Design of nonrecursive digital filters to meet maximum and minimum frequency response constraints

A new design method designs nonrecursive digital filters directly from maximum and minimum frequency response constraints. The method will find the minimal length filter required to meet the constraints, or design a filter of any longer length desired. This latter option is helpful when there are constraints on monotonicity in certain bands or when finite word length must be considered. When the frequency response constraints are equal to the deviation of an optimal filter, the optimal filter is designed. If the constraints are loosened, a choice of many filter designs is available.