## transfer function

Started by in comp.dsp14 years ago 7 replies

I am having difficulty calculating the inverse Laplace transform of the following transfer function: H(s) = (Gdc * w^2) / (s^2 + 2*eta*w*s +...

I am having difficulty calculating the inverse Laplace transform of the following transfer function: H(s) = (Gdc * w^2) / (s^2 + 2*eta*w*s + w^2) where: eta = damping ratio Gdc = DC gain w = undamped natural frequency What steps do you use? I am having difficulty getting the transfer function into a form that will allow me to take advantage of Laplace Transform tables for easy...

## why fourier transform in AM and FM why not LT

Started by in comp.dsp14 years ago 7 replies

Hello friends, I am little confused that why do we always apply fourier transform for amplitude modulation, frequency modulation why not laplace...

Hello friends, I am little confused that why do we always apply fourier transform for amplitude modulation, frequency modulation why not laplace transform. Second question is that when I studied control system then everywhere Laplace Transform is used. So please tell me why we use LT in controls and why FT in communication.

## Question about fourier transform and laplace transform

Started by in comp.dsp14 years ago 5 replies

Hi 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? ...

## Why in Fourier Transform, sigma = 0?

Started by in comp.dsp14 years ago 6 replies

hi! i'm working on some mathematical problem in frequency shifting or Translation frequency of a signal... i'm confuse what transformation...

hi! i'm working on some mathematical problem in frequency shifting or Translation frequency of a signal... i'm confuse what transformation should use, is it Fourier or Laplace? i don't understand why in Fourier Transform, the sigma have to be 0? and i found that if i use Laplace Transform first shift teorem, it will give me a phase and magnitude shift...is it true? thanks

## Unilateral Laplace transform of 1/t

Started by in comp.dsp13 years ago 17 replies

An electrical engineering textbook has an excercise problem requesting the Laplace transform of 1/t, and wanted it to be done using...

An electrical engineering textbook has an excercise problem requesting the Laplace transform of 1/t, and wanted it to be done using Laplace transform properties. Since this raised some concern, I looked up Gradshteyn and Ryzhik (6th ed.). On p. 1100 it states that t^nu has transform gamma(nu + 1)/s^(nu + 1) but requires nu > -1. I guess if it is not listed in G&R, it doesn't exist :-). In

## meaning of 'j' term in Fourier, Laplace transform

Started by in comp.dsp13 years ago 15 replies

Hello, this thing has been bothering me for some time and I have not been able to find a reasonable answer t this. But can you please me what...

Hello, this thing has been bothering me for some time and I have not been able to find a reasonable answer t this. But can you please me what the term 'j' stands for in the Fourier transform when we multiply our signal (be it in time or frequency domain) by an imaginary/complex exponential function. My question is not based on the idea if quadrature signals. Secondly, why cant we use the Lapla...

## inversion of joint laplace-fourier transform

Started by in comp.dsp13 years ago 4 replies

Hello all together, my question comes from the financial mathematics sector (pricing barrier options) but I am sure that you are the experts...

Hello all together, my question comes from the financial mathematics sector (pricing barrier options) but I am sure that you are the experts for this. I am trying to invert the following construct (equation 4.3/4.4 in http://laurent.nguyenngoc.free.fr/data/options-levy.pdf): Int(0,INF)exp(-q*T)dTInt(-INF,INF)exp(i*u*k)dkInt(0,INF)exp(-v*h)dhf(T,k,h) This is a combination of a laplace trans...

## Using Z-transform with continous time signals

Started by in comp.dsp13 years ago 23 replies

Hello, can we use Z-transform on continuous time signals to find their z-domain analysis. (what do we really realize in z-domain and how is it...

Hello, can we use Z-transform on continuous time signals to find their z-domain analysis. (what do we really realize in z-domain and how is it different from frequency domain analysis) and also can we use Laplace for discrete time signals. Also what kind of analysis/information can we get from i) Laplace Transform ii) Z Transform iii) Fourier Transform iv) Hilbert Transform (PS. n...

## why should I apply a transform ?

Started by in comp.dsp12 years ago 7 replies

hi..., => DFT, DCT, DWT, => Z-transform, Laplace transform..etc and the list goes on...... keep all this aside for 10 min for the...

hi..., => DFT, DCT, DWT, => Z-transform, Laplace transform..etc and the list goes on...... keep all this aside for 10 min for the sake of discussion Lets talk...about.., Q) Why should I transform any signal ? this is the question which is bothering me a lot.. Excluding these reasons any other new stuff from you people 1) to reduce Redundancy 2) to perform the job of f

## From Z-transform to Laplace

Started by in comp.dsp12 years ago 3 replies

Hello, I have a transfer function from ARMA or AR model having some high order. I want to obtain H(s). My approach is to assume that H(s) will...

Hello, I have a transfer function from ARMA or AR model having some high order. I want to obtain H(s). My approach is to assume that H(s) will have a form that will result in a high H(z) ARMA/AR model , and find a relation between these two!! I would appertiate any suggestion or comment,

## Scilab, Laplace transform, root-locus and transient response

Started by in comp.dsp12 years ago

I created a web with problems and examples of transient response (steady-state error, response to ramp, response to step, response to impulse,...

