Verification of the validity of the position information of a vehicle

A procedure for validating position data received in vehicle surveillance applications, in which vehicles transmit position data indicating their own position to surrounding vehicles (3, 5; 5 '), the procedure comprising the steps of: receiving (S1 ), with a radio-radiometric antenna arrangement (21, 23) of a receiving unit (3), a signal (13; 13 ', 13 ") that carries position data indicating an assumed position (PADS-B (5); PADS-B (5 '), PADS-B (15 ")) of a vehicle, transmitted from a radio source (5; 5', 15"); estimate (S2) the azimuth from the receiving unit (3) to said radio source (5; 5 ', 15 ") using said radiogoniometric antenna arrangement (21, 23) and the received signal (13; 13', 13"); estimate (S3) the distance between the unit (3) of reception and the radio source (5; 5 ', 15 ") based on the flight time, TOF, of a signal that propagates between them at a known speed; calculate (S4) an estimated position (PEST (5); PEST (5 '), PEST (15 ")) from the radio source (5; 5', 15") based on the estimated azimuth and the estimated distance, and determine (S5) a deviation value indicating the deviation / coincidence between the assumed position (PADS-B (5); PADS-B (5 '), PADS-B (15 ")) of a vehicle according to the received data position and estimated position (PEST (5); PEST (5 '), PEST (15 ")) of the radio source (5; 5', 15"), characterized in that the signal (13; 13 ', 13 ") that carries the position data also includes information on the moment of transmission that indicates the moment in which it was transmitted, and because the stage of estimating the TOF includes the steps of establishing the moment at which the signal was transmitted based on the information of the moment of transmission, and determine the time elapsed between the transmission and the reception of the signal.