Automatic Decorrelation And Parameter Tuning Real-Time Kinematic Method and Apparatus

• US 20080074319A1
• Filed: 11/09/2007
• Published: 03/27/2008
• Est. Priority Date: 04/19/2004
• Status: Active Grant

• Current Assignee: MiTAC International Corporation (MiTAC Holdings Corp.)
• Original Assignee: Magellan Navigation Incorporated (MiTAC Holdings Corp.)
• Inventors: DAI, Liwen, HAN, Shaowei
• Granted Patent: US 7,663,539 B2
• Time in Patent Office: Days
• US Class Current: 342/357.04
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

A method of and computer-readable medium containing instructions for high accuracy, reliable position determination. The ADAPT-RTK Technology (Automatic Decorrelation and Parameter Tuning Real-Time Kinematic technology) is described using an innovative decorrelation algorithm to decorrelate the correlation between L1 and L2 measurements through a functional model and a stochastic model reducing the impact on performance of distance dependent biases.

Claims

1. A method of providing improved real time kinematics determination, comprising the steps of:

determining a first position estimate using a received signal and an other received signal;

enhancing ambiguity resolution of the first position estimate by decorrelating a first and second measurement based on the received signal and the other received signal, respectively; and

deriving a second position estimate based on the enhanced ambiguity resolution.

2. The method as claimed in claim 1, wherein the received signals are GPS signals.

3. The method as claimed in claim 1, wherein the received signals are signals received by a GPS receiver.

4. The method as claimed in claim 1, wherein the first and second measurements are decorrelated using the function:

5. The method as claimed in claim 4, wherein {tilde over (L)}₂=L₂−

α

L₁, {tilde over (H)}₂=H₂−

α

H₁, and

6. The method as claimed in claim 1, wherein the first and second measurements are decorrelated using a coefficient determined by the function:

7. The method as claimed in claim 1, wherein at least one of a ratio smoothing function and an ambiguity stability function are used if a baseline is 10 kilometers or greater.

8. The method as claimed in claim 7, wherein the ratio smoothing function is:

{tilde over (R)}atio=Ratio+{tilde over (R)}atio*(N−

1)/N

where N is the width of the moving window.

9. The method as claimed in claim 7, wherein the ambiguity stability function includes the steps of:

incrementing a counter for each epoch in which double differenced ambiguities remain the same; and

if the double differenced ambiguities are not zero and less than 50 epochs are counted, resetting the counter.

10. A computer readable medium comprising:

at least one sequence of machine executable instructions in machine form, wherein execution of the instructions by a processor cause the processor to;

determine a first position estimate using a received signal and an other received signal;

enhance ambiguity resolution of the first position estimate by decorrelating a first and second measurement based on the received signal and the other received signal, respectively; and

derive a second position estimate based on the enhanced ambiguity resolution.