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The module will provide analysis and examples of how a continuous-time signal is converted to a digital signal and processed.

Dt processing of ct signals

Dsp system


Y c H LP Y T
where we know that Y X G and G is the frequency response of the DT LTI system. Also, remember that T So,
Y c H LP G T X T
where Y c and H LP are CTFTs and G T and X T are DTFTs.
X 2 T k X c 2 k T OR X T 2 T k X c k s
Therefore our final output signal, Y c , will be:
Y c H LP G T 2 T k X c k s
Now, if X c is bandlimited to s 2 s 2 and we use the usual lowpass reconstruction filter in the D/A, :


Y c G T X c s 2 0


For bandlimited signals sampled at or above the Nyquist rate, we can relate the input and output of the DSP systemby:

Y c G eff X c
where G eff G T s 2 0


G eff is LTI if and only if the following two conditions are satisfied:

  • G is LTI (in DT).
  • X c T is bandlimited and sampling rate equal to or greater than Nyquist. For example, if we had a simplepulse described by X c t u t T 0 u t T 1 where T 1 T 0 . If the sampling period T T 1 T 0 , then some samples might "miss" the pulse while othersmight not be "missed." This is what we term time-varying behavior .

If 2 T 2 B and 1 B T , determine and sketch Y c using .

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Application: 60hz noise removal

Unfortunately, in real-world situations electrodes also pick up ambient 60 Hz signals from lights, computers, etc. . In fact, usually this "60 Hz noise" is much greater in amplitude than the EKG signal shown in . shows the EKG signal; it is barely noticeable as it has become overwhelmed by noise.

Our EKG signal, y t , is overwhelmed by noise.

Dsp solution

Sampling period/rate

First we must note that Y is bandlimited to60 Hz. Therefore, the minimum rate should be 120 Hz. In order toget the best results we should set f s 240 Hz . s 2 240 rad s

Digital filter

Therefore, we want to design a digital filter that will remove the 60Hz component and preserve the rest.

Questions & Answers

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
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Akash Reply
it is a goid question and i want to know the answer as well
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Do somebody tell me a best nano engineering book for beginners?
s. Reply
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Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
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.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
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abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
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Ramkumar Reply
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Sravani Reply
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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
what is system testing
what is the application of nanotechnology?
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
anybody can imagine what will be happen after 100 years from now in nano tech world
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
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, Intro to digital signal processing. OpenStax CNX. Jan 22, 2004 Download for free at http://cnx.org/content/col10203/1.4
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