Patent ID: 8346469

Claim:
A method for determining protection levels in a satellite navigation system, which method comprises: determining, with a device for receiving signals of the satellite navigation system, an integrity risk at an alert limit for a plurality of application situations; determining, with said device, alert limit intervals between horizontal and vertical alert limits producing an excessive integrity risk that exceeds a specified integrity risk and horizontal and vertical alert limits producing an acceptable integrity risk that does not exceed said specified integrity risk; carrying out, with said device, interval nesting sequences for the alert limit intervals determined by (a) determining horizontal integrity risks at centers of horizontal intervals and changing ends of the horizontal intervals until the horizontal interval size is no larger than a selected percentage of a lower horizontal alert limit, and (b) determining vertical integrity risks at centers of vertical intervals and changing ends of the vertical intervals until the vertical interval size is no larger than a selected percentage of a lower vertical alert limit; setting, with said device, a horizontal protection level to an upper end of the horizontal interval having said horizontal interval size; and setting, with said device, a vertical protection level to an upper end of the vertical interval having said vertical interval size.