Abstract: Helical wind rotor, comprising at least two blades (1) which, as observed in cross section, are of substantially equivalent shape and curved, and are located parallel with the rotational axis (o) and so that the blades (1) are arranged most suitably at equal intervals with respect to the rotation angle of a cylindrical co-ordinate system (o, z). In order to bring about helical form of the wind rotor, the blade cross sections (sp) are arranged to revolve in the longitudinal direction (z) of the wind rotor. The blade cross section (sp) belonging to the wind rotor is arranged substantially different from the shape of semicircle, so as to enable manufacturing of the blade of a substantially planar blank. The invention also relates to a method for manufacturing a wind rotor of the above presented type.

Abstract: The invention relates to a method in connection with a QAM receiver wherein, particularly when making use of a 32QAM, 64QAM demodulator lator a like, a digital transmission signal (1) to be transmitted is down-converted in a tuner and band-filtered with a first filter to a preferably fixed, standard intermediate frequency (5). This is followed by a further subsequent down-conversion by a first oscillator and filtering with a second filter to a so-called low intermediate frequency (6) which is equal to the symbol rate used in image transmission or its low odd multiple, whereafter an AD converter (7) is used under the synchronization of a second oscillator (8) for picking up samples (X) from the symbol sequence of a processed signal (6) to a demodulator (9), capable of regulating the above-mentioned, preferably voltage-controlled oscillators.