Frederick L Nelson

US Patent:

7071870, Jul 4, 2006

Filed:

Jul 13, 2005

Appl. No.:

11/181410

Inventors:

Richard T. Sharpe - Torrance CA, US
Frederick W. Nelson - Waukee IA, US
Terence D. Pickett - Waukee IA, US
Ronald R. Hatch - Wilmington CA, US
Yunchun Yang - Harbor City CA, US

Assignee:

Navcom Technology, Inc. - Torrance CA

International Classification:

H04B 7/185
G01S 5/14

US Classification:

34235704, 34235703

Abstract:

The present invention includes a method for a combined use of a local RTK system and a regional, wide-area, or global differential carrier-phase positioning system (WADGPS) in which disadvantages associated with the RTK and the WADGPS navigation techniques when used separately are avoided. The method includes determining a floating ambiguity value and a first position of an object using WADGPS in a first mode of operation, and determining a second position of the object using the local RTK system in a second mode of operation.

US Patent:

7117417, Oct 3, 2006

Filed:

Jul 30, 2003

Appl. No.:

10/630302

Inventors:

Richard T. Sharpe - Torrance CA, US
Ronald R. Hatch - Wilmington CA, US
Frederick W. Nelson - Waukee IA, US

Assignee:

Navcom Technology, Inc. - Torrance CA

International Classification:

G06F 11/00
G01S 1/00
G01C 21/26

US Classification:

714746, 34235702, 34235712, 701214

Abstract:

A method for generating satellite clock corrections for a WADGPS network computers satellite clock corrections after removing other substantial error components. Errors caused by the ionosphere refraction effects are removed from GPS measurements taken at reference stations using dual-frequency GPS measurements. The multipath noise are removed by smoothing of GPS pseudorange code measurements with carrier-phase measurements. The tropospheric refraction effect can be largely removed by modeling, and if desired, can be improved by the use of small stochastic adjustments included in the computation of the clock correction. After removing the above error factors, satellite clock corrections are computed for individual reference stations, and an average clock correction is formed for each of a plurality of satellites by taking an average or weighted average of the satellite clock corrections over reference stations to which the satellite is visible.

US Patent:

7119741, Oct 10, 2006

Filed:

Jan 13, 2004

Appl. No.:

10/757340

Inventors:

Richard T. Sharpe - Torrance CA, US
Frederick W. Nelson - Waukee IA, US
Terence D. Pickett - Urbandale IA, US
Ronald R. Hatch - Wilmington CA, US
Yunchun Yang - Harbor City CA, US

Assignee:

Navcom Technology, Inc. - Torrance CA

International Classification:

H04B 7/185
G01S 5/14

US Classification:

34235704, 34235703

Abstract:

The present invention includes a method for a combined use of a local RTK system and a regional, wide-area, or global differential carrier-phase positioning system (WADGPS) in which disadvantages associated with the RTK and the WADGPS navigation techniques when used separately are avoided. The method includes using a known position of a user receiver that has been stationary or using an RTK system to initialize the floating ambiguity values in the WADGPS system when the user receiver is moving. Thereafter, the refraction-corrected carrier-phase measurements obtained at the user GPS receiver are adjusted by including the corresponding initial floating ambiguity values and the floating ambiguity values are treated as well known (small variance) in subsequent processes to position the user receiver in the WADGPS system.

US Patent:

7427950, Sep 23, 2008

Filed:

Jul 14, 2006

Appl. No.:

11/457745

Inventors:

Daniel J. Eslinger - Redondo Beach CA, US
Jing Sun - Torrance CA, US
Richard T. Sharpe - Torrance CA, US
Frederick W. Nelson - Waukee IA, US
Terence D. Pickett - Urbandale IA, US
Ronald R. Hatch - Wilmington CA, US

Assignee:

Navcom Technology, Inc. - Torrance CA

International Classification:

G01S 5/14

US Classification:

34235703, 34235704

Abstract:

The present invention includes a method for a combined use of a local positioning system, a local RTK system and a regional, wide-area, or global differential carrier-phase positioning system (WADGPS) in which disadvantages associated with the local positioning system, the RTK and the WADGPS navigation techniques when used separately are avoided. The method includes determining a first position of the object based on information from the WADGPS, and determining a second position of the object based on position information from a local positioning/RTK positioning system. Thereafter, position determined by the WADGPS and the position determined by the local positioning/RTK positioning system are compared. The WADGPS position is used for navigating the object when the WADGPS position and local positioning/position differ by more than a predefined threshold, and using the local positioning/RTK position for navigating the object when the WADGPS position and local positioning/RTK position differ by less than the predefined threshold.

US Patent:

20050203702, Sep 15, 2005

Filed:

Mar 12, 2004

Appl. No.:

10/800178

Inventors:

Richard Sharpe - Torrance CA, US
Frederick Nelson - Waukee IA, US
Terence Pickett - Urbandale IA, US
Ronald Hatch - Wilmington CA, US
Yunchun Yang - Harbor City CA, US

International Classification:

G01C021/26

US Classification:

701213000

Abstract:

The present invention includes a method for performing backup dual-frequency navigation during a brief period when one of two frequencies relied upon by dual-frequency navigation is unavailable. The method includes synthesizing the code and carrier-phase measurements on the unavailable frequency using the carrier-phase measurements on the retained frequency and a model of ionospheric refraction effects, which is updated when measurements on both frequencies are available.

US Patent:

57641846, Jun 9, 1998

Filed:

Mar 10, 1997

Appl. No.:

8/814033

Inventors:

Ronald R. Hatch - Wilmington CA
Frederick Nelson - Fenton IL

Assignee:

Deere & Company - Moline IL

International Classification:

H04B 7185
G01S 502

US Classification:

342357

Abstract:

In a DGPS, accurate post-processed corrections to user receiver locations are made while minimizing the amount of data required to be stored at reference station and user receiver positions. Further, such corrections are available even if reference station corrections cannot be received by the user in real-time. The user receiver acquires in-view GPS satellites, computes, and stores user stand-alone position, time of computation, and acquired satellite identification. Reference stations generate correction data for the same satellites at the same time period, which correction data are broadcast but need not be received by the user in real-time. Almanac information for the relevant satellites is also made available to at least the user receiver. Stand-alone user receiver positional data and the almanac data for the same acquired satellites are used by a CPU, located at a remote site able to receive reference station transmissions and/or in the user receiver, to compute corrections to user receiver positions.