SAMPLED DATA SYSTEMS WITH RANDOM INPUTS 281 
One example of system synthesis has been given, that of the Wiener 
filter for sampled data. This synthesis technique leads to the transfer 
function of the linear filter which will minimize the mean-square error of 
prediction or smoothing. An example which is worked out shows that 
under certain circumstances a simpler filter, such as a zero-order hold, 
may be more desirable than the optimum filter. The optimum filter 
always remains as a guide, however, to indicate how well the practical 
filter performs. 
