4.2 Java1483-spectrum analysis using java, frequency resolution  (Page 5/19)

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Spectrum of an ideal sinusoid

That having been said, different people will probably interpret these results in different ways. Let's begin by stating that the theoretical spectrum for asinusoid of infinite length in the absence of noise is a single vertical line having zero width and infinite height.

In the real world of measurements, however, there is no such thing as a sinusoid of infinite length. Rather, every measurement that we make musttruncate the sinusoid at some point in time. For a theoretical signal of infinite length, every spectral analysis that we can perform is an imperfectestimate of the spectrum.

Two viewpoints

There are at least two ways to think of the pulses shown in Figure 1 .

1. Each pulse is a truncated section of an ideal sinusoid of infinite length.
2. Each pulse is a signal having a definite planned start and stop time.

The way that you interpret the results shown in Figure 2 depends on your viewpoint regarding the pulses.

The first viewpoint

If your viewpoint is that each pulse is a truncated section of an ideal sinusoid of infinite length, then the width of each of the peaks (beyond zero width) is the result of measurement error introduced by the truncation process.

The second viewpoint

If your viewpoint is that each pulse is a signal having a definite planned start and stop time, then the widths and the shape of each of the peaksdescribes the full range of frequency components required to physically generate such a pulse. This is the viewpoint that is consistent with the hypothetical situation involving a device on a submarine that I described earlier in this module.

A simplified hypothetical situation

Assume for the moment that the hypothetical device on the submarine contains only one rotating machine and that this device is turned on and off occasionallyin short bursts. Because of the rotating machine, when the device is turned on, it will emit acoustic energy whose frequency matches the rotating speed of themachine.

(In reality, it will probably also emit acoustic energy at other frequencies as well, but we will consider it to be a very ideal machine. Wewill also assume the complete absence of any other acoustic noise in the environment.)

Assume that you have a recording window of 400 samples, and that you are able to record five such bursts within each of five separate recording windows.Further assume that the lengths of the individual bursts match the time periods indicated by the pulses in Figure 1 .

The spectra of the bursts

If you perform spectral analysis on each of the five individual 400-sample windows containing the bursts, and if you normalize the peak values for plottingpurposes, you should get results similar to those shown in Figure 2 .

The spectral bandwidth of the signal

The frequency range over which energy is distributed is referred to as the bandwidth of the signal. As you can see in Figure 2 , shorter pulses require wider bandwidth.

For example, considerably more bandwidth is required of a communication system that is required to reliably transmit a series of short truncatedsinusoids than one that is only required to reliably transmit a continuous tone at a single frequency.

how can chip be made from sand
is this allso about nanoscale material
Almas
are nano particles real
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
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
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
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
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
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?
what is a peer
What is meant by 'nano scale'?
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 ?
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
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