## Forums Search for: fourier

## Fourier Transform Tutorial

Hi, I have created a Fourier Transform tutorial. It is located here: http://www.fourier-series.com/f-transform/index.html It uses...

Hi, I have created a Fourier Transform tutorial. It is located here: http://www.fourier-series.com/f-transform/index.html It uses interactive flash programs to help you see how the fourier transform works. There are currently 5 flash modules with lots of embedded audio in each module. The site also includes tutorials on the fourier series, complex numbers, the discrete fourier trans...

## DFT of a Fourier summation

inIf I have an expression for the Fourier expansion of a signal, is it valid to take the FFT or the DFT of the signal (e.g. in Matlab) in order...

If I have an expression for the Fourier expansion of a signal, is it valid to take the FFT or the DFT of the signal (e.g. in Matlab) in order to examine its spectral contents? In particular, I have a Fourier sum that describes an RF pulse-modulation process. The sum is equivalent to the fourier series expansion of a PWM waveform multiplied by the fourier series expansion of an RF rectangular ...

## fourier transform of impulse train

inHi everybody.. could any one plz explain me how to get the spectra of dirac com function.my doubt is that what type of signals are...

Hi everybody.. could any one plz explain me how to get the spectra of dirac com function.my doubt is that what type of signals are fourier transformable?Can we take fourier transform for a sine/cosine signal.I get confused vth fourier series and transform while apllying for a signal. Thanks for all who gonna reply. Regards, RAMA

## Fourier Series Tutorial

inHi, I have created a tutorial for the fourier series. It is located at www.fourier-series.com It has audio lectures and interactive flash...

Hi, I have created a tutorial for the fourier series. It is located at www.fourier-series.com It has audio lectures and interactive flash programs that let you see how the fourier series actually works.

## Filtering view of the Fourier transform

inHello Forum, I found in a book the Fourier transform interpreted as a filtering operation: Given a signal f(t), The complex coefficient at...

Hello Forum, I found in a book the Fourier transform interpreted as a filtering operation: Given a signal f(t), The complex coefficient at frequency w0 given by the Fourier transform is X(w0). Say that the signal spectrum is X(w+w0) as if it was the result of a modulation. X(w+w0) is centered at w0. The Fourier integral has {f(t)*exp(-j*w0*t)} as integrand. This step can be seen as a de...

## are these two Fourier transform the same thing?

inHi all, Just looking for a quick confirmation: for a function f1(t)=g(t)u(t), f2(t)=g(t-c) u(t-c), where "u(t)" is the Heaviside...

Hi all, Just looking for a quick confirmation: for a function f1(t)=g(t)u(t), f2(t)=g(t-c) u(t-c), where "u(t)" is the Heaviside function, also called step function. Let G(f) be the Fourier transform of g(t), U(f) be the Fourier Transform of u(t). The two approaches: 1. First find Fourier transform of f1(t)=g(t)u(t), that's to say, G(f) convolve with U(f), then multiply it ...

## Fourier Transform Question

inSuppose I have a signal x(t) with Fourier Transform X(jw). It is known that if one scales the time axis by a factor K, then the frequency axis...

Suppose I have a signal x(t) with Fourier Transform X(jw). It is known that if one scales the time axis by a factor K, then the frequency axis is scaled by 1/K. I am curious about non-linear scalings of the time axis. Is there a way to derive the Fourier Transform of x(exp(t)), given that one knows the Fourier Transform of x(t)?? Bob Adams

## Numeric Sequence & Inverse Discrete Fourier Transform

inHello Everyone, I am trying to analyze a sequence of integral values that come from an unknown but potentially non-random source. At the...

Hello Everyone, I am trying to analyze a sequence of integral values that come from an unknown but potentially non-random source. At the least, the series seem to fail the chi-square test. I had an idea for analyzing the sequence by applying a fourier transform on the values. The fourier transform seems to indicate that the sequence could be periodic. For example, in the fourier transfor...

## Question about fourier transform and laplace transform

inHi I am a computer engineering student.I have to know the difference between Fourier transform and Laplace transform. Because we have studied...

Hi I am a computer engineering student.I have to know the difference between Fourier transform and Laplace transform. Because we have studied laplace transform previous semester, that time to find a frequency response of a system we replaced s by jw in a s domain transfer function, but now we are using Fourier transform. Can we get Fourier transform by replacing s by jw in a Laplace transform? ...

## Flash website- end of an era

inOver 10 years ago I started a website ( www.fourier-series.com)in which I b= uilt interactive flash programs to teach various engineering...

Over 10 years ago I started a website ( www.fourier-series.com)in which I b= uilt interactive flash programs to teach various engineering concepts. I In= itially designed these programs to personally understand DSP and then to pa= ss along what I learned to others****. These topics were fourier series, di= screte fourier series, fourier transforms filtering I/Q modulation and also= some RF s...

