Digital camera with GNSS picture location determination

• US 7,719,467 B2
• Filed: 03/08/2007
• Issued: 05/18/2010
• Est. Priority Date: 03/08/2007
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Norda, Carl Jacob, Loomis, Peter Van Wyck
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US11/715,769
• Publication Number:
  US 20080218407A1
• Time in Patent Office: 1,167 Days
• Field of Search: 342/357.06, 342/357.12, 342/357.13, 701/213, 701/215
• US Class Current: 342/357.31
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station

Abstract

A digital camera for providing a short burst of global navigation satellite system (GNSS) signal samples in a picture data file with an approximate time for reading by a computer apparatus some time later for determining the geographical location and an accurate time of the picture.

Claims

1. A location system for a digital camera, comprising:

a global navigation satellite system (GNSS) signal sampler to sample a GNSS signal when a digital camera picture is taken to provide a sequence of samples of said GNSS signal and to apply a time tag to said GNSS signal samples corresponding to a time of said picture, said time tag having a receiver time error;

an event time calibrator to calibrate said time tag according to at least one prior or later said receiver time error that is resolved by processing said GNSS signal samples for at least one prior or later said picture, respectively; and

a computer apparatus to process said GNSS signal samples and said time tag to mutually resolve said receiver time error together with coordinates of a GNSS picture position.

2. The camera system of claim 1, further comprising:

a digital camera including said GNSS signal sampler; and

a picture device for taking said digital camera picture;

a real time clock for generating said time tag having said receiver time error local to said digital camera; and

a picture file formatter to write said picture data, said GNSS signal samples and said time tag into a computer-readable picture data file medium; and

wherein;

said computer apparatus is configured to read said picture file data medium to mutually resolve said GNSS picture position, said receiver time error, and a replica clocking offset local to the computer apparatus.

3. The camera system of claim 1, wherein:

said receiver time error is greater than thirty seconds.

4. The camera system of claim 1, wherein:

said receiver time error may be up to at least twelve hours.

5. The camera system of claim 1, wherein:

said GNSS signal samples represent said GNSS signals for a time period less than a time length between transmissions of encoded data bits having a GNSS system clock time.

6. The camera system of claim 5, wherein:

said GNSS signal samples represent less than six seconds of said GNSS signals.

7. The camera system of claim 1, wherein:

said computer apparatus includes;

a velocity estimator to estimate, for said time tag, five GNSS satellite velocities corresponding to five GNSS satellites, respectively;

correlators to correlate said GNSS signal samples to determine five code phase offsets corresponding to said five GNSS satellites, respectively; and

a GNSS matrix resolver to use said five GNSS satellite velocities with said five code phase offsets to mutually resolve five unknowns of a replica clocking offset local to said correlators, said receiver time error local to said GNSS signal sampler, and three dimensions of said GNSS picture position.

8. The camera system of claim 7, wherein:

said computer apparatus includes;

a velocity estimator to estimate, for said time tag, K GNSS satellite velocities corresponding to K GNSS satellites, respectively, for said K at least four;

correlators to determine K code phase offsets, for said GNSS signal samples, corresponding to said K GNSS satellites, respectively; and

a GNSS matrix resolver to use said K GNSS satellite velocities with said K code phase offsets to mutually resolve unknowns of a replica clocking offset local to said correlators, said receiver time error local to said GNSS signal sampler, and said GNSS picture position.

9. The camera system of claim 8, wherein:

said GNSS matrix resolver is constructed to use said K GNSS satellite velocities in a satellite velocity positioning matrix having K row vectors corresponding to said K GNSS satellites, respectively, and five columns, said five columns including three said columns for estimated unit vectors between an estimated said GNSS picture position and estimated locations-in-space of said K GNSS satellites, one said column for a constant, and one said column for estimated range rates between said estimated GNSS picture position and said estimated locations-in-space of said K GNSS satellites; and

then using said satellite velocity positioning matrix and said code phase offsets for said mutual resolution of said unknowns.

10. The camera system of claim 2, wherein:

said digital camera includes an altimeter for providing data representative of an altitude; and

said computer apparatus is constructed for using said altitude with said GNSS signal samples for determining said GNSS picture position.

11. A method for providing a global navigation satellite system (GNSS)-based position for a picture, comprising:

converting a scene into digital picture data;

sampling a GNSS signal for providing a sequence of samples of said GNSS signal corresponding to said picture data;

generating a time tag for said GNSS signal samples corresponding to a time of said picture data, said time tag having a receiver time error;

calibrating said time tag according to at least one prior or later said receiver time error that is resolved by processing said GNSS signal samples for at least one prior or later said picture, respectively; and

processing said GNSS signal samples and said time tag for mutually resolving said receiver time error together with coordinates of a GNSS picture position.

12. The method of claim 11, further comprising:

writing said picture data with said GNSS signal samples and said time tag from a digital camera into a picture data file medium;

reading said picture file data medium in a computer apparatus; and

mutually resolving said GNSS picture position, said receiver time error that is local to said scene, and a replica clocking offset that is local to said computer apparatus.

13. The method of claim 11, wherein:

said receiver time error is greater than thirty seconds.

14. The method of claim 11, wherein:

said receiver time error may be up to at least twelve hours.

15. The method of claim 11, wherein:

said GNSS signal samples represent said GNSS signals for a time period less than a time period between transmissions of encoded data bits having a GNSS system clock time.

16. The method of claim 15, wherein:

said GNSS signal samples represent less than six seconds of said GNSS signals.

17. The method of claim 11, wherein:

the step of processing includes;

estimating, for said time tag, five GNSS satellite velocities corresponding to five GNSS satellites, respectively;

correlating said GNSS signal samples for determining five code phase offsets corresponding to said five GNSS satellites, respectively; and

using said five GNSS satellite velocities with said five code phase offsets for mutually resolving five unknowns of a replica clocking offset local to said correlators, said receiver time error local to said GNSS signal sampler, and three dimensions of said GNSS picture position.

18. The method of claim 17, wherein:

the step of processing includes;

estimating, for said time tag, K GNSS satellite velocities corresponding to K GNSS satellites, respectively, for said K at least four;

correlating said GNSS signal samples for determining K code phase offsets corresponding to said K GNSS satellites, respectively; and

using said K GNSS satellite velocities with said K code phase offsets for mutually resolving unknowns of a replica clocking offset local to said correlators, said receiver time error local to said GNSS signal sampler, and said GNSS picture position.

19. The method of claim 18, wherein:

the step of processing includes using orbital satellite parameters for determining a satellite velocity positioning matrix having K row vectors corresponding to said K satellites, respectively, and five columns, said five columns including three said columns for estimated unit vectors between an estimated said GNSS picture position and estimated locations-in-space of said K GNSS satellites, one said column for a constant, and one said column for estimated range rates between said estimated GNSS picture position and said estimated locations-in-space of said K GNSS satellites, said estimated range rates computed from said estimated unit vectors and said estimated satellite velocities; and

then using said satellite velocity positioning matrix and said code phase offsets for said mutual resolution of said unknowns.

20. The method of claim 11, further comprising:

reading an altimeter for determining an altitude; and

using said altitude with said GNSS signal samples for determining said GNSS picture position.

21. A tangible medium having computer-readable instructions for reading by a computer for carrying out the following steps:

converting a scene into digital picture data;

sampling a GNSS signal for providing a sequence of samples of said GNSS signal corresponding to said picture data;

generating a time tag for said GNSS signal samples corresponding to a time of said picture data, said time tag having a receiver time error;

calibrating said time tag according to at least one prior or later said receiver time error that is resolved by processing said GNSS signal samples for at least one prior or later said picture, respectively; and

processing said GNSS signal samples for mutually resolving said receiver time error with coordinates of a GNSS picture position.