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Analog and Discrete Waveforms with fs = 100 Hz and f = 10 Hz

Analog and Discrete Waveforms with fs = 100 Hz and f = 210 Hz


Now change the Number of quantization levels for some fixed values of Frequency and Sampling Frequency. As the number of quantization levels is increased, the Digital waveform becomes smoother and a smaller amount of quantization error or noise is generated.

Digital Waveform with Different Numbers of Quantization Levels: (a) 8, (b) 6, (c) 32

Signal reconstruction

Next, set the frequency f = 100 size 12{f="100"} {} Hz and vary the sampling frequency. Observe the reconstructed waveform. [link] shows the reconstructed signals for three different values of skipped samples. If the sampling frequency is increased, fewer samples are skipped during the analog-to-digital conversion, which makes the reconstruction process more accurate.

Signal Reconstruction with Different Number of Samples Skipped in ADC: (a) 20, (b)10, (c) 5

Dtft and dft

In this example, let us compute and compare the DTFT and DFT of digital signals with the CTFT and FS of analog signals. [link] illustrates the completed block diagram of this transform comparison system. As discussed previously, to simulate an analog signal, consider a small time interval ( dt = 0 . 001 ) size 12{ \( ital "dt"=0 "." "001" \) } {} . The corresponding discrete signal is considered to be the same signal with a larger time interval ( dt 1 = 0 . 01 ) size 12{ \( ital "dt"1=0 "." "01" \) } {} .

Block Diagram of a DTFT and DFT Transformation System

Generate a periodic square wave with the time period T = 0 . 1 size 12{T=0 "." 1} {} . Connect the input variable mode to an Enum Control to make the signal periodic or aperiodic. If the signal is periodic (case 0), compute the FS of the analog signal and the DFT of the digital signal using the fft function over one period of the signal. For aperiodic signals, only one period of the square wave is considered and the remaining portion is padded with zeros. For aperiodic signals, the transformations are CTFT (for analog signals) and DTFT (for digital signals), which are computed using the fft function. In fact, this function provides a computationally efficient implementation of the DFT transformation for periodic discrete-time signals. However, because simulated analog signals are actually discrete with a small time interval, this function is also used to compute the Fourier series for continuous-time signals. Because DFT requires periodicity, one needs to treat aperiodic signals as periodic with a period T = size 12{T= infinity } {} to apply this useful function. That is why the fft function is also used for aperiodic signals to compute CTFT and DTFT (as done in the earlier labs). However, in practice, it should be noted that the period of the zero padded signal is not infinite but assumed long enough to obtain a close approximation. Apply the same approach to the computation of CTFT and DTFT. Because DTFT is periodic in the frequency domain, for digital signals, repeat the frequency representation using the textual statement yd=repmat( yd,1,9) , noting that the fft function computes the transformation for one period only.

Front Panel of a DTFT and DFT Transformation System: Aperiodic Signal

Questions & Answers

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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
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
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
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?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian 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, An interactive approach to signals and systems laboratory. OpenStax CNX. Sep 06, 2012 Download for free at http://cnx.org/content/col10667/1.14
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