Path: news.mathworks.com!not-for-mail
From: <HIDDEN>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Effect of sampling frequency for FFT
Date: Fri, 30 Oct 2009 15:11:01 +0000 (UTC)
Organization: The MathWorks, Inc.
Lines: 14
Message-ID: <hcevm5$se2$1@fred.mathworks.com>
References: <hcev3g$lej$1@fred.mathworks.com>
Reply-To: <HIDDEN>
NNTP-Posting-Host: webapp-05-blr.mathworks.com
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 8bit
X-Trace: fred.mathworks.com 1256915461 29122 172.30.248.35 (30 Oct 2009 15:11:01 GMT)
X-Complaints-To: news@mathworks.com
NNTP-Posting-Date: Fri, 30 Oct 2009 15:11:01 +0000 (UTC)
X-Newsreader: MATLAB Central Newsreader 1406655
Xref: news.mathworks.com comp.soft-sys.matlab:581299


"juho salminen" <jssalmi3@cc.hut.fi> wrote in message <hcev3g$lej$1@fred.mathworks.com>...
> Hi, 
> 
> I have done some tests with artificial sinusoidial data with white noise added on it. It seems, that the higher sampling frequency I have, the better is signal to noise ratio in FFT. With this I mean, that I take FFT with constant window length, let's say 500 samples. Signal itself is kept constant, let's say 30Hz. 
> Highter sampling frequency then, of course, reduces the time window size. 
> This should simulate measurements of some sinusoid with  different sampling frequencies
> 
> Do you know what would cause better SNG values, when sampling frequency increases?
> 
> Thanks already for answers,
> 
> -Juho

Note: I am talking about SNR (!)  for detecting amplitde of signal. Amplitudes seem to be always closer to right value, when sampling frequency is increased