86.1 Introduction A structural representation using interconnected basic building blocks is the first step in the hardware or software implementation of an LTI digital filter The structural representation provides the key relations between some pertinent internal variables with the input and output that in turn provides the key to the implementation• A structural representation using interconnected basic building blocks is the first step in the hardware or software implementation of an LTI digital filter • The structural representation provides the key relations between some pertinent internal variables with the input and output that in turn provides the key to the implementation §6.1 Introduction