AbstractThe use of the function filtration method to increase immunity to interference in ask systems is discussed. To achieve increased immunity, a function elimination filter (f.e.f.) was constructed to eliminate any sine‐wave interference (s.w.i.) witha prioriunknown parameters. When there is no random noise, such a filter provides a zero error probability, in spite of the existence of s.w.i. It is shown that there exist some situations when the use of an f.e.f. provides an error probability less than that achieved by a matched filter (m.f.), even if the input process includes both s.w.i. and random nois