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To start the second experiment, double click on the icon named Sampling and Reconstruction Using A Sample and Hold . [link] shows the initial setup for this exercise. It contains 4 Scopes to monitor the processing done in the sampling and reconstruction system. It also contains a Network Analyzer for measuring the frequency response and the impulse response of the system.

The Network Analyzer works by generating a weighted chirp signal (shown on Scope 1 ) as an input to the system-under-test. The frequency spectrumof this chirp signal is known. The analyzer then measures the frequency content of theoutput signal (shown on Scope 4 ). The transfer function is formed by computing the ratio of the outputfrequency spectrum to the input spectrum. The inverse Fourier transform of this ratio, whichis the impulse response of the system, is then computed.

In the initial setup, the Sample-and-Hold and Scope 3 are not connected. There is no sampling in this system, just two cascaded low-pass filters.Run the simulation and observe the signals on the Scopes . Wait for the simulation to end.

Submit the figure containing plots of the magnitude response, the phase response, and the impulse response of this system.Use the tall mode to obtain a larger printout by typing orient('tall') directly before you print.

Double-click the Sample-and-Hold and set its Sample time to 1. Now, insert the Sample-and-Hold in between the two filters and connect Scope 3 to its output. Run the simulation and observethe signals on the Scopes .

Submit the figure containing plots of the magnitude response, the phase response, and the impulse response of this system.Explain the reason for the difference in the shape of this magnitude response versus the previous magnitude response.Give an analytical expression for the behavior of the magnitude plot for frequencies below 0 . 45 Hz.

Discrete-time interpolation

For help on printing figures in Simulink select the link.

Simulink model for discrete-time interpolation.

In the previous experiments, we saw that the frequency content of a signal must be limited to half the sampling rate in orderto avoid aliasing effects in the reconstructed signal. However, reconstruction can be difficultif the sampling rate is chosen to be just above the Nyquist frequency. Reconstruction is much easier for a higher samplingrate because the sampled signal will better “track” the original analog signal.

From another perspective, the analog output filter must have a very sharp cutoff in order to accurately reconstructa signal that was sampled just above the Nyquist rate. Such filters are difficult and expensive to manufacture.Alternatively, a higher sampling rate allows the use analog output filters that have a slow roll-off.These filters are much less expensive. However, a high sampling rate is not practical in most applications, asit results in unnecessary samples and excessive storage requirements.

A practical solution to this dilemma is to interpolate the digital signal to create new (artificial) samples between the existing samples.This may be done by first upsampling the digital representation, and then filtering out unwanted components using a discrete-time filter.This discrete-time filter serves the same purpose as an analog filter with a sharp cutoff, but it is generally simplerand more cost effective to implement.

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
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
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar 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, Purdue digital signal processing labs (ece 438). OpenStax CNX. Sep 14, 2009 Download for free at http://cnx.org/content/col10593/1.4
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