Technique for robust characterization of weak RF emitters and accurate time difference of arrival estimation for passive ranging of RF emitters
AssigneeRaytheon Company
InventorsKapriel V. Krikorian, Robert A. Rosen
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Abstract
A system for locating the position of an emitter emitting a signal having time domain features is described. At least two platforms are used. Both have a receiver for detecting the emitter signal, an FFT channelizer to act as a bandpass filter for extracting the time domain features from the emitter signal, and a thresholder for thresholding the time domain signal. An FFT transform and a correlator using templates further extract frequency domain markers identifying the emitter. The frequency domain markers identifying the emitter are transmitted between platforms using a wireless link increasing the probability of detection of the emitter at all platforms.
Claims30
A system for locating the position of an emitter, said emitter emitting a cyclostationary signal having time domain features and noise, said cyclostationary signal occupying a band within a first frequency range, said system comprising:
- a first platform having a first motion, said first platform located at a first range from said emitter, and a second platform having a second motion, said second platform located at a second range from said emitter,
- said first platform having tunable bandpass means for detecting said cyclostationary signal within said band, said band within said first frequency range, said tunable bandpass means extracting said time domain features and noise from said cyclostationary signal to obtain a result;
- means for thresholding said result to reduce said noise thus generating a second result;
- means for extracting frequency domain markers from said second result using one or more templates;
- means for computing said first range from said frequency domain markers;
- means for transmitting said frequency domain markers to said second platform using a wireless link, said second platform having means for receiving said frequency domain markers from said first platform using said wireless link, said wireless link operating within a second frequency range, said second frequency range separate and distinct from said first frequency range;
- and
- means at said second platform for using said frequency domain markers detected by said first platform to enhance detection of said cyclostationary signal and said time domain features and noise at said second platform.
A system for locating the position of an emitter, said emitter emitting a cyclostationary signal having time domain features and noise, said cyclostationary signal occupying a band within a first frequency range, said system comprising:
- a first platform having a first motion, said first platform located at a first range from said emitter, and a second platform having a second motion, said second platform located at a second range from said emitter,
- said first platform having a first tunable bandpass filter tuned for detecting said cyclostationary signal within said band, said band within said first frequency range, said first tunable bandpass filter extracting said time domain features and noise from said cyclostationary signal;
- fast Fourier transform for extracting frequency components from said time domain features and noise from said cyclostationary signal extracted by said bandpass filter;
- correlator for multiplying one or more first templates with said frequency components from said fast Fourier transform for obtaining frequency domain markers;
- computer for computing said first range from said frequency domain markers;
- transmitter for transmitting said frequency domain markers to said second platform using a wireless link, said second platform having a receiver for receiving said frequency domain markers from said first platform using said wireless link, said wireless link operating within a second frequency range, said second frequency range separate and distinct from said first frequency range;
- second tunable bandpass filter at said second platform tuned using said frequency domain markers detected by said first platform for the detection of said cyclostationary signal and said time domain features and noise at said second platform;
- and
- template adjuster at said second platform for generating second templates in response to said frequency domain markers at said second platform.
A system for locating the position of an emitter, said emitter emitting a signal having features, said signal occupying a band within a first frequency range, said system comprising:
- a first platform located at a first range from said emitter, and a second platform located at a second range from said emitter;
- said first platform having a receiver for detecting said signal;
- a bandpass filter for extracting said features from said signal within said band;
- a correlator using first templates for computing markers and said first range from said features;
- and
- a transmitter for transmitting said markers to said second platform using a second frequency range, said second frequency range different from said first frequency range;
- said second platform having a receiver, said receiver operating within said second frequency range for receiving said markers from said first platform, and
- second templates for using said markers detected by said first platform to enhance detection of said signal at said second platform.
A method for locating the position of an emitter, said emitter emitting a cyclostationary signal having time domain features and noise, said cyclostationary signal occupying a band within a first frequency range, said method comprising the steps of:
- detecting said cyclostationary signal using a bandpass filter tuned to said band to obtain digital samples, said detecting from a first platform having a first motion, said first platform located at a first range from said emitter;
- thresholding said digital samples by comparing said digital samples to a threshold, setting the digital value of said digital samples to zero for all samples below a threshold and leaving all other digital samples unchanged thus obtaining a first result;
- converting said first result from the time domain to the frequency domain using an FFT thus obtaining a second result;
- extracting frequency domain markers from said second result by using one or more templates correlated with said second result;
- computing said first range from said frequency domain markers;
- transmitting said frequency domain markers to a second platform using a wireless link,
- receiving said frequency domain markers at said second platform from said first platform using said wireless link, said wireless link operating within a second frequency range, said second frequency range separate and distinct from said first frequency range;
- and
- detecting of said cyclostationary signal and said time domain features and noise at said second platform using said frequency domain markers computed by said first platform.
Dependencies are inferred from the claim text.