a single satellite is used for geolocation, then device complexity and cost are reduced, but measurement precision deteriorates compared to multi-satellite TDOA/FDOA systems
Solution Approach 1:
The patent transitions from using multiple satellites (spatial dimension) to using a single satellite with a linear array (angular dimension). By introducing the dimension of direction of arrival measurement through the linear array, the system compensates for having only one satellite, using the angular information from the array to provide the second curve needed for accurate location determination.
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 interferer location using a simpler configuration compared to traditional methods, reducing complexity and allowing location determination with a single satellite, achieving comparable accuracy with fewer array elements.
Implementation Method 1
a linear array onboard a satellite and including a plurality of elements configured to receive signals from the interferer
Implementation Method 2
The FDOA signature is created as a result of a Doppler shift between the receiver and the transmitter (i.e., the interferer)
Data Source
AI summary
A method for locating an interferer is provided. The method includes determining, from one of a time difference of arrival (TDOA) signature and a frequency difference of arrival (FDOA) signature between a first signal received at a satellite at a first location and a second signal received at the same satellite at a second location, a first curve on which the interferer lies, determining, from direction of arrival information generated using signals received from the interferer at a plurality of elements of a linear array on the satellite, a second curve on which the interferer lies, and determining, based on an intersection between the first and second curves, the location of the interferer.