A decimator for use in digital signal processing has an input line for receiving a sequence of input samples at a first sampling rate and a first register for accumulating input samples for which the order in the sequence is a power of a predetermined number greater than one. A control unit for outputs samples from the first register at a second sampling rate. Typically accumulates input samples for which the order in the sequence is a not power of the predetermined number so that the first register accumulates input samples for which the order of said sequence is a power of the predetermined number combined with a current accumulated value in the second register.