Method and Apparatus for Providing Integrity Information for Users of a Global Navigation System

Method for providing integrity information for users of a global navigation system, said method comprising:

• a plurality of space vehicles transmitting information to a device for position detection;
• wherein the transmitted information includes,
• a first information from the global navigation system about the accuracy of a signal in space error SISE of a faulty space vehicle;
• and
• a second information that specifies whether or not the global navigation system assesses the faulty space vehicle as faulty.

A device for position detection by means of a global navigation system in which a plurality of space vehicles transmit information to the device for determining the position of the device in space;

• wherein the device comprises:
• receiving means for receiving an integrity information that includes a first information from the global navigation system about the accuracy of a signal in space error SISE of a faulty space vehicle;
• and a second information that specifies whether or not the global navigation system assesses the faulty space vehicle as faulty;
• processing means for calculating an integrity risk from the received first and second information, and from further information;
• and
• alert means for raising an alert if the calculated integrity risk is larger than an allowed integrity risk.

The method for determining integrity risk of information disseminated from space vehicles in a global navigation system which provides integrity information that includes a first information from the global navigation system about the accuracy of a signal in space error SISE of a faulty space vehicle;

• and a second information that specifies whether or not the global navigation system assesses the faulty space vehicle as faulty;
• said method comprising:
• checking that the integrity information received for every integrity data stream is the integrity information generated by the integrity function of the ground infrastructure;
• selecting out of redundant and positively checked integrity data-streams the integrity data stream to be used;
• determining from selected and positive checked integrity information and the navigation information which signals are valid;
• computing an integrity risk at the alert limit for the critical operation period wherein only valid signals are considered;
• and
• computing a number of critical space vehicles for the critical operation period, considering only space vehicles that provide valid signals;
• and
• generating an alert for the user which indicates whether or not the received information should be used for position detection.