A method for searching a digital transmission having unknown carrier and symbol frequencies in a modulated reception signal, includes performing successive trials of several carrier and symbol frequencies, using decreasing values of the symbol frequency, demodulating the reception signal with the tried carrier frequency, filtering the demodulated signal in a band having a width corresponding to the currently tried symbol frequency, and producing samples of the filtered signal. For each currently tried symbol frequency, forming a complex indicator having a real component and an imaginary component established from the successive samples of the filtered signal such that they have cyclostationary properties and that one of the components tends to cancel when the other component tends towards a relative maximum, building the spectrum of the variation of the complex indicator, searching for a singular spike in the spectrum, and determining the real symbol frequency from the frequency of the spike.