Paul Evan Braisted

US Patent:

6342853, Jan 29, 2002

Filed:

Apr 15, 1999

Appl. No.:

09/293521

Inventors:

Rudolph M. Kalafus - Los Gatos CA
Paul Braisted - San Jose CA

Assignee:

Trimble Navigation Limited - Sunnyvale CA

International Classification:

G01S 502

US Classification:

34235703, 342 33, 701215

Abstract:

A precision approach capable dual differential global positioning system (DGPS) receiver avionics system. The system of the present invention includes a first and a second DGPS receiver. The first and second DGPS receivers are both adapted to interface with an autopilot in an aircraft. The DGPS receivers each determine the position of the aircraft as the aircraft proceeds along a flight path. Both DGPS receivers are further adapted to employ carrier aiding to smooth the code phase measurements used in determining the position of the aircraft. Within a predetermined range along the approach path of the aircraft and when the output of the first DGPS receiver and the output of the second DGPS receiver are proximate within a predetermined distance, the DGPS receivers determine a transition point. After the transition point, the DGPS receivers utilize DGPS carrier phase tracking to determine the position of the aircraft relative to its position at the transition point. The low noise characteristics of the carrier phase tracking allows the DGPS receivers to properly interface with the autopilot of the aircraft.

US Patent:

56468571, Jul 8, 1997

Filed:

Mar 31, 1995

Appl. No.:

8/414443

Inventors:

Paul McBurney - Palo Alto CA
Paul Braisted - San Jose CA

Assignee:

Trimble Navigation Limited - Sunnyvale CA

International Classification:

G05D 100

US Classification:

3644497

Abstract:

Methods for GPS-assisted determination of location coordinates of a mobile user or selected position on or adjacent to the Earth's surface with improved accuracy. Elevation readings from an altimeter or barometer are integrated with readings of the GPS-determined elevation coordinate for that location, using Kalman filter techniques, minimum least square techniques, or comparison of certain statistically defined parameters associated with the altimeter and GPS variables, such as the standard deviation of the expected errors in these variables. The resulting elevation coordinate may be a statistical blend or filtered blend of the altimeter value and a GPS-determined value for the elevation coordinate; or this resulting elevation coordinate can be chosen to be one or the other of these values, based upon comparison of time varying statistical parameters corresponding to the altimeter and the GPS.

US Patent:

58085815, Sep 15, 1998

Filed:

Dec 7, 1995

Appl. No.:

8/568832

Inventors:

Paul E. Braisted - San Jose CA
Martin Beckmann - Austin TX

Assignee:

Trimble Navigation Limited - Sunnyvale CA

International Classification:

H04B 7185
G01S 502

US Classification:

342357

Abstract:

In a GPS navigation satellite receiver, a pseudorange step detection method integrates the pseudorange rates to predict expected changes in the pseudoranges from one measurement to the next. The pseudorange rate is directly measured as the carrier Doppler shift. The pseudorange and pseudorange rate from a last measurement from each satellite and a pseudorange rate from a new measurement are used to estimate the expected pseudorange. Such estimate accounts for vehicle velocity and accelerations. The expected pseudorange is compared to a newly measured pseudorange. An impermissible pseudorange step is declared when the difference exceeds a variable threshold. Tests can be done on measurements taken up to ten seconds apart, e. g. , using a threshold of five hundred meters. The maximum position dilution of precision is typically set at a value of twelve.

US Patent:

59459433, Aug 31, 1999

Filed:

Sep 17, 1997

Appl. No.:

8/932323

Inventors:

Rudolph M. Kalafus - Los Gatos CA
Paul Braisted - San Jose CA

Assignee:

Trimble Navigation - Sunnyvale CA

International Classification:

G01S 502

US Classification:

342357

Abstract:

A precision approach capable dual differential global positioning system (DGPS) receiver avionics system. The system of the present invention includes a first and a second DGPS receiver. The first and second DGPS receivers are both adapted to interface with an autopilot in an aircraft. The DGPS receivers each determine the position of the aircraft as the aircraft proceeds along a flight path. Both DGPS receivers are further adapted to employ carrier aiding to smooth the code phase measurements used in determining the position of the aircraft. Within a predetermined range along the approach path of the aircraft and when the output of the first DGPS receiver and the output of the second DGPS receiver are proximate within a predetermined distance, the DGPS receivers determine a transition point. After the transition point, the DGPS receivers utilize DGPS carrier phase tracking to determine the position of the aircraft relative to its position at the transition point. The low noise characteristics of the carrier phase tracking allows the DGPS receivers to properly interface with the autopilot of the aircraft.

