Hal L Levitt

US Patent:

6501258, Dec 31, 2002

Filed:

Sep 28, 2001

Appl. No.:

09/965249

Inventors:

Hal L Levitt - Baltimore MD
Sokhom Kith - Fairfax VA
Dale L. Reynolds - Elizabeth CO

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

G01R 2317

US Classification:

324 7637, 324 7636, 356347, 356345

Abstract:

A signal processing apparatus for providing electrical frequency measurements of input signals. In one embodiment, a power splitter divides an RF input signal into first and second input signals. An RF channelizer having a filter bank receives the first input signal and determines a coarse frequency measurement. An optical modulator modulates an optical carrier signal with the second input signal, and a beam splitter divides the modulated carrier signal into a plurality of optical signals that each feed into one of a plurality of optical frequency discriminators (âOFDâ). Each OFD uses a fiber optic delay line and spatial domain sampling techniques to extract a phase measurement. An ambiguity resolver receives the phase measurement from each OFD and determines a single, absolute phase measurement, which is translated to a fine frequency measurement. A frequency encoder combines the coarse and fine frequency measurements to produce a final frequency measurement having increased resolution.

US Patent:

6509729, Jan 21, 2003

Filed:

Jan 9, 2001

Appl. No.:

09/756239

Inventors:

Hal L. Levitt - Baltimore MD

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

C01R 2317

US Classification:

324 7636, 324 7635, 324 7637

Abstract:

A signal processing apparatus for providing concurrent electrical frequency measurements of multiple, time-coincident signal inputs. In one embodiment of the present invention, an input signal is received that contains a plurality of individual signals independent of each other in frequency, phase, and electrical amplitude. A power splitter splits the input signal into two separate input signals. A delay line introduces a time delay to one of the two separate input signals. Two Bragg cells within a channelized optical phase measurement (COPM) device modulates two optical carrier signals with the delayed and non-delayed input signals, respectively, separating the modulated delayed and non-delayed input signals into multiple time-concurrent frequency channel signals. Upon exiting the Bragg cells, the two optical beams interfere spatially to develop an interference pattern along the phase and frequency channel number axes of a photodetector array. The resulting spatial intensity pattern phase variation is decoded to provide coarse frequency, phase, and amplitude measurements.

US Patent:

63078953, Oct 23, 2001

Filed:

Apr 1, 1998

Appl. No.:

9/052676

Inventors:

Edward Alexander - Falls Church VA
Anthony Spezio - Laurel MD
Hal Levitt - Baltimore MD
Brian Krantz - Gaithersburg MD

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

H03K 900

US Classification:

375316

Abstract:

A system for extracting the complex Fourier coefficients from an unknown RF signal to classify the RF signal is disclosed. The extraction system utilizes optical signal processing in combination with the generation of electronic timing and control signals. The system employs an optical processor comprising a Bragg cell to yield the Fourier coefficients including the amplitude, phase and frequency parameters thereof. The system further includes a parallel arrangement that provide for parallel processing to reduce the computational time needed to determine the complex Fourier coefficients including the amplitude, phase and frequency parameters thereof.

US Patent:

53231260, Jun 21, 1994

Filed:

Jun 30, 1993

Appl. No.:

8/083776

Inventors:

Anthony E. Spezio - Laurel MD
Saurabh Dalal - Lanham MD
Edward M. Alexander - Falls Church VA
Hal L. Levitt - Baltimore MD

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

H01P 518

US Classification:

333109

Abstract:

A circuit link, and method for using link, for self initializing any device peratively connected to the link. An input signal is split into two portions, one of which is delayed so that the undelayed signal can transverse the circuit link before the delayed signal. A pair of quadrature splitters are operatively connected to one another to split and combine the undelayed and delayed signals in their turns, and recombine them in their turns, in a manner effective to cause one of the circuit link's outputs to be nonzero responsive to the delayed signal, and zero responsive to the undelayed signal, with the opposite result on the other circuit output. The undelayed signal is thus available to initialize any device requiring initialization, and the delayed signal, unperturbed by any such device, is thus available for use as the circuit link's ultimate output. The circuit is especially useful with frequency selective limiters (FSL's), which are commonly used as channelizers in multichannel communication systems, and which are ineffective before initialization.

US Patent:

60611359, May 9, 2000

Filed:

Mar 31, 1998

Appl. No.:

9/050960

Inventors:

Hal L. Levitt - Baltimore MD
Dennis W. Prather - Woodbine MD
Edward T. Gill - San Jose CA

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

G01B 902

US Classification:

356354

Abstract:

A spatial image separator includes a separating arrangement that separates an incident image pattern into a plurality of segments. The spatial image separator additionally includes a manner of relocating and selectively recombining a set of the segments toward at least one output position. This is accomplished in a manner which preserves information content while significantly improving energy utilization.

US Patent:

56822383, Oct 28, 1997

Filed:

Jun 12, 1995

Appl. No.:

8/489663

Inventors:

Hal L. Levitt - Baltimore MD
Anthony Y. Tse - Greenbelt MD

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

G01B 902

US Classification:

356345

Abstract:

A signal processing apparatus for providing accurate electrical phase difference measurement of multiple concurrent signal inputs is disclosed. Phase measurement of an individual signal input is accomplished utilizing an efficient spatial sampling scheme. In operation, measurement and reference wideband RF inputs, differing primarily in phase over frequency, are respectively applied to two RF Channelizer components. Each Channelizer separates the composite input bandwidth into multiple time-coincident frequency output channels. Corresponding pairs of output channels then phase modulate a common independent carrier which propagates to the detection plane of a photodetector array forming a spatial interference pattern along one axis for each frequency channel number. A preferred detector element scaling relative to the interference pattern affords efficient phase difference measurement incorporating three detector elements at each frequency channel. Conversion of the preferred three detector element intensity values to relative signal phase is accomplished with an algorithm.

US Patent:

50581902, Oct 15, 1991

Filed:

Sep 14, 1990

Appl. No.:

7/582275

Inventors:

Hal L. Levitt - Baltimore MD
Gordon W. Anderson - Washington DC
Anthony E. Spezio - Laurel MD

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

G06K 912

US Classification:

382 68

Abstract:

An image processing system and method are provided which use a selectively ccessed detector array comprised of subarrays. Regions of image activity are located within the detection array through readout of the activity determining elements. Each subarray is evaluated to determine whether any image activity has been detected by the corresponding subarray. Data is only read for the active subarrays. Thus, the activity indicator allows efficient transfer of relevant data from the detector array without requiring previous information. This results in reduced data flow and generally shorter readout cycles. The activity determination can be a non-destructive process so that data contained in the detection array remains available for sensor readout. This eliminates the need to perform one detector exposure cycle to determine activity and a second cycle to read out data from the detector.