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From: R_Tim_Coslet@cup.portal.com
Newsgroups: sci.electronics,sci.physics
Subject: Re: A question about the Nyquist theorm
Message-ID: <39342@cup.portal.com>
Date: 16 Feb 91 16:06:11 GMT
References: <91046.095459F0O@psuvm.psu.edu> <1751@manta.NOSC.MIL>
Organization: The Portal System (TM)
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In Article: <1751@manta.NOSC.MIL>
	north@manta.NOSC.MIL (Mark H. North) writes:
>In article <91046.095459F0O@psuvm.psu.edu> F0O@psuvm.psu.edu writes:
>>
>>     I was reading an article that states the Nyquist theorm as:
>>     "The sample frequency must be at least twice the highest frequency
>>component within the analog signal for an accurate representation of the
>>analog signal".
>
>This is an incorrect statement of the Nyquist theorem. The sample freq
>must be *greater* than twice the highest freq component...
>
Looks accurate to me, it says "at least twice" and you say "*greater* than 
twice". Both wordings mean the same to me (although the second is probably
clearer due to the emphasis).

While the Nyquist criteria sets a minimum theoretical sampling rate, practical
sampling rates are generally at least 5 times max frequency component (and
more samples may be required if better reproduction is required, 5 times is
just a "rule of thumb").

                                        R. Tim Coslet

Usenet: R_Tim_Coslet@cup.portal.com             BIX:    r.tim_coslet
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