Envelope calculation by means of phase shifting

The method involves scanning (601) portion received signal of the level sensor at discrete times. The samples of the sampled received signal are converted into digital samples. The new value for a digital sample of the first digital samples is calculated (605) by shifting the phase of the sampling value of the sampled portion of the received signal by a predetermined angle. The envelope curve value is calculated (606) from the first digital sample and the data generated by the rotation of the new phase value. Independent claims are included for the following: (1) level sensor for calculating envelope curve of envelope and for determining fill level; (2) sensing and signal processing arrangement; and (3) program element stored on computer-readable storage medium for calculating envelope curve of envelope and for determining fill level.