Two commercially available digital filters with selectable, fixed time
constants and triangular pulse response are discussed to outline thei
r potential advantages over traditional analog filters with semi-Gauss
ian pulse shape. A solution for the ''resolution or throughput rate''
dilemma is offered by the preloaded digital filter fulfilling the post
ulate for the ideal adaptive filter with optimum resolution at any cou
nting rate. Throughput rates of > 100 kc/s are demonstrated for the pr
eloaded digital filter at resolutions superior to those of fixed shapi
ng time filters.