<< Chapter < Page
  Digital signal processing - dsp     Page 5 / 14
Chapter >> Page >

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 Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Digital signal processing - dsp. OpenStax CNX. Jan 06, 2016 Download for free at https://legacy.cnx.org/content/col11642/1.38
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Digital signal processing - dsp' conversation and receive update notifications?