US Patent:

60554770, Apr 25, 2000

Filed:

Jul 3, 1997

Appl. No.:

8/887954

Inventors:

Paul McBurney - Palo Alto CA
Paul Braisted - San Jose CA

Assignee:

Trimble Navigation Ltd. - Sunnyvale CA

International Classification:

G01S 500
G05D 100

US Classification:

701207

Abstract:

Methods for GPS-assisted determination of location coordinates of a mobile user or selected position on or adjacent to the Earth's surface with improved accuracy. Elevation readings from an altimeter or barometer are integrated with readings of the GPS-determined elevation coordinate for that location, using Kalman filter techniques, minimum least square techniques, or comparison of certain statistically defined parameters associated with the altimeter and GPS variables, such as the standard deviation of the expected errors in these variables. The resulting elevation coordinate may be a statistical blend or filtered blend of the altimeter value and a GPS-determined value for the elevation coordinate; or this resulting elevation coordinate can be chosen to be one or the other of these values, based upon comparison of time varying statistical parameters corresponding to the altimeter and the GPS.

US Patent:

48478628, Jul 11, 1989

Filed:

Apr 7, 1988

Appl. No.:

7/178980

Inventors:

Paul E. Braisted - San Jose CA
Ralph F. Eschenbach - Redwood City CA

Assignee:

Trimble Navigation, Ltd. - Sunnyvale CA

International Classification:

H04K 100

US Classification:

375 1

Abstract:

Two receiver channels each driven by a common local oscillator signal are employed. The signal developed by the first receiver channel is used to drive in phase (I) and quadrature (Q) counters of a Castas-loop, which phase-locks to the signal. The signal developed by the second receiver channel is used to drive another pair of in phase (I) and quadrature (Q) counters, which develop signals from which heading information is calculated.

US Patent:

59174447, Jun 29, 1999

Filed:

Nov 20, 1995

Appl. No.:

8/561086

Inventors:

Peter V. W. Loomis - Sunnyvale CA
Ralph Eschenbach - Woodside CA
Paul Braisted - San Jose CA
Chung Lau - Sunnyvale CA

Assignee:

Trimble Navigation Ltd. - Sunnyvale CA

International Classification:

G01S 502

US Classification:

342357

Abstract:

A method for fast acquisition, in as little as 6-15 seconds, of signals from a satellite in a Satellite Positioning System (SATPS), such as GPS or GLONASS, that does not require permanent storage of satellite ephemeris information at an SATPS ground station. This SATPS signal acquisition method can be used whenever the "new" station initially powers up or has lost lock on one or more SATPS signals that must be (re)acquired. A reference SATPS station provides the new SATPS station with an estimated reference station location and ephemeris information for one or more identified SATPS satellites visible from the reference station. The new station receives and uses this information to establish carrier frequency ranges to search for the identified SATPS satellite, by limiting the search to a reduced frequency range based upon estimated Doppler shift of SATPS signals received from this satellite. The actual frequency shift may differ from the estimated Doppler shift, due in part to errors in a frequency source used by the new station. When a first SATPS satellite signal is acquired and locked onto by the new station, the error in the new station frequency source is estimated, and the frequency range for searching for an SATPS signal from another satellite is reduced.

US Patent:

49705237, Nov 13, 1990

Filed:

Mar 27, 1989

Appl. No.:

7/328870

Inventors:

Paul E. Braisted - San Jose CA
Ralph F. Eschenbach - Redwood City CA

Assignee:

Trimble Navigation, Ltd. - Sunnyvale CA

International Classification:

G01S 502
G01S 352

US Classification:

342418

Abstract:

To reduce error introduced by the local oscillator in the velocity calculations, the receiver has two "tracking channels" and a microcomputer. With numbers required to, simultaneously, lock each of the "tracking channels" each to a respective satellite signal, the microcomputer employs a differential doppler technique to calculate the receiver velocity. The microcomputer calculates a number which represents the difference between the apparent doppler frequency shift of the carrier signal which is transmitted by the first "tracking channel" satellite and which is measured over a specific time period and the apparent doppler frequency shift of the carrier signal which is transmitted by the second "tracking channel" satellite and which is measured over substantially the same time period.