Solution separation method and apparatus for ground-augmented global positioning system

A navigation system for a vehicle, comprising:

• first receiving means for mounting to the vehicle and for receiving a plurality of signals from a plurality of satellite transmitters;
• second receiving means for mounting to the vehicle and for receiving correction data;
• and
• solution means for determining a position solution for the vehicle, based on the plurality of signals and at least a first portion of the received correction data;
• subsolution means for determining a plurality of position subsolutions for the vehicle, with each position subsolution based on the plurality of signals and another portion of the correction data different from the first portion.

A navigation system for a vehicle, comprising:

• receiving means for mounting to the vehicle and for receiving correction data;
• solution means for mounting to the vehicle and for determining a position solution for the vehicle, based on a plurality of pseudoranges and received correction data;
• and
• subsolution means for determining a one or more position subsolutions for the vehicle, with each position subsolution based on the plurality of pseudoranges and a respective portion of the received correction data.

A system for a vehicle, comprising:

• solution means for determining a position solution for the vehicle, based on the plurality of pseudoranges and a plurality of differential pseudorange corrections;
• subsolution means for determining one or more position subsolutions for the vehicle, with each position subsolution based on the plurality of pseudoranges and a subset of the differential pseudorange corrections;
• solution separation means for determining one or more separations, with each separation based on a difference between the position solution and at least one of the position subsolutions;
• and
• means for determining a protection limit based on at least one of the separations.

A navigation system for a vehicle, comprising:

• a GPS receiver for determining a plurality of pseudoranges;
• a receiver for receiving a plurality of pseudorange corrections;
• a processor and software means operative on the processor for:
• determining a position solution based on the plurality of pseudoranges and the plurality of pseudorange corrections;
• determining one or more position subsolutions, with each position subsolution based on the plurality of pseudoranges and a portion of the differential pseudorange corrections;
• determining one or more separations, with each separation based on a difference between the position solution and at least one of the position subsolutions;
• and
• determining a protection limit based on at least one of the separations.

A machine-readable medium comprising:

• means for determining a position solution for the vehicle, based on the plurality of pseudoranges and a plurality of differential pseudorange corrections;
• means for determining one or more position subsolutions for the vehicle, with each position subsolution based on the plurality of pseudoranges and a subset of the differential pseudorange corrections;
• means for determining one or more separations, with each separation based on a difference between the position solution and at least one of the position subsolutions;
• and
• means for determining a protection limit based on at least one of the separations.

A method of determining a protection limit for a navigation or guidance system, comprising:

• determining a position solution based on the plurality of pseudoranges and a plurality of differential pseudorange corrections;
• determining one or more position subsolutions, with each position subsolution based on the plurality of pseudoranges and a portion of the differential pseudorange corrections;
• determining one or more separations, with each separation based on a difference between the position solution and at least one of the position subsolutions;
• and
• determining a protection limit based on at least one of the separations.

A method of determining a protection limit for a navigation or guidance system, comprising:

• a step for determining a position solution based on the plurality of pseudoranges and a plurality of differential pseudorange corrections;
• a step for determining one or more position subsolutions, with each position subsolution based on the plurality of pseudoranges and a portion of the differential pseudorange corrections;
• a step for determining one or more separations, with each separation based on a difference between the position solution and at least one of the position subsolutions;
• and
• a step for determining a protection limit based on at least one of the separations.

A method of operating and monitoring a differential position measurement system for a vehicle, the method comprising:

• determining a position solution for the vehicle, based on past and present values of a plurality of pseudoranges, past and present values of a plurality of pseudorange corrections, and past and present values of vehicle motion data;
• determining one or more position subsolutions for the vehicle, with each position subsolution based on the past and present values of pseudoranges, past and present values of the pseudorange corrections, and past and present values of the vehicle motion data;
• and
• determining one or more protection limits based on the position solution and one or more of the position subsolutions.