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Note that I deleted much of the code from Listing 2 for brevity. You can view the missing code in Listing 14 near the end of the module.

Compute the complex spectrum

The code in Listing 3 calls the static transform method of the ForwardRealToComplex01 class to compute and save the complex spectrum of the time series shown in the top plot of Figure 1 .

Listing 3. Compute the complex spectrum.
ForwardRealToComplex01.transform(timeDataIn, realSpect,imagSpect, angle,magnitude, zero,0.0, 1.0);

The method parameters

I explained the transform method in the earlier module titled Spectrum Analysis using Java, Sampling Frequency, Folding Frequency, and the FFT Algorithm . The three middle plots in Figure 1 are plots of the data returned in the arrays referred to by realSpect , imagSpect , and magnitude by the transform method.

The angle results returned by the transform program are not used in this module.

One of the parameters (zero) establishes that the first sample in the time series array referred to by timeDataIn represents the zero time origin.

The parameters also specify that the complex spectrum is to be computed at a set of equally spaced frequencies ranging from zero (0.0) to the sampling frequency (1.0) .

Perform the inverse Fourier transform

The code in Listing 4 calls the static inverseTransform method of the InverseComplexToReal01 class to perform an inverse Fourier transform on the complex spectral data, producing the output time series shownin the bottom plot in Figure 1 .

Listing 4. Perform the inverse Fourier transform.
InverseComplexToReal01.inverseTransform( realSpect,imagSpect, timeDataOut);}//end constructor

I will explain the inverseTransform method later.

An object of the class dsp035

Listing 4 also signals the end of the constructor. Once the constructor has completed executing, an object of the Dsp035 class exists. The array objects belonging to the object have been populated with the original timeseries, the complex spectrum of the original time series, and the output time series produced by performing an inverse Fourier transform on that complexspectrum. This data is ready for plotting.

The interface methods

All of the remaining code in Dsp035 consists of the six methods necessary to satisfy the interface named GraphIntfc01 . Those methods are required to provide data to the plotting program, as explainedin earlier modules in this series.

If you have studied the earlier modules in this series, you probably don't want to hear any more about those methods, so I won't discuss them further. Youcan view the six interface methods in Listing 14 near the end of the modules.

The InverseComplexToReal01 class

The static method named inverseTransform performs a complex-to-real inverse discrete Fourier transform returning a real result only.In other words, the method transforms a complex input to a real output.

Questions & Answers

what is variations in raman spectra for nanomaterials
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Crow Reply
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RAW Reply
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Damian
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Professor
I think
Professor
what is the stm
Brian Reply
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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?
LITNING Reply
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LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
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LITNING
scanning tunneling microscope
Sahil
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Rafiq
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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
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Anam
what is Nano technology ?
Bob Reply
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
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
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?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
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biomolecules are e building blocks of every organics and inorganic materials.
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research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
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nano basically means 10^(-9). nanometer is a unit to measure length.
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Source:  OpenStax, Digital signal processing - dsp. OpenStax CNX. Jan 06, 2016 Download for free at https://legacy.cnx.org/content/col11642/1.38
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