<< Chapter < Page Chapter >> Page >

Though far from optimal, the receiver that you will build contains all the elements of a fully functional receiver.It provides a simple way to ask and answer what if questions. What if there is noise in the system? What if the modulation frequencies are not exactly as specified?What if there are errors in the received digits? What if the data rate is not high enough?What if there are distortion, reflections, or echoes in the transmission channel? What if the receiver is moving?

The first layer of the Software Receiver Design onion begins with a sketch of a digital radio.

An illustrative design

The first design is a brief tour of the outer layer of the onion. If some of the terminologyseems obscure or unfamiliar, rest assured that succeeding sections and chapters will revisit the words and refine theideas. The design is shown in [link] through [link] . While talking about these figures, it will become clear that some ideas are being oversimplified.Eventually, it will be necessary to come back and examine thesemore closely.

The shaded notes are reminders to return and think about these areas moredeeply later on.

In keeping with Shannon's goal of reproducing at one pointa message known at another point, suppose that it is desired to transmit a text message from one place to another.Of course, there is nothing magical about text; however, .mp3 sound files, .jpg photos, snippets of speech,raster scanned television images, or any other kind of information would do, as long as it can be appropriately digitizedinto ones and zeros.

Can every kind of message be digitized into ones and zeros?

Perhaps the simplest possible scheme would be to transmit a pulse to represent a one and to transmit nothingto represent a zero. With this scheme, however, it is hard to tell the difference betweena string of zeroes and no transmission at all. A common remedy is to send a pulse with a positive amplitude to represent a oneand a pulse of the same shape, but negative amplitude to represent a zero.In fact, if the receiver could distinguish pulses of different sizes, then it would be possible to send two bits with each symbol,for example, by associating the amplitudes Many such choices are possible. These particular values were chosen becausethey are equidistant and so noise would be no more likely to flip a 3 into a 1 than to flip a1 into a - 1 . of + 1 , - 1 , + 3 and - 3 with the four choices 10, 01, 11, and 00.The four symbols ± 1 , ± 3 are called the alphabet , and the conversion from the original message (the text) into thesymbol alphabet is accomplished by the coder in the transmitter diagram [link] . The first few letters, the standard ASCII (binary) representationof these letters, and their coding into symbols are:

letter binary ASCII code symbol string a 01 10 00 01 -1 , 1 , - 3 , - 1 b 01 10 00 10 - 1 , 1 , - 3 , - 1 c 01 10 00 11 - 1 , 1 , - 3 , 3 d 01 10 01 00 - 1 , 1 , - 1 , - 3
An idealized baseband transmitter.
An idealized baseband transmitter.

In this example, the symbols are clustered into groups of four, and each cluster is called a frame.Coding schemes can be designed to increase the security of a transmission, to minimize the errors, or to maximizethe rate at which data are sent. This particular scheme is not optimized in any of these senses, but it isconvenient to use in simulation studies.

Questions & Answers

who was the first nanotechnologist
Lizzy Reply
k
Veysel
technologist's thinker father is Richard Feynman but the literature first user scientist Nario Tagunichi.
Veysel
Norio Taniguchi
puvananathan
Interesting
Andr
I need help
Richard
anyone have book of Abdel Salam Hamdy Makhlouf book in pdf Fundamentals of Nanoparticles: Classifications, Synthesis
Naeem Reply
what happen with The nano material on The deep space.?
pedro Reply
It could change the whole space science.
puvananathan
the characteristics of nano materials can be studied by solving which equation?
sibaram Reply
plz answer fast
sibaram
synthesis of nano materials by chemical reaction taking place in aqueous solvents under high temperature and pressure is call?
sibaram
hydrothermal synthesis
ISHFAQ
how can chip be made from sand
Eke Reply
is this allso about nanoscale material
Almas
are nano particles real
Missy Reply
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
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
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
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
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
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
STM - Scanning Tunneling Microscope.
puvananathan
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 Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




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