Impulse response Definition and 86 Threads

In signal processing, the impulse response, or impulse response function (IRF), of a dynamic system is its output when presented with a brief input signal, called an impulse. More generally, an impulse response is the reaction of any dynamic system in response to some external change. In both cases, the impulse response describes the reaction of the system as a function of time (or possibly as a function of some other independent variable that parameterizes the dynamic behavior of the system).
In all these cases, the dynamic system and its impulse response may be actual physical objects, or may be mathematical systems of equations describing such objects.
Since the impulse function contains all frequencies, the impulse response defines the response of a linear time-invariant system for all frequencies.

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  1. B

    Transfer function to Pole-Zero Plot to Impulse Response Curve

    Homework Statement The question gives a transfer function. and we are asked to put it into pole zero form and then we are asked to sketch the positions of the poles and zeros of the system on the complex plane and then sketch the impulse response corresponding to each pole. i have...
  2. A

    Unit step response and unit impulse response

    In my ODE course I learned that for a time invariant operator p(D), if p(D)x=q(t) then p(D)\dot{x}=\dot{q}(t). Then the professor "justified" that the derivative of the unit step response, v(t), is the unit impulse response, w(t), because the derivative of unit step function is the Dirac...
  3. J

    I can't understand the discrete time unit impulse response and convolution

    hi, i have trouble in understanding the concepts of the impulse response first of all, let's assume that we have a signal y[n] = x[n] which is time invariant and linear, hence if I understand correctly linear means that if for input a*x1[n] we have an output a*y1[n] b*x2[n] we...
  4. P

    Calculating Unit Impulse Response

    I am trying to teach myself DSP, owing to bad lecture notes. In particular at the moment I'm trying to calculate impulse responses for LTI systems, given the system equation. I would really appreciate it if someone could tell me if my working and assumptions below are correct for the following...
  5. J

    I cant understand the impulse response in convolution

    Homework Statement i have this graph http://img858.imageshack.us/img858/1346/56954457.png and i need to find h-1[k] i don't understand, i know that the impulse response is the response for input -> δ[n], in this case it will be δ[n+1], but i don't understand how to calulate the response...
  6. G

    How to Find the Unit Impulse Response h[n]?

    Find h[n], the unit impulse response of the system descrived by the following equation: y[n]+3y[n-1]+2y[n-2]=x[n]+3x[n-1]+3x[n-2] Can this be rewritten as?(n-->n+2) y[n+2]+3y[n+1]+2y[n]=x[n+2]+3x[n+1]+3x[n]
  7. J

    Finding the impulse response of a system without using Z-Transform

    Homework Statement Find the impulse response of the following: Assume the system is initially at rest. y[n] - (1/2) y[n-1] = x[n] + 2 x[n-1] + x[n-2] The Attempt at a Solution To find the impulse response y[n]: we know that y[n] = homogenous solution + particular solution so... lamda -...
  8. B

    Finding the impulse response of a system

    Homework Statement So the problem asks to find the impulse response h(t) provided y(t) = integral from -infinity to t of e^-(t-tau)*x(tau-2)dtau Homework Equations none The Attempt at a Solution I understand that the way to begin this problem is to substitute delta(t) for x(t). Therefore the...
  9. G

    Detrmine the unit impulse response

    Homework Statement Find the unut impulse response h[n] of this system y[n+1]+2y[n]=x[n] Homework Equations I have no clue on how to slove this problem, som pointers would be nice. Thx
  10. M

    Impulse response function & Laplace transforms

    i am given the Laplace transform of an impulse response function, as well as its input. i am supposed to find its output. H(s) = 1/s2 + s + 1 x(t) = sin2(t-1)U(t-1) what i have done so far is the following: i know that Y(s) = H(s)X(s) and from this i can easily find y(t) so i found X(s)...
  11. A

    What is the dimension of the impulse response of an electric circuit?

