Method and apparatus for determining an integrity risk in a satellite reference system
Methods and apparatus of determining an integrity risk of a satellite reference system are provided. Galileo parameters according to the Galileo integrity concept are detected. The Galileo parameters are imaged onto satellite based augmentation system (SBAS) parameters used in the SBAS. The integrity risk of the satellite reference system is determined according to the SBAS integrity concept using the SBAS parameters.
1. A method of determining an integrity risk of a satellite reference system comprising the steps of:
detecting Galileo parameters according to a Galileo integrity concept;
mapping the Galileo parameters onto satellite based augmentation system (SBAS) parameters, and
determining the integrity risk for the satellite reference system according to the SBAS integrity concept using the SBAS parameters.
2. The method according to claim 1 , wherein
the step of detecting involves detecting of the Galileo parameters' signal in space accuracy (SISA), signal in space monitoring accuracy (SISMA) and of a probability of a ranging signal failure,
the step of mapping comprises computing a signal in space monitored accuracy (SISMdA) parameter, and
the step of determining comprises using the SISMdA parameter as a timing or orbiting fraction of the user differential range error (UDRE) in protection level equations standardized for the SBAS.
3. The method according to claim 1 , wherein a range error distribution of faultless satellites is bounded by a Gaussian distribution with a zero mean value and a signal in space accuracy (SISA) standard deviation, and a distribution of the difference between an estimated signal in space error and an actual true signal in space error is bounded by a Gaussian distribution with a zero mean value and a signal in space monitoring accuracy (SISMA) standard deviation.
4. The method according to claim 1 , wherein a Gaussian function with a standard deviation SISMdA and a zero mean value bounds a weighted sum of a faultless and faulty distribution of a satellite.
5. The method according to claim 4 , wherein a range error distribution of a faulty satellite is a Gaussian distribution with a standard deviation SISMA and a mean value, which is a prefactor k_fa reflecting a permitted error alarm rate multiplied by a square root of a sum of a square of SISMA and a square of SISA.
6. The method according to claim 1 , wherein two-frequency ranging signals are used and an ionospheric contribution of wide area augmentation system (WAAS) equations is correspondingly adapted to the Galileo equations.
7. A computer program comprising a computer-readable program carrier that stores a computer program for:
detecting Galileo parameters according to a Galileo integrity concept;
mapping the Galileo parameters onto satellite based augmentation system (SBAS) parameters, and
determining the integrity risk for the satellite reference system according to the SBAS integrity concept using the SBAS parameters.
8. An apparatus for determining an integrity risk of a satellite reference system, the system comprising:
a device that detects Galileo parameters according to a Galileo integrity concept;
a device that maps the Galileo parameters onto satellite based augmentation system (SBAS) parameters; and
a device that determines the integrity risk for the satellite reference system according to the SBAS integrity concept using the SBAS parameters.
9. The apparatus according to claim 8 , wherein
the detection involves detecting of the Galileo parameters' signal in space accuracy (SISA), signal in space monitoring accuracy (SISMA) and of a probability of a ranging signal failure,
the mapping comprises computing a signal in space monitored accuracy (SISMdA) parameter, and
the determining comprises using the SISMdA parameter as a timing or orbiting fraction of the user differential range error (UDRE) in protection level equations standardized for the SBAS.
10. The apparatus according to claim 8 , wherein a range error distribution of faultless satellites is bounded by a Gaussian distribution with a zero mean value and a signal in space accuracy (SISA) standard deviation, and a distribution of the difference between an estimated signal in space error and an actual true signal in space error is bounded by a Gaussian distribution with a zero mean value and a signal in space monitoring accuracy (SISMA) standard deviation.
11. The apparatus according to claim 8 , wherein a Gaussian function with a standard deviation SISMdA and a zero mean value bounds a weighted sum of a faultless and faulty distribution of a satellite.
12. The apparatus according to claim 11 , wherein a range error distribution of a faulty satellite is a Gaussian distribution with a standard deviation SISMA and a mean value, which is a prefactor k_fa reflecting a permitted error alarm rate multiplied by a square root of a sum of a square of SISMA and a square of SISA.
13. The apparatus according to claim 8 , wherein two-frequency ranging signals are used and an ionospheric contribution of wide area augmentation system (WAAS) equations is correspondingly adapted to the Galileo equations.