Geolocating Unknown RF Signals via Power Fluctuation Similarity
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Solution Overview
Problem
Existing methods for geolocating the source of unknown radio frequency satellite interference signals are unreliable due to constraints such as precise ephemeris data requirements, limited availability of adjacent satellites, and insufficient energy crosstalk, leading to inefficiencies in identifying interference sources.
Innovation Solution
The method involves measuring the similarity in power fluctuations between an unknown signal and known signals, using simultaneous and continuous data acquisition, and subtracting downlink path influences to increase sensitivity and accuracy, allowing for the estimation of the unknown transmitter's location based on the positions of known transmitters with similar power fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequency measurements of signals from a single satellite are used to determine transmitter location, then the method can be implemented with limited satellite resources, but the reliability is reduced due to lack of multiple independent measurement paths
Solution Approach 1:
The patent applies multi-functionality by using a single satellite to perform multiple functions: it transmits both known signals (for reference) and receives unknown interference signals, enabling both calibration and measurement functions from one satellite resource. This resolves the contradiction by making the satellite system versatile enough to provide reliable geolocation data even when multiple satellites are not available.
Solution Approach 2:
The patent introduces an intermediary approach by using power fluctuation characteristics as a mediator between the received signal and the transmitter location determination. Instead of directly using frequency or phase measurements which require multiple satellites, the power fluctuation pattern serves as an intermediary fingerprint that can be matched to identify transmitter location with a single satellite.
2Measurement precision
If cross-talk measurements between multiple antennas are used to calculate lines of position, then location can be determined through signal intersection, but the method fails when sufficient energy crosstalk is not available
Solution Approach 1:
The patent replaces the mechanical signal intersection method (requiring multiple LOPs from cross-talk measurements) with a pattern matching approach. Instead of relying on geometric intersection of multiple measurement lines, the system substitutes this with comparing power fluctuation fingerprints against a database, achieving reliable location determination without requiring sufficient energy crosstalk conditions.
Solution Approach 2:
The patent changes the measurement parameter from cross-talk energy levels to power fluctuation characteristics. By monitoring how signal power varies over time rather than measuring instantaneous cross-talk energy, the system obtains location information that does not depend on the signal strength or crosstalk availability, thus resolving the reliability issue.
3Measurement precision
If angle of arrival measurements using phased array antennas are used to find transmitter direction, then location can be determined through vector intersection, but the method requires precise ephemeris data and adjacent satellites with overlapping beams
Solution Approach 1:
The patent extracts the essential location information from power fluctuation patterns rather than requiring the full complex measurement system. By taking out only the power variation characteristic and using it as a fingerprint for location identification, the system eliminates the need for precise ephemeris data, adjacent satellites, and complex phased array processing, thus reducing device complexity and measurement constraints.
Solution Approach 2:
The patent inverts the traditional approach by instead of measuring direction vectors and intersecting them to find location, it uses location information (from power fluctuation matching) to understand signal characteristics. This inversion removes the stringent requirements for precise ephemeris and beam overlapping, as the system works backward from power patterns rather than forward from geometric measurements.
4Measurement precision
If simultaneous and continuous data acquisition is performed to catch high rate power fluctuations, then measurement sensitivity is increased, but data processing requirements and system complexity increase
Solution Approach 1:
The patent applies partial action by focusing data acquisition only on the power fluctuation aspect rather than full signal characterization. Instead of processing complete signal waveforms continuously, the system selectively monitors only the power envelope variations, achieving sufficient precision for location determination while reducing the overall data processing burden and system complexity.
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
This approach enhances the reliability and accuracy of geolocating interference sources by leveraging the similarity in power fluctuations, reducing the impact of atmospheric and hardware-induced noise, and enabling precise localization of interference sources.
Implementation Method 1
These measurements are taken at different times in order to be used for determining the transmit location of an unknown emitter position taking into account variations in frequency due to Doppler.
Implementation Method 2
Sensitivity of the measurement may be increased in that downlink path influences, such as a power fluctuation of a beacon signal and/or a transponder noise floor and/ or an average power fluctuation of the unknown signal and the known signal, are subtracted from the unknown signal and the at least one known signal.
Data Source
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AI summary
The invention relates to a method for locating a terrestrial transmitting source (TR2) of an unknown signal (s2) which is transmitted via satellite (SAT) to a terrestrial receiver (REC), wherein the method comprises the step of - comparing a power fluctuation (PF2) of the unknown signal (s2) with a power fluctuation (PF1) of at least one known signal (s1) allocated to a terrestrial transmitting source (TR1) and determining a degree of similarity (DGS) between the power fluctuation (PF2) of the unknown signal (s2) and the power fluctuation (PF1) of the at least one known signal (s1).