<< Chapter < Page Chapter >> Page >
Sources of corruption include multipath interference, changing channel gains, interference from other users, broadband noise, and narrowband interferences.
Sources of corruption include multipath interference, changing channel gains, interference fromother users, broadband noise, and narrowband interferences.

Broadband noise

When the signal arrives at the receiver, it is small and must be amplified. While it is possible to build high-gainamplifiers, the noises and interferences will also be amplified along with the signal. In particular, any noise in the amplifier itself will be increased. This is often called “thermal noise” and is usually modelled as white(independent) broadband noise. Thermal noise is inherent in any electronic components and is caused by smallrandom motions of electrons, like the Brownian motion of small particles suspended in water.

Such broadband noise is another reason that a bandpass filter is applied at the front end of the receiver. Byapplying a suitable filter, the total power in the noise (compared to the total power in the signal) can often be improved. [link] shows the spectrum of the signal as a pair of triangles centered at the carrier frequency ± f c with bandwidth 2 B . The total power in the signal is the area under the triangles. The spectrum of the noiseis the flat region, and its power is the shaded area. After applying the bandpass filter, the power in the signalremains (more or less) unchanged, while the power in the noise is greatly reduced. Thus, the signal-to-noise ratio (SNR) improves.

Narrowband noise

Noises are not always white; that is, the spectrum may not always be flat. Stray sine waves (and othersignals with narrow spectra) may also impinge on the receiver. These may be caused by errant transmitters that accidentlybroadcast in the frequency range of the signal, or they may be harmonics of a lower frequency waveas it experiences nonlinear distortion. If these narrowband disturbances occur out of band, they willautomatically be attenuated by the bandpass filter just as if they were a component of the wideband noise.However, if they occur in the frequency region of the signal, they decrease the SNR in proportion to theirpower. Judicious use of a “notch” filter (one designed to remove just the offending frequency) can be an effectivetool.

[link] shows the spectrum of the signal as the pair of triangles, along with three narrowband interferersrepresented by the three pairs of spikes. After the bandpass filter, the two pairs of out-of-band spikes are removed,but the in-band pair remains.

The signal-to-noise ratio is depicted graphically as the ratio of the power of the signal (the area under the triangles) to the power in the noise (the shaded area). After the bandpass filter, the power in the noise decreases, and so the SNR increases.
The signal-to-noise ratio is depicted graphically as the ratio of the power of the signal (the area under thetriangles) to the power in the noise (the shaded area). After the bandpass filter, the power in the noise decreases,and so the SNR increases.
Three narrowband interferers are shown in the top figure (the three pairs of spikes). The BPF cannot remove the in-band interferer, though a narrow notch filter can, at the expense of changing the signal in the region where the narrow band noise occurred.
Three narrowband interferers are shown in the top figure (the three pairs of spikes). The BPF cannot remove the in-band interferer,though a narrow notch filter can, at the expense of changing the signal in the region where the narrow band noise occurred.

Applying a narrow notch filter tuned to the frequency of the interferer allows its removal,although this cannot be done without also affecting the signal somewhat.

Questions & Answers

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
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
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
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