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Thread Subject:
Confusing angular freq term... Sin(wt) Cos(wt) ...w value?

Subject: Confusing angular freq term... Sin(wt) Cos(wt) ...w value?

From: Sam Clark

Date: 26 Feb, 2013 13:57:07

Message: 1 of 3

Hi,

I've got a program which implements cos(2.0*t), takes the FFT and plots the result.

However when this is done the effective frequency on my FFT graph relates to roughly 1250Hz. Can anyone explain why for me please?

I understand w = 2*pi*f so if w = 2.0 then f = 0.31Hz....which is clearly not correct.

Subject: Confusing angular freq term... Sin(wt) Cos(wt) ...w value?

From: Godzilla

Date: 26 Feb, 2013 14:41:08

Message: 2 of 3

"Sam Clark" <destroythemap666@hotmail.co.uk> wrote in message <kgievj$7op$1@newscl01ah.mathworks.com>...
> Hi,
>
> I've got a program which implements cos(2.0*t), takes the FFT and plots the result.
>
> However when this is done the effective frequency on my FFT graph relates to roughly 1250Hz. Can anyone explain why for me please?
>
> I understand w = 2*pi*f so if w = 2.0 then f = 0.31Hz....which is clearly not correct.

Post what you mean by 'relates to roughly 1250Hz'

Subject: Confusing angular freq term... Sin(wt) Cos(wt) ...w value?

From: TideMan

Date: 26 Feb, 2013 22:27:16

Message: 3 of 3

On Wednesday, February 27, 2013 2:57:07 AM UTC+13, Sam Clark wrote:
> Hi,
>
>
>
> I've got a program which implements cos(2.0*t), takes the FFT and plots the result.
>
>
>
> However when this is done the effective frequency on my FFT graph relates to roughly 1250Hz. Can anyone explain why for me please?
>
>
>
> I understand w = 2*pi*f so if w = 2.0 then f = 0.31Hz....which is clearly not correct.

Well, obviously, the frequency on your FFT graph is wrong.
How did you calculate it?
Show us the code.

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