Abstract: A method of calibration includes obtaining an estimation of the ground speed of an aircraft by an inertial unit V.sub.inertial and by a radar V.sub.radar in at least two different flight orientations and in using these estimations to determine the drift in speed B and a rotation matrix R corresponding to positioning errors of the radar with respect to inertial unit on the basis of the matrix relationship:V.sub.inertial =RV.sub.radar +Bapplied for each of the flight orientations. The ground speed and ground speed drift vectors are expressed by their x, y and z components in a referential system related to the aircraft, and the matrix of rotation R being defined on the basis of the angles of positioning error in terms of yaw .phi., attitude .theta. and roll .psi.

Abstract: A method and system for determining a modulus of a speed of movement of a carrier of radar, including (a) illuminating a same zone on the ground laterally, with radar of the carrier, at times t.sub.1 and t.sub.2 ; (b) measuring respective distances D.sub.1 and D.sub.2 of the carrier to the same zone at the times t.sub.1 and t.sub.2, and Doppler frequency shifts F.sub.d1 and F.sub.d2 of respective echoes returned by the same zone during the times t.sub.1 and t.sub.2 ; and (c) deducing the modulus .vertline.V.sub.h .vertline. of the speed of movement of the carrier based on a relationship ##EQU1## with .lambda. being a wavelength of a radar wave transmitted by the radar. The method and system require neither the locking of the radar to the carrier nor a course drift of the carrier. In this way, precision is improved and it possible to obtain accurate imaging radar modes having images in which distances can be measured with precision.