Inexpensive monitoring technique for achieving high level integrity monitoring for differential GPS

An integrity monitor differential global positioning system (GPS) navigation system, comprising:

• a radio receiver adapted to receive a GPS differential correction message from a broadcast;
• a GPS sensor coupled to receive said differential correction message from said radio receiver, said GPS sensor adapted to determine a first position using said differential correction message, said GPS sensor further adapted to provide navigation data directly to a plurality of primary flight instruments of an aircraft, said GPS sensor certified to a first certification level;
• and
• a GPS monitor coupled to said GPS sensor, said GPS monitor coupled to receive said differential correction message from said radio receiver, said GPS monitor certified to a second certification level below said first certification level, said GPS monitor adapted to determine a second position using said differential correction message and monitor said GPS sensor to detect a fault condition by comparing said first position and said second position, such that said GPS monitor ensures the integrity of said GPS sensor and ensures said navigation data is provided in accordance with said first certification level.

In an integrity monitor differential global positioning system (GPS) navigation system, a method for providing high integrity navigation data for aircraft navigation, the method comprising the steps of:

• a) receiving a GPS (global positioning system) signal;
• b) receiving a GPS differential correction message from a broadcast by using a radio receiver;
• c) determining a first position from said differential correction message and said GPS signal using a GPS sensor certified to a first certification level;
• d) providing navigation data directly to a plurality of primary flight instruments of an aircraft by using said GPS sensor;
• e) determining a second position from said differential correction message and said GPS signal using a GPS monitor certified to a second certification level having less stringent requirements than said first certification level;
• f) ensuring said navigation data complies with the requirements of said first certification level by comparing said first position and said second position to detect a fault condition;
• and
• g) ensuring the integrity of said GPS sensor by comparing said first position and said second position.