Patent ID: 7848883

Claim:
A method for determining a ground position of a craft using position data emitted in a periodic manner and inertial data: A/ at each emission of position data, using the position data to determine the position of the craft; and B/ between two successive emissions of position data, taking into account said inertial data, and: a) dividing the time gap between these two successive emissions into a plurality of timespans of the same duration, delimited by intermediate times; and d) for each intermediate time, determining the position of the craft with the aid of said inertial data, wherein: the following operations are moreover performed: B/ b) at each of said intermediate times, determining an inertial speed of the craft based on the corresponding inertial data; and B/ c) for each timespan, calculating the average of the inertial speeds of the two intermediate times delimiting the timespan, and the ground displacement of the craft during said timespan is deduced therefrom; and in step d), for each intermediate time, determining the position of the craft based on its position at the previous intermediate time and based on its displacement during the timespan delimited by the two corresponding intermediate times, current and previous, wherein in steps B/c) and B/d), the position of the craft is determined with the aid of the following expressions: { x i + 1 = x i + [ ( vx i + 1 + vx i ) · d ⁢ ⁢ t ] / 2 y i + 1 = [ ( vy i + 1 + vy i ) · d ⁢ ⁢ t ] / 2 vx i + 1 = vx i + ( Vx i + 1 - Vx i ) vy i + 1 = vy i + ( Vy i + 1 - Vy i ) in which: x i+1 and y i+1 are the coordinates in a horizontal plane of said position of the craft at an intermediate time t i+1 ; x i and y i are the coordinates in the horizontal plane of said position of the craft at a previous intermediate time t i ; Vx i+1 and Vy i+1 are the coordinates in the horizontal plane of the inertial speed of the craft at the intermediate time t i+1 ; Vx i and Vy i are the coordinates in the horizontal plane of the inertial speed of the craft at the intermediate time t i ; dt is the duration of the timespan; and vx i and vy i are calculated speeds which are adjusted in regard to the speed of a reception antenna used to generate the position data, at each emission of said position data.