Continuous Waveform Geolocation via Frequency-Domain Analysis
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Solution Overview
Problem
Existing sensing platforms face challenges in accurately locating continuous waveform emitters, such as communications terminals, due to the absence of well-defined events like pulse leading edges, which hinders the measurement of Time Difference of Arrival (TDOA) and Frequency Difference of Arrival (FDOA).
Innovation Solution
The solution involves using multiple sensors to sample and digitize portions of continuous waveforms, applying time shifting and correlation to determine TDOA, and employing a maximum likelihood estimation process to combine TDOA and FDOA measurements across platforms, leveraging broadband connectivity for precise geolocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional TDOA measurement methods are used, then location accuracy is improved for pulsed emitters, but measurement is not feasible for continuous waveform emitters due to absence of well-defined events
Solution Approach 1:
The patent transforms the measurement parameter from time-domain features (pulse leading edges) to frequency-domain features (spectral characteristics). By applying Fourier transforms to continuous waveform samples and analyzing frequency spectra, the system can extract location-measurable parameters from emitters that lack traditional time-domain events, thereby extending TDOA methodology to continuous waveforms.
Solution Approach 2:
The patent replaces direct time-domain sampling and event detection with frequency-domain analysis. Instead of detecting physical events like pulse leading edges in the time domain, the system uses spectral analysis in the frequency domain to identify characteristic features of continuous waveforms, enabling TDOA measurement where traditional methods fail.
2Measurement precision
If multi-platform collaborative targeting is implemented, then geolocation accuracy is improved through geometry exploitation, but system complexity increases
Solution Approach 1:
The patent creates a universal geolocation framework that handles both pulsed and continuous waveform emitters through the same processing pipeline. The frequency-domain analysis method serves as a common denominator that unifies the measurement approach across different emitter types, reducing the need for separate specialized systems while maintaining high geolocation accuracy through multi-platform collaboration.
Solution Approach 2:
The patent introduces frequency-domain spectral analysis as an intermediary processing step between signal reception and location calculation. This intermediary transformation converts diverse waveform types into a standardized frequency-domain representation that can be uniformly processed by the geolocation algorithm, simplifying the overall system architecture despite multi-platform complexity.
3Measurement precision
If continuous waveform sampling is performed across multiple platforms, then location determination becomes feasible, but data processing requirements increase
Solution Approach 1:
The patent extracts only the essential frequency-domain characteristics from continuous waveform samples rather than processing entire time-domain signals. By applying Fourier transforms and analyzing spectral features, the system extracts location-relevant parameters while discarding redundant temporal data, significantly reducing processing volume while maintaining location determination capability.
Solution Approach 2:
The patent employs periodic sampling of continuous waveforms at synchronized intervals across multiple platforms. This periodic approach allows for efficient frequency-domain analysis by capturing representative spectral information at regular intervals, reducing the total data volume requiring processing while ensuring sufficient information 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
This approach enables fast and accurate geolocation of continuous waveform emitters, overcoming the limitations of single-platform implementations and extending precision geolocation techniques to non-traditional targets, including communications terminals, by utilizing advanced Electronic Support Measures (ESM) and broadband connectivity.
Implementation Method 1
a first sensor mounted on a first platform for sampling a first portion of a continuous waveform occurring in a time window
Implementation Method 2
correlating the first and second signal samples to determine a time difference of arrival measurement
Implementation Method 3
applying a maximum likelihood estimation process to combine multiple time difference of arrival measurements between multiple pairs of platforms, to estimate the location of an emitter of the continuous waveform
Data Source
AI summary
An apparatus comprises a first sensor mounted on a first platform for sampling a first portion of a continuous waveform occurring in a time window and for producing a first signal sample, a second sensor mounted on a second platform for sampling a second portion of the continuous waveform occurring in the time window for producing a second signal sample, and a processor for determining time difference of arrival measurements and for applying a maximum likelihood estimation process to combine multiple time difference of arrival measurements between multiple pairs of platforms, to estimate the location of an emitter of the continuous waveform. A method performed by the apparatus is also provided.