I created a web with problems and examples of transient response (steady-state error, response to ramp, response to step, response to impulse, peak time, settling time, maximum overshoot, Routh's stability ),root-locus (damping ratio, undamped natural frecuency) and Laplace Transform http://cpbas.webcindario.com/eng/control/TransientResponse/index.php

## Differences between laplace transform, z transform and fourier transform

Started by in comp.dsp3 years ago 20 replies

Hi All, I have studied three diff kinds of transforms, The laplace transform, the z transform and the fourier transform. As per my...

Hi All, I have studied three diff kinds of transforms, The laplace transform, the z transform and the fourier transform. As per my understanding the usage of the above transforms are: Laplace Transforms are used primarily in continuous signal studies, more so in realizing the analog circuit equivalent and is widely used in the study of transient behaviors of systems. The Z transform is the ...

## Modelling of a RC series connection in time and frequency domain

Started by in comp.dsp12 years ago 28 replies

Hi! Suppose there is resistor R and a capacitor C connected in series. A voltage U_0 is applied at time t=0. The current in the time domain...

Hi! Suppose there is resistor R and a capacitor C connected in series. A voltage U_0 is applied at time t=0. The current in the time domain is then I(t) = U_0/R * e^(-t/RC) (1) Taking a Laplace transform and substituting s by j*2*\pi*f, I get the frequency domain current: I(f) = U_0*C/(j*2*\pi*f*R*C+1) (2) Now the problem: I defined values for U_0, R and C, calc...

## Laplace Transform vs Fourier transform

Started by in comp.dsp12 years ago 55 replies

Hello Forum, everyone is familiar with the Fourier transform and its importance. Its independent variable, the angular frequency w, is a...

Hello Forum, everyone is familiar with the Fourier transform and its importance. Its independent variable, the angular frequency w, is a measurable physical quantity. What about the Laplace transform? What is, conceptually, the advantage of taking the Laplace transform of a signal instead of the Fourier transform? I know that by looking at its zeros and poles we can assess the stability of...

## Stability from laplace transform analysis

Started by in comp.dsp12 years ago 1 reply

All, Can any one pls explain me how "sigma" in s in laplace transform > 0 means un-stable system and < 0 means stable system? My...

All, Can any one pls explain me how "sigma" in s in laplace transform > 0 means un-stable system and < 0 means stable system? My understanding is completely reverse to that. BR, Dhaval

## Numerical inversion of Z-transform?

Started by in comp.dsp12 years ago 5 replies

I'm trying to do some research into existing methods for doing numerical inverse discrete laplace transform (a.k.a.. Z-transform). My problem...

I'm trying to do some research into existing methods for doing numerical inverse discrete laplace transform (a.k.a.. Z-transform). My problem is that numerical methods are really needed when you have non-rational Z-transform expression which do not posess a closed form inverse. For rational expressions in z this is not really a problem since you can always do them "manually" (or perhaps by...

## continuous fourier transform c#

Started by in comp.dsp10 years ago 9 replies

Hi, I have seen lots of links on google and yahoo, to the FFT, DFT etc. But nothing for CTFT, can anybody please point me in the right...

Hi, I have seen lots of links on google and yahoo, to the FFT, DFT etc. But nothing for CTFT, can anybody please point me in the right directions to coded examples of CTFT and laplace transforms in a control process. Thanks Tinkerz

## Designing a loop filter for software PLL with following known information

Started by in comp.dsp10 years ago 13 replies

Hi, I want to design a software PLL to correct a frequency offset in a baseband BPSK signal and after referring to the book Phase Locked Loops by...

Hi, I want to design a software PLL to correct a frequency offset in a baseband BPSK signal and after referring to the book Phase Locked Loops by Ronald Best I understand most of it. I still have questions regarding designing of the loop filter. L(s) = tau2*s + 1 ___________ tau1*s The laplace transform of the loop filter is as shown above and I can use bilinear transform...

## charge pump related loop simulation in PLL

Started by in comp.dsp3 years ago 2 replies

Hello all: Though my question is not in the strict DSP, I cannot find another appropriate forum to discuss about it. As a hobby, I am interested...

Hello all: Though my question is not in the strict DSP, I cannot find another appropriate forum to discuss about it. As a hobby, I am interested in a PLL simulation. On numerous tutorials, I know there are current sources in a charge pump type phase detector. I realize that the current source makes the voltage cross the capacitor linearly increase. It is seen the Laplace transform of the RC ...

## Math versus signal processing; terminology differences?

Started by in comp.dsp18 years ago 9 replies

As a signal-processing person, I am trying to wade through some heavy-duty math papers and having a problem. Suppose that you have a...

As a signal-processing person, I am trying to wade through some heavy-duty math papers and having a problem. Suppose that you have a signal-processing network that is represented by a transfer function (either Laplace or Z, doesn't matter right now). Suppose that this transfer function is of the form; H(s) = a(s) + b(s) + c(s) ... to infinity Assume, for example, that a(s), b(s), etc, ...