## how, if at all, do AMDF & ASDF relate to fourier transforms?

inhello, can anyone tell me how or if AMDF & ASDF relates to fourier transforms please? -- do AMDF & ASDF make use of fourier transforms? or are...

hello, can anyone tell me how or if AMDF & ASDF relates to fourier transforms please? -- do AMDF & ASDF make use of fourier transforms? or are part of their logic based on fourier transforms in some way? or are AMDF & ASDF, and fourier transforms entirely different logic/algorithms? or maybe some AMDF & ASDF implementions use fourier transforms and some don't -- it's the implemetor of AMDF...

## Deconvolution by Fourier method

inIn order to convolve two functions 'a' and 'b', we can take their Fourier Transform(FT) and multiply them in Fourier domain i.e. C= FT(a) *...

In order to convolve two functions 'a' and 'b', we can take their Fourier Transform(FT) and multiply them in Fourier domain i.e. C= FT(a) * FT(b) c = IFT(C) and then Inverse Ft(IFT) of 'C' gives us the convolution of 'a' and 'b'. Now if we want to deconvolve 'a' from 'c' to get 'b' we can do B = FT(c)/FT(a) b = IFT(B) Now if 'a' is a square wave i face the problem of 'DIVIDE by ZERO', a...

## looking for references on "Generalized/Complex Fourier Transform"?

inHi all, I recently got to know there is a type of Fourier Transform called "Generalized or Complex Fourier Transform". It extends the...

Hi all, I recently got to know there is a type of Fourier Transform called "Generalized or Complex Fourier Transform". It extends the frequency domain variable to a strip on the complex plane. There is regularity associated with the transform in this domain. I am not familiar with the complex/generalized Fourier Transform though I knew the Fourier transform with the transform domain variab...

## Appendix A: Types of Fourier Transforms

inJust to inscribe this on the wall in cyberspace: There are _four basic kinds_ of Fourier transforms*: The continuous Fourier transform, AKA...

Just to inscribe this on the wall in cyberspace: There are _four basic kinds_ of Fourier transforms*: The continuous Fourier transform, AKA _the_ Fourier transform: A continuous-time signal of infinite extent is transformed by X(w) = \int_{-\infty}^{\infty} x(t) * e^{j*w*t} dt At times (as when finding power spectra) this may be a limit, taking the average over time, rather than f...

## Confused about DFT and Fourier Series and Fourier Transform?

inDear all, I am confused by the four transforms in Signal & Systems... The Continuous Time Fourier Transform(CTFT) is most understandable;...

Dear all, I am confused by the four transforms in Signal & Systems... The Continuous Time Fourier Transform(CTFT) is most understandable; DFT and Fourier Series alone are individually recoginizable and understandable... Not sure about how does DTFT kick in... Anyway, remembering all of these four transforms' formulas are already very headache... very easily got confuse one with anot...

## PSD vs. Fourier transform

inHello, I have a confusion regarding Fourier transform of a time signal and the PSD. By definition, power spectral density (PSD) is the Fourier...

Hello, I have a confusion regarding Fourier transform of a time signal and the PSD. By definition, power spectral density (PSD) is the Fourier transform of the autocorrelation function. Suppose my time-domain signal is a voltage signal. I sample this at the correct rate, and taking the Fourier transform gives me the maginitudes of of various frequency components present in the signal (with...

## Inverse Fourier/Laplace transform of a periodic function?

inHI, If a function F(u) is known to be a Fourier transform of some function f(t), and F(u) is periodic in u, which can be deemed as...

HI, If a function F(u) is known to be a Fourier transform of some function f(t), and F(u) is periodic in u, which can be deemed as frequency variable, with a period 2*pi. If I want to find its inverse Fourier transform, I know I should try either DTFT/IDTFT, or Fourier series, for such a periodic function, and the target function f(t) in the time-domain should be a discrete comb-like fu...

## What is DSP equivalent of Planck's constant?"

inMy original title was going to be approximately Murky region between "Fourier Series" and "Fourier Transform" Think there should be a...

My original title was going to be approximately Murky region between "Fourier Series" and "Fourier Transform" Think there should be a similarly simple title with "periodic" ;/ I suspect that deep down I see the FFT as just a convenient method to calculate a 'Fourier Series' valid over a specified time period.

## what's the Fourier transform of this function?

inSuppose I have a function f(u), and define g(s)=int(f(u), u from -inf to s), what is the Fourier transform of this function? I could see it...

Suppose I have a function f(u), and define g(s)=int(f(u), u from -inf to s), what is the Fourier transform of this function? I could see it may need some additional conditions, or generalized Fourier transforms, etc. Any thoughts?

## discrete fourier series and transform

inSirs, While reading on frequency representation, I am a little confused with discrete fourier series (as opposed to discrete fourier transform)...

Sirs, While reading on frequency representation, I am a little confused with discrete fourier series (as opposed to discrete fourier transform) and its application. Can I get some inputs please. Thanks, manish _____________________________ Posted through www.DSPRelated.com