## Forums Search for: FFT

## angle funtion doesnt give right phase angles

intemp contains an 8 point fft. >>temp = fft(x,num_pts) temp = Columns 1 through 5 0.0000 -0.0000 - 4.0000i 1.4142 +...

temp contains an 8 point fft. >>temp = fft(x,num_pts) temp = Columns 1 through 5 0.0000 -0.0000 - 4.0000i 1.4142 + 1.4142i -0.0000 + 0.0000i -0.0000 Columns 6 through 8 -0.0000 - 0.0000i 1.4142 - 1.4142i -0.0000 + 4.0000i

## Signal processing help required

inI am de-convolving A and B by the standard method of taking FFTs of both time signals and dividing FFT of B by FFT of A, then taking the iFFT of...

I am de-convolving A and B by the standard method of taking FFTs of both time signals and dividing FFT of B by FFT of A, then taking the iFFT of the result to get the de-convolved time signal. A is a time domain signal of 650 discrete data points and B is a time domain signal of 3500 discrete data points. My question/problem is about the differing signal lengths, also getting my head around the...

## Calulate FFT, FRF of time history data

With strain time-history and excitation time-history data, how can I determine the FFT of the time-series data with MATLAB, calculate the strain...

With strain time-history and excitation time-history data, how can I determine the FFT of the time-series data with MATLAB, calculate the strain frequency response function (FRF) and finally plot relationship of magnitude of strain FRF vs. frequency (Hz).

## How to do FFT of random signal?

Using Hanning window. I want to plot the Magnitude_Frequency figure. Which command should I use? Thanks! =20 =20

Using Hanning window. I want to plot the Magnitude_Frequency figure. Which command should I use? Thanks! =20 =20

## 3D filtering.

inHi, I am dealing with 3d data. I am supposed to do a 3d fft followed with a 3d butterworth filter. can somebody tell me how to do it ?...

Hi, I am dealing with 3d data. I am supposed to do a 3d fft followed with a 3d butterworth filter. can somebody tell me how to do it ? ( specificaly multidimensional filtering ? ) -Ankur

## Re: spectrum and fft

Hi! checking this again, I have come out with the following doubt, Using Dr. Valozic example, N=2^12; ...

Hi! checking this again, I have come out with the following doubt, Using Dr. Valozic example, N=2^12; P2=2*4*atan(1); t=[0:P2/N:P2]; x=sin(2*t); f=1/(t(3)-t(2)); [xs,fxs]=pwelch(x,N,f); sum(x.^2)/N %% ans =

## Plotting CCDF

i want to plot the CCDf of the ofdm signal i have calculated my peak to average power as meanSquareValue = Y4'*Y4/length(Y4); peakValue =...

i want to plot the CCDf of the ofdm signal i have calculated my peak to average power as meanSquareValue = Y4'*Y4/length(Y4); peakValue = max(Y4.*conj(Y4)); where Y4 is the fft of the signal ...how should i proceed Regards

## Fourier Transform

inhi everybody I just apply a FFT with 1024 samples (k=1024), to function (i.e): y=sin(2*pi*2.48e9*x+0.1*rand(1,1025))+1 ...

hi everybody I just apply a FFT with 1024 samples (k=1024), to function (i.e): y=sin(2*pi*2.48e9*x+0.1*rand(1,1025))+1 After calculating those 1024 values, how can I draw its power spectrum? How define frequency axis? Thanks.

## FFT Magnitude doubt

Hi Sorry there was some problem with previous mail. Its not == but = only. I dont know hot it got changed. Any how find below...

Hi Sorry there was some problem with previous mail. Its not == but = only. I dont know hot it got changed. Any how find below the new piece of code. ********************************************************* clear all; clc; Fs=100; t=[0:100]/Fs; s

## Re: ofdm simulation (ifft/fft) & NoiseVar

http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=6957 hi.. follow this link and download the m-fil... ofdm...

http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=6957 hi.. follow this link and download the m-fil... ofdm code is there... r u working in only ofdm... or u r workning on papr reduction also... thanku

## saving graph data (sry)

ini know this is a simple thing and im gonna get s**t for asking, but i've been searching the internet for an hour and i cant find an answer. i...

i know this is a simple thing and im gonna get s**t for asking, but i've been searching the internet for an hour and i cant find an answer. i have a graph of an fft and i want to save the data points to a csv file(or some other editable file). how do i do it?

## Change of scale in plot

Hi ! I am using the MATLAB fft() and psd() functions and performing an analysis on a wave file. I am getting a plot using...

Hi ! I am using the MATLAB fft() and psd() functions and performing an analysis on a wave file. I am getting a plot using the abs vale of the same. Could anyone tell me how to go about changing the scale of the axes ? Thanx AnM

## Power Spectral Density

inDear All, I am really strugling to write a nice program giving me the curve of the PSD of a random data. If I use the FFT function I will...

Dear All, I am really strugling to write a nice program giving me the curve of the PSD of a random data. If I use the FFT function I will get a descreat representation and not smooth and continues like I found in some publication. Could any one help me with some matlab code to plot a continues PSD. Thanks very much regards

## Fraunhofer image formation

Hi there Thanks to those people who replied to my phase wrapping problem, I think I understand the situation better now. I have (possibly...

Hi there Thanks to those people who replied to my phase wrapping problem, I think I understand the situation better now. I have (possibly obvious) question with regards to Fraunhofer diffraction, please help! Basically I'm confused as to the difference between a point spread function (obtained using an FFT) and the images that you see on photographic film in standard optics textbooks, e.g. f...

## fast fourier code

inhello everyone, i am performing fft,ifft & nested for loops on 21x1985 matrix. it is taking a lot of time. is there any...

hello everyone, i am performing fft,ifft & nested for loops on 21x1985 matrix. it is taking a lot of time. is there any function that i can use to do it faster. i'v heard of something called vectorization but couldnt find it anywhere. This is very urgent . tha

## using ifft in MATLAB

I am having trouble getting the following problem to work-can anybody help me? problem:Obtain the 1024-point inverse FFT of...

I am having trouble getting the following problem to work-can anybody help me? problem:Obtain the 1024-point inverse FFT of a sequence of numbers whose imaginary parts are all zero, and the real parts are the following: b(1)=b(1023)=0.5 b(3)=b(1021)=0.1

## More on the spectrum

Hi everyone. I got some more questions on the power spectrum. Basically, I have done my own function (nothing very...

Hi everyone. I got some more questions on the power spectrum. Basically, I have done my own function (nothing very sofisticated) which detrends the signal, gets the number of integer segments you can apply depending on the length of the fft window you want to apply (passed as

## frequency identifier using fft

Hi, I'm working on my Thesis and part of it is the identification of=20 frequencies in a .wav file, using a function generator with a...

Hi, I'm working on my Thesis and part of it is the identification of=20 frequencies in a .wav file, using a function generator with a 90Hz=20 signal and using matlab with my program I'm supposed to get a=20 variable called fre with 90 and another one (valor) with 1, this=20 tells me that I have a signal of 90Hz, but it appears something=20 completely different it says 281 and 1 Here is my ...

## fprintf or ??

inHi, I'm new to matlab without any detailed knowledge in fft. Referring to command sequence below, the original data (seg)...

Hi, I'm new to matlab without any detailed knowledge in fft. Referring to command sequence below, the original data (seg) and its fft2(seg), First a short question: Why the first number has not any imaginary part? And now to the long question:

## MESA (Maximum Entropy Spectral Analysis)

Does anyone know how to calculate Phase of a time series using MESA instead of using FFT? It would be nice to have someone explain...

Does anyone know how to calculate Phase of a time series using MESA instead of using FFT? It would be nice to have someone explain it in plain english (showing where everthing came from and show all variables). I have found many formula's on the internet but they are in engineering t