Abstract: A digital pre-modulation filter with a finite impulse response having the value k(t)=h(t).multidot.w(t), where h(t) represents an impulse response of the type that is customary for a modulator, for generating in response to data signals an angle-modulated carrier signal having a substantially constant amplitude, and w(t) represents a window function by which the impulse response of the pre-modulation filter is truncated softly. It turns out to be possible to reduce the disturbing effects with respect to the power spectrum caused by such a soft truncation and cancel them with respect to the phase of the angle-modulated carrier signal. Thereto, according to the invention the impulse response k(t)=A{g(t)+x(t)}.multidot.w(t) is selected where A is a correction factor which is usually equal to one, g(t) is the untruncated impulse response of the filter, x(t) is a constant c.sub.