Vehicle location method and system

(Amended) A vehicle location method for locating a target vehicle, comprising:

• providing global position information indicative of a position of the target vehicle in latitude and longitude coordinates;
• converting the global position information to a relative position with respect to a reference waypoint;
• assigning the target vehicle a time slot based on the target vehicle's relative position;
• and
• transmitting the target vehicle's global position information beginning at a predetermined time within the target vehicle's assigned time slot.

A vehicle location system for locating a target vehicle, comprising:

• a receiver aboard the target vehicle that receives global position information indicative of a position of the target vehicle in latitude and longitude coordinates;
• means for dividing a predetermined area into a plurality of grid segments having predetermined dimensions in latitude and longitude, each grid segment having a reference waypoint, the target vehicle being positioned in one of the grid segments;
• means for converting the global position information to a relative position with respect to the reference waypoint of the grid segment in which the target vehicle is located;
• means for assigning the target vehicle a time slot based on the target vehicle's relative position;
• and
• a transmitter that transmits the target vehicle's global position information during the target vehicle's assigned time slot.

A vehicle location system whereby position data regarding a target aircraft located on an airport surface are made available to other aircraft and to an airport traffic control tower by transmitting a data message containing position coordinates of the aircraft, during a uniquely defined time slot, comprising:

• means for dividing the airport surface into grid segments having predetermined dimensions in latitude and longitude;
• means for assigning a reference waypoint to each grid segment at a predetermined location within the grid segment;
• means aboard the target aircraft for generating a synthetic latitude function time mapped onto the grid segment within which the target aircraft is located in accordance with a predetermined time period and sequence;
• means aboard the target aircraft for generating a synthetic longitude function time mapped onto the grid segment within which the target aircraft is located in accordance with a predetermined time period and sequence, the synthetic latitude and longitude functions together defining a plurality of time slots;
• means for assigning the target aircraft a time slot based on the relative position of the aircraft with respect to the reference waypoint for the grid segment in which the target aircraft is located;
• and
• a transmitter aboard the target aircraft, the transmitter being adapted to transmit the data message during the assigned time slot.

A vehicle location method of locating a target vehicle, comprising:

• receiving at the target vehicle from a fixed ground station uncorrected position coordinates of the ground station, the uncorrected position coordinates being determined by the fixed ground station based on GPS signals received from a plurality of GPS satellites visible from the fixed ground station;
• calculating a ground station pseudo-range for each of the plurality of GPS satellites visible from a fixed ground station using the uncorrected position coordinates, each ground station pseudo-range being indicative of a distance from the fixed ground station to a different one of the visible GPS satellites;
• calculating a ground station actual range for each of the plurality of visible GPS satellites, each ground station actual range being indicative of a difference between surveyed coordinates of the ground station and an ephemeris of a different one of the GPS satellites;
• determining a GPS correction factor for each of the visible GPS satellites based on a difference between the ground station pseudo-range and the ground station actual range for the GPS satellite;
• calculating a vehicle pseudo-range from the target vehicle to a selected one of the GPS satellites;
• adjusting the vehicle pseudo-range by the GPS correction factor for the selected GPS satellite, thereby obtaining an actual vehicle range;
• and
• determining the position of the target vehicle in latitude and longitude coordinates based on the actual vehicle range.