Availability Enhancements for CAT IIIB LAAS

Shively, Curtis A.; Hsiao, Thomas T.

doi:10.1002/j.2161-4296.2004.tb00340.x

Cited by 17 publications

(27 citation statements)

References 4 publications

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“…Comparing equation (13), (14)to the equation (15), we could find that in case1,the j i μ and j i σ are the same with the conservative estimation without considering the prior information.…”

Section: The Argument About the Distribution Of Waas Correction Errormentioning

confidence: 73%

“…GIVE, the position accuracy of WAAS and LAM decreases 1.3% and 1.7% respectively, the availability of WAAS and LAM decreases 0.33% and 0.50% respectively. However, in the normal condition, the availability of LAM is worse than LAAS, and it has not achieved the standard required by GSL C (99.9%-99.999%) [14].This is because the error of WAAS correction is bigger, so the protect level of LAM is also bigger, and LAM availability is impacted.…”

Section: The Simulation Conditionmentioning

confidence: 94%

“…Second, the number of the criterion satellites in the geometry is less than or equal to the number of the criterion satellites required by the system. Definition of the criterion satellite is that, in the condition of no other faults, if the satellite is fault, the max VPL will be bigger than VAL [14].In the paper, a conservative method is used to judge that a satellite is criterion satellite or not. In a geometry configuration, we move a satellite each time, if the new maximal vertical protect level calculated by the residual satellites is bigger thanVAL , the satellite is criterion satellite, otherwise, the satellite is not criterion satellite.…”

Section: The Calculation Of the Lam Availabilitymentioning

confidence: 98%

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Research on improvement of position accuracy for satellite navigation

Wang

Zhang

2008

2008 IEEE/AIAA 27th Digital Avionics Systems Conference

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Some deficiencies of the system of exciting satellite navigation augmentation are analyzed in the application of civil aviation. Since there is no local monitoring in Wide Area Augmentation System (WAAS), the protect level is increased, and the availability is reduced, so it could not satisfy the requirement of the precise approach. Moreover, because the Local Area Augmentation System (LAAS) could not solve the problem brought by ionosphere storms, the LAAS certification becomes complex and expensive. The basic principle of the new satellite navigation augmentation system named Local Airport Monitor (LAM) proposed by Federal Aviation Administration (FAA) is introduced. And the error distribution characteristic of LAM is discussed by sorting three conditions. Moreover, the expressions of LAM protection level and availability are studied. Some conclusions are obtained by simulations. In normal condition, the position accuracy of LAM is better than the one of WAAS and similar to LAAS and the availability of LAM is better than the one of WAAS and worse than LAAS. When there are ionosphere storms, the position precision and availability of LAM and WAAS reduce a little, but the position precision and availability of LAAS reduce 20.5% and 19.3% respectively. Furthermore, the availability of LAM is analyzed and simulated. And some conclusions are obtained: airborne user should first choose satellites whose elevation is lower than 10 degree and bigger than 70 degree. Reference station and airborne should use GAD-A and AAD-B receiver respectively, thus, the availability of LAM could bigger than 99.99%

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Section: The Argument About the Distribution Of Waas Correction Errormentioning

confidence: 73%

Section: The Simulation Conditionmentioning

confidence: 94%

Section: The Calculation Of the Lam Availabilitymentioning

confidence: 98%

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Research on improvement of position accuracy for satellite navigation

Wang

Zhang

2008

2008 IEEE/AIAA 27th Digital Avionics Systems Conference

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“…As others have done before, this effort examines PLs only under the H0, or fault-free, hypothesis (Rife and Pullen 2005a;Shively and Hsiao 2004). This is appropriate for the analysis of a generic PL formulation not closely tied to the configuration of any particular system such as LAAS or WAAS.…”

Section: Protection Levels In Aviation Safetymentioning

confidence: 98%

Statistical characterization of composite protection levels for GPS

2010

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A statistical characterization is presented of Global Positioning System (GPS) user range error as a normally distributed random variable with non-zero mean over the length of the aircraft precision approach operation, correlated from one GPS measurement epoch to another and from one satellite to another. This leads directly to modeling GPS error in the position domain as multivariate normal with non-zero mean. Based on this model, a vertical composite protection level VPL c and a horizontal composite protection level HPL c are each calculated as scalar values from a univariate normal distribution displaced from the origin by the worst-case position domain bias combination possible, given the maximum possible individual satellite bias magnitudes and the satellite geometry. A method is then presented by which exact values-that is, values accurate to a user-defined error tolerance and consistent with statistical assumptions-of VPL c and HPL c are obtained, and by which computationally efficient approximations may be evaluated. A statistical quadratic form under the multivariate normal distribution is used to derive a new class of protection levels based on the probability enclosed within a radius defined in two or more dimensions. A central Chi-square representation of this quadratic form is also presented and is incorporated into a six-step computational procedure for the two-dimensional composite radial protection level RPL c . This procedure is extended to the spherical protection level (SPL c ) and the ellipsoidal protection level (EPL c ).

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“…The total error at the aircraft using the jth subset of satellites with the WAAS corrections is (11) Recalling that DS vert, j is an estimate of E MWAAS,vert, j corrupted by the monitor error (12) substitution of Equation (12) into Equation (11) gives…”

Section: Bound On Aircraft Error and Integrity Requirementmentioning

confidence: 99%