<< Chapter < Page Chapter >> Page >
Two impulse-response measurement methods are demonstrated, with source code provided in Matlab and Pure Data (PD).The measurement technique using Golay complementary sequences is particularly robust to additive white noise, while the swept sine measurementtechnique is robust to a weakly nonlinear motor exciting the linear system being measured.


Linear system to be measured

[link] depicts a linear system characterized by an impulse response h ( n ) , driven by an input signal s ( n ) , and producing the output signal r ( n ) . The system identification problem is to estimate h ( n ) given known input/output signals s ( n ) and r ( n ) . This module illustrates the swept-sine and the Golay complementary sequence techniques for identifying finite impulse responses. The firstexample measures the impulse response of a highpass filter using the Golay method, and the second example measures the impulse response ofa weakly nonlinear loudspeaker driver using the swept-sine method.

Summary of objectives

  • To provide a general framework for characterizing single-input, single-output linear systems .
  • To demonstrate how to measure the impulse response of a linear system using Golay complementary sequences .
  • To explain some of the limitations of making measurements using standard sound interfaces.
  • To demonstrate how to find the minimum-phase spectrum corresponding to a complex spectrum.
  • To explain how to measure the impulse response of a system even if the excitation source motor is weakly nonlinear . This measurement technique uses a sine sweep test signal.


  1. Install a sound card, sound interface, or other full-duplex data acquisition card.
  2. Consider testing the data acquisition card viewing the soundcard set-up instructions .
  3. Install either MATLAB or Octave .
  4. Install pd . (Alternatively, you may use other software that is capable of recording a system's output for a given inputexcitation signal. The software should also be capable of reading and writing WAV files. For example, any multitrack recordingsoftware should be fine.)
  5. Download tf_meas.zip and unzip the contents into a conveniently located local directory.

Linear system

Consider the causal, single-input single-output (SISO) system shown in [link] . For simplicity, we will take the system to be linear and discrete-time, so that it is characterized by its impulseresponse h ( n ) or equivalently its transfer function H ( z ) , which is the z transform of h ( n ) .

h ( n ) H ( z )

We will assume that both h ( n ) and H ( z ) exist so that we can discuss measuring them interchangeably. We will further assume that h ( n ) has finite length so that we can measure the response to an input signal in a finite amount of time. The goal of this document isto explain how to excite the system with a signal s ( n ) , measure the response r ( n ) , and use s ( n ) and r ( n ) to determine h ( n ) (and equivalently H ( z ) ). In particular, it is useful to pick a signal s ( n ) that contains a large amount of energy so that measurement noise will not significantly corrupt the measurement results.

Linear system

Limitations of sound interfaces

Sound cards and sound interfaces are not designed for making transfer function measurements. They merely provide a cost-effective solutionsince almost all computers have sound cards. We demonstrate these weaknesses given measurements made on a PreSonus Firepod soundinterface. The output from channel 1 was directly connected to the line input on channel 1, and the sampling rate was f S = 44 . 1 kHz.

Questions & Answers

I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Impulse response measurement toolbox. OpenStax CNX. Jun 23, 2008 Download for free at http://cnx.org/content/col10519/1.5
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Impulse response measurement toolbox' conversation and receive update notifications?