General Causal FIR FiltersThe most general case--a TDL having a tap after every delay element--is the general causal Finite Impulse Response (FIR) filter, shown in Fig.2.22. It is restricted to be causal because the output may not depend on ``future'' inputs , , etc. The FIR filter is also called a transversal filter. FIR filters are described in greater detail in .
difference equation for the th-order FIR filter in Fig.2.22 is, by inspection,
Feedforward Comb Filters
TDL for Parallel Processing