In order to determine spectral and/or periodic portions in a sequence of data (d(n)) containing binary values (0; 1) at a number (N) of position numbers (n), the data sequence (d(n)) is evaluated by position number at discrete evaluation points (m) with a complex analysis function (f(n, m)). To this end, to form a complex binary analysis function (BA(n, m)) on the complex analysis function (f(n, m)), a comparator function (k) is used in accordance with the prescription: k (f(n, m)) = + 1 for f(n, m) > (S); k (f(n, m)) = - 1 pour f(n, m)