## Non uniform discrete fourier transform (NDFT) and Non uniform inverse discrete fourier transform (NIDFT)

Started by in Matlab DSP15 years ago

Hello, I am a new member of this group and i want to post a question regarding a project that i am working on. I have to implement in a...

Hello, I am a new member of this group and i want to post a question regarding a project that i am working on. I have to implement in a communication channel both Non uniform discrete fourier transform (NDFT) and Non uniform inverse discrete fourier transform (NIDFT). I know the uniform discrete fourier transform (DFT) can be implemented in mat lab using the FFT algorithm. I am wondering if any...

## Fourier?

Started by in Matlab DSP20 years ago

Hi! In Symbolic Math Toolbox Version 1.1 (Student Edition) 5-23-94, With: > fourier('cos(wo*t)') the answer is: ...

Hi! In Symbolic Math Toolbox Version 1.1 (Student Edition) 5-23-94, With: > fourier('cos(wo*t)') the answer is: ans = pi*(Dirac(w-wo)+Dirac(w+wo)) But, for: > fourier('cos(wo*(t-d))') I get: ans

## how can I see fourier transform?

Started by in Matlab DSP19 years ago 7 replies

I want to see the fourier transform of a function, say cos(t). I typed: >>syms t; >>fourier (cos(t)) but it gives error and...

I want to see the fourier transform of a function, say cos(t). I typed: >>syms t; >>fourier (cos(t)) but it gives error and says: ??? syms t Missing operator, comma, or semi-colon. what should I do?

## fast fourier transform

Started by in Matlab DSP15 years ago 1 reply

Hi all, I am new to signal processing as well as matlab. I have a symmetrical rectangular pulse in time domain. I would like to peform...

Hi all, I am new to signal processing as well as matlab. I have a symmetrical rectangular pulse in time domain. I would like to peform fourier transform of this signal using fft command using matlab. I would like to obtain the same results using continuous fourier transform (for this case I have a analytical solution which is a function of frequency 'f'). I would like to plot ...

## Fast Fourier Transform

Started by in Matlab DSP15 years ago

Hi, I am very new to Matlab, and I'm supposed to use the built-in FFT function to do discrete Fourier Transform for f(x) = sin x + 4 cos(5x) +...

Hi, I am very new to Matlab, and I'm supposed to use the built-in FFT function to do discrete Fourier Transform for f(x) = sin x + 4 cos(5x) + (sin(6x))^2 on the interval [-pi, pi] with a uniform partition for the interval with n = 9. Then I have to (a) Plot the magnitudes of the Fourier coefficients and (b) Compute the first-order derivates at the grid points via FFT and compare them with f'(...

## FOURIER TRANSFORM OF SIGNUM USING MATLAB

Started by in Matlab DSP17 years ago

i'm trying ot find the transform of signum(t) on matlab. I used this code syms t w fourier(sign(t)) but i got...

i'm trying ot find the transform of signum(t) on matlab. I used this code syms t w fourier(sign(t)) but i got an error saying sign does not take in values of type sym. How else would I get to see the fourier transform displayed on matlab

## Iterative algorithm for signal reconstruction

Started by in Matlab DSP15 years ago

Hi everybody, I was wondering a question about iterative procedures for signal reconstruction from Fourier Transform Phase or Signed Fourier...

Hi everybody, I was wondering a question about iterative procedures for signal reconstruction from Fourier Transform Phase or Signed Fourier Transform Magnitude (Oppenheim, Hayes, Van Hove): to your knowledge, can these techniques apply to non-stationnary 1-D signals ? Or should I inevitably go in for the use of iterative reconstruction from short-time Fourier transform ? In anycase...

## Fourier Transform

Started by in Matlab DSP15 years ago

Hi all, I'm new to Matlab, and I'm trying to evaluate a function via fast fourier transform using Matlab, then compare the values at...

Hi all, I'm new to Matlab, and I'm trying to evaluate a function via fast fourier transform using Matlab, then compare the values at each gridpoint with the exact value. The function is y1 = cos(x)-20*sin(5*x)+6*sin(12*x) on the interval [-pi, pi], using n = 9 gridpoints. I first tried to find the Fourier coefficients F1: n = 9; x = -pi:(2*pi/(n-1)):pi; y1 = cos(x)-20*sin(5*x)+6*sin...

## fourier transform

Started by in Matlab DSP20 years ago

hi how can i get a fourier transform for a signal in simulink 2.. i tried spectrum analyzer but i couldn't connect it. thanks ...

hi how can i get a fourier transform for a signal in simulink 2.. i tried spectrum analyzer but i couldn't connect it. thanks

## Duality in continous fourier transform

Started by in Matlab DSP13 years ago

Hi, If X(w) is the Fourier Transform (FT) of x(t), I know that the FT of dx(t)/dt is jwX(w). Using the duality property I obtained that the FT of...

Hi, If X(w) is the Fourier Transform (FT) of x(t), I know that the FT of dx(t)/dt is jwX(w). Using the duality property I obtained that the FT of tx(t) is (2pi/j)(dX(-w)/dw), but I found in a table that the correct FT is in fact jX(w). Could you help me to find the mistake here? I will be thankful if somebody could help me with that. Luis Felipe

## Fourier Linear Combiner

Started by in Matlab DSP18 years ago

Haaai all Has anyone heard/worked with fourier linear combiners? If so, i would like to get some help from them... Any...

Haaai all Has anyone heard/worked with fourier linear combiners? If so, i would like to get some help from them... Any literature where i can find more details about it would also help. Thanks much, Rick

## fourier series coefficients

Started by in Matlab DSP12 years ago 2 replies

hello all, I have a one period square wave on the interval[0,2] defined as: y(t)= 1, 0

hello all, I have a one period square wave on the interval[0,2] defined as: y(t)= 1, 0

## Fourier-Mellin Transform

Started by in Matlab DSP20 years ago

Any body knows where I can find the *.m file for Fourier-Mellin Transform ? Thank a lot

Any body knows where I can find the *.m file for Fourier-Mellin Transform ? Thank a lot

## Fourier Transform Plot in MATLAB Symbolic

Started by in Matlab DSP13 years ago

I used fourier command in Symbolic toolbox and got " i*pi*(dirac(w+1)-dirac(w-1))". I am wondering how I can plot this as a function of...

I used fourier command in Symbolic toolbox and got " i*pi*(dirac(w+1)-dirac(w-1))". I am wondering how I can plot this as a function of w? Can anyone help me with that thank you Amin

## CTFS

Started by in Matlab DSP20 years ago

hi, can anybody help me ? i need code for continous time fourier series and continous time inverse fourier series. thanks ...

hi, can anybody help me ? i need code for continous time fourier series and continous time inverse fourier series. thanks regards fatima

## HELP -- Inverse Short Time Fourier

Started by in Matlab DSP18 years ago

HI, i'm searching for a tool in simulink that implement a ISTFT (Inverse SHort Time Fourier)... Who can help me? ...

HI, i'm searching for a tool in simulink that implement a ISTFT (Inverse SHort Time Fourier)... Who can help me? Thanks, Luis Guilherme

## FT of abs(f)

Started by in Matlab DSP20 years ago 1 reply

Helo there, Is there a mathematical relationship between the Fourier Transform of a function and the Fourier Transform of the...

Helo there, Is there a mathematical relationship between the Fourier Transform of a function and the Fourier Transform of the absolute value of the same function. I tried to use the fact that abs(f)=sqrt(f^2), but could not reach a lean mathematical relation...note that f is a

## anybody know the Fourier-Mellin Transform?

Started by in Matlab DSP20 years ago

hi, i am trying to simulate a optical pattern recognition problem using matlab.but i don't know how to realize the fourier-mellin...

hi, i am trying to simulate a optical pattern recognition problem using matlab.but i don't know how to realize the fourier-mellin transform using matlab. does anyone know the problem? waiting for your response. thanks a lot!

## frequency domain filtering?

Started by in Matlab DSP19 years ago 2 replies

Hi all, this is regarding my doubt in frequeny domain filtering. is it means to say that we convert a signal x(n) into its...

Hi all, this is regarding my doubt in frequeny domain filtering. is it means to say that we convert a signal x(n) into its frequency domain and we get the fourier coefficients which represent the amplitude and phase of the frequency components. then we make the fourier

## fft of step functions

Started by in Matlab DSP15 years ago

Hi, I want to do fast fourier transform (using matlab) of the following functions a) step function.i.e f(t) = 0.0 if t =0 and ...

Hi, I want to do fast fourier transform (using matlab) of the following functions a) step function.i.e f(t) = 0.0 if t =0 and b) step function with exponential decay parameter g(t) = 0.0 if t =0 Here the time domain is from (-infinity to +infinity) The obtained results would be compared with continuous fourier transfo