wsmith@mdbs.UUCP (Bill Smith) (09/28/89)
I have seen a few terms in comp.dsp recently that I am unfamiliar with. Would someone be kind enough to mail me a definition? I'll try to post a summary if someone else hasn't beaten me to it. The term that I am most unfamiliar with is "decimation." Also, although phase shift is fairly clear what it means, I am curious what a hi-fi system that had excessive phase shift would sound like. Would if affect mainly sounds like a rim shot on a drum that are I could imagine are similar to an impulse function and thus have a large high freqency component? Thanks. Bill Smith uunet!pur-ee!mdbs!wsmith
charlie@oakhill.UUCP (Charlie Thompson) (09/30/89)
In article <1453@mdbs.UUCP>, wsmith@mdbs.UUCP (Bill Smith) writes: > > I have seen a few terms in comp.dsp recently that I am unfamiliar with. > Would someone be kind enough to mail me a definition? I'll try to post > a summary if someone else hasn't beaten me to it. > > The term that I am most unfamiliar with is "decimation." > > Bill Smith > uunet!pur-ee!mdbs!wsmith Folklore has it that decimation was first carried out by the Romans... when they lined the people of a village up and killed every 10th person. This, I guess, showed who was boss or something. The term has come to mean the inclusion/deletion of every Nth item ( not necessarily 10 ). In the sampling process taking every Nth sample is referred to as N:1 decimation. This reduces the sample rate by a factor of N. This cannot, however, be done without regard to the spectral content of the orginal signal and it's sample rate. Usually the decimation process is preceded by a bandwidth reduction filter. The bandwidth of the original signal must be reduced or aliasing will occur due to the decimation process. Many filters get called decimation filters...usually they are just some form of lowpass filter to reduce the bandwidth. This is sort of a simple explanation not meant for DSP textbooks. -C.T.