Abstract: A method for identifying capsule defects in a tobacco filter includes measuring values for density and/or moisture content of the filter using a microwave measurement device. The measured values are compared with a threshold value and a presence of a capsule defect in the filter is determined if the measured valued undershoots the threshold value. A value for a degree of fluctuation of the measured values is determined at a region in front of a measurement location and/or behind the measurement location in which at least one measured value is below the threshold value. The value for the degree of fluctuation is compared with a predetermined capsule threshold value. The capsule defect comprises a broken capsule when the value for the degree of fluctuation exceeds the capsule threshold value, and the capsule defect comprises a missing capsule when the value for the degree of fluctuation undershoots the capsule threshold value.

Abstract: A method and device for measuring the position of sections with an absorbing substance in multi-segment filter rods of the tobacco processing industry by measuring a varying shift of the resonance frequency A and/or spread of the resonance line B during movement of the rod in the longitudinal direction, using a microwave resonator, which has a field concentration in a spatial area, wherein this spatial area is smaller in the rod direction than the segment length to be determined, forming a difference quotient ?A of the resonant frequency shift A and/or ?B of the resonance line spread B relative to the longitudinal direction, determining local extreme values of the respective difference quotients, and assigning local extreme values as a position of a transition from a section with higher content of absorbing substance to a section without, or with lower content, of absorbing substance, and vice versa.