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Truncated sinusoids

Each pulse consists of a cosine wave that has been truncated at a different length. The frequency of the cosine wave is the same for every pulse. As youwill see when we examine the code, the frequency of the cosine wave is 0.0625 times the sampling frequency. If you do the arithmetic, you will conclude thatthis results in 16 samples per cycle of the cosine wave.

In all five cases, the length of the time series upon which spectral analysis will be performed is 400 samples. For those four cases where the length of thepulse is less than 400 samples, the remaining samples in the time series have a value of zero.

Will compute at 400 frequencies

When the spectral analysis is performed later, the number of individual frequencies at which the amplitude of the spectral energy will be computed willbe equal to the total data length. Therefore, the amplitude of the spectral energy will be computed at the same 400 frequencies for each of the five timeseries. That makes it convenient for us to stack the spectral plots up vertically and compare them (as in Figure 2 ) . This makes it easy for us to compare the distribution of energy across the frequency spectrum for pulsesof different lengths.

Graph03 and graph06

The plots in Figure 1 were produced using the program named Graph03 . Other plots in this module will be produced using the program named Graph06 . I explained those programs in earlier modules, and I provided the source code for both programs in the previous module titled Spectrum Analysis using Java, Sampling Frequency, Folding Frequency, and the FFT Algorithm . Therefore, I won't repeat those explanations or provide the source code for those programs in this module.

The program named Dsp031a

A complete listing of the program named Dsp031a is provided in Listing 9 near the end of the module.

This program displays sinusoidal pulses identical to those processed by the program named Dsp031 , which will be discussed later.

Time series containing sinusoidal pulses

The program named Dsp031a creates and displays five separate time series, each 400 samples in length. Each time series contains a pulse andthe pulses are different lengths.

Each pulse consists of a truncated sinusoid. The frequency of the sinusoid for each of the pulses is the same.

Frequency values are specified as type double as a fraction of the sampling frequency. The frequency of each sinusoid is 0.0625 times thesampling frequency.

The pulse lengths

The lengths of the five pulses are:

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

Beginning of the class named Dsp031a

This program is very similar to programs that I explained in previous modules in this series, so my explanation will be very brief. As usual, I will explainthe program in fragments.

The beginning of the class, along with the declaration and initialization of several variables is shown in Listing 1 . The names of the variables along with the embedded comments should make the code self explanatory.

Listing 1. Beginning of the class named Dsp031a.
class Dsp031a implements GraphIntfc01{ final double pi = Math.PI;int len = 400;//data length int numberPulses = 5;//Frequency of the sinusoids double freq = 0.0625;//Amplitude of the sinusoids double amp = 160;//Following arrays will contain sinusoidal data 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];

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
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What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
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Adin Reply
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Damian Reply
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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.
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s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
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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?
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s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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