Method of enhancing receiver autonomous GPS navigation integrity monitoring and GPS receiver implementing the same

A method of navigating an aircraft using a global positioning system (GPS) receiver, the method comprising:

• receiving GPS satellite signals from a plurality of GPS satellites;
• determining a least squares navigation solution for the GPS aircraft as a function of the received satellite signals;
• determining as a function of the received satellite signals a first correction to the least squares navigation solution, wherein the least squares navigation solution and the first correction to the least squares navigation solution are together indicative of a first navigation solution which is offset by the first correction from the least squares navigation solution;
• navigating the aircraft using the first navigation solution;
• wherein determining as a function of the received satellite signals the first correction to the least squares navigation solution further includes determining as a function of the received satellite signals a maximal integrity correction to the least squares navigation solution, the first navigation solution being a maximal integrity navigation solution;
• and
• determining as a function of the received satellite signals a horizontal uncertainty limit (HUL) radius RMI for the maximal integrity navigation solution, wherein the maximal integrity navigation solution and the HUL radius RMI together define a smallest circle in horizontal space centered at the maximal integrity navigation solution which contains a true horizontal position of the aircraft with a probability of 0.999.

A global navigation satellite system (GNSS) receiver comprising:

• an antenna adapted to receive GNSS satellite signals from each of a plurality of GNSS satellites;
• navigation solution determining means, coupled to the antenna and receiving the GNSS satellite signals from each of the plurality of GNSS satellites, for determining both a horizontal position of a least squares navigation solution for the receiver and a horizontal position of a first navigation solution for the receiver as functions of measurements corresponding to the received GNSS satellite signals, wherein the horizontal position of the first navigation solution for the receiver is offset from the horizontal position of the least squares navigation solution for the receiver;
• and
• means for computing relative magnitudes of partitions of parity space, each of which is defined as that subset of parity space whose constituent points all have a greatest proximity of points in parity space to a characteristic line of a particular measurement.