Horizontal/vertical protection level adjustment scheme for RAIM with baro measurements
AssigneeTrimble Navigation Limited
InventorsLawrence O. Lupash, Joseph M. Wlad
Life of this patent
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Abstract
The method of supplementing the satellite data by the satellite-calibrated baro data when the receiver autonomous integrity monitoring function (RAIM) is unavailable and when the horizontal protection level (HPL) does not satisfy the horizontal alert limit (HAL) requirement is disclosed. The baro data is adjusted to compensate for the lack of baro calibration in the position solution domain. The HPL is re-computed using the satellite-calibrated adjusted baro data. The re-computed HPL could satisfy the HAL requirement which would make the RAIM function available when it would be otherwise unavailable.
Claims8
A method for satellite supplementary navigation of a moving platform using a satellite data supplemented by a satellite-calibrated baro data;
- said moving platform including a satellite receiver and a barosensor;
- said method comprising the steps of:
- (a) acquiring a plurality of satellite signals;
- (b) checking whether a satellite configuration is substantially sufficient;
- (c) if said satellite configuration is substantially sufficient, and if said satellite data obtained from said substantially sufficient satellite configuration utilizing said satellite receiver is substantially sufficient,
- (c1) continuously computing a horizontal protection level (HPL) and a vertical protection level (VPL);
- (c2) checking whether said horizontal protection level (HPL) is less than or equal to a horizontal alert limit (HAL);
- (c3) if said horizontal protection level (HPL) is less than or equal to said horizontal alert limit (HAL), declaring a receiver autonomous integrity monitoring (RAIM) function available and declaring said satellite data obtained by using said satellite receiver as substantially sufficient for obtaining position fixes of said moving platform;
- (c4) if said horizontal protection level (HPL) is greater than said horizontal alert limit (HAL), declaring said receiver autonomous integrity monitoring (RAIM) function unavailable and declaring said satellite data obtained by using said satellite receiver as not substantially sufficient for obtaining position fixes of said moving platform;
- and
- (d) if said satellite configuration is not substantially sufficient, or if said satellite data obtained from said substantially sufficient satellite configuration is not substantially sufficient, supplementing said satellite data by said satellite-calibrated baro data obtained utilizing said barosensor.
The method of step 2, wherein said step of adjusting said (HPLbaro) in order to compensate for the lack of baro data measurement in the satellite position solution domain further includes the step of:
- off-line computation of a set of interpolation coefficients used in the computation of an HPL adjustment coefficient βh.
The method of step 2, wherein said step of adjusting said (VPLbaro) in order to compensate for the lack of baro data measurement in the satellite position solution domain further includes the step of:
- off-line computation of a set of interpolation coefficients used in the computation of a VPL adjustment coefficient βv.
The method of step 2, wherein said step of adjusting said (HPLbaro) in order to compensate for the lack of baro data calibration in the satellite position solution domain further includes the steps of:
- real time computation of an HPL adjustment coefficient βh;
- and
- multiplying said (HPLbaro) by said adjustment coefficient βh in order to obtain said adjusted horizontal position level (HPLadj).
The method of step 2, wherein said step of adjusting said (VPLbaro) in order to compensate for the lack of baro data calibration in the satellite position solution domain further includes the steps of:
- real time computation of a VPL adjustment coefficient βv;
- and
- multiplying said (VPLbaro) by said adjustment coefficient βv in order to obtain said adjusted horizontal position level (VPLadj).
Dependencies are inferred from the claim text.