I am trying to simulate a rational sample rate conversion architetcure using CIC filters (decimation) and farrow structure (interpolation). Input data is QPSK modulated and upsampled by a large factor (325 to be exact). I try to decimate the signal by 125 in three stages. each stage is in turn a CIC (3-stage) decimation (by a factor of 5) filter. However the constellation i get after CIC filter shows alot of points centered at origin.I havent used any compensation filter...or may be i should increase the oversampling ratio. any suggestion(s) will be of valuable help. best regards, fahim
poor constellation after CIC filter
Started by ●February 21, 2006