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Our goal in digital communications was to transmit a grayscale image shown below:

This image was represented as a matrix with dimensions 512x512 with each entry having values from 0 to 255. The values from 0 to 255 in each entry of the matrix were taken, converted into a string of 0s and 1s and fed in four bits at a time into the 16 QAM modulator. This was then passed through a noisy channel which added an error of random numbers between -2.5 to 2.5 to the transmitted signal. The receiver collected the received signal, demodulated it and reconstructed the received image with noise. This was done with a raised cosine filter, a Butterworth filter and with no filter at all. We also compared the bit error with the original image for the raised cosine filter and the Butterworth filter. Below is the image received with noise using a raised cosine filter in the modulation phase:

Using the Butterworth filter in the modulation phase the received image with noise was:

Using no filter at all during the modulation scheme the received image was:

Error calculations and filter evaluations

The bit error was calculated by analyzing the bit-representation of the original grayscale image and comparing it the bit-representation of the received image. The percentage of incorrect bits was calculated to be 34.55% when using the raised cosine filter, and 34.45% when using the Butterworth filter. From these results we can see that the performance of the Butterworth filter and the raised cosine filter are about the same, with the Butterworth filter performing slightly better. The bit error in the received image using no filter was 47%, however, percent error for the number of incorrect grayscale pixels was calculated to be 99%. The percent error for the number of incorrect grayscale pixels using the Butterworth filter was 95.64%. The percent error for the number of incorrect grayscale pixels using the raised cosine filter was 95.66%. This is high because this includes even the slightest error which might be indistinguishable to the human eye.

We can also see the importance of using filters in the upsampling stage of the modulation phase of the digital communication scheme by looking at the received image without the use of a filter. The use of a digital filter allows the image to be recovered with far greater accuracy.

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
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
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
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
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
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.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
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
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Digital filters in 16-qam communication. OpenStax CNX. Dec 11, 2011 Download for free at http://cnx.org/content/col11384/1.1
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