<< Chapter < Page
  Digital signal processing - dsp     Page 8 / 14
Chapter >> Page >

Perform the spectral analysis

Finally, the code in Listing 5 creates the array objects that will receive the results of the spectral analysis, and calls the transform method of the ForwardRealToComplex01 class to perform the spectral analysis.

Listing 5. Perform the spectral analysis.
mag = new double[dataLen];real = new double[dataLen];imag = new double[dataLen];angle = new double[dataLen];ForwardRealToComplex01.transform(data,real, imag,angle,mag,zeroTime,lowF,highF);}//end constructor

Listing 5 also signals the end of the constructor. At this point, the object has been instantiated and it's array objects have been populated with the inputand output data from the spectral analysis process. This data is ready to be handed over to the plotting program to be plotted, as shown in Figure 2 .

The getparameters method

The getParameters method, called in Listing 3 , reads parameter and pulse data from the file named Dsp034.txt , and deposits that data into the variables and the pulse array declared in Listing 2 .

The code in the getParameters method is straightforward, so I won't bore you with an explanation. You can view the method in Listing 6 near the end of the module.

The interface methods

As pointed out earlier, the Dsp034 class implements the GraphIntfc01 interface. As such, the class must define the six methods declared in that interface. These methods are called by the plottingprogram to obtain the data that is to be plotted.

You have seen implementations of these methods in several earlier modules, so there is nothing new here. Consequently, I won't discuss the interface methods.You can view the methods in Listing 6 near the end of the module.

The one thing that you might want to pay attention to in these methods is the scaling that is applied to the data before it is returned. This is an attempt tocause all of the curves to plot reasonably well within a value range of -180 to +180. This range is dictated by the fact that this is the range of values forthe phase angle data.

Now that you understand the inner workings of the program, let's look at some more examples, this time getting the input data from the file named Dsp034.txt .

More examples

The simplest pulse of all, an impulse

The simplest pulse that you can create is a single non-zero valued sample among a bunch of zero-valued samples. This simple pulse, commonly called animpulse in digital signal processing, is an extremely important type of signal. It is used for a variety of purposes in testing both digital and analogsignal processing systems.

Let's examine the result of performing spectral analysis on an impulse.

The parameters used for this experiment are shown in Figure 4 .

Figure 4. The simplest pulse of all, an impulse.
Parameters read from file Data length: 400Pulse length: 11 Sample for zero time: 0Lower frequency bound: 0.0 Upper frequency bound: 0.5Pulse Values 180.00.0 0.00.0 0.00.0 0.00.0 0.00.0 0.0

Screen output from the getparameters method

The data that you see in Figure 4 is the screen output from the method named getParameters . To orient you with this format, the second item in Figure 4 indicates that the entire length of the data upon which spectral analysis was performed was 400 samples. All 400 samples had a value of zeroexcept for the values of the sample in the pulse that occurred at the beginning. In this program, setting the total data length to 400 causes the spectralanalysis to be performed at 400 individual frequencies.

Questions & Answers

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
analytical skills graphene is prepared to kill any type viruses .
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.
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?