Abstract: A data transmission method, particularly in electric networks, in which coded data are blockwise modulated onto several carrier frequencies within one or several particular frequency bands by an orthogonal frequency division multiplex method (OFDM) and in which the signal corresponding to a data block and obtained by inverse Fourier transformation is transferred to a receiver for a predetermined time duration (T), where individual signals succeed as signal blocks in time. In some embodiments, each signal is multiplied with a window function before transmission, the absolute value of the Fourier transform of which has a zero crossing at the respectively used carrier frequencies, and has secondary maxima, which have a damping of at least −30 dB in relation to the main maximum. In some embodiments, a digital filter can be used instead of the window function, the digital filter having an odd number of coefficients Ck, k=−m, . . . 0, . . .