Path: utzoo!attcan!uunet!cbmvax!vu-vlsi!cheung From: cheung@vu-vlsi.Villanova.EDU (Wilson Cheung) Newsgroups: comp.sys.amiga Subject: Re: Sampling at 29KHz (long) Message-ID: <1615@vu-vlsi.Villanova.EDU> Date: 31 May 88 19:35:36 GMT References: <2845@polya.STANFORD.EDU> <734@eos.UUCP> <53788@sun.uucp> <5872@cup.portal.com> Organization: Villanova Univ. EE Dept. Lines: 13 In article <5872@cup.portal.com>, doug-merritt@cup.portal.com writes: > >it are the 44 khz sampling signal used by a CD player: > >[ waveforms deleted ] > aliasing. With a sampling rate of A of a sine of frequency B, you'll > always get two aliased components of frequencies A-B (here 26Khz) and > A+B (62Khz). that aliasing is occuring here since 44 Khz is more than double 18 Khz. What he is looking at is the result of the sampling process, repeated spectra of the original signal. To obtain the original signal you must pick out one of these repeated spectra. This is done by using a low pass filter that cuts off around 22 Khz (half the sampling rate). Wilson Cheung