Method to improve carrier smoothing of code pseudorange for global positioning and GNSS receiver implementing the same

• US 6,266,009 B1
• Filed: 03/26/1999
• Issued: 07/24/2001
• Est. Priority Date: 03/26/1999
• Status: Expired due to Term

• Current Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Original Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Inventors: Hwang, Patrick Y.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/277,310
• Time in Patent Office: 851 Days
• Field of Search: 342/357.01, 342/357.17, 701/200, 701/207, 701/213, 701/214, 375/130-153, 375/346
• US Class Current: 342/357.27
• CPC Class Codes: G01S 19/32 Multimode operation in a single same satellite system, e.g. GPS L1/L2
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry

Abstract

A method of smoothing a global navigational satellite system (GNSS) code pseudorange measurement included tracking first and second GNSS signals, at first and second respective frequencies, from a first satellite. A first pseudorange measurement is determined from the first GNSS signal. A smoothed pseudorange measurement is calculated from the determined first pseudorange measurement as a function of both the first and second GNSS signals. In some embodements, the smoothed pseudorange measurement is calculated from the determined first pseudorange measurement as a function of a generalized code pseudorange measurement and as a function of a generalized carrier phase measurement. At least one of the generalized code phase measurement. At least one of the generalized code pseudorange measurement and the generalized carrier phase measurement are dual frequence measurements determined as a function of both the first and second GNSS signals.

Claims

1. A method of smoothing a global navigational satellite system (GNSS) code pseudorange measurement, the method comprising:

tracking a first GNSS signal, at a first frequency, from a first satellite;

tracking a second GNSS signal, at a second frequency, from the first GNSS satellite;

determining a first pseudorange measurement ρ

₁ from the tracked first GNSS signal;

calculating a smoothed pseudorange measurement {circumflex over (Ψ

)} from the determined first pseudorange measurement ρ

₁ as a function of both the first and second GNSS signals.

2. The method of claim 1, wherein calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} further comprises calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} from the determined first pseudorange measurement ρ

₁ as a function of a generalized code pseudorange measurement Ψ and

as a function of a generalized carrier phase measurement Φ

, wherein at least one of the generalized code pseudorainge measurement Ψ and

the generalized carrier phase measurement Φ

are dual frequency measurements determined as a function of both the first and second GNSS signals.

3. The method of claim 2, and further comprising:

measuring a first carrier phase from the first GNSS signal to obtain a first carrier phase measurement φ

₁;

measuring a second carrier phase from the second GNSS signal to obtain a second carrier phase measurement φ

₂; and

wherein calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} includes calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} as a function of both of the first carrier phase measurement φ

₁ and the second carrier phase measurement φ

₂.

4. The method of claim 3, wherein calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} as a function of both of the first carrier phase measurement φ

₁ and the second carrier phase measurement φ

₂ further comprises calculating the smoothed pseudorange measurement as a function of a difference between the first and second carrier phase measurements.

5. The method of claim 4, wherein the first GNSS signal is an L1 GNSS signal and the second GNSS signal is an L2 GNSS signal.

6. The method of claim 4, wherein calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} further comprises calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} as a function of the generalized code pseudorange measurement Ψ and

as a function of the generalized carrier phase measurement Φ

defined by the relationships;

7. The method of claim 4, wherein calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} further comprises calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} as a function of the generalized code pseudorange measurement Ψ and

as a function of the generalized carrier phase measurement Φ

defined by the relationship;

8. The method of claim 4, and further comprising determining a second pseudorange measurement ρ

₂ from the tracked second GNSS signal.

9. The method of claim 8, wherein the smoothed pseudorange measurement {circumflex over (Ψ

)} does not contain an ionspheric delay component.

10. The method of claim 9, wherein calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} further comprises calculating the smoothed pseudorange measurement {circumflex over (Ψ

)} as a function of the generalized code pseudorange measurement Ψ and

as a function of the generalized carrier phase measurement Φ

defined by the relationships;

 

Ψ

=ρ

₁−

1/α

(ρ

₁−

ρ

₂)≡

ρ

₂−

1/β

(ρ

₂−

ρ

₁) and

11. A method of smoothing global navigational satellite system (GNSS) code pseudorange measurements, the method comprising:

tracking a first GNSS signal, at a first frequency, from a first satellite;

tracking a second GNSS signal, at a second frequency, from the first GNSS satellite;

determined a generalized code pseudorange measurement Ψ

from at least one of the first and second GNSS signals;

determining a generalized carrier phase measurement Φ

from at least one of phase first and second GNSS signals, wherein at least one of the generalized code pseudorange measurement Ψ and

the generalized carrier phase measurement Φ

is determined from both of the first and second GNSS signals;

subtracting the generalized carrier phase measurement Φ

from the generalized code pseudorange measurement Ψ

to obtain difference data;

filtering the difference data to obtain filtered difference data having components removed; and

adding the generalized carrier phase measurement Φ

to the filtered difference data to obtain a smoothed pseudorange measurement {circumflex over (Ψ

)}.

12. The method of claim 11, and further comprising:

determining a first pseudorange measurement ρ

₁ from the tracking first GNSS signal, wherein determining the generalized code pseudorange measurement Ψ

further includes determining the generalized code pseudorange measurement Ψ

as a function for the first pseudorange measurement ρ

₁;

determining a first carrier phase from the first GNSS signal to obtain a first carrier phase measurement φ

₁; and

determining a second carrier phase from the second GNSS signal to obtain a second carrier phase measurement φ

₂, wherein determining the generalized carrier phase measurement Φ

further includes determining the generalized carrier phase measurement Φ

as a function of both the first carrier phase measurement φ

₁ and the second carrier phase measurement φ

₂.

13. The method of claim 12, wherein determining the generalized carrier phase measurement Φ

as a function of both the first carrier phase measurement φ

₁and the second carrier phase measurement φ

₂further includes determining the generalized carrier phase measurement Φ

as a function of a difference between the first carrier phase measurement φ

₁ and the second carrier phase measurement φ

₂.

14. The method of claim 13, wherein determining the generalized code pseudorange measurement Ψ

and determining the generalized carrier phase measurement Φ

further includes determining the generalized code pseudorange measurement Ψ and

the generalized carrier phase measurement Φ

using the relationships;

15. The method of claim 14, and further comprising determining a second pseudorange measurement ρ

₂ from the tracked second GNSS signal.

16. The method of claim 15, wherein determining the generalized code pseudorange measurement Ψ

and determining the generalized carrier phase measurement Φ

further include determining the generalized code pseudorange measurement Ψ and

the generalized carrier phase measurement Φ

using the relationships;

17. The method of claim 13, wherein determining the generalized code pseudorange measurement Ψ

and determining the generalized carrier phase measurement Φ

further includes determining the generalized code pseudorange measurement Ψ and

the generalized carrier phase measurement Φ

using the relationships;

18. A global navigational satellite system (GNSS) receiving apparatus comprising:

signal tracking means for tracking a first GNSS signal, at a first frequency, from a first satellite and a second GNSS signal, at a second frequency, from the first GNSS satellite;

pseudorange determining means for determining a first pseudorange measurement ρ

₁ from the first GNSS signal; and

pseudorange measurement smoothing means for calculating a smoothed pseudorange measurement {circumflex over (Ψ

)} from the determined first pseudorange measurement ρ

₁ as a function of both the first GNSS signal and as a function of the second GNSS signal.