    Hi all The impulse response h(t) of an electric circuit (maybe in some special cases) is the derivative of the step response s(t) of the same circuit. right? So does it mean they have different dimension, namely if the dimension of s(t) is X, then the dimension of h(t)=ds/dt is x over...
  12. O

    Discrete LTI filter impulse response

    If I have the unit impulse response function for a discrete-time LTI system (Unit sequence response?), h[n], how can I calculate the time taken for the output to fall below 1% of its initial value, after a unit impulse is applied to the input? In particular, I have: h[n]=(\alpha...
  13. K

    Identifying Impulse Response Function from State Equations

    Hi, given the state equations of a system, x(dot) = Ax + Bu y = Cx is the impulse response function of this system C(e^(At))B? If not, how can i identify the impulse response from a given state equations? Please advise. Thank you.
  14. M

    Convolution and Impulse Response

    If one has input x(t), then convolving x(t) with impulse response of the system would give the zero-state of the system. For example, we have a system described as : (D^{2} + 4D + 3)y(t) = (D+5)f(t). I computed system impulse response which is : h(t) = 2e^{-t} - e^{-3t} Now if say f(t) =...
  15. D

    Impulse response of recursive DT system

    Homework Statement y[n] - 1.8\cos (\frac{\pi }{{16}})y[n - 1] + 0.81y[n - 2] = x[n] + 0.5x[n - 1] Determine the impulse response h[n] by calculating the zero-state response with x[n] = \delta [n] Homework Equations y[n] - 1.8\cos (\frac{\pi }{{16}})y[n - 1] + 0.81y[n - 2] = x[n] +...
  16. N

    HELP Impulse Response h(n) problem

    HELP! Impulse Response h(n) problem Please help me solve this problem. Atleast the correct answer indication is also very much appreciated. A system has impulse response h(n) = (1/2)^n-3 U(n-3) and the input is x(n) = 3^n U(n) a)Find the output by direct convolution. b)Find the output...
  17. H

    Dsp help - impulse response of system in z domain

    Homework Statement I am given an LTI system where I need to obtain the impulse response and difference equation of H(z). H(z) = (1-0.5z^-3) / [(1-0.5z^-1)(1-0.25z^-1)] and |z| > 0.5 Homework Equations The Attempt at a Solution I am pretty lost about what to do. I...
  18. X

    Impulse Response for a 2nd Order Diffy Q

    y'' + 6y' + 4y = x(t) I found the eigenvalues to be -.764 and -5.24, no problems here. Next, since the order of the response is greater than the order of the excitation, I assumed the unit response took the form: h(t) = k_1e^{-.764t} + k_2e^{-5.24t} So now I must find the values for k_1 and...
  19. Q

    What is the difference between pulse response and impulse response?

    I would like to know the difference between pulse response and impulse response. I looked for "pulse" and "impulse" on the internet and found that on some websites they had been used interchangeably. Apart from that I checked out some books and found that they use the term "impulse response"...
  20. E

    Temporal Impulse response of one electron

    Hi, I am a little bit confused about the impulse response of one electron. Assume that we have LTI system characterized by impulse response h(t) with unit gain, int{h(t)} = 1. Let the input is current i(t) [Amp]. So the output current will be i(t)*h(t). We can view it as i(t) is...
  21. S

    Computing impulse response (help)

    I am trying to find the impulse response h[n] of a LSI system: y[n]+ay[n-1]=bx[n]-cx[n-1]. The way that I think to solve this problem is compute the z-transform, and from this H(z)=Y(z)/X(z). Then take the inverse z-transform to find h[n]. Is there another way to compute this? Also, for H(z)...
  22. D

    Multi-Step linear systems problem - Build ODE, impulse response, systems balance

    I messed up on the title of the thread.. I had a few questions but ended up solving them on my own. The only question I have is how to solve this ODE. Thanks. Homework Statement Solve the ODE (dx/dt)= f(t) - .1x Where f(t) = 2+sin(t)2. The attempt at a solution I faintly remember doing...
  23. C

    Finding impulse response of a system

    Hi, I have a question regarding on how to determine the impulse response of an LTI system which has the following conditions: 1).its input is x(n) = u(n) and output is y(n) = (1/2)nu(n) ,and 2).x(-1) = -1/3; x(0) = 1; x(1) = 1/2, and x(n) = 0 for all other values of n My approach: I...
  24. R

    Solving for Impulse Response h(t) Given z'(t) + 4z(t) = 4x(t)

    1. Find the impulse response h(t) given: z'(t) + 4z(t) = 4x(t) 2. The attempt at a solution I first decided to divide through by 4 (1/4)z'(t) + z(t) = x(t) since we are looking for impulse response I made the following substitutions: let z(t) = h(t) let x(t) = dirac(t)...
  25. A

    Calculating impulse response in convolution.

    Homework Statement y(t) = \int ^{t}_{-\infty} e^{-(t-\tau)} x(\tau-2)d\tau Find h(t), given that the continuous time linear time invariant signal has input x(t) and output y(t). 2. The attempt at a solution I was wondering if I can simply manipulate the expression until i get it in the...
  26. E

    Why Do We Use the Inverse Impulse Response in Practical Applications?

    hello all i just want to know why we use the inverse impulse response ? and i need a practical example on it ?/ and how?/? i need Quiqly answer as soon as u can please...:smile:
  27. Y

    Transfer function to impulse response

    Homework Statement Given the transfer function of a linear, time-invariant system H(z)=\frac{z^2+5z}{z^2+5} compute the impulse response. Homework Equations We are supposed to compute the inverse z-transform with partial fraction decomposition but the problem here is the irreducible...
  28. S

    Impulse Response In A Discrete System

    Hey guys, this is my first post and I'm looking for a bit of help This is going to sound really easy (and I know it is) but I can't for the life of me remember how to work out the Impulse Response Function of this system. I've tried google for a few hours but nowhere that gives it in laymans...
  29. R

    HELP Impulse Response h(t) problem

    HELP! Impulse Response h(t) problem Please help me solve this problem. Atleast the correct answer indication is also very much appreciated. Compute the impulse response h(t) for (dy(t))/dt -4y(t)=x(t) a. y(t) = e^4t b. y(t) = 1- e^4t c. y(t) = e^-4t d. y(t) = 1- e^-4t Compute the impulse...
  30. P

    Impulse Response: Understanding & Applying Maths

    This thread would've fitted in a lot of categories, but as it's the mathematics I can't quite grasp, I decided to fit it here. I'll be treating the discrete case, so I suppose it's precalculus maths. Anyways, I know how to compute problems with the impulse response method, but I'm kinda baffled...
  31. C

    Impulse Matching: Finding the Unit Impulse Response

    Impulse Matching In regards to finding the unit impulse response of a system. We assume that x(t) = \delta (t) and that the intials conditions at t=0^_ are all zero. The impulse response h(t) therefore must consists of the systems's modes for when t \geq 0^+. But why is it that h(t) = A...
  32. Y

    How Do You Find the Impulse Response h(t) for a Differential Equation System?

    can someone show me how to find the impulse response h(t)? questions: Determine the impulse response h(t) for the system characterized by the differential equation y(2)(t) + 2 y(1)(t) + 17 y(t) = x(2)(t) + 5 x(1)(t) + 18 x(t) thanks
  33. L

    Impulse response and convolution? any help from anyone?

    hey, i did my undergrad in music and english and now am lost beyond reckoning with the impulse response stuff in my postgrad. Could anyone help with these exercises? They're examples from my lecture notes and have no idea how my lecturer got the answers. Please help? Ex.1) Show that x(t)*h(t)...
  34. L

    Impulse response? I need a bit of help with this if anyone can?

    hey, i did my undergrad in music and english and now am lost beyond reckoning with the impulse response stuff in my postgrad. Could anyone help with these exercises? They're examples from my lecture notes and have no idea how my lecturer got the answers. Please help? Ex.1) Show that x(t)*h(t)...
  35. L

    Help with impulse response and convolution?

    hey, i did my undergrad in music and english and now am lost beyond reckoning with the impulse response stuff in my postgrad. Could anyone help with these exercises? They're examples from my lecture notes and have no idea how my lecturer got the answers. Please help? Ex.1) Show that...
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