A method and device for the evaluation of signals of a sensor, in particular of a microwave sensor, is proposed for the detection of the thickness, mass, density and/or moisture of at least one fiber sliver moving relative to the sensor on drafting equipment. A high-frequency unit assigned to the sensor produces a number of first digital signals in digital form of the current state of the (at least one) fiber sliver. The method according to the invention is characterized in that a second digital signal, representing the current sliver thickness or sliver mass of the (at least one) fiber sliver and which is then used to control the drafting equipment and/or to judge the fiber sliver quality, is formed according to an algorithm from the first digital signals made available. In addition a suitable device for the evaluation of the signals of a sensor is proposed.