US Government As Represented by the Secretary of the Army

Kenneth Irving Ranney

Anthony Frank Martone

Kyle Alexander Gallagher

Gregory James Mazzaro

Stephen Dorn Freeman

David Chun Wong

Tuan That Ton

Lam Huy Nguyen

Jeffrey P Sichina

Kelly D Sherbondy

Kwok Foo Tom

Brian R Phelan

Roberto Innocenti

Geoffrey H Goldman

Marc Allan Ressler

Calvin Duc Le

Neal Tesny

Traian V Dogaru

Abigail S Hedden

John C Merritt, Iv

Jerry Lee Silvious

Roger P Cutitta

Daniel T Galanos

Andre C Magill

William J Diehl

Edward A Viveiros, Jr

Dannielle Tadas

Method and apparatus for detecting and characterizing a pulse sequence using a finite impulse filter to determine a pulse width (PW) of pulses within the pulse sequence. The method and apparatus may also apply a histogram to the filtered pulses to determine the pulse rate interval (PRI) of pulses in the pulse sequence.

Method and apparatus for detecting and characterizing pulse sequences

According to embodiments, a radar system includes: at least one radio receiver which is comprised of: an antenna configured to receive RF data including both the direct-path RF signal transmitted from a radio transmitter and a reflected RF signal when the transmitted RF signal is reflected from the target; a memory configured to store the same predetermined RF waveform profile data used by the transmitter to generate and transmit the RF signal; a timing unit to provide timing; a matched filter application configured to generate and apply a matched filter for identifying RF signal signatures in RF data; and one or more processors configured to: (i) analyze the received RF data to identify multiple, repeated, individual RF signals corresponding to the direct-path transmitted RF signal; (ii) split the identified RF signals corresponding to the direct-path transmitted RF signal into a plurality of repeating units each having an interval time; (iii) create a matched filter using the predetermined transmit waveform (stored in memory) and apply the matched filter to each of repeating units to provide (a) a plurality of direct-path transmitted RF signal arrival times; and (b) a plurality of reflected RF signal arrival times; (iv) adjust relative arrival times and phases of the repeating units of the direct-path transmitted RF signal; and (v) generate radar data from the reflected RF signal further using the adjusted times and phases for arrival times of the repeating units of the direct-path transmitted RF signal.

Asynchronous, coherent, radar transmitter-receiver system

Apparatus and method configured to determine locations of man-made objects within synthetic aperture radar (SAR) imagery. The apparatus and method prescreen SAR imagery to identify potential locations of man-made objects within SAR imagery. The potential locations are processed using a change detector to remove locations of natural objects to produce a target image containing location of substantially only man-made objects.

Method and apparatus for performing dual polarization change detection using polarimetric synthetic aperture radar imagery

A method and apparatus for receiving signals from an unknown transmitting source and providing the location of the unknown transmitting source comprising a series of channels for receiving signals radiated by the unknown transmitting sources, generating preprocessed time domain data and generating a SAR image depicting a location of the unknown transmitting source, and a processor for processing the preprocessed time domain data to enhance a pixel value at each pixel location within the SAR image by summing signal data from each channel related to each pixel location to generate an enhanced SAR image.

Method and apparatus for providing a passive transmitter based synthetic aperture radar

Apparatus for augmenting a received signal comprising a receiver configured to receive a signal, a digitizer configured to generate a digitized version of the received signal at two different times, and a signal processor, coupled to the digitizer, configured to determine a phase relationship between the digitized signals at the two different times, adjust a phase of at least one of the digitized signals based on the phase relationship to combine the two digitized signals to form an augmented signal.

Method and apparatus for performing signal augmentation

Embodiments of the present invention implement a novel methodology for processing radar image data from a radar system having one or more transmitter and receiver antenna pairs. The novel methodology deliberately operates on spectrally-notched radar data. It uses a specially-adapted version of the CLEAN algorithm to mitigate the effects of frequency-band notching. Following that, it performs a non-linear sidelobe-reduction algorithm to further eliminate artifacts and produce radar imagery of much higher quality. In some cases, it exploits a specific version of the recursive sidelobe minimization (RSM) algorithm which operates in the frequency and aperture (spatial) domain.

System and method for enabling radar operation in a spectrally congested environment

A radar assembly for receiving signals at spaced frequencies from an unknown transmitting source comprising a receiver operative to receive signals; the receiver comprising a series of channels, each channel comprising a low pass filter configured to allow passage of a signal from an unknown transmitting source, an analog to digital converter configured to transform the signal from the unknown transmitting source to a digital signal, a Hilbert transform configured to transform the digital signal from the unknown transmitting source into a single sideband signal, a Fourier transform configured to transform the single sideband signal into a plurality of regularly spaced frequency samples, and an inverse Fourier transform for extracting regularly spaced frequency samples; whereby extracted pulses form a train of pulses that are inputted into an imager which utilizes synthetic aperture radar to form an image of the area of interest containing the unknown transmitting device and method thereof.

Passive non-linear synthetic aperture radar and method thereof

A spectrum sensing radar system including a spectrum power sensing module configured to sense electromagnetic signal powers in a plurality of sub-frequencies and generate a sensed power set including a plurality of sensed electromagnetic signal powers corresponding to each of the plurality of sub-frequencies; a multi-objective function module configured to receive the sensed power set and calculate a first objective function for each of the plurality of sub-frequencies, wherein the first objective function includes a power function divided by an empirical measure of interference of the sensed power set to form a signal plus noise objective function for a sub-frequency of the plurality of sub-frequencies, and wherein the power function further includes a peak transmit power of the radar system multiplied by a gain of an antenna of the radar system, multiplied by a wavelength of a carrier of the sub-frequency.

Spectrum sensing for advanced radar performance

A system for determining the location of a man-made object based upon symmetry of the object comprising a receiver configured to receive radar signals comprising cross-polarized and co-polarized responses; at least one processor configured to combine the horizontal-horizontal polarimetric responses and vertical-vertical polarimetric responses to form co-polarimetric images and operate on one or both of the vertical-horizontal polarimetric responses and horizontal-vertical polarimetric responses to form cross-polarized images; the at least one processor configured to process the co-polarized and cross-polarized images to locate areas of interest containing a maximum in the co-pol image and a null state in the co-pol image indicating the potential detection of a man-made object; the at least one processor being configured to filter data using buffer regions and/or skipping of pixels in the vicinity of an area of interest. A method for detection of man-made objects is also disclosed.

System for detecting man-made objects using polarimetric synthetic aperture radar imagery with error reduction and method of use

Embodiments of the present invention concern locating targets using non-linear radar with a matched filter which uses exponential value of the transmit signal. According to embodiments, a method of non-linear radar target location includes: transmitting a signal of a transmit waveform towards a target; receiving a signal from the target; creating a matched filter by generating an exponential function of the transmit waveform corresponding to a particular harmonic of the interest; and applying the matched filter to the received signal to generate and output a signature waveform for the target of the particular harmonic of interest. In other embodiments, the matched filtering may be combined with sidelobe reduction.

Methods and systems for locating targets using non linear radar with a matched filter which uses exponential value of the transmit signal

Method for determining distance to target using a multitone nonlinear radar system comprising providing a transmitter that transmits a signal comprising at least two predetermined frequency components; receiving transmitted signal upon reflection from target; determining the phase relationships of the frequency components when signal strikes target; determining distance the signal has travelled to target based upon the phase relationship of the frequency signal components at the time of reflection from target; computing the distance to target. A system comprising a transmitter subsystem that transmits radar signal comprising at least two frequency components; a receiver subsystem configured to receive a return signal comprising intermodulation and harmonic products; at least one processor configured to extract frequency samples from the return signal within a frequency range, apply a window function to the extracted frequency samples and perform an inverse fast Fourier transform on the resulting function to create a range profile.

Multitone radar with range determination and method of use

A method for optimizing bandwidth selection of a radar transmission in a frequency bandwidth in which the frequency bandwidth is divided into a plurality of sub-bands having a plurality of different bandwidths. The energy level is measured for each sub-band and a range resolution is also determined for each sub-band. Thereafter, a sub-band is selected in the frequency range where the signal to interference plus noise ratio plus the range resolution is maximum. Thereafter, a radar transmission is transmitted in the selected sub-band with a bandwidth corresponding to the bandwidth of the selected sub-band.

Method and apparatus for bandwidth selection for radar transmission

A system and method for locating a man-made object comprising a transmitter and receiver combination or transceiver configured to emit mixtures of polarizations comprising HH, VV, VH and or HV polarization images, at least one processor configured to form co-polarimetric and cross-polarimetric images, to select a pixel under test and analyze the surrounding pixels by performing spatial averaging using the cross polarimetric image, and to replace the pixel under test and the pixels adjacent thereto with an average pixel value calculated from the pixel under test and pixels adjacent thereto; the at least one processor configured to diminish background effects to produce clearer co-polarimetric and cross-polarimetric images and to locate the left-right point of symmetry indicative of a man-made object by comparing each pixel under test in the cross-polarimetric image to pixels in the vicinity to locate an intensity differential in excess of 3 dB.

Method and system for detecting man-made objects using polarimetric, synthetic aperture radar imagery

Embodiments of the present invention relate cognitive radar and RF technologies, and more particularly, to spectrum sensing processing for rapidly monitoring the RF spectrum for channel availability and activity. The goal is to find and use unoccupied RF channels to broadcast and receive information. According to one embodiment, a method for analyzing a received RF signal to determine unused channels, or frequencies, therein, comprises: analyzing a received RF signal to determine anchor points that represent high energy frequency locations; calculating distances between the determined anchor points; identifying and eliminating clusters or isolated anchor points defined as a high energy region of interference based on the calculated distances; and selecting at least one remaining unoccupied frequency for transmitting or receiving a RF signal. The method may further include performing an optional quality or risk assessment on remaining frequencies of the waveform, and eliminating high risk frequencies from consideration in some instances.

Fast method for wideband spectrum sensing

A method and system for forming an image comprising at least one processor for performing the following: initializing an N by P image array Iby setting all values to a large number; inputting at least one image frame; randomly selecting and removing a subset of pixel locations from the total number of available pixel locations to form a preliminary image array I; for each pixel location comparing the complex magnitude of each pixel in the image array Iwith the magnitude of the corresponding pixel in image array I, and if the pixel value in the image array Iis smaller than the corresponding pixel in the image array Ior if the Ivalue equals 0, then the current pixel value in image array Iis replaced by the pixel value in the image array I; and repeating for a number of iterations to form an image.

Growing community of inventors

Rockville, MD, United States of America

Kenneth Irving Ranney