# Discrete-time signals and signal processing

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## A world of signals and signal processing

Technological innovations have revolutionized the way we view and interact with the world around us. Editing a photo, re-mixing a song, automatically measuring and adjusting chemical concentrations in a tank: each of these tasks requires real-world data to be captured by a computer and then manipulated digitally to extract the salient information. Ever wonder how signals from the physical world are sampled, stored, and processed without losing the information required to make predictions and extract meaning from the data? Signal processing is the study of signals and systems that extract information from the world around us.

## Signals, defined

Perhaps the place to start the study of signal processing is the dictionary. The dictionary definition of a signal will serve us quite well:
A signal is "is a detectable physical quantity...by which messages or information can be transmitted."
And this information aspect is very, very critical to us. In other words, signals carry information. Signals are all around us; we encounter them throughout our day. Speech signals, for example, transmit language from one person to another via acoustic waves.If you're interested in looking for, for example, airplanes our other targets and sensing them by electromagnetic waves, you can use radar signal processing. Electrophysiological signals carry information about processes that are going on inside our bodies, things like EKGs or MRI images. And finally, financial signals transmit information about events in the economy, signals like stock prices over time or other economic markers.So as you can see, signals are really very common in the world. And this course is about signals and the signal processing systems that manipulate signals in order to understand or make transformations on the information in those signals.

## Signals are functions

Signal
A signal is a function that maps an independent variable to a dependent variable.
Mathematically, we're going to think of signals as functions, and a function is just a mapping from an independent variable that we can change to a dependent variable that depends on that independent variable. The terminology $x(n)$ is how we're going to denote a signal. It consists of an independent variable, $n$ , that for each different value of $n$ , it produces the value $x(n)$ .

## Discrete-time signals

Perhaps you are wondering about the use of brackets--instead of parentheses--in our signal function notation $x(n)$ . This is the typical way to refer to discrete-time signals. A discrete-time signal is a signal where the independent variable $n$ is an integer (as opposed to a continuous-time signal $x(t)$ , whose independent variable $t$ is a real number).

where we get a research paper on Nano chemistry....?
what are the products of Nano chemistry?
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
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
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
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
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?
what is a peer
What is meant by 'nano scale'?
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 ?
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?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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