Newsgroups: comp.dsp
Path: utzoo!utgpu!cunews!bnrgate!bmerh2!news
From: myhui@bnr.ca (Michael Hui)
Subject: Re: trivial low pass filter question
Message-ID: <1991May06.035647.4707@bmerh2.bnr.ca>
Sender: news@bmerh2.bnr.ca (Usenet News Admin)
Organization: Bell Northern Research, Ottawa, Ontario Canada
References: <1991May5.211712.16328@quorum.com>
Date: Mon, 06 May 91 03:56:47 GMT

In article <1991May5.211712.16328@quorum.com> bradr@quorum.com (Brad Rubenstein) writes:
>I have a signal sampled at rate f1, and I want to resample it at f2
>(<f1) as efficiently as possible.  It appears, to prevent objectionable
>aliasing, I have to band-limit the original signal to frequencies below

Discrete-Time Signal Processing
by
Alan V. Oppenheim, Ronald W. Schafer    TK5102.5.02452 1989  ISBN 0-13-216292-X

page 101 to 112 is a clear discription of sampling rate conversion.

After reading this section, you'll see that the "correct" way to do it, when
compared to your suggestion of averaging neighbouring samples, only amount to
multiplying those samples by a factor before adding them up and dividing.
Of course, there is a bit more involved than that, but those additional details
involve shuffling data around, rather than doing arithmatic.

      Michael MY Hui      Ottawa Canada      myhui@bnr.ca