the invention refers to a procedure and a device for measuring the degree of compaction attained when compacting a foundation by means of a vibrating compaction tool . the movement of that part of the compaction tool which rests on the foundation is sensed and analyzed . the time interval elapsing between successive passages of the movement signal through the zero point or other reference level is measured . alternatively , the ratio between the absolute values of the extreme positive and extreme negative values of the motion in relation to the said level is also measured . by means of the relative magnitudes of these time intervals and amplitude relationships respectively a quantity is formed which comprises a measure of the degree of compaction of the foundation . the invention also refers to electronic devices which sense the movement and calculate the time intervals and amplitude relationships and calculate a quantity as a function of these , which comprises a measure of the degree of compaction attained in the foundation .