John A Mark

US Patent:

6360602, Mar 26, 2002

Filed:

Jul 29, 1999

Appl. No.:

09/362969

Inventors:

Daniel A. Tazartes - West Hills CA
Yumi Yoshida - Glendale CA
John G. Mark - Pasadena CA

Assignee:

Litton Systems, Inc. - Woodland Hills CA

International Classification:

G01P 1513

US Classification:

7351418, 73 138

Abstract:

A closed loop accelerometer includes apparatus within an associated digital rebalance loop for reducing the presence of low frequency moding noise in the accelerometer output. In one embodiment, the digitized corrective signal is applied to a moving average filter. In a second embodiment, the corrective signal is modulated with a random function and, in a third embodiment, the digitized corrective signal is both randomized and applied to a moving average filter. In each embodiment, the periodic moding noise that results from the analog-to-digital conversion within the rebalance loop is significantly reduced from that observed in prior art systems.

US Patent:

6424419, Jul 23, 2002

Filed:

Jul 28, 2000

Appl. No.:

09/628071

Inventors:

Daniel Tazartes - West Hills CA
John Mark - Pasadena CA
Albert V. Scappaticci - Calabasas CA

Assignee:

Northrop Grumman Corporation - Woodland Hills CA

International Classification:

G01C 1966

US Classification:

356473, 372 99

Abstract:

A system and method for controlling the cavity length of a ring laser gyroscope to properly tune the resonant wavelengths of the ring laser gyroscope during moments when experiencing sudden shocks or high g force accelerations. The system controls the position of a movable mirror in the laser cavity of the gyroscope to control the length of the laser cavity. The system measures the acceleration experienced by the laser cavity, wherein the position of the movable mirror is adjusted to counteract the effects of the acceleration on the movable mirror in a real-time response to the measured acceleration. By adjusting the position of the movable mirror, the resonant wavelengths propagating in the ring laser gyroscope will be maintained at their desired intensity and continue to lase even after experiencing this acceleration. The system may further include a control servo-loop for providing additional cavity length control in order to maintain the desired intensity of the wavelengths propagating within the gyroscope.

US Patent:

6538745, Mar 25, 2003

Filed:

Feb 8, 2000

Appl. No.:

09/499910

Inventors:

Daniel A. Tazartes - West Hills CA
John G. Mark - Pasadena CA
Brian T. Lottman - Moorpark CA
Shaw W. Fann - Woodland Hills CA

Assignee:

Litton Systems, Inc. - Woodland Hills CA

International Classification:

G01C 1966

US Classification:

356467

Abstract:

The invention is a method and apparatus for processing signals with frequencies f and f from a multioscillator ring laser gyro, the method being repeated at regular time intervals. The difference f , of f and f is a measure of the angular rotation rate of the ring laser gyro and the sum f of f and f divided by 2 is the Faraday bias frequency. The first step of the method comprises determining two or more of the values M , M , M , and M of a set of functions M (f ), M (f ), M (f ), and M (f ). The second step comprises storing two or more processed values M , M , M , and M of the functions M (f ), M (f ), M (f ), and M (f ) if the corresponding values of M , M , M , and M are valid. A processed value is derived from the value for the present time interval and zero or more processed values for prior time intervals. The third step comprises determining f or a function thereof from zero or more valid function values obtained as a result of executing the first step during the current time interval, zero or more processed values obtained as a result of executing the second step during a prior time interval, and zero or more extrapolated values obtained by extrapolating the processed values obtained as a result of executing the second step during a prior time interval to the present time interval.

US Patent:

6760111, Jul 6, 2004

Filed:

Oct 4, 2000

Appl. No.:

09/555726

Inventors:

John G. Mark - Pasadena CA
Mauricio Ribes - Vitacura-Santiago, CL
Daniel A. Tazartes - West Hills CA

Assignee:

Litef GmbH - Freiburg im Breisgau

International Classification:

G01C 1972

US Classification:

356464

Abstract:

Apparatus and a method for compensating production or operationally-induced inaccuracies in the binary-weighted electrodes of a high-resolution digital phase modulator of, for example, a fiber optic gyroscope. Programmable correction values are employed to increase the accuracy of each binary-weighted planar electrode. In the invention, a less significant component of the binary drive signal, if appropriate after compensation in a low resolution digital-to-analog converter, is converted into an analog signal that is applied to a specific or a separate additional electrode of the digital phase modulator.

US Patent:

6796724, Sep 28, 2004

Filed:

Jul 28, 2001

Appl. No.:

09/917578

Inventors:

Arnold E. Goldman - Calabasas CA
K. Juergen Flamm - Tarzana CA
John G. Mark - Pasadena CA
Ike Song - Montebello CA

Assignee:

Litton Systems, Inc. - Woodland Hills CA

International Classification:

G02B 636

US Classification:

385 91, 385 49, 385 52

Abstract:

A sleeve ( ) enables attachment of an optic fiber ( ) to a multi-integrated optic chip ( ) in optical communication therewith, and maintains alignment of the fiber at its end adjacent the chip. The sleeve includes a symmetrically-shaped cavity ( ) bounded by termini ( ) which are respectively disposed to fit onto the chip and to accept the fiber. An adhesive ( ) within the cavity symmetrically bonds the fiber to the chip. The adhesive cures symmetrically in the cavity, to eliminate undesired motion of the fiber from its preferred alignment position vis-a-vis the chip connection point ( ) or to provide a repeatable motion to achieve the optimum alignment position of the fiber with respect to the chip. The sleeve may be left in place or, alternatively, it may be removed. The sleeve controls, defines and confines the index matching adhesive and/or fluid between fiber end ( ) and connection point ( ) by defining the areas and volume actually in contact with the adhesive or fluid.

US Patent:

6829763, Dec 7, 2004

Filed:

May 16, 2000

Appl. No.:

09/572298

Inventors:

John G. Mark - Pasadena CA
Daniel A. Tazartes - West Hills CA
Jonathan A. Lincoln - West Hills CA
Philip T. Kent - Chatsworth CA

Assignee:

Litton Systems, Inc. - Woodland Hills CA

International Classification:

G06F 946

US Classification:

718102, 718100, 718103, 718104, 718107

Abstract:

The invention is a method and apparatus for repetitively executing a plurality of software packages at a plurality of rates utilizing a common set of computational resources. The method consists of counting contiguous time increments and executing a plurality of software packages. Each software package is executed during each time increment in one or more sequences of time increments. The time increments in each sequence recur at a predetermined rate, and the time increments assigned to one software package do not overlap the time increments assigned to any other of the plurality of software packages.

US Patent:

6871561, Mar 29, 2005

Filed:

Mar 7, 2002

Appl. No.:

10/093158

Inventors:

John G. Mark - Pasadena CA, US
Daniel A. Tazartes - West Hills CA, US

Assignee:

Northrop Grumman Corporation - Woodland Hills CA

International Classification:

G01D021/00
F16M001/00
F16F001/00

US Classification:

738665, 248614, 248638, 267150

Abstract:

Multiple isolators are configured with respect to an assembly (), such as a sensor assembly in an inertial navigation system or other system where cross-axis acceleration or rotation coupling is undesirable. The system utilizes a set of isolators (and or and ) that are substantially matched to each other, but may have uncorrelated axial stiffness and radial stiffness. The system configuration does not introduce cross-axis coupling, such as cross-axis translational coupling and cross-axis rotational coupling.

US Patent:

6904377, Jun 7, 2005

Filed:

Mar 17, 2003

Appl. No.:

10/390200

Inventors:

G. Kevin Liu - Simi Valley CA, US
John Mark - Pasadena CA, US
Daniel A. Tazartes - West Hills CA, US

Assignee:

Northrop Grumman Corporation - Woodland Hills CA

International Classification:

G01C017/38
G01C019/00
G01L001/00

US Classification:

702 92, 702 41, 7350402, 7350408, 7350418

Abstract:

System and method for measuring force-dependent gyroscopic sensitivity. A force-effect model of the effects of acceleration on the output of a gyro triad is determined. Rotation sequences are then devised to permit excitation and observation of force-effect model parameters in order to provide calibration information for these parameters. A state diagram containing the gyro triad force-effect model parameters is derived from the force-effect model, where moving from one position in the state diagram to another position indicates the gyro triad error which would occur in rotating the gyro triad according to a corresponding motion. Searching for all possible closed loop paths achievable through the state diagram, by a multiple-axes rate table with a specified number of rotations, to separate gyro triad error calibration from the accelerometer calibration. Closed loop paths having minimal lengths and exhibiting larger error sensitivity are chosen to perform error parameter calibration and reduce force-dependent gyroscopic sensitivity.