Abstract: An apparatus for measuring a surface comprises first sensors, which are distributed two-dimensionally in space, said first sensors interacting with the surface in a contactless manner using a microwave range of electromagnetic signals, and the first sensors receive at least two of the microwave signals of the interaction with information relating to distances between the sensors and the surface as a reflection, the microwave signals of the interaction representing both dimensions of the space of two-dimensional distribution of the first sensors. A data processing unit receives said information on the distances, and determines at least one geometrical parameter of the surface on the basis of the information.

Abstract: An apparatus for measuring a surface comprises first sensors, which are distributed two-dimensionally in space, said first sensors interacting with the surface in a contactless manner using a microwave range of electromagnetic signals, and the first sensors receive at least two of the microwave signals of the interaction with information relating to distances between the sensors and the surface as a reflection, the microwave signals of the interaction representing both dimensions of the space of two-dimensional distribution of the first sensors. A data processing unit receives said information on the distances, and determines at least one geometrical parameter of the surface on the basis of the information.

Abstract: For clipping a signal with respect to a clipping threshold (Amax), a signal portion above the clipping threshold and a peak (Pk) in the signal portion are detected, a clipping function depending on end times (ts, te) of the signal portion, the amplitude of the detected peak and the clipping threshold is derived, and the signal portion is clipped by multiplying it by the clipping function. The first portion can be enlarged up to the lowest boundary points (t1+1, t2?1) on the first ascending portion and the last descending portion of the detected peak. Spectral leakage in the sidebands out to the frequency band of the clipped signal is eliminated by a filtering device. The filtered dipped signal to the input of the amplifier has peaks as close to the saturation threshold of a power amplifier as possible.

Abstract: For clipping a signal with respect to a clipping threshold (Amax), a signal portion above the clipping threshold and a peak (Pk) in the signal portion are detected, a clipping function depending on end times (ts, te) of the signal portion, the amplitude of the detected peak and the clipping threshold is derived, and the signal portion is clipped by multiplying it by the clipping function. The first portion can be enlarged up to the lowest boundary points (t1+1, t2?1) on the first ascending portion and the last descending portion of the detected peak. Spectral leakage in the sidebands out to the frequency band of the clipped signal is eliminated by a filtering device. The filtered dipped signal to the input of the amplifier has peaks as dose to the saturation threshold of a power amplifier as possible.

Abstract: For measuring the water content of a web in the wire section of a paper machine, at least one radiofrequency-operated resonator sensor forms an electric near field, in which a web affects the resonance frequency of each resonator sensor. The water content of the web is measured as a function of the resonance frequency of each resonator sensor in a measuring unit.

Abstract: For measuring the water content of a web in the wire section of a paper machine, at least one radiofrequency-operated resonator sensor forms an electric near field, in which a web affects the resonance frequency of each resonator sensor. The water content of the web is measured as a function of the resonance frequency of each resonator sensor in a measuring unit.