GNSS Surveying Methods and Apparatus

• US 20110285587A1
• Filed: 02/20/2010
• Published: 11/24/2011
• Est. Priority Date: 02/22/2009
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Vollath, Ulrich, Talbot, Nicholas Charles
• Granted Patent: US 9,322,918 B2
• Time in Patent Office: Days
• US Class Current: 342/357.62
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/072 Ionosphere corrections
• CPC Class Codes: G01S 19/074 providing integrity data, e.g. WAAS
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry

Abstract

Methods and apparatus are presented for improved productivity in determining static position of an antenna of a GNSS rover, such as in stop-and-go surveying. Computer-implemented methods and apparatus provide for determining a static position of an antenna of a GNSS rover from observations of GNSS signals collected at the antenna over multiple epochs and from correction data for at least one of the epochs. In some forms this comprises: acquiring first-epoch rover observations of GNSS signals received at the antenna during a first epoch, obtaining first-epoch correction data for the first epoch, determining a synchronized rover antenna position for the first epoch from the first-epoch rover observations and the first-epoch correction data, acquiring subsequent-epoch rover observations from the received GNSS satellite signals for at least one subsequent epoch for which correction data is unavailable, determining that the antenna position remained static for at least two static epochs, and determining an updated rover antenna position from the synchronized rover antenna position and the subsequent-epoch rover observations of at least one static epoch of the at least one subsequent epoch.

Claims

1. A method of determining a static position of an antenna of a GNSS rover from observations of GNSS signals collected at the antenna over multiple epochs and from correction data for at least one of the epochs, comprising:

acquiring first-epoch rover observations of GNSS signals received at the antenna during a first epoch,

obtaining first-epoch correction data for the first epoch,

determining a synchronized rover antenna position for the first epoch from the first-epoch rover observations and the first-epoch correction data,

acquiring subsequent-epoch rover observations from the received GNSS satellite signals for at least one subsequent epoch for which correction data is unavailable,

determining that the antenna position remained static for at least two static epochs, and

determining an updated rover antenna position from the synchronized rover antenna position and the subsequent-epoch rover observations of at least one static epoch of the at least one subsequent epoch.

2. The method of claim 1, wherein the correction data comprises at least one of:

correction data prepared from observations of a base station, correction data prepared from observations of a network of reference stations, and precise orbit and clock information for satellites broadcasting the GNSS signals.

3. The method of claim 1, wherein a minimum number of static epochs is mandated by at least one of:

(1) use input, (2) a minimum occupation time at a survey point, and (3) an estimated accuracy of the updated rover antenna position.

4. The method of claim 1, wherein said at least two static epochs comprise the first epoch and at least one said subsequent epoch, and wherein determining an updated rover antenna position comprises:

for each said subsequent epoch of the static epochs, determining an unsynchronized rover antenna position from the rover observations of the respective subsequent epoch, and

combining the synchronized roves antenna position with the unsynchronized rover antenna positions of each subsequent epoch of the static epochs to obtain the updated rover antenna position.

6. The method of claim 1, wherein said at least two static epochs comprise respective said subsequent epochs, and wherein determining an updated rover antenna position comprises:

for each said static epoch, determining an unsynchronized roves antenna position change relative to the synchronized antenna position from the rover observations of the respective subsequent epoch and the rover observations of the first epoch, and

combining the synchronized rover antenna position with the unsynchronized rover antenna position changes to obtain the updated rover antenna position.

7. The method of claim 6, wherein combining comprises adding.

8. The method of claim 1, wherein determining that the antenna position remained static for at least two static epochs comprises:

receiving user input designating a static time interval, and

determining that the static epochs are within the static time interval.

9. The method of claim 1, wherein determining that the antenna position remained static for at least two static epochs comprises receiving input from a physical sensor comprising at least one of:

a contact switch, an inertial sensor, and a motion detector.

10. The method of claim 1, wherein determining that the antenna position remained static for at least two epochs comprises:

determining an unsynchronized rover antenna position for each of a plurality of epochs,

comparing the unsynchronized rover antenna positions or respective epochs, and

designating said respective epochs as static epochs when the difference between the unsynchronized rover antenna positions is less than a predetermined threshold.

11. The method of claim 1, wherein determining an updated rover position comprises forming a difference between epoch carrier-phase rover observations of a current epoch and carrier-phase rover observations or a reference epoch, and computing from the difference a change to rover position between the current epoch and the reference epoch.

46. A computer-usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement the method according to claim 1.

5. The method of clam 4, wherein combining comprises averaging.

12-33. -33. (canceled)

34. Surveying apparatus, comprising a GNSS rover having a receiver and a rover antenna for receiving GNSS signals and a data link and at least one associated processor to determine a static position of the antenna from observations of GNSS signals collected at the antenna over multiple epochs and from correction data for at least one of the epochs, wherein:

the receiver is operative to measure GNSS signals received at the antenna during a first epoch to obtain first-epoch rover observations,

the data link is operative to obtain first-epoch correction data for the first epoch,

the processor is operative to determine a synchronized rover antenna position for the first epoch mom the first-epoch rover observations and the first-epoch correction data,

the receiver is operative to measure GNSS signals received at the antenna during at least one subsequent epoch for which correction data is unavailable to obtain subsequent-epoch rover observations,

the processor is operative to determine that the antenna position remained static for at least two static epochs, and

the processor is operative to determine an updated rover antenna position from the synchronized rover antenna position and the subsequent-epoch rover observations of at least one static epoch of the at least one subsequent epoch and to store a representation of the updated rover antenna position in a physical storage medium.

35. The apparatus of claim 34, wherein the data is operative to obtain at least one of:

correction data prepared from measurements of GNSS signals received at an antenna of a base station receiver, correction data prepared from measurements of GNSS signals received at respective antennas of reference station receivers of a network of reference stations, and precise orbit and clock information defining physical orbits of satellites broadcasting the GNSS signals and defining clock parameters of clocks of the satellites.

36. The apparatus of claim 34, wherein the processor is operative to define a minimum number of static epochs by at least one of:

(i) receiving input from a user, (2) measuring a minimum occupation time of the GNSS rover at a survey point, and (3) determining a minimum estimated accuracy of the updated rover antenna position.

37. The apparatus of claim 34, wherein said at least two static epochs comprise the first epoch and at least one said subsequent epoch, and wherein the processor is operative to determine an updated rover antenna position comprises operating the processor by:

determining, for each said subsequent epoch of the static epochs, an unsynchronized rover antenna position from the rover observations of the respective subsequent epoch, and

combining the synchronized rover antenna position with the unsynchronized rover antenna positions of each subsequent epoch of the static epochs to obtain the updated rover antenna position.

38. The apparatus of claim 37, wherein combining comprises averaging.

39. The apparatus of claim 34, wherein said at least two static epochs comprise respective said subsequent epochs, and wherein the processor is operative to determine an updated rover antenna position by:

determining, for each said static epoch, an unsynchronized rover antenna position change relative to the synchronized antenna position from the rover observations of the respective subsequent epoch and the rover observations of the first epoch, and

combining the synchronized rover antenna position with the unsynchronized rover antenna position changes to obtain the updated rover antenna position.

40. The method of claim 39, wherein combining comprises adding.

41. The apparatus of claim 34, wherein determining that the antenna position remained static for at least two static epochs comprises:

receiving user input designating a static time interval, and

operating the processor to determine that the static epochs are within the static time interval.

42. The apparatus of claim 34, wherein determining that the antenna position remained static for at least two static epochs comprises receiving input from a physical sensor comprising at least one of:

a contact switch, an inertial sensor, and a motion detector.

43. The apparatus of claim 34, wherein determining that the antenna position remained static for at least two epochs comprises operating the processor to:

determine an unsynchronized rover antenna position for each of a plurality of epochs,

compare the unsynchronized rover antenna positions of respective epochs, and

designate said respective epochs as static epochs when the difference between the unsynchronized rover antenna positions is less than a predetermined threshold.

44. The apparatus of claim 34, wherein the processor is operative to determine an updated rover position by forming a difference between epoch carrier-phase rover observations of a current epoch and carrier-phase rover observations of a reference epoch, and computing from the difference a change in rover position between the current epoch and the reference epoch.

45. (canceled)