System and method for compensating for scintillation and for facilitation of long-baseline RTK
AssigneeDeere & Company
InventorsYufeng Zhang, Liwen Dai
Life of this patent
Estimating the term…
Abstract
The system and method facilitates Real-Time-Kinematic (RTK) GNSS with long baseline between a rover receiver and a base station receiver, even in the presence of scintillation or ionospheric disturbances that spatially fluctuate. Residual atmospheric errors can be estimated by a dual error model in a filter to promote efficient fixing or resolution of carrier phase ambiguities.
Claims22
A system for-a estimating a position by a rover receiver in wireless communication with a base station receiver at a known location, the rover receiver and the base station receiver capable of receiving a plurality of Global Navigation Satellite System (GNSS) signals from GNSS satellites, the system comprising:
- a measurement module configured to obtain initial code pseudo-range measurements and initial carrier phase measurements from the signals transmitted by GNSS satellites;
- a wireless communications device associated with the rover receiver and the base station receiver, the wireless communications device configured to receive satellite orbit and clock corrections from an augmentation system;
- a correction data estimator configured to generate measurement range errors and atmospheric related aiding data based on the known location of the base station receiver, with the aid of satellite orbit and clock corrections from the augmentation system;
- a wireless link for sending the range errors and aiding information to the rover receiver;
- the measurement module configured to use the range errors and the aiding information from base station receiver to correct the initial code pseudo-range measurements and the initial carrier phase measurements to mitigate errors in the signal, to result in corrected code pseudo-range measurements and corrected carrier phase measurements;
- an atmospheric modeling module configured to estimate the residual of atmosphere delay with a dual error model that is configured to apply a preset error model before ambiguities are fixed or resolved, and to apply an adaptive error model after ambiguities are fixed or resolved;
- and
- an ambiguity resolution module configured to conduct ambiguity resolution to fix carrier phase ambiguities for qualified or eligible ambiguities,
- wherein the adaptive error model has a system or software instructions of the atmospheric modeling module to predict ionospheric activity level for each measurement epoch by epoch, and
- wherein the system to predict ionosphere activity level is based on the time-differenced Geometry-Free (TDGF) for each satellite in accordance with the following equation:
- Δ
-
- L
- ij
- =
- (
- L
- ij
- t
- -
- L
- ij
- k
- )
- /
- (
- t
- -
- k
- )
- =
- Δ
-
- d
- .
- ion
- f
- i
- 2
- -
- d
- ion
- .
- f
- j
- 2
- +
- Δσ
- ij
- where the carrier phase measurements for frequency i and j at time t, Lijt, and carrier phase measurements for frequency i and j at time k, Lijk, are differenced, and where the dot above the Δ{dot over (d)}ion indicates a time derivative or a change rate in ionospheric error term between time t and k;
- where the dot above indicates a time derivative or change in ionospheric delay between time t and k;
- fi is measurement frequency i;
- fj is measurement frequency j;
- where Δσij is the change in measurement error for frequencies i and j at between t and at time k.
Dependencies are inferred from the claim text.