# 0.2 The six elements

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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.

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 $s\left(t\right)$ 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 $s\left(t\right){e}^{-2\pi jft}$ . The resulting transform $S\left(f\right)$ is a function of frequency. $S\left(f\right)$ is called the spectrum of the signal $s\left(t\right)$ 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.

how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
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what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
how did you get the value of 2000N.What calculations are needed to arrive at it
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