a signal dispersion cancellation structure receives incoming signal samples at an incoming rate , stores these samples in a first memory and then writes these samples at a submultiple of the incoming rate into a plurality of second memories . each second memory is associated with a finite impulse response filter and the second memory samples are coupled to the associated fir filter at the incoming rate . advantageously , apparatus is also provided which enables any sample in a second memory to be provided to the associated fir filter and outputted therefrom at a time related to the position of any signal dispersion .