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Introduction and motivation for a graduate electrical engineering course on Signal Theory.

Introduction and motivation

Most areas of electrical and computer engineering (beyond signal processing) deal with signals. Communications is about transmitting, receiving, and interpreting signals. Signals are used to probe and model systems in control and circuit design. The images acquired by radar systems and biomedical devices are signals that change in space and time, respectively. Signals are used in microelectronic devices to convey digital information or send instructions to processors.

This course will provide a mathematical framework to handle signals and operations on signals. Some of the questions that will be answered in this course include:

  • What is a signal? How do we represent it?
  • How do we represent operations on signals?
  • What does it mean for signals to be similar/different from each other?
  • When is a candidate signal a good/bad approximation (i.e., a simplified version) of a target signal?
  • When is a signal “interesting” or “boring”?
  • How can we characterize groups of signals?
  • How do we find the best approximation of a target signal in a group of candidates?

Course overview

Signal theory

The signal theory presented in this course has three main components:

  • Signal representations and signal spaces , which provide a framework to talk about sets of signal and to define signal approximations.
  • Distances and norms to evaluate and compare signals. Norms provide a measure of strength, amplitude, or “interestingness” of a signal, and distances provide a measure of similarity between signals.
  • Projection theory and signal estimation to work with signals that have been distorted, aiming to recover the best approximation in a defined set.

Operator theory

Operators are mathematical representations of systems that manipulate a signal. The operator theory presented in this course has three main components:

  • Operator properties that allow us to characterize their effect on signals in a simple fashion.
  • Operator characterization that allow us to model their effect on arbitrary inputs.
  • Operator operations (no pun intended) that allow us to create new systems and reverse the effect of a system on a signal.

Optimization theory

Optimization is an area of applied mathematics that, in the context of our course, will allow us to determine the best signal output for a given problem using defined metrics, such as signal denoising or compression, codebook design, and radar pulse shaping. The optimization theory presented in this course has three main components:

  • Optimization guarantees that rely on properties of the metrics and signal sets we search over to formally ensure that the optimal signal can be found.
  • Unconstrained optimization , where we search for the optimum over an entire signal space.
  • Constrained optimization , where the optimal signal must meet additional specific requirements.


As an example, consider the following communications channel:

Communications channel
Block diagram for a communications channel

A mathematical formulation of this channel requires us to:

  • establish which signals x can be input into the transmitter;
  • how the transmitter F , the channel H , and the receiver G are characterized;
  • how the concatenation of the blocks F and H is expressed;
  • how the noise addition operation is formulated;
  • how we measure whether the decoded message x ^ is a good approximation of the input x ;
  • how is the receiver G designed to be optimal for all the choices above.

For this example, by the end of the course, you will be able to solve the problem of selecting the transmitter/receiver pair F , G that minimizes the power of the error e = x ^ - x while meeting maximum transmission power constraints power ( F ( x ) ) power ( x ) < P max .

Questions & Answers

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
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.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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Source:  OpenStax, Signal theory. OpenStax CNX. Oct 18, 2013 Download for free at http://legacy.cnx.org/content/col11542/1.3
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