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- Path: news.jhu.edu!robodude
- From: robodude@deanwong.rad.jhu.edu (Zsolt Szabo)
- Newsgroups: comp.sys.amiga.audio
- Subject: Re: Paula chip and Amiga audio
- Date: 7 Feb 1996 02:57:19 GMT
- Organization: The Dungeon
- Message-ID: <4f94ef$e7@news.jhu.edu>
- References: <wfblanDL5rJB.IK8@netcom.com> <4ekcsm$13p@news.jhu.edu> <4f3gn9$q7m@news.fonorola.net> <4f4mar$hqg@news.cs.tu-berlin.de>
- NNTP-Posting-Host: 128.220.158.43
-
- In article <4f4mar$hqg@news.cs.tu-berlin.de>,
- Tor-Einar Jarnbjo <bjote@cs.tu-berlin.de> wrote:
- >
- >Isn't there a great rule saying that everything which does not
- >"belong" to the signal, is to be considered as noise. Concluding
- >that these frequencies are noise?
- >
- >Tor-Einar
- >
-
-
- But there is no extra signal generated because of aliasing. Here's a diagram:
-
- Example 1. Sound in the frequency domain with a high enough sampling rate
- to avoid aliasing (Nyquist sample rate):
-
- amplitude |
- ^ /\ /\ | /\ /\
- | _______/__\__/__\_|_/__\__/__\______
- |
- | frequency ->
- |
-
- As you can see, the individual samples do not overlap at all in the
- frequency domain and therefore do not produce any aliasing.
-
-
- Example 2. Sound in the frequency domain sampled below nyquist sampling
- frequency:
-
- amplitude |
- ^ /\/\/\/\
- | _______/____|___\______
- |
- | frequency ->
- |
-
-
- In this case the samples are overlaping and are producing aliasing. But
- in fact there is no new signal produced; it is merely an average of the
- original two, and hence it is not noise.
-
-
- --
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