Interpolator/decimator filter structure and a notch filter therefor

摘要: A filter structure (Figure 4) including a notch (C) des­ igned to have transmission zero at frequency slightly dis­ placed from one half of the lower sampling rate inter­ polator/decimator, and thus providing increase in attenuation half-rate frequency. The is comprised two like all-pass-­ network filters (31 33) has feed forward feedback connections (39 41), latter connection (41) coefficient multiplier (43). made between tapped output (T) second filters, an input node (35). (33) characterised by throughput transform functions X(Z) Y(Z) given following expressions:- = [Z⁻¹ - K] / [1 KZ⁻¹]; and, α Z⁻¹ where unit delay operator, K coeffic­ ient α, dependant constant.