Abstract: A multichannel, digital filter capable of operation in either decimination or interpolation mode receives sequences of time multiplexed sampled from M input channels and filters the input values from each channel to produce filtered output data for each channel. The filter includes N serially connected digital low pass filters for each channel. Low pass filter N+1 is executed only half as often as low pass filter N, thereby providing a decimation or interpolation function, depending on which mode is selected. The filter may include apparatus for sequencing the low pass filters and for storing the state variables employed by such filters. In decimation mode, the filter may either operate in a single or multipass mode.