means of the oscillation inducing arrangement an oscillating torque is generated which induces the compactor drum 10 to perform an oscillating rotation o around the axis of rotation d during the compaction process meaning during the forward motion of the roller compactor in the direction of travel f this oscillating rotation in the rolling motion of the compactor drum 10 is transferred along the rolling direction r by way of example acceleration sensors 16 18 may be provided in the area of a bearing shell 14 of the compactor drum 10 in doing so the acceleration sensor 16 for registering the acceleration of the compactor drum 10 in a horizontal direction h may be of such design that it lies along a direction substantially parallel to the plane of the subgrade u to be compacted the acceleration sensor 18 may be designed or arranged in order to detect a vertical acceleration a v meaning an acceleration in a vertical direction v which is substantially orthogonal to the horizontal direction h and thus also orthogonal to the subgrade to be compacted the output signals provided by the two acceleration sensors 16 18 can be transmitted to a data acquisition analysis unit 20 it should be pointed out here that the acceleration may also take place in other areas of the compactor drum 10 such as the interior of the drum mantle 12 which would then require the respective extrapolation of the horizontal or vertical acceleration through coordinate transformation the horizontal acceleration a h and the vertical acceleration a v will be recorded repeatedly during a particular period of oscillating movement o the sampling rate should be at least ten times that of the oscillation frequency of the compactor drum 10 so that during each period of.