<< Chapter < Page Chapter >> Page >

The six elements of drama are plot, theme, character, language, rhythm, and spectacle.

—Aristotle

At first glance, block diagrams such as the communication system shown in [link] probably appear complex and intimidating. There are so many different blocks and so many unfamiliarnames and acronyms! Fortunately, all the blocks can be built from six simple elements:

  • Signal generators such as oscillators , which create sine and cosine waves,
  • Linear time-invariant filters , which augment or diminish the amplitude of particularfrequencies or frequency ranges in a signal,
  • Samplers , which change analog (continuous time) signals into discrete-time signals,
  • Static nonlinearities such as squarers and quantizers which can add frequency content to a signal,
  • Linear time varying systems such as mixers that shift frequencies around in useful and understandable ways, and
  • Adaptive elements , which track the desired values of parameters as they slowly change over time.

This section provides a brief overview of these six elements. In doing so, it also reviews some of the key ideas fromsignals and systems. Later chapters explore how the elementswork, how they can be modified to accomplish particular tasks within the communication system, and how they canbe combined to create a large variety of blocks such as those that appear in [link] .

The elements of a communication system have inputs and outputs; the element itself operates on its input signal tocreate its output signal. The signals that form the inputs and outputsare functions that represent the dependence of some variable of interest (such as avoltage, current, power, air pressure, temperature, etc.) on time.

The action of an element can be described by the manner in which it operates in the “time domain,” that is, how the element changes theinput waveform moment by moment into the output waveform.Another way of describing the action of an element is by how it operates in the “frequency domain,”that is, by how the frequency content of the input relates to the frequency content of the output. [link] illustrates these two complementary ways of viewing the elements. Understanding both the time domain and frequency domainbehavior is essential. Accordingly, the following sections describe theaction of the six elements in both time and frequency.

The element transforms the input signal x into the output signal y. The action of an element can be thought of in terms of its effect on the signals in time, or (via the Fourier transform) in terms of its effect on the spectra of the signals.
The element transforms the input signal x into the output signal y . The action of an element can be thought of in terms of its effect on the signals in time, or (via the Fourier transform)in terms of its effect on the spectra of the signals.

Readers who have studied signals and systems (often required in electrical engineering degrees),will recognize that the time domain representation of a signal and its frequency domain representationare related by the Fourier transform, which is briefly reviewed in the next section.

Finding the spectrum of a signal

A signal s ( t ) can often be expressed in analytical form as a function of time t , and the Fourier transform is defined as in [link] as the integral of s ( t ) e - 2 π j f t . The resulting transform S ( f ) is a function of frequency. S ( f ) is called the spectrum of the signal s ( t ) and describes the frequencies present in the signal.For example, if the time signal is created as a sum of three sinewaves, the spectrum will have spikes corresponding to each of the constituent sines.If the time signal contains only frequencies between 100 and 200 Hz, the spectrum will be zero for all frequencies outside of this range.

Questions & Answers

what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
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.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
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
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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
Good
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, Software receiver design. OpenStax CNX. Aug 13, 2013 Download for free at http://cnx.org/content/col11510/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Software receiver design' conversation and receive update notifications?

Ask