Method and system for detection of broadband energy
AssigneeNorthrop Grumman Corporation
InventorPaul H. Haley
Life of this patent
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Abstract
A system and related method for the detection of low power broadband signal sources in a high noise environment. The system uses multiple collinear arrays of sensors to receive data signals. The sensor-to-sensor spacing within the arrays is greater than one-half the wavelength of the center frequency associated with the broadband spectrum of interest. The signals are processed using nonlinear spectral estimation to remove periodic signals from the data signals to obtain broadband data. A cross correlation matrix is formed from the broadband data. Nonlinear spectral estimation is applied to the cross correlation matrix to determine the angular direction of the low power broadband signal sources with respect to the arrays.
Claims25
A method for detecting a broadband frequency emitting source using an array of sensors for receiving broadband signals, said method comprising the steps of:
- (a) converting the broadband signals into digital data by sampling the broadband signals at a predetermined sampling rate;
- and
- (b) detecting spatial coherence of the digital data by effectively applying an angle-domain narrow band filter.
A method for detecting a broadband frequency emitting source using an array of sensors for receiving broadband signals, the broadband signals of a spectrum having a spectrum wavelength corresponding to a center frequency of the spectrum, the sensors of the array are spaced a distance greater than one-half of the spectrum wavelength, said method comprising the steps of:
- (a) generating complex data from the broadband signals received by the sensors in dependence upon the center frequency;
- (b) converting the complex data into complex digital data by sampling the complex data at a predetermined sampling rate;
- (c) processing the complex digital data to detect the presence of the broadband frequency emitting source by effectively applying an angle-domain narrow band filter;
- and
- (d) determining, based on said processing step (c), a direction of the detected source relative to the array.
A method for detecting angular direction of broadband frequency emitting sources using first and second arrays of sensors for receiving broadband signals, the broadband signals of a spectrum having a spectrum wavelength corresponding to a center frequency of the spectrum, the sensors of the first array are uniformly spaced apart a first distance greater than one-half of the spectrum wavelength, said method comprising the steps of:
- (a) synchronously modulating the broadband signals received by the sensors of the second array to generate modulated signals using a carrier signal having the center frequency;
- (b) filtering the modulated signals with a time-domain low pass filter to generate complex analog data;
- (c) converting the complex analog data into complex digital data by sampling the complex analog data at a predetermined sampling rate;
- (d) processing the complex digital data to detect the presence of the broadband frequency emitting sources by angle-domain narrow band filtering;
- (e) determining, based on said processing step (d) corresponding to the complex digital data of the second array, a coarse estimate of the angular direction of detected sources relative to the array;
- and
- (f) repeating steps (a) through (d) for the broadband signals received by the sensors of the first array to determine, based upon the coarse estimate from step (e), a precise estimate of the angular direction of the broadband frequency emitting sources relative to the array.
A method for detecting angular direction of broadband frequency emitting sources using first and second collinear arrays of sensors for receiving broadband signals, the broadband signals of a spectrum having a spectrum wavelength corresponding to a center frequency of the spectrum, the sensors of the first collinear array are uniformly spaced apart a first distance greater than one-half of the spectrum wavelength, comprising the steps of:
- (a) synchronously modulating the broadband signals received by the sensors of the second collinear array to generate modulated signals using a carrier signal having the center frequency;
- (b) filtering the modulated signals with a time-domain low pass filter to generate complex analog data;
- (c) converting the complex analog data into complex digital data by sampling the complex analog data at a predetermined sampling rate below a Nyquist frequency;
- (d) estimating time periodic signals within the complex digital data using nonlinear spectral estimation of the time periodic signals in the time domain;
- (e) forming complex broadband data by removing the time periodic signals from the complex digital data;
- (f) forming a plurality of complex vectors from the complex broadband data, each vector corresponding to a sample of the broadband signals received by the sensors;
- (g) converting the plurality of complex vectors into complex data matrices by computing an outer product of each of the complex vectors with a transpose complex conjugate of each of the complex vectors;
- (h) averaging the complex data matrices corresponding to a predetermined number of samples to produce a cross correlation matrix having diagonals;
- (i) removing the complex broadband data corresponding to sensors that have failed;
- (j) averaging the diagonals of the cross correlation matrix to form a complex root vector having roots;
- (k) estimating the roots of the diagonals of the cross correlation matrix using nonlinear spectral estimation in an angular domain;
- (l) determining from the complex digital data of the second collinear array a coarse estimate of the angular direction of detected sources relative to the array;
- and
- (m) repeating steps (a) through (k) for the broadband signals received by the sensors of the first collinear array to determine, based upon the coarse estimate from step (l), a precise estimate of the angular direction of the broadband frequency emitting sources relative to the array.
A system for detecting a broadband frequency emitting source by receiving broadband signals, the broadband signals of a spectrum having a spectrum wavelength corresponding to a center frequency of the spectrum, said system comprising:
- a collinear array of sensors having a sensor-to-sensor spacing greater than one-half of the spectrum wavelength for receiving the broadband signals;
- and
- filter means for producing an angle domain narrow band filter to detect the presence and angular position of the broadband frequency emitting source based on spatial coherence of the broadband signals.
A system for detecting a broadband frequency emitting source by receiving broadband signals, the broadband signals of a spectrum having a spectrum wavelength corresponding to a center frequency of the spectrum, said system comprising:
- a first array of sensors having a first sensor-to-sensor spacing greater than one-half of the spectrum wavelength;
- generator means for generating complex data from the broadband signals received by the sensors;
- conversion means for converting the complex data into complex digital data at a predetermined sampling rate;
- and
- control means for processing the complex digital data to detect the presence and angular position of the broadband frequency emitting source by angle domain narrow band filtering.
A system for detecting broadband frequency emitting sources by receiving broadband signals, the broadband signals of a spectrum having a spectrum wavelength corresponding to a center frequency of the spectrum, said system comprising:
- a first collinear array of sensors having a first sensor-to-sensor spacing greater than one-half of the spectrum wavelength for receiving the broadband signals;
- a second collinear array of linearly spaced sensors having a second sensor-to-sensor spacing for receiving the broadband signals;
- modulation means for generating complex data from the broadband signals received by the sensors in dependence upon the center frequency;
- conversion means for converting the complex data into complex digital data at a predetermined sampling rate below the Nyquist frequency;
- and
- control means for processing the complex digital data to detect the presence and angular position of the broadband frequency emitting sources by angle domain narrow band filtering, said control means includes means for forming complex broadband data by removing time periodic signals from the complex digital data;
- means for forming a plurality of complex vectors from the complex broadband data, each vector corresponding to a sample of the broadband signals received by the sensors;
- means for converting the plurality of complex vectors into complex data matrices by computing the outer product of each of the complex data matrices;
- means for averaging the complex data matrices corresponding to a predetermined number of samples to generate an average complex data matrix having diagonals;
- means for removing the complex broadband data corresponding to sensors determined to have failed;
- means for averaging the diagonals of the average complex data matrices to form a complex root vector;
- and
- means for solving for roots of a difference equation that the complex root vector satisfies.
Dependencies are inferred from the claim text.