Proper Scaling of FFT of an non-periodic signal
I am trying to calculate the FFT of some sampled data, and have had
some trouble determining the correct way to scale the resulting FFT
Technical note 1703 states to properly scale the FFT (Mx) of a signal
(x), the FFT should be divided by N, where
However, I have determined that this only applies for the case where
the signal x is <periodic>.
What I want to know is how to scale the FFT is the signal is NOT
periodic. Is there a way to accomplish this? I need to determine the
proper magnitude of the FFT for data resulting from an input
sine-sweep, or from a series of...How to apply fft in matlab and see the waveform of fft of a given signal
I need help in matlab code for applying fft and perform fft waveform
of a given signal....who can help me??
> I need help in matlab code for applying fft and perform fft
> of a given signal....who can help me??
My_Spectrum = fft(My_Signal);
My_Spectrum_Conventional = fftshift(My_Spectrum);
Thanks for your kindness.
I still working on my project.more question will be coming if you don
mind helping me.
s...periodic signal by matlab
I want to generate periodic signals of ones and zeros by matlab. It's a periodic signal with active and passive periods, the active period has a value of one and the passive period has zero value. It consists of 7 passive and 6 active periods, starting with passive. Each period is 42 seconds.
Could you guide me through this, thanks.
On Apr 2, 10:43=A0am, "BrnoM " <kentman...@seznam.cz> wrote:
> I want to generate periodic signals of ones and zeros by matlab. It's a p=
eriodic signal with active and passive periods, the active period has a v...How to scale the FFT in Matlab
Hellow! anyone can tell me how to scale the FFT?
suppposed i have a 10 seconds data
x(t),after FFT(x(t)),i will plot Freq-Amplitude,then how to scale the
dt = 1/Fs
t = dt*(0:N-1)
T = N*dt
df = 1/T
f = df*(0:N-1)
max(t) = T - dt
max (f) = Fs - df
Hope this helps.
...FFT scaling of array/FFT scaling of differential function
I have a problem with scaling my graphs for FFT functions.
I am currently implementing forced oscillators and the result output is from the following code
[t x] =ode45(@vanderpol, 0:2*pi/100:4000, [0 1]);
This returns the correct output array. When i transform this however the graphs are not scaled- can someone please help?
i used the following code to transform:
I have looked at alot of different forum posts and can't get help with this (i have tried multiple methods) ... can anyone help me?
Thanks in advance.
...FFT of a discrete signal in Matlab
Fs=1024;% sampling frequency
N=256;% number of samples
x = load('-ascii', 'signal.txt');
%FFT koko taajuusalueelta
figure, plot(f, Xm);AXIS([0 Fs/2 0 1])
Is there anything wrong with the fft of the signal, the plot looks
more like a time domain signal, whereas i was expecting at least some
Uspikes representing the signal frequencies!
Any one who knows about this?
Umutesi Faith skrev:
> Fs=1024;% sampling frequency
> Ts=1/Fs;%sampling interval
> N=256;% number o...how to find fft in matlab for ecg signal
i'm doing my project in matlab for ecg noise cancellation i would like to know how to find fft in matlab for ecg signal
On 2/2/2011 1:47 AM, sugasini vaithiyanathan wrote:
> i'm doing my project in matlab for ecg noise cancellation i would like to know how to find fft
> in matlab for ecg signal
How about using fft?
...Prediction in Matlab with non period signal
This is a student's problem. ;)
I fight with prediction in Matlab with NNT ToolBox. There is some example
about how to use enclosed function but....i spent more than 16 hours on it
and I'm not sure if I'm right becouse it isn't work correct!
I have 1000 samples of signal "W" - this is not period. I want to learn my
net and use it to predict next 20 samples from: 1001 to 1020.
I tryed :
net = newlin([min max],1,0,0.1) % this create a new linear layer with
min/max value, 1 output, 0 delay,0.1 learning rate
%!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!...About FFT (Periodic, non-periodic)
I have read 'a guide to the FFT' in the 'File exchange'
, but confusing about the FFT
The author recommend the following commands
when we'd like to see the spectrum in the frequency domain.
1. fftshift(fft(fftshift(�)))/Fs for (non-periodic signal)
Here, Fs: sampling frequency
2. fftshift(fft(fftshift(�)))/Np for (periodic signal)
Here, Np:number of samples
But what's the difference? and Should i have to divide it
by Np for periodic signal?
beom lee wrote:
> I have read 'a guide to the FFT' in the 'File exchange'
> , but co...how to find period of ecg signal using matlab
iam doing my assainment in biomedical engg.im unable to write a
program to find period of a signal using matlab.
could any body help me.
"rami reddy" <firstname.lastname@example.org> wrote in message
> iam doing my assainment in biomedical engg.im unable to write a
> program to find period of a signal using matlab.
> could any body help me.
help pwelch may get you started.
BTW, the wide keys at the left and right ends of the second row of your
keyboard will allow you to use upper case letters.
...Matlab FFT Reconstruction from Physiologic Frequency-Varying Signal
I am analyzing a physiologic signal that has a varying fundamental
frequency. To create a more accurate reconstruction from the FFT, I wish to
include the bins immediately and symmetrically on either side of the
fundamental bins. I refer to this as the "distribution method."
I am confident I have been able to do a reconstruction using the
fundamental bins (a standard reconstruction). I also performed a
reconstruction for the distribution method. The mean squared error
(comparing both reconstructions to data in the time domain) for the
distribution method is ...FFT of a known periodic signal of arbitrary length with a radix-2 algorithm
I've browsed a bit, so hopefully I've got all my information in order.
I haven't been able to find an answer for this specific problem.
It's for image processing. I'm simplifying 2D regions by applying
low-pass filters to their contours. Specifically, I take an 8-connected
clockwise contour of (arbitrary) n points, and make two new functions,
x(i) and y(i), out of the points' coordinates. Then I do a DFT on each,
apply a Gaussian or low-pass cutoff filter, inverse DFT, and replot. It
works like a charm if I use a naive O(n^2) DFT implementation - but of
course, it'...convolution between periodic signal and random signal
I am trying to convolve a sine wave with a random signal.
Instead of using conv function, I am multiplying them in the
frequency domain and then taking the ifft. I have taken care
of the zero padding issue in the time domain. The problem is
instead of getting a dual-dirac histogram, I always end up
with the histogram of random signal. Can anyone suggest a
proper convolution code between a sine wave (or any periodic
waveform) and random signal?
Thanking everyone in advance.....
Check the fft of the sine wave alone - do you get two peaks and zeros
everywhere else? (To get this...FFT Matlab
I have been collecting emg signal and would like to look at the
frequency of the signal. In Matlab I know there is an FFT function
which I have been using, but ran into a problem when using it. The
example given in the help says it is using a 512-point FFT. I tried
using a 512-point FFT and a 2056-point FFT and noticed that they look
very different. Is the only difference that the 512 gives less points
to plot than the 2056?
I noticed when I plotted signal of a specific length (1:1000) then
plotted more of the same signal (1:2000), the frequency spectrum
overlapped completely if I used th...