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Introduction to the Signals chapter

To describe signals and to understand that signals can carry information we need tools for mathematical description and manipulation of signals.

In this chapter we introduce several important signals and show simple methods of describing them. Depending on which type of signals we are looking at, it will bedifferent methods availiable for manipulating them. The elementary operations for manipulating signals and sequences will be described.

    Contents of this chapter

  • Introduction (current module)
  • Discrete time signals
  • Analog signals
  • Discrete vs Analog signals
  • Frequency definitions and periodicity
  • Energy&Power
  • Exercises

The simplest signals are one-dimensional and what follows is a classification of them.

Classification of signals

Analog signals

An analog signal is a continuous function of a continuous variable. Referring to , this corresponds to that both the 1st AND the 2nd axis is continuous. The 1st axiswill in general correspond to the variable t , meaning time. In this context we define

  • signal range - the possible amplitude values the signal can take
  • signal axis - the time interval for which the signal exists
Reference axes

Time discrete signals

A time discrete signal is a continuous signal of a discrete variable. Referring to , we have the 1st axis discrete while the 2nd axis is continuous. Often we assign the values of the 1st axis to a variable n . Time discrete signals often originate from analog signals being sampled.More on that in the Sampling theorem chapter.

Time discrete signal
Note that the signal is only defined for integer values along the 1st axis. We do not have any information other than the values at index points.

Digital signals

Let the signal be a discrete function of a discrete variable, e.g. 1st and 2nd axis discrete, then the signal will be digital . Examples of digital signals are a binary sequence. Digital signals often arise from samplinganalog signals and the samples being assigned to a discrete value.

Periodic vs non periodic signals

All the signals mentioned above can be periodic. For time discrete and digital signals one has to be extra cautious when "declaring" periodicity as wewill see in Frequency definitions&periodicity . shows a periodic signal with period T 0 and an aperiodic signal.

Periodic signal
Aperiodic signal
(Figures by Melissa Selik)

Matlab file


Take a look at

  • Discrete time signals
  • Analog signals
  • Discrete vs Analog signals
  • Frequency definitions and periodicity
  • Energy&Power
  • Exercises

Questions & Answers

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?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
While the American heart association suggests that meditation might be used in conjunction with more traditional treatments as a way to manage hypertension
Beverly Reply
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Source:  OpenStax, Information and signal theory. OpenStax CNX. Aug 03, 2006 Download for free at http://legacy.cnx.org/content/col10211/1.19
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