David Anthony Langford

US Patent:

7230980, Jun 12, 2007

Filed:

Sep 17, 2002

Appl. No.:

10/245222

Inventors:

David W. Langford - Madison AL, US
Dennis L. Troutman - Huntsville AL, US

Assignee:

Time Domain Corporation - Huntsville AL

International Classification:

H04B 1/38
H04L 5/16

US Classification:

375219, 375340, 375342, 375349, 375358, 702 97, 702 94

Abstract:

A method for calibrating an impulse radio distance measuring system comprising an impulse radio transceiver by conducting a pulse through a transmit receive switch to an antenna, receiving return energy which has been discharged across the transmit receive switch, determining a time of arrival of the return energy. The return energy is comprised of two distinct pulses, one of which represents discharge of the transmit switch as the original pulse travels to the antenna, the second represents energy reflected from the antenna and again discharged across the transmit receive switch while the switch is in the transmit position. The timing of the un-reflected energy is determined then the timing of the reflected energy relative to the un-reflected energy is determined through auto-correlation of the time domain scan of the received composite waveforms.

US Patent:

7298314, Nov 20, 2007

Filed:

Oct 4, 2004

Appl. No.:

10/958165

Inventors:

Hans Gregory Schantz - Huntsville AL, US
David Wesley Langford - Madison AL, US

Assignee:

Q-Track Corporation - Huntsville AL

International Classification:

G01S 13/08

US Classification:

342125, 342 90

Abstract:

A system and method for electromagnetic position determination utilizing a calibration process. For calibration, a transmitter is positioned at multiple locations in an area of interest and multiple receivers receive and record signal characteristics from the transmitter to generate a calibration data set. The unknown position of a transmitter may be determined by receiving signals from the transmitter by multiple receivers. A locator data set is generated based on the comparison between two received signal characteristics determined for each receiver. The locator data set is compared with the calibration data set to determine the unknown position. In one embodiment, the signal comparisons are the differences between electric and magnetic field phase. Further embodiments utilize signal amplitude differences. A reciprocal method utilizing a single receiver and multiple transmitter locations is disclosed.

US Patent:

7538715, May 26, 2009

Filed:

Aug 8, 2006

Appl. No.:

11/500660

Inventors:

David Wesley Langford - Madison AL, US
Hans Gregory Schantz - Huntsville AL, US

Assignee:

Q-Track Corporation - Huntsville AL

International Classification:

G01S 13/00

US Classification:

342 90, 4554561

Abstract:

An unknown location for a transmitter/receiver is determined using a calibration process. An area is established with reference receivers at known locations and a mobile transmitter provides a location signal. An alternative embodiment uses reference transmitters and a mobile receiver. For calibration, the transmitter is placed at multiple measured locations and signal measurements are taken to generate a calibration map. Multiple signal measurements may be taken at each receiver, and multiple receivers may be used. In one embodiment, signal measurements include a near-field phase. In operation, one or more location signals are measured at one or more receivers. The measured signals are compared with the calibration maps to generate a set of comparison maps which are combined to generate a likelihood map. A likely region and most likely location are determined from the likelihood map and may be displayed relative to a map of the environment.

US Patent:

7592949, Sep 22, 2009

Filed:

Nov 19, 2007

Appl. No.:

11/986319

Inventors:

Hans Gregory Schantz - Huntsville AL, US
David Wesley Langford - Madison AL, US

Assignee:

Q-Track Corporation - Huntsville AL

International Classification:

G01S 7/40

US Classification:

342174, 342165

Abstract:

A system and method for electromagnetic position determination utilizing a calibration process. For calibration, a transmitter is positioned at multiple locations in an area of interest and multiple receivers receive and record signal characteristics from the transmitter to generate a calibration data set. The unknown position of a transmitter may be determined by receiving signals from the transmitter by multiple receivers. A locator data set is generated based on the comparison between two received signal characteristics determined for each receiver. The locator data set is compared with the calibration data set to determine the unknown position. In one embodiment, the signal comparisons are the differences between electric and magnetic field phase. Further embodiments utilize signal amplitude differences. A reciprocal method utilizing a single receiver and multiple transmitter locations is disclosed.

US Patent:

7859452, Dec 28, 2010

Filed:

Sep 21, 2009

Appl. No.:

12/563960

Inventors:

Hans Gregory Schantz - Huntsville AL, US
David Wesley Langford - Madison AL, US

Assignee:

Q-Track Corporation - Huntsville AL

International Classification:

G01S 7/40

US Classification:

342174, 342165

Abstract:

A calibration system for a position determination system, the calibration system includes, in one embodiment, a calibration transmitter producing a calibration signal, a plurality of calibration receivers for receiving the calibration signal, each of the calibration receivers of the plurality of calibration receivers having a respective known calibration receiver position, and each of the calibration receivers of the plurality of calibration receivers including means for receiving a first signal characteristic of said calibration signal, means for receiving a second signal characteristic of said calibration signal, and a comparison unit for comparing said first signal characteristic and said second signal characteristic of said calibration signal to generate a calibration comparison result. In various embodiments, signal comparisons may be differences between electric and magnetic field phase or may utilize signal amplitude differences. A system utilizing a receiver and multiple transmitter locations is disclosed.

US Patent:

8643538, Feb 4, 2014

Filed:

Dec 23, 2010

Appl. No.:

12/977067

Inventors:

Hans Gregory Schantz - Huntsville AL, US
Robert Edward DePierre - Huntsville AL, US
David Wesley Langford - Madison AL, US

Assignee:

Q-Track Corporation - Huntsville AL

International Classification:

G01S 11/00
G01S 13/84

US Classification:

342125, 342118, 342127

Abstract:

A system and method for determining a position of a locus comprising a locator device for disposition at the locus; the locator device configured for receiving an electromagnetic signal from a beacon device, the locator device receiving at a distance from the beacon device within near field range of the electromagnetic signal; the locator device configured for distinguishing at least two characteristics of the electromagnetic signal sensed at the locus; the system employing the at least two characteristics to effect the determining of the position of the locus.

US Patent:

20030058971, Mar 27, 2003

Filed:

Sep 21, 2001

Appl. No.:

09/957745

Inventors:

David Langford - Madison AL, US
Michael Nieburg - Huntsville AL, US
Gregory Shreve - San Pedro CA, US

International Classification:

H03D001/00

US Classification:

375/343000

Abstract:

A system and method for determining angular offset of an impulse radio transmitter using an impulse radio receiver coupled to two antennae. The antennae are separated by some known distance, and, in one embodiment, one antennae is coupled to the radio with cable delay. Impulse signals from the antennae are measured to determine the time difference of arrival of one such signal received by one antenna compared to that of the other antenna. Time differential is measured by autocorrelation of the entire impulse radio scan period, by detecting the leading edges of both incoming signals or various combinations of these methods. Using a tracking receiver, the pulses may be continuously tracked thus providing real time position information.

US Patent:

20110207209, Aug 25, 2011

Filed:

Feb 17, 2011

Appl. No.:

13/030039

Inventors:

Aaron Hammons - Huntsville AL, US
Micah B. Harvey - Madison AL, US
David W. Langford - Madison AL, US
Joseph McGinty - Madison AL, US
Steven M. Faes - Canisteo NY, US
Christopher D. Pittman - Huntsville AL, US

International Classification:

C12M 3/06
C12M 3/00

US Classification:

4352971, 4352972, 4352831, 4353031

Abstract:

Culture systems, devices and related methods and articles may automate the culturing or incubation process according to defined culturing protocols. Such may employ removable multi-well growth cassette. Wells may be subdivided into subwells. Such may employ removable media and waste cartridges and/or gas canisters to supply consumables, which may be supplied in kits, for example with processor executable culturing protocols. Direct fluidic coupling between growth cassettes and the removable cartridges or canisters may be employed. Operational and/or environmental conditions may be sensed or monitored, and may be used to adjust or alter operation. A microscopy subsystem may capture images which may be stored and/or analyzed. Analysis may be used to adjust or alter operation.