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

Started by kork...@pacbell.net in Matlab DSP12 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 Predrag Valozic in Matlab DSP17 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 zghofrani in Matlab DSP16 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 shiva_r97 in Matlab DSP12 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 Rayne in Matlab DSP13 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 tough_guy_1977 in Matlab DSP15 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 arnaud_trolle in Matlab DSP12 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 wu_weidong in Matlab DSP13 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 michael melek in Matlab DSP18 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 luis...@yahoo.com in Matlab DSP10 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 msthesis0 in Matlab DSP15 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 Kurt in Matlab DSP9 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 Anonymous in Matlab DSP17 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 Amin Mohaghegh in Matlab DSP11 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 Fatima Nayyar in Matlab DSP17 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 Luis Guilherme Pereira Lima in Matlab DSP15 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 Arnaldo Batista in Matlab DSP17 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 hufada in Matlab DSP17 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 krishnam acharya in Matlab DSP16 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 shiv...@yahoo.com in Matlab DSP12 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