<< Chapter < Page
  Digital signal processing - dsp     Page 7 / 19
Chapter >> Page >


This program performs spectral analyses on five separate time series, each 400 samples in length.

Each time series contains a pulse and the pulses are different lengths. (The lengths of the individual pulses match that shown in Figure 1 .) Each pulse consists of a truncated sinusoid. The frequency of the sinusoid for each pulseis the same.

All frequency values are specified as type double as a fraction of the sampling frequency. The frequency of all five sinusoids is 0.0625 times thesampling frequency.

The lengths of the pulses are:

  • 25 samples
  • 50 samples
  • 100 samples
  • 200 samples
  • 400 samples

If this sounds familiar, it is because the pulses are identical to those displayed in Figure 1 and discussed under Dsp031a above.

Uses a DFT algorithm

The spectral analysis process uses a DFT algorithm and computes the amplitude of the spectral energy at 400 equally spaced frequencies between zero and thefolding frequency.

(Recall from the module titled Spectrum Analysis using Java, Sampling Frequency, Folding Frequency, and the FFT Algorithm that the folding frequency is one-half the sampling frequency.)

This program computes and displays the amplitude spectrum at frequency intervals that are one-half of the frequency intervals for a typical FFTalgorithm.

Normalize the results

The results of the spectral analysis are multiplied by the reciprocal of the lengths of the individual pulses to normalize all five plots to the same peakvalue. Otherwise, the results for the short pulses would be too small to see on the plots.

Will discuss in fragments

Once again, this program is very similar to programs explained in the previous module titled Spectrum Analysis using Java, Sampling Frequency, Folding Frequency, and the FFT Algorithm . Therefore, this discussion will be very brief.

Beginning of the class named Dsp031

The code in Listing 3 declares and initializes some variables and creates the array objects that will contain the sinusoidal pulses.

In addition, the code in Listing 3 declares reference variables that will be used to refer to array objects containing results of the spectral analysisprocess that are not used in this program.

Finally, Listing 3 declares reference variables that will be used to refer to array objects containing the results plotted in Figure 2 and Figure 3 .

Given the names of the variables, the comments, and what you learned in the earlier modules, the code in Listing 3 should be self explanatory.

Listing 3. Beginning of the class named Dsp031.
class Dsp031 implements GraphIntfc01{ final double pi = Math.PI;int len = 400;//data length //Sample that represents zero time.int zeroTime = 0; //Low and high frequency limits for the// spectral analysis. double lowF = 0.0;double highF = 0.5; int numberSpectra = 5;//Frequency of the sinusoids double freq = 0.0625;//Amplitude of the sinusoids double amp = 160;//Following arrays will contain data that is // input to the spectral analysis process.double[] data1 = new double[len]; double[]data2 = new double[len];double[] data3 = new double[len]; double[]data4 = new double[len];double[] data5 = new double[len];//Following arrays receive information back // from the spectral analysis that is not used// in this program. double[]real; double[]imag; double[]angle;//Following arrays receive the magnitude // spectral information back from the spectral// analysis process. double[]mag1; double[]mag2; double[]mag3; double[]mag4; double[]mag5;

Questions & Answers

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.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
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
Berger describes sociologists as concerned with
Mueller Reply
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?