Simulating asynchronous timing-recovery loops using multirate techniques

When simulating a receiver one will usually be operating with as small a number of samples per symbol as possible, and generally these samples will not coincide with the optimum samples of the underlying analogue waveform. To reconstruct the optimum sample points from the samples available, a generic loop structure is discussed and a polyphase-filter-based fractional delay element implementation described. The effect of delay quantisation on the detector´s S-curve characteristic is demonstrated