Position and velocity Kalman filter for use with global navigation satelite system receivers
AssigneeNovAtel Inc.
InventorThomas John Ford
Life of this patent
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Abstract
A GPS receiver utilizes measurements which span previous and current times, such as delta phase measurements, in a modified Kalman filter. The modified Kalman filter updates position information relating to both the current and the previous times, and s propagates the current position and velocity related information. Using both the current and the previous position related information in the filter in conjunction with delta phase measurements, essentially eliminates the effect of system dynamics from the system model, and a position difference can thus be formed that is directly observable by the phase difference measured between the previous and current time epochs.
Claims13
A GPS receiver including:
- A. an antenna for receiving signals from a plurality of GPS satellites;
- B. an acquisition and tracking processor for acquiring and tracking the satellite signals and making carrier phase and code measurements;
- C. a pseudorange and Doppler rate processor for determining pseudoranges to the respective satellites and associated Doppler rates based on the carrier phase and code measurements;
- D. a pseudorange/delta phase Kalman filter for using pseudoranges, Doppler rates and delta phase measurements to update current and previous position related information and propagate current position and velocity related information and for determining a position of the GPS receiver using the propagated information.
A method of determining GPS position including:
- A. receiving signals from a plurality of GPS satellites;
- B. acquiring and tracking carriers and codes in the satellite signals;
- C. determining pseudoranges and Doppler rates based on the carrier and code measurements;
- D. updating current and previous position related information using the pseudoranges, Doppler rates and delta phase measurements;
- E. propagating the updated current position information and velocity information;
- F. using the propagated position and velocity information to determine GPS position.
A method of determining position using a Kalman filter, the method including the steps of:
- A. receiving signals from a plurality of GPS satellites;
- B. acquiring and tracking carriers and codes in the satellite signals;
- C. determining pseudoranges and Doppler rates based on the carrier and code measurements;
- D. measuring a parameter that over time measures position change;
- E. using the parameter to update position information relating to a current and a previous position and using the pseudoranges and Doppler rates to update and propagate current position related information;
- F. using the propagated current position related information to determine a position.
Dependencies are inferred from the claim text.