MODULATION AND DEMODULATION PROCESS IN DIGITAL SIGNAL TRANSMISSION Russian patent published in 2004 - IPC

FIELD: communication systems; transmission of frequency- modulated signals. SUBSTANCE: modulated signals S_j(n) of length T, where i = (0; q 1) differing in frequency so that signal frequencies x_i(n), where f_i = f_o+iΔf, is lowest frequency and f_o is frequency deviation, are placed in agreement during modulation of modulating signal with q character Δf-, where j = (0; q 1), n is sequence number of character; during demodulation frequency of modulated signal x_i(n) is converted into demodulated signal where A is constant corresponding to conversion scale, demodulated signal a_i obtained is compared with threshold levels, and decision is taken on characters S_j(n) transmitted. EFFECT: provision for modulation and demodulation of signal invariant to carrier and reference frequency without adapting to threshold level. 1 cl, 7 dwg