The United States of America as Represented by the Director, National

The United States of America as Represented by the Director of National

Other

USA as Represented by Secretary of the Navy

The United States of America as Represented by the National Security Agency

The United States of America as Represented by the Director of the

The United States of America as Represented by the Director of the National Security Agency

U.S. Government as Represented by Director, National Security Agency

The United States Government as Represented by the Director of the

Jonathan Drew Cohen

A method of constructing graph abstractions using a computer is described. The abstraction is presented on a computer display and used by a human viewer to understand a more complicated set of raw graphs. The method provides rapid generation of an abstraction that offers an arbitrary composition graph of vertices into composite vertices, dispersing and marshaling of composite vertices, arbitrary hiding and showing of portions of the composition, and marking of points of elision.

Method for constructing graph abstractions

A method of full-text scanning for matches in a large dictionary of keywords is described, suitable for SDI (selective dissemination of information). The method is applicable to large dictionaries (hundreds of thousands of entries) and to arbitrary byte sequences for both patterns and sample streams. The approach employs Boyer-Moore-Horspool skipping, extended to pattern collections and digrams, followed by an n-gram hash test, which also identifies a subset of feasible keywords for conventional pattern matching at each location of a putative match.

Method for finding large numbers of keywords in continuous text streams

A method and apparatus providing full-text scanning for matches in a large dictionary is described. The invention is suitable for SDI (selective dissemination of information) systems, accommodating large dictionaries (10,to 10,entries) and rapid processing. A preferred embodiment employs a hardware primary test on a single commercially-available gate-array board hosted by a computer, in which a software secondary test is conducted. No delimiter cues such as spaces or punctuation are required.

Device and method for full-text large-dictionary string matching using n-gram hashing

Index terms are drawn from text documents without the need for language-specific processes or training and are suitable as gists for the subject documents. Index terms are extracted on the basis of scores of constituent n-grams relative to n-gram counts in a corpus. A method of extracting joint index terms to represent a plurality of documents is also provided.

Language-independent method of generating index terms

An apparatus is described which detects the presence or absence of coherent light and provides an estimate of the coherent light's wavelength. The apparatus employs a common-path 'polarization interferometer' in which the two linear polarization paths act as interferometer legs. Electro-optic modulation is used to effect periodic differential path length changes in the interferometer. The apparatus performs synchronous time-integrating detection on the light emerging from the interferometer to measure coherent contributions in the presence of obscuring incoherent light.

Electro-optic coherent light detector

An outer product shearing interferometer for an optical source of one-dimensional extent which provides interference between every two points on the source. The interferometer comprises an input plane containing the source, an output plane for observing the outer product, a hologram which imparts the sum of two contributions whose phases are bilinear functions of the spatial coordinates, a two-dimensional Fourier transform system which illuminates the hologram with the transform of light from the input plane, and a one-dimensional Fourier transform system which takes light from the hologram and illuminates the output plane.

Outer product optical interferometer with hologram

An outer product shearing interferometer for an optical source of one-dimensional extent which provides simultaneous interference between every two points on the source. The interferometer comprises an input plane containing the source, an output plane for observing the outer product, an imaging system between the two planes, and a mask positioned in the transform plane of the imaging system and having slits arranged to effect the desired outer product. The desired outer product results from a simultaneous application of many lateral shears instead of only one at a time.

Outer product optical interferometer with mask

An apparatus is described which performs real time spectrum analysis of large bandwidth radio frequency signals. The apparatus allows the simultaneous monitoring of all frequencies within the band of interest, and operates in the presence of multiple frequencies.

Microwave and millimeter-wave spectrum analyzer

An apparatus is described which performs optical processing on electrical signals to calculate the triple product integral in a manner which accommodates high bandwidth signals, which processes were formerly possible only in mechanically unstable designs.

High bandwidth triple product processor using a shearing interferometer

An apparatus is described which performs acoustooptical signal processing functions with incoherent light, which procedures were formerly possible only with coherent light devices. Specific embodiments include an optical excisor, i.e., a programmable filter; a multichannel radiometer, i.e., an apparatus which estimates the power spectrum of a signal accompanied by noise; and an ambiguity processor, i.e., a time versus frequency cross correlator.

Incoherent light optical processor

Common path time and frequency domain optical adaptive linear predictors are disclosed, characterized by wide bandwidth operation for use in channel equalization, source redundancy removal, speech encoding, and other areas. The predictors are noninterferometric, avoiding the instability of such processors in the prior art.

Common path acoustoptic adaptive linear predictors

A space integrating optical ambiguity processor in which two one-dimensional modulators provide two-dimensional processing capability. Signals to be processed drive orthogonal Bragg cells oriented 40.degree. to the axes of the output detector. The resulting product is transformed in one dimension and imaged in the other, thereby creating a light intensity distribution representative of the cross ambiguity between the input signals.

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Hanover, MD, United States of America

Jonathan Drew